DAGCombiner.cpp revision ca2424423416032dc95dae4c106a5cf99795e589
1//===-- DAGCombiner.cpp - Implement a DAG node combiner -------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by Nate Begeman and is distributed under the 6// University of Illinois Open Source License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This pass combines dag nodes to form fewer, simpler DAG nodes. It can be run 11// both before and after the DAG is legalized. 12// 13// FIXME: Missing folds 14// sdiv, udiv, srem, urem (X, const) where X is an integer can be expanded into 15// a sequence of multiplies, shifts, and adds. This should be controlled by 16// some kind of hint from the target that int div is expensive. 17// various folds of mulh[s,u] by constants such as -1, powers of 2, etc. 18// 19// FIXME: select C, pow2, pow2 -> something smart 20// FIXME: trunc(select X, Y, Z) -> select X, trunc(Y), trunc(Z) 21// FIXME: Dead stores -> nuke 22// FIXME: shr X, (and Y,31) -> shr X, Y (TRICKY!) 23// FIXME: mul (x, const) -> shifts + adds 24// FIXME: undef values 25// FIXME: make truncate see through SIGN_EXTEND and AND 26// FIXME: divide by zero is currently left unfolded. do we want to turn this 27// into an undef? 28// FIXME: select ne (select cc, 1, 0), 0, true, false -> select cc, true, false 29// 30//===----------------------------------------------------------------------===// 31 32#define DEBUG_TYPE "dagcombine" 33#include "llvm/ADT/Statistic.h" 34#include "llvm/CodeGen/SelectionDAG.h" 35#include "llvm/Support/Debug.h" 36#include "llvm/Support/MathExtras.h" 37#include "llvm/Target/TargetLowering.h" 38#include <algorithm> 39#include <cmath> 40#include <iostream> 41using namespace llvm; 42 43namespace { 44 Statistic<> NodesCombined ("dagcombiner", "Number of dag nodes combined"); 45 46 class DAGCombiner { 47 SelectionDAG &DAG; 48 TargetLowering &TLI; 49 bool AfterLegalize; 50 51 // Worklist of all of the nodes that need to be simplified. 52 std::vector<SDNode*> WorkList; 53 54 /// AddUsersToWorkList - When an instruction is simplified, add all users of 55 /// the instruction to the work lists because they might get more simplified 56 /// now. 57 /// 58 void AddUsersToWorkList(SDNode *N) { 59 for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end(); 60 UI != UE; ++UI) 61 WorkList.push_back(*UI); 62 } 63 64 /// removeFromWorkList - remove all instances of N from the worklist. 65 /// 66 void removeFromWorkList(SDNode *N) { 67 WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), N), 68 WorkList.end()); 69 } 70 71 public: 72 void AddToWorkList(SDNode *N) { 73 WorkList.push_back(N); 74 } 75 76 SDOperand CombineTo(SDNode *N, const std::vector<SDOperand> &To) { 77 ++NodesCombined; 78 DEBUG(std::cerr << "\nReplacing "; N->dump(); 79 std::cerr << "\nWith: "; To[0].Val->dump(); 80 std::cerr << " and " << To.size()-1 << " other values\n"); 81 std::vector<SDNode*> NowDead; 82 DAG.ReplaceAllUsesWith(N, To, &NowDead); 83 84 // Push the new nodes and any users onto the worklist 85 for (unsigned i = 0, e = To.size(); i != e; ++i) { 86 WorkList.push_back(To[i].Val); 87 AddUsersToWorkList(To[i].Val); 88 } 89 90 // Nodes can end up on the worklist more than once. Make sure we do 91 // not process a node that has been replaced. 92 removeFromWorkList(N); 93 for (unsigned i = 0, e = NowDead.size(); i != e; ++i) 94 removeFromWorkList(NowDead[i]); 95 96 // Finally, since the node is now dead, remove it from the graph. 97 DAG.DeleteNode(N); 98 return SDOperand(N, 0); 99 } 100 101 SDOperand CombineTo(SDNode *N, SDOperand Res) { 102 std::vector<SDOperand> To; 103 To.push_back(Res); 104 return CombineTo(N, To); 105 } 106 107 SDOperand CombineTo(SDNode *N, SDOperand Res0, SDOperand Res1) { 108 std::vector<SDOperand> To; 109 To.push_back(Res0); 110 To.push_back(Res1); 111 return CombineTo(N, To); 112 } 113 private: 114 115 /// SimplifyDemandedBits - Check the specified integer node value to see if 116 /// it can be simplified or if things it uses can be simplified by bit 117 /// propagation. If so, return true. 118 bool SimplifyDemandedBits(SDOperand Op) { 119 TargetLowering::TargetLoweringOpt TLO(DAG); 120 uint64_t KnownZero, KnownOne; 121 uint64_t Demanded = MVT::getIntVTBitMask(Op.getValueType()); 122 if (!TLI.SimplifyDemandedBits(Op, Demanded, KnownZero, KnownOne, TLO)) 123 return false; 124 125 // Revisit the node. 126 WorkList.push_back(Op.Val); 127 128 // Replace the old value with the new one. 129 ++NodesCombined; 130 DEBUG(std::cerr << "\nReplacing "; TLO.Old.Val->dump(); 131 std::cerr << "\nWith: "; TLO.New.Val->dump()); 132 133 std::vector<SDNode*> NowDead; 134 DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New, NowDead); 135 136 // Push the new node and any (possibly new) users onto the worklist. 137 WorkList.push_back(TLO.New.Val); 138 AddUsersToWorkList(TLO.New.Val); 139 140 // Nodes can end up on the worklist more than once. Make sure we do 141 // not process a node that has been replaced. 142 for (unsigned i = 0, e = NowDead.size(); i != e; ++i) 143 removeFromWorkList(NowDead[i]); 144 145 // Finally, if the node is now dead, remove it from the graph. The node 146 // may not be dead if the replacement process recursively simplified to 147 // something else needing this node. 148 if (TLO.Old.Val->use_empty()) { 149 removeFromWorkList(TLO.Old.Val); 150 DAG.DeleteNode(TLO.Old.Val); 151 } 152 return true; 153 } 154 155 /// visit - call the node-specific routine that knows how to fold each 156 /// particular type of node. 157 SDOperand visit(SDNode *N); 158 159 // Visitation implementation - Implement dag node combining for different 160 // node types. The semantics are as follows: 161 // Return Value: 162 // SDOperand.Val == 0 - No change was made 163 // SDOperand.Val == N - N was replaced, is dead, and is already handled. 164 // otherwise - N should be replaced by the returned Operand. 165 // 166 SDOperand visitTokenFactor(SDNode *N); 167 SDOperand visitADD(SDNode *N); 168 SDOperand visitSUB(SDNode *N); 169 SDOperand visitMUL(SDNode *N); 170 SDOperand visitSDIV(SDNode *N); 171 SDOperand visitUDIV(SDNode *N); 172 SDOperand visitSREM(SDNode *N); 173 SDOperand visitUREM(SDNode *N); 174 SDOperand visitMULHU(SDNode *N); 175 SDOperand visitMULHS(SDNode *N); 176 SDOperand visitAND(SDNode *N); 177 SDOperand visitOR(SDNode *N); 178 SDOperand visitXOR(SDNode *N); 179 SDOperand visitSHL(SDNode *N); 180 SDOperand visitSRA(SDNode *N); 181 SDOperand visitSRL(SDNode *N); 182 SDOperand visitCTLZ(SDNode *N); 183 SDOperand visitCTTZ(SDNode *N); 184 SDOperand visitCTPOP(SDNode *N); 185 SDOperand visitSELECT(SDNode *N); 186 SDOperand visitSELECT_CC(SDNode *N); 187 SDOperand visitSETCC(SDNode *N); 188 SDOperand visitSIGN_EXTEND(SDNode *N); 189 SDOperand visitZERO_EXTEND(SDNode *N); 190 SDOperand visitSIGN_EXTEND_INREG(SDNode *N); 191 SDOperand visitTRUNCATE(SDNode *N); 192 SDOperand visitBIT_CONVERT(SDNode *N); 193 SDOperand visitFADD(SDNode *N); 194 SDOperand visitFSUB(SDNode *N); 195 SDOperand visitFMUL(SDNode *N); 196 SDOperand visitFDIV(SDNode *N); 197 SDOperand visitFREM(SDNode *N); 198 SDOperand visitFCOPYSIGN(SDNode *N); 199 SDOperand visitSINT_TO_FP(SDNode *N); 200 SDOperand visitUINT_TO_FP(SDNode *N); 201 SDOperand visitFP_TO_SINT(SDNode *N); 202 SDOperand visitFP_TO_UINT(SDNode *N); 203 SDOperand visitFP_ROUND(SDNode *N); 204 SDOperand visitFP_ROUND_INREG(SDNode *N); 205 SDOperand visitFP_EXTEND(SDNode *N); 206 SDOperand visitFNEG(SDNode *N); 207 SDOperand visitFABS(SDNode *N); 208 SDOperand visitBRCOND(SDNode *N); 209 SDOperand visitBR_CC(SDNode *N); 210 SDOperand visitLOAD(SDNode *N); 211 SDOperand visitSTORE(SDNode *N); 212 SDOperand visitINSERT_VECTOR_ELT(SDNode *N); 213 SDOperand visitVINSERT_VECTOR_ELT(SDNode *N); 214 215 SDOperand ReassociateOps(unsigned Opc, SDOperand LHS, SDOperand RHS); 216 217 bool SimplifySelectOps(SDNode *SELECT, SDOperand LHS, SDOperand RHS); 218 SDOperand SimplifySelect(SDOperand N0, SDOperand N1, SDOperand N2); 219 SDOperand SimplifySelectCC(SDOperand N0, SDOperand N1, SDOperand N2, 220 SDOperand N3, ISD::CondCode CC); 221 SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand N1, 222 ISD::CondCode Cond, bool foldBooleans = true); 223 224 SDOperand BuildSDIV(SDNode *N); 225 SDOperand BuildUDIV(SDNode *N); 226public: 227 DAGCombiner(SelectionDAG &D) 228 : DAG(D), TLI(D.getTargetLoweringInfo()), AfterLegalize(false) {} 229 230 /// Run - runs the dag combiner on all nodes in the work list 231 void Run(bool RunningAfterLegalize); 232 }; 233} 234 235//===----------------------------------------------------------------------===// 236// TargetLowering::DAGCombinerInfo implementation 237//===----------------------------------------------------------------------===// 238 239void TargetLowering::DAGCombinerInfo::AddToWorklist(SDNode *N) { 240 ((DAGCombiner*)DC)->AddToWorkList(N); 241} 242 243SDOperand TargetLowering::DAGCombinerInfo:: 244CombineTo(SDNode *N, const std::vector<SDOperand> &To) { 245 return ((DAGCombiner*)DC)->CombineTo(N, To); 246} 247 248SDOperand TargetLowering::DAGCombinerInfo:: 249CombineTo(SDNode *N, SDOperand Res) { 250 return ((DAGCombiner*)DC)->CombineTo(N, Res); 251} 252 253 254SDOperand TargetLowering::DAGCombinerInfo:: 255CombineTo(SDNode *N, SDOperand Res0, SDOperand Res1) { 256 return ((DAGCombiner*)DC)->CombineTo(N, Res0, Res1); 257} 258 259 260 261 262//===----------------------------------------------------------------------===// 263 264 265struct ms { 266 int64_t m; // magic number 267 int64_t s; // shift amount 268}; 269 270struct mu { 271 uint64_t m; // magic number 272 int64_t a; // add indicator 273 int64_t s; // shift amount 274}; 275 276/// magic - calculate the magic numbers required to codegen an integer sdiv as 277/// a sequence of multiply and shifts. Requires that the divisor not be 0, 1, 278/// or -1. 279static ms magic32(int32_t d) { 280 int32_t p; 281 uint32_t ad, anc, delta, q1, r1, q2, r2, t; 282 const uint32_t two31 = 0x80000000U; 283 struct ms mag; 284 285 ad = abs(d); 286 t = two31 + ((uint32_t)d >> 31); 287 anc = t - 1 - t%ad; // absolute value of nc 288 p = 31; // initialize p 289 q1 = two31/anc; // initialize q1 = 2p/abs(nc) 290 r1 = two31 - q1*anc; // initialize r1 = rem(2p,abs(nc)) 291 q2 = two31/ad; // initialize q2 = 2p/abs(d) 292 r2 = two31 - q2*ad; // initialize r2 = rem(2p,abs(d)) 293 do { 294 p = p + 1; 295 q1 = 2*q1; // update q1 = 2p/abs(nc) 296 r1 = 2*r1; // update r1 = rem(2p/abs(nc)) 297 if (r1 >= anc) { // must be unsigned comparison 298 q1 = q1 + 1; 299 r1 = r1 - anc; 300 } 301 q2 = 2*q2; // update q2 = 2p/abs(d) 302 r2 = 2*r2; // update r2 = rem(2p/abs(d)) 303 if (r2 >= ad) { // must be unsigned comparison 304 q2 = q2 + 1; 305 r2 = r2 - ad; 306 } 307 delta = ad - r2; 308 } while (q1 < delta || (q1 == delta && r1 == 0)); 309 310 mag.m = (int32_t)(q2 + 1); // make sure to sign extend 311 if (d < 0) mag.m = -mag.m; // resulting magic number 312 mag.s = p - 32; // resulting shift 313 return mag; 314} 315 316/// magicu - calculate the magic numbers required to codegen an integer udiv as 317/// a sequence of multiply, add and shifts. Requires that the divisor not be 0. 318static mu magicu32(uint32_t d) { 319 int32_t p; 320 uint32_t nc, delta, q1, r1, q2, r2; 321 struct mu magu; 322 magu.a = 0; // initialize "add" indicator 323 nc = - 1 - (-d)%d; 324 p = 31; // initialize p 325 q1 = 0x80000000/nc; // initialize q1 = 2p/nc 326 r1 = 0x80000000 - q1*nc; // initialize r1 = rem(2p,nc) 327 q2 = 0x7FFFFFFF/d; // initialize q2 = (2p-1)/d 328 r2 = 0x7FFFFFFF - q2*d; // initialize r2 = rem((2p-1),d) 329 do { 330 p = p + 1; 331 if (r1 >= nc - r1 ) { 332 q1 = 2*q1 + 1; // update q1 333 r1 = 2*r1 - nc; // update r1 334 } 335 else { 336 q1 = 2*q1; // update q1 337 r1 = 2*r1; // update r1 338 } 339 if (r2 + 1 >= d - r2) { 340 if (q2 >= 0x7FFFFFFF) magu.a = 1; 341 q2 = 2*q2 + 1; // update q2 342 r2 = 2*r2 + 1 - d; // update r2 343 } 344 else { 345 if (q2 >= 0x80000000) magu.a = 1; 346 q2 = 2*q2; // update q2 347 r2 = 2*r2 + 1; // update r2 348 } 349 delta = d - 1 - r2; 350 } while (p < 64 && (q1 < delta || (q1 == delta && r1 == 0))); 351 magu.m = q2 + 1; // resulting magic number 352 magu.s = p - 32; // resulting shift 353 return magu; 354} 355 356/// magic - calculate the magic numbers required to codegen an integer sdiv as 357/// a sequence of multiply and shifts. Requires that the divisor not be 0, 1, 358/// or -1. 359static ms magic64(int64_t d) { 360 int64_t p; 361 uint64_t ad, anc, delta, q1, r1, q2, r2, t; 362 const uint64_t two63 = 9223372036854775808ULL; // 2^63 363 struct ms mag; 364 365 ad = d >= 0 ? d : -d; 366 t = two63 + ((uint64_t)d >> 63); 367 anc = t - 1 - t%ad; // absolute value of nc 368 p = 63; // initialize p 369 q1 = two63/anc; // initialize q1 = 2p/abs(nc) 370 r1 = two63 - q1*anc; // initialize r1 = rem(2p,abs(nc)) 371 q2 = two63/ad; // initialize q2 = 2p/abs(d) 372 r2 = two63 - q2*ad; // initialize r2 = rem(2p,abs(d)) 373 do { 374 p = p + 1; 375 q1 = 2*q1; // update q1 = 2p/abs(nc) 376 r1 = 2*r1; // update r1 = rem(2p/abs(nc)) 377 if (r1 >= anc) { // must be unsigned comparison 378 q1 = q1 + 1; 379 r1 = r1 - anc; 380 } 381 q2 = 2*q2; // update q2 = 2p/abs(d) 382 r2 = 2*r2; // update r2 = rem(2p/abs(d)) 383 if (r2 >= ad) { // must be unsigned comparison 384 q2 = q2 + 1; 385 r2 = r2 - ad; 386 } 387 delta = ad - r2; 388 } while (q1 < delta || (q1 == delta && r1 == 0)); 389 390 mag.m = q2 + 1; 391 if (d < 0) mag.m = -mag.m; // resulting magic number 392 mag.s = p - 64; // resulting shift 393 return mag; 394} 395 396/// magicu - calculate the magic numbers required to codegen an integer udiv as 397/// a sequence of multiply, add and shifts. Requires that the divisor not be 0. 398static mu magicu64(uint64_t d) 399{ 400 int64_t p; 401 uint64_t nc, delta, q1, r1, q2, r2; 402 struct mu magu; 403 magu.a = 0; // initialize "add" indicator 404 nc = - 1 - (-d)%d; 405 p = 63; // initialize p 406 q1 = 0x8000000000000000ull/nc; // initialize q1 = 2p/nc 407 r1 = 0x8000000000000000ull - q1*nc; // initialize r1 = rem(2p,nc) 408 q2 = 0x7FFFFFFFFFFFFFFFull/d; // initialize q2 = (2p-1)/d 409 r2 = 0x7FFFFFFFFFFFFFFFull - q2*d; // initialize r2 = rem((2p-1),d) 410 do { 411 p = p + 1; 412 if (r1 >= nc - r1 ) { 413 q1 = 2*q1 + 1; // update q1 414 r1 = 2*r1 - nc; // update r1 415 } 416 else { 417 q1 = 2*q1; // update q1 418 r1 = 2*r1; // update r1 419 } 420 if (r2 + 1 >= d - r2) { 421 if (q2 >= 0x7FFFFFFFFFFFFFFFull) magu.a = 1; 422 q2 = 2*q2 + 1; // update q2 423 r2 = 2*r2 + 1 - d; // update r2 424 } 425 else { 426 if (q2 >= 0x8000000000000000ull) magu.a = 1; 427 q2 = 2*q2; // update q2 428 r2 = 2*r2 + 1; // update r2 429 } 430 delta = d - 1 - r2; 431 } while (p < 64 && (q1 < delta || (q1 == delta && r1 == 0))); 432 magu.m = q2 + 1; // resulting magic number 433 magu.s = p - 64; // resulting shift 434 return magu; 435} 436 437// isSetCCEquivalent - Return true if this node is a setcc, or is a select_cc 438// that selects between the values 1 and 0, making it equivalent to a setcc. 439// Also, set the incoming LHS, RHS, and CC references to the appropriate 440// nodes based on the type of node we are checking. This simplifies life a 441// bit for the callers. 442static bool isSetCCEquivalent(SDOperand N, SDOperand &LHS, SDOperand &RHS, 443 SDOperand &CC) { 444 if (N.getOpcode() == ISD::SETCC) { 445 LHS = N.getOperand(0); 446 RHS = N.getOperand(1); 447 CC = N.getOperand(2); 448 return true; 449 } 450 if (N.getOpcode() == ISD::SELECT_CC && 451 N.getOperand(2).getOpcode() == ISD::Constant && 452 N.getOperand(3).getOpcode() == ISD::Constant && 453 cast<ConstantSDNode>(N.getOperand(2))->getValue() == 1 && 454 cast<ConstantSDNode>(N.getOperand(3))->isNullValue()) { 455 LHS = N.getOperand(0); 456 RHS = N.getOperand(1); 457 CC = N.getOperand(4); 458 return true; 459 } 460 return false; 461} 462 463// isOneUseSetCC - Return true if this is a SetCC-equivalent operation with only 464// one use. If this is true, it allows the users to invert the operation for 465// free when it is profitable to do so. 466static bool isOneUseSetCC(SDOperand N) { 467 SDOperand N0, N1, N2; 468 if (isSetCCEquivalent(N, N0, N1, N2) && N.Val->hasOneUse()) 469 return true; 470 return false; 471} 472 473// FIXME: This should probably go in the ISD class rather than being duplicated 474// in several files. 475static bool isCommutativeBinOp(unsigned Opcode) { 476 switch (Opcode) { 477 case ISD::ADD: 478 case ISD::MUL: 479 case ISD::AND: 480 case ISD::OR: 481 case ISD::XOR: return true; 482 default: return false; // FIXME: Need commutative info for user ops! 483 } 484} 485 486SDOperand DAGCombiner::ReassociateOps(unsigned Opc, SDOperand N0, SDOperand N1){ 487 MVT::ValueType VT = N0.getValueType(); 488 // reassoc. (op (op x, c1), y) -> (op (op x, y), c1) iff x+c1 has one use 489 // reassoc. (op (op x, c1), c2) -> (op x, (op c1, c2)) 490 if (N0.getOpcode() == Opc && isa<ConstantSDNode>(N0.getOperand(1))) { 491 if (isa<ConstantSDNode>(N1)) { 492 SDOperand OpNode = DAG.getNode(Opc, VT, N0.getOperand(1), N1); 493 AddToWorkList(OpNode.Val); 494 return DAG.getNode(Opc, VT, OpNode, N0.getOperand(0)); 495 } else if (N0.hasOneUse()) { 496 SDOperand OpNode = DAG.getNode(Opc, VT, N0.getOperand(0), N1); 497 AddToWorkList(OpNode.Val); 498 return DAG.getNode(Opc, VT, OpNode, N0.getOperand(1)); 499 } 500 } 501 // reassoc. (op y, (op x, c1)) -> (op (op x, y), c1) iff x+c1 has one use 502 // reassoc. (op c2, (op x, c1)) -> (op x, (op c1, c2)) 503 if (N1.getOpcode() == Opc && isa<ConstantSDNode>(N1.getOperand(1))) { 504 if (isa<ConstantSDNode>(N0)) { 505 SDOperand OpNode = DAG.getNode(Opc, VT, N1.getOperand(1), N0); 506 AddToWorkList(OpNode.Val); 507 return DAG.getNode(Opc, VT, OpNode, N1.getOperand(0)); 508 } else if (N1.hasOneUse()) { 509 SDOperand OpNode = DAG.getNode(Opc, VT, N1.getOperand(0), N0); 510 AddToWorkList(OpNode.Val); 511 return DAG.getNode(Opc, VT, OpNode, N1.getOperand(1)); 512 } 513 } 514 return SDOperand(); 515} 516 517void DAGCombiner::Run(bool RunningAfterLegalize) { 518 // set the instance variable, so that the various visit routines may use it. 519 AfterLegalize = RunningAfterLegalize; 520 521 // Add all the dag nodes to the worklist. 522 for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(), 523 E = DAG.allnodes_end(); I != E; ++I) 524 WorkList.push_back(I); 525 526 // Create a dummy node (which is not added to allnodes), that adds a reference 527 // to the root node, preventing it from being deleted, and tracking any 528 // changes of the root. 529 HandleSDNode Dummy(DAG.getRoot()); 530 531 532 /// DagCombineInfo - Expose the DAG combiner to the target combiner impls. 533 TargetLowering::DAGCombinerInfo 534 DagCombineInfo(DAG, !RunningAfterLegalize, this); 535 536 // while the worklist isn't empty, inspect the node on the end of it and 537 // try and combine it. 538 while (!WorkList.empty()) { 539 SDNode *N = WorkList.back(); 540 WorkList.pop_back(); 541 542 // If N has no uses, it is dead. Make sure to revisit all N's operands once 543 // N is deleted from the DAG, since they too may now be dead or may have a 544 // reduced number of uses, allowing other xforms. 545 if (N->use_empty() && N != &Dummy) { 546 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) 547 WorkList.push_back(N->getOperand(i).Val); 548 549 removeFromWorkList(N); 550 DAG.DeleteNode(N); 551 continue; 552 } 553 554 SDOperand RV = visit(N); 555 556 // If nothing happened, try a target-specific DAG combine. 557 if (RV.Val == 0) { 558 if (N->getOpcode() >= ISD::BUILTIN_OP_END || 559 TLI.hasTargetDAGCombine((ISD::NodeType)N->getOpcode())) 560 RV = TLI.PerformDAGCombine(N, DagCombineInfo); 561 } 562 563 if (RV.Val) { 564 ++NodesCombined; 565 // If we get back the same node we passed in, rather than a new node or 566 // zero, we know that the node must have defined multiple values and 567 // CombineTo was used. Since CombineTo takes care of the worklist 568 // mechanics for us, we have no work to do in this case. 569 if (RV.Val != N) { 570 DEBUG(std::cerr << "\nReplacing "; N->dump(); 571 std::cerr << "\nWith: "; RV.Val->dump(); 572 std::cerr << '\n'); 573 std::vector<SDNode*> NowDead; 574 DAG.ReplaceAllUsesWith(N, std::vector<SDOperand>(1, RV), &NowDead); 575 576 // Push the new node and any users onto the worklist 577 WorkList.push_back(RV.Val); 578 AddUsersToWorkList(RV.Val); 579 580 // Nodes can end up on the worklist more than once. Make sure we do 581 // not process a node that has been replaced. 582 removeFromWorkList(N); 583 for (unsigned i = 0, e = NowDead.size(); i != e; ++i) 584 removeFromWorkList(NowDead[i]); 585 586 // Finally, since the node is now dead, remove it from the graph. 587 DAG.DeleteNode(N); 588 } 589 } 590 } 591 592 // If the root changed (e.g. it was a dead load, update the root). 593 DAG.setRoot(Dummy.getValue()); 594} 595 596SDOperand DAGCombiner::visit(SDNode *N) { 597 switch(N->getOpcode()) { 598 default: break; 599 case ISD::TokenFactor: return visitTokenFactor(N); 600 case ISD::ADD: return visitADD(N); 601 case ISD::SUB: return visitSUB(N); 602 case ISD::MUL: return visitMUL(N); 603 case ISD::SDIV: return visitSDIV(N); 604 case ISD::UDIV: return visitUDIV(N); 605 case ISD::SREM: return visitSREM(N); 606 case ISD::UREM: return visitUREM(N); 607 case ISD::MULHU: return visitMULHU(N); 608 case ISD::MULHS: return visitMULHS(N); 609 case ISD::AND: return visitAND(N); 610 case ISD::OR: return visitOR(N); 611 case ISD::XOR: return visitXOR(N); 612 case ISD::SHL: return visitSHL(N); 613 case ISD::SRA: return visitSRA(N); 614 case ISD::SRL: return visitSRL(N); 615 case ISD::CTLZ: return visitCTLZ(N); 616 case ISD::CTTZ: return visitCTTZ(N); 617 case ISD::CTPOP: return visitCTPOP(N); 618 case ISD::SELECT: return visitSELECT(N); 619 case ISD::SELECT_CC: return visitSELECT_CC(N); 620 case ISD::SETCC: return visitSETCC(N); 621 case ISD::SIGN_EXTEND: return visitSIGN_EXTEND(N); 622 case ISD::ZERO_EXTEND: return visitZERO_EXTEND(N); 623 case ISD::SIGN_EXTEND_INREG: return visitSIGN_EXTEND_INREG(N); 624 case ISD::TRUNCATE: return visitTRUNCATE(N); 625 case ISD::BIT_CONVERT: return visitBIT_CONVERT(N); 626 case ISD::FADD: return visitFADD(N); 627 case ISD::FSUB: return visitFSUB(N); 628 case ISD::FMUL: return visitFMUL(N); 629 case ISD::FDIV: return visitFDIV(N); 630 case ISD::FREM: return visitFREM(N); 631 case ISD::FCOPYSIGN: return visitFCOPYSIGN(N); 632 case ISD::SINT_TO_FP: return visitSINT_TO_FP(N); 633 case ISD::UINT_TO_FP: return visitUINT_TO_FP(N); 634 case ISD::FP_TO_SINT: return visitFP_TO_SINT(N); 635 case ISD::FP_TO_UINT: return visitFP_TO_UINT(N); 636 case ISD::FP_ROUND: return visitFP_ROUND(N); 637 case ISD::FP_ROUND_INREG: return visitFP_ROUND_INREG(N); 638 case ISD::FP_EXTEND: return visitFP_EXTEND(N); 639 case ISD::FNEG: return visitFNEG(N); 640 case ISD::FABS: return visitFABS(N); 641 case ISD::BRCOND: return visitBRCOND(N); 642 case ISD::BR_CC: return visitBR_CC(N); 643 case ISD::LOAD: return visitLOAD(N); 644 case ISD::STORE: return visitSTORE(N); 645 case ISD::INSERT_VECTOR_ELT: return visitINSERT_VECTOR_ELT(N); 646 case ISD::VINSERT_VECTOR_ELT: return visitVINSERT_VECTOR_ELT(N); 647 } 648 return SDOperand(); 649} 650 651SDOperand DAGCombiner::visitTokenFactor(SDNode *N) { 652 std::vector<SDOperand> Ops; 653 bool Changed = false; 654 655 // If the token factor has two operands and one is the entry token, replace 656 // the token factor with the other operand. 657 if (N->getNumOperands() == 2) { 658 if (N->getOperand(0).getOpcode() == ISD::EntryToken) 659 return N->getOperand(1); 660 if (N->getOperand(1).getOpcode() == ISD::EntryToken) 661 return N->getOperand(0); 662 } 663 664 // fold (tokenfactor (tokenfactor)) -> tokenfactor 665 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) { 666 SDOperand Op = N->getOperand(i); 667 if (Op.getOpcode() == ISD::TokenFactor && Op.hasOneUse()) { 668 AddToWorkList(Op.Val); // Remove dead node. 669 Changed = true; 670 for (unsigned j = 0, e = Op.getNumOperands(); j != e; ++j) 671 Ops.push_back(Op.getOperand(j)); 672 } else { 673 Ops.push_back(Op); 674 } 675 } 676 if (Changed) 677 return DAG.getNode(ISD::TokenFactor, MVT::Other, Ops); 678 return SDOperand(); 679} 680 681SDOperand DAGCombiner::visitADD(SDNode *N) { 682 SDOperand N0 = N->getOperand(0); 683 SDOperand N1 = N->getOperand(1); 684 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 685 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 686 MVT::ValueType VT = N0.getValueType(); 687 688 // fold (add c1, c2) -> c1+c2 689 if (N0C && N1C) 690 return DAG.getNode(ISD::ADD, VT, N0, N1); 691 // canonicalize constant to RHS 692 if (N0C && !N1C) 693 return DAG.getNode(ISD::ADD, VT, N1, N0); 694 // fold (add x, 0) -> x 695 if (N1C && N1C->isNullValue()) 696 return N0; 697 // fold ((c1-A)+c2) -> (c1+c2)-A 698 if (N1C && N0.getOpcode() == ISD::SUB) 699 if (ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.getOperand(0))) 700 return DAG.getNode(ISD::SUB, VT, 701 DAG.getConstant(N1C->getValue()+N0C->getValue(), VT), 702 N0.getOperand(1)); 703 // reassociate add 704 SDOperand RADD = ReassociateOps(ISD::ADD, N0, N1); 705 if (RADD.Val != 0) 706 return RADD; 707 // fold ((0-A) + B) -> B-A 708 if (N0.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N0.getOperand(0)) && 709 cast<ConstantSDNode>(N0.getOperand(0))->isNullValue()) 710 return DAG.getNode(ISD::SUB, VT, N1, N0.getOperand(1)); 711 // fold (A + (0-B)) -> A-B 712 if (N1.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N1.getOperand(0)) && 713 cast<ConstantSDNode>(N1.getOperand(0))->isNullValue()) 714 return DAG.getNode(ISD::SUB, VT, N0, N1.getOperand(1)); 715 // fold (A+(B-A)) -> B 716 if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(1)) 717 return N1.getOperand(0); 718 719 if (!MVT::isVector(VT) && SimplifyDemandedBits(SDOperand(N, 0))) 720 return SDOperand(); 721 722 // fold (a+b) -> (a|b) iff a and b share no bits. 723 if (MVT::isInteger(VT) && !MVT::isVector(VT)) { 724 uint64_t LHSZero, LHSOne; 725 uint64_t RHSZero, RHSOne; 726 uint64_t Mask = MVT::getIntVTBitMask(VT); 727 TLI.ComputeMaskedBits(N0, Mask, LHSZero, LHSOne); 728 if (LHSZero) { 729 TLI.ComputeMaskedBits(N1, Mask, RHSZero, RHSOne); 730 731 // If all possibly-set bits on the LHS are clear on the RHS, return an OR. 732 // If all possibly-set bits on the RHS are clear on the LHS, return an OR. 733 if ((RHSZero & (~LHSZero & Mask)) == (~LHSZero & Mask) || 734 (LHSZero & (~RHSZero & Mask)) == (~RHSZero & Mask)) 735 return DAG.getNode(ISD::OR, VT, N0, N1); 736 } 737 } 738 739 return SDOperand(); 740} 741 742SDOperand DAGCombiner::visitSUB(SDNode *N) { 743 SDOperand N0 = N->getOperand(0); 744 SDOperand N1 = N->getOperand(1); 745 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val); 746 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val); 747 MVT::ValueType VT = N0.getValueType(); 748 749 // fold (sub x, x) -> 0 750 if (N0 == N1) 751 return DAG.getConstant(0, N->getValueType(0)); 752 // fold (sub c1, c2) -> c1-c2 753 if (N0C && N1C) 754 return DAG.getNode(ISD::SUB, VT, N0, N1); 755 // fold (sub x, c) -> (add x, -c) 756 if (N1C) 757 return DAG.getNode(ISD::ADD, VT, N0, DAG.getConstant(-N1C->getValue(), VT)); 758 // fold (A+B)-A -> B 759 if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1) 760 return N0.getOperand(1); 761 // fold (A+B)-B -> A 762 if (N0.getOpcode() == ISD::ADD && N0.getOperand(1) == N1) 763 return N0.getOperand(0); 764 return SDOperand(); 765} 766 767SDOperand DAGCombiner::visitMUL(SDNode *N) { 768 SDOperand N0 = N->getOperand(0); 769 SDOperand N1 = N->getOperand(1); 770 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 771 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 772 MVT::ValueType VT = N0.getValueType(); 773 774 // fold (mul c1, c2) -> c1*c2 775 if (N0C && N1C) 776 return DAG.getNode(ISD::MUL, VT, N0, N1); 777 // canonicalize constant to RHS 778 if (N0C && !N1C) 779 return DAG.getNode(ISD::MUL, VT, N1, N0); 780 // fold (mul x, 0) -> 0 781 if (N1C && N1C->isNullValue()) 782 return N1; 783 // fold (mul x, -1) -> 0-x 784 if (N1C && N1C->isAllOnesValue()) 785 return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT), N0); 786 // fold (mul x, (1 << c)) -> x << c 787 if (N1C && isPowerOf2_64(N1C->getValue())) 788 return DAG.getNode(ISD::SHL, VT, N0, 789 DAG.getConstant(Log2_64(N1C->getValue()), 790 TLI.getShiftAmountTy())); 791 // fold (mul x, -(1 << c)) -> -(x << c) or (-x) << c 792 if (N1C && isPowerOf2_64(-N1C->getSignExtended())) { 793 // FIXME: If the input is something that is easily negated (e.g. a 794 // single-use add), we should put the negate there. 795 return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT), 796 DAG.getNode(ISD::SHL, VT, N0, 797 DAG.getConstant(Log2_64(-N1C->getSignExtended()), 798 TLI.getShiftAmountTy()))); 799 } 800 801 // (mul (shl X, c1), c2) -> (mul X, c2 << c1) 802 if (N1C && N0.getOpcode() == ISD::SHL && 803 isa<ConstantSDNode>(N0.getOperand(1))) { 804 SDOperand C3 = DAG.getNode(ISD::SHL, VT, N1, N0.getOperand(1)); 805 AddToWorkList(C3.Val); 806 return DAG.getNode(ISD::MUL, VT, N0.getOperand(0), C3); 807 } 808 809 // Change (mul (shl X, C), Y) -> (shl (mul X, Y), C) when the shift has one 810 // use. 811 { 812 SDOperand Sh(0,0), Y(0,0); 813 // Check for both (mul (shl X, C), Y) and (mul Y, (shl X, C)). 814 if (N0.getOpcode() == ISD::SHL && isa<ConstantSDNode>(N0.getOperand(1)) && 815 N0.Val->hasOneUse()) { 816 Sh = N0; Y = N1; 817 } else if (N1.getOpcode() == ISD::SHL && 818 isa<ConstantSDNode>(N1.getOperand(1)) && N1.Val->hasOneUse()) { 819 Sh = N1; Y = N0; 820 } 821 if (Sh.Val) { 822 SDOperand Mul = DAG.getNode(ISD::MUL, VT, Sh.getOperand(0), Y); 823 return DAG.getNode(ISD::SHL, VT, Mul, Sh.getOperand(1)); 824 } 825 } 826 // fold (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2) 827 if (N1C && N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse() && 828 isa<ConstantSDNode>(N0.getOperand(1))) { 829 return DAG.getNode(ISD::ADD, VT, 830 DAG.getNode(ISD::MUL, VT, N0.getOperand(0), N1), 831 DAG.getNode(ISD::MUL, VT, N0.getOperand(1), N1)); 832 } 833 834 // reassociate mul 835 SDOperand RMUL = ReassociateOps(ISD::MUL, N0, N1); 836 if (RMUL.Val != 0) 837 return RMUL; 838 return SDOperand(); 839} 840 841SDOperand DAGCombiner::visitSDIV(SDNode *N) { 842 SDOperand N0 = N->getOperand(0); 843 SDOperand N1 = N->getOperand(1); 844 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val); 845 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val); 846 MVT::ValueType VT = N->getValueType(0); 847 848 // fold (sdiv c1, c2) -> c1/c2 849 if (N0C && N1C && !N1C->isNullValue()) 850 return DAG.getNode(ISD::SDIV, VT, N0, N1); 851 // fold (sdiv X, 1) -> X 852 if (N1C && N1C->getSignExtended() == 1LL) 853 return N0; 854 // fold (sdiv X, -1) -> 0-X 855 if (N1C && N1C->isAllOnesValue()) 856 return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT), N0); 857 // If we know the sign bits of both operands are zero, strength reduce to a 858 // udiv instead. Handles (X&15) /s 4 -> X&15 >> 2 859 uint64_t SignBit = 1ULL << (MVT::getSizeInBits(VT)-1); 860 if (TLI.MaskedValueIsZero(N1, SignBit) && 861 TLI.MaskedValueIsZero(N0, SignBit)) 862 return DAG.getNode(ISD::UDIV, N1.getValueType(), N0, N1); 863 // fold (sdiv X, pow2) -> simple ops after legalize 864 if (N1C && N1C->getValue() && !TLI.isIntDivCheap() && 865 (isPowerOf2_64(N1C->getSignExtended()) || 866 isPowerOf2_64(-N1C->getSignExtended()))) { 867 // If dividing by powers of two is cheap, then don't perform the following 868 // fold. 869 if (TLI.isPow2DivCheap()) 870 return SDOperand(); 871 int64_t pow2 = N1C->getSignExtended(); 872 int64_t abs2 = pow2 > 0 ? pow2 : -pow2; 873 unsigned lg2 = Log2_64(abs2); 874 // Splat the sign bit into the register 875 SDOperand SGN = DAG.getNode(ISD::SRA, VT, N0, 876 DAG.getConstant(MVT::getSizeInBits(VT)-1, 877 TLI.getShiftAmountTy())); 878 AddToWorkList(SGN.Val); 879 // Add (N0 < 0) ? abs2 - 1 : 0; 880 SDOperand SRL = DAG.getNode(ISD::SRL, VT, SGN, 881 DAG.getConstant(MVT::getSizeInBits(VT)-lg2, 882 TLI.getShiftAmountTy())); 883 SDOperand ADD = DAG.getNode(ISD::ADD, VT, N0, SRL); 884 AddToWorkList(SRL.Val); 885 AddToWorkList(ADD.Val); // Divide by pow2 886 SDOperand SRA = DAG.getNode(ISD::SRA, VT, ADD, 887 DAG.getConstant(lg2, TLI.getShiftAmountTy())); 888 // If we're dividing by a positive value, we're done. Otherwise, we must 889 // negate the result. 890 if (pow2 > 0) 891 return SRA; 892 AddToWorkList(SRA.Val); 893 return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT), SRA); 894 } 895 // if integer divide is expensive and we satisfy the requirements, emit an 896 // alternate sequence. 897 if (N1C && (N1C->getSignExtended() < -1 || N1C->getSignExtended() > 1) && 898 !TLI.isIntDivCheap()) { 899 SDOperand Op = BuildSDIV(N); 900 if (Op.Val) return Op; 901 } 902 return SDOperand(); 903} 904 905SDOperand DAGCombiner::visitUDIV(SDNode *N) { 906 SDOperand N0 = N->getOperand(0); 907 SDOperand N1 = N->getOperand(1); 908 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val); 909 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val); 910 MVT::ValueType VT = N->getValueType(0); 911 912 // fold (udiv c1, c2) -> c1/c2 913 if (N0C && N1C && !N1C->isNullValue()) 914 return DAG.getNode(ISD::UDIV, VT, N0, N1); 915 // fold (udiv x, (1 << c)) -> x >>u c 916 if (N1C && isPowerOf2_64(N1C->getValue())) 917 return DAG.getNode(ISD::SRL, VT, N0, 918 DAG.getConstant(Log2_64(N1C->getValue()), 919 TLI.getShiftAmountTy())); 920 // fold (udiv x, (shl c, y)) -> x >>u (log2(c)+y) iff c is power of 2 921 if (N1.getOpcode() == ISD::SHL) { 922 if (ConstantSDNode *SHC = dyn_cast<ConstantSDNode>(N1.getOperand(0))) { 923 if (isPowerOf2_64(SHC->getValue())) { 924 MVT::ValueType ADDVT = N1.getOperand(1).getValueType(); 925 SDOperand Add = DAG.getNode(ISD::ADD, ADDVT, N1.getOperand(1), 926 DAG.getConstant(Log2_64(SHC->getValue()), 927 ADDVT)); 928 AddToWorkList(Add.Val); 929 return DAG.getNode(ISD::SRL, VT, N0, Add); 930 } 931 } 932 } 933 // fold (udiv x, c) -> alternate 934 if (N1C && N1C->getValue() && !TLI.isIntDivCheap()) { 935 SDOperand Op = BuildUDIV(N); 936 if (Op.Val) return Op; 937 } 938 return SDOperand(); 939} 940 941SDOperand DAGCombiner::visitSREM(SDNode *N) { 942 SDOperand N0 = N->getOperand(0); 943 SDOperand N1 = N->getOperand(1); 944 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 945 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 946 MVT::ValueType VT = N->getValueType(0); 947 948 // fold (srem c1, c2) -> c1%c2 949 if (N0C && N1C && !N1C->isNullValue()) 950 return DAG.getNode(ISD::SREM, VT, N0, N1); 951 // If we know the sign bits of both operands are zero, strength reduce to a 952 // urem instead. Handles (X & 0x0FFFFFFF) %s 16 -> X&15 953 uint64_t SignBit = 1ULL << (MVT::getSizeInBits(VT)-1); 954 if (TLI.MaskedValueIsZero(N1, SignBit) && 955 TLI.MaskedValueIsZero(N0, SignBit)) 956 return DAG.getNode(ISD::UREM, VT, N0, N1); 957 return SDOperand(); 958} 959 960SDOperand DAGCombiner::visitUREM(SDNode *N) { 961 SDOperand N0 = N->getOperand(0); 962 SDOperand N1 = N->getOperand(1); 963 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 964 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 965 MVT::ValueType VT = N->getValueType(0); 966 967 // fold (urem c1, c2) -> c1%c2 968 if (N0C && N1C && !N1C->isNullValue()) 969 return DAG.getNode(ISD::UREM, VT, N0, N1); 970 // fold (urem x, pow2) -> (and x, pow2-1) 971 if (N1C && !N1C->isNullValue() && isPowerOf2_64(N1C->getValue())) 972 return DAG.getNode(ISD::AND, VT, N0, DAG.getConstant(N1C->getValue()-1,VT)); 973 // fold (urem x, (shl pow2, y)) -> (and x, (add (shl pow2, y), -1)) 974 if (N1.getOpcode() == ISD::SHL) { 975 if (ConstantSDNode *SHC = dyn_cast<ConstantSDNode>(N1.getOperand(0))) { 976 if (isPowerOf2_64(SHC->getValue())) { 977 SDOperand Add = DAG.getNode(ISD::ADD, VT, N1,DAG.getConstant(~0ULL,VT)); 978 AddToWorkList(Add.Val); 979 return DAG.getNode(ISD::AND, VT, N0, Add); 980 } 981 } 982 } 983 return SDOperand(); 984} 985 986SDOperand DAGCombiner::visitMULHS(SDNode *N) { 987 SDOperand N0 = N->getOperand(0); 988 SDOperand N1 = N->getOperand(1); 989 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 990 991 // fold (mulhs x, 0) -> 0 992 if (N1C && N1C->isNullValue()) 993 return N1; 994 // fold (mulhs x, 1) -> (sra x, size(x)-1) 995 if (N1C && N1C->getValue() == 1) 996 return DAG.getNode(ISD::SRA, N0.getValueType(), N0, 997 DAG.getConstant(MVT::getSizeInBits(N0.getValueType())-1, 998 TLI.getShiftAmountTy())); 999 return SDOperand(); 1000} 1001 1002SDOperand DAGCombiner::visitMULHU(SDNode *N) { 1003 SDOperand N0 = N->getOperand(0); 1004 SDOperand N1 = N->getOperand(1); 1005 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1006 1007 // fold (mulhu x, 0) -> 0 1008 if (N1C && N1C->isNullValue()) 1009 return N1; 1010 // fold (mulhu x, 1) -> 0 1011 if (N1C && N1C->getValue() == 1) 1012 return DAG.getConstant(0, N0.getValueType()); 1013 return SDOperand(); 1014} 1015 1016SDOperand DAGCombiner::visitAND(SDNode *N) { 1017 SDOperand N0 = N->getOperand(0); 1018 SDOperand N1 = N->getOperand(1); 1019 SDOperand LL, LR, RL, RR, CC0, CC1; 1020 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1021 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1022 MVT::ValueType VT = N1.getValueType(); 1023 unsigned OpSizeInBits = MVT::getSizeInBits(VT); 1024 1025 // fold (and c1, c2) -> c1&c2 1026 if (N0C && N1C) 1027 return DAG.getNode(ISD::AND, VT, N0, N1); 1028 // canonicalize constant to RHS 1029 if (N0C && !N1C) 1030 return DAG.getNode(ISD::AND, VT, N1, N0); 1031 // fold (and x, -1) -> x 1032 if (N1C && N1C->isAllOnesValue()) 1033 return N0; 1034 // if (and x, c) is known to be zero, return 0 1035 if (N1C && TLI.MaskedValueIsZero(SDOperand(N, 0), MVT::getIntVTBitMask(VT))) 1036 return DAG.getConstant(0, VT); 1037 // reassociate and 1038 SDOperand RAND = ReassociateOps(ISD::AND, N0, N1); 1039 if (RAND.Val != 0) 1040 return RAND; 1041 // fold (and (or x, 0xFFFF), 0xFF) -> 0xFF 1042 if (N1C && N0.getOpcode() == ISD::OR) 1043 if (ConstantSDNode *ORI = dyn_cast<ConstantSDNode>(N0.getOperand(1))) 1044 if ((ORI->getValue() & N1C->getValue()) == N1C->getValue()) 1045 return N1; 1046 // fold (and (any_ext V), c) -> (zero_ext V) if 'and' only clears top bits. 1047 if (N1C && N0.getOpcode() == ISD::ANY_EXTEND) { 1048 unsigned InMask = MVT::getIntVTBitMask(N0.getOperand(0).getValueType()); 1049 if (TLI.MaskedValueIsZero(N0.getOperand(0), 1050 ~N1C->getValue() & InMask)) { 1051 SDOperand Zext = DAG.getNode(ISD::ZERO_EXTEND, N0.getValueType(), 1052 N0.getOperand(0)); 1053 1054 // Replace uses of the AND with uses of the Zero extend node. 1055 CombineTo(N, Zext); 1056 1057 // We actually want to replace all uses of the any_extend with the 1058 // zero_extend, to avoid duplicating things. This will later cause this 1059 // AND to be folded. 1060 CombineTo(N0.Val, Zext); 1061 return SDOperand(); 1062 } 1063 } 1064 // fold (and (setcc x), (setcc y)) -> (setcc (and x, y)) 1065 if (isSetCCEquivalent(N0, LL, LR, CC0) && isSetCCEquivalent(N1, RL, RR, CC1)){ 1066 ISD::CondCode Op0 = cast<CondCodeSDNode>(CC0)->get(); 1067 ISD::CondCode Op1 = cast<CondCodeSDNode>(CC1)->get(); 1068 1069 if (LR == RR && isa<ConstantSDNode>(LR) && Op0 == Op1 && 1070 MVT::isInteger(LL.getValueType())) { 1071 // fold (X == 0) & (Y == 0) -> (X|Y == 0) 1072 if (cast<ConstantSDNode>(LR)->getValue() == 0 && Op1 == ISD::SETEQ) { 1073 SDOperand ORNode = DAG.getNode(ISD::OR, LR.getValueType(), LL, RL); 1074 AddToWorkList(ORNode.Val); 1075 return DAG.getSetCC(VT, ORNode, LR, Op1); 1076 } 1077 // fold (X == -1) & (Y == -1) -> (X&Y == -1) 1078 if (cast<ConstantSDNode>(LR)->isAllOnesValue() && Op1 == ISD::SETEQ) { 1079 SDOperand ANDNode = DAG.getNode(ISD::AND, LR.getValueType(), LL, RL); 1080 AddToWorkList(ANDNode.Val); 1081 return DAG.getSetCC(VT, ANDNode, LR, Op1); 1082 } 1083 // fold (X > -1) & (Y > -1) -> (X|Y > -1) 1084 if (cast<ConstantSDNode>(LR)->isAllOnesValue() && Op1 == ISD::SETGT) { 1085 SDOperand ORNode = DAG.getNode(ISD::OR, LR.getValueType(), LL, RL); 1086 AddToWorkList(ORNode.Val); 1087 return DAG.getSetCC(VT, ORNode, LR, Op1); 1088 } 1089 } 1090 // canonicalize equivalent to ll == rl 1091 if (LL == RR && LR == RL) { 1092 Op1 = ISD::getSetCCSwappedOperands(Op1); 1093 std::swap(RL, RR); 1094 } 1095 if (LL == RL && LR == RR) { 1096 bool isInteger = MVT::isInteger(LL.getValueType()); 1097 ISD::CondCode Result = ISD::getSetCCAndOperation(Op0, Op1, isInteger); 1098 if (Result != ISD::SETCC_INVALID) 1099 return DAG.getSetCC(N0.getValueType(), LL, LR, Result); 1100 } 1101 } 1102 // fold (and (zext x), (zext y)) -> (zext (and x, y)) 1103 if (N0.getOpcode() == ISD::ZERO_EXTEND && 1104 N1.getOpcode() == ISD::ZERO_EXTEND && 1105 N0.getOperand(0).getValueType() == N1.getOperand(0).getValueType()) { 1106 SDOperand ANDNode = DAG.getNode(ISD::AND, N0.getOperand(0).getValueType(), 1107 N0.getOperand(0), N1.getOperand(0)); 1108 AddToWorkList(ANDNode.Val); 1109 return DAG.getNode(ISD::ZERO_EXTEND, VT, ANDNode); 1110 } 1111 // fold (and (shl/srl/sra x), (shl/srl/sra y)) -> (shl/srl/sra (and x, y)) 1112 if (((N0.getOpcode() == ISD::SHL && N1.getOpcode() == ISD::SHL) || 1113 (N0.getOpcode() == ISD::SRL && N1.getOpcode() == ISD::SRL) || 1114 (N0.getOpcode() == ISD::SRA && N1.getOpcode() == ISD::SRA)) && 1115 N0.getOperand(1) == N1.getOperand(1)) { 1116 SDOperand ANDNode = DAG.getNode(ISD::AND, N0.getOperand(0).getValueType(), 1117 N0.getOperand(0), N1.getOperand(0)); 1118 AddToWorkList(ANDNode.Val); 1119 return DAG.getNode(N0.getOpcode(), VT, ANDNode, N0.getOperand(1)); 1120 } 1121 // fold (and (sign_extend_inreg x, i16 to i32), 1) -> (and x, 1) 1122 // fold (and (sra)) -> (and (srl)) when possible. 1123 if (SimplifyDemandedBits(SDOperand(N, 0))) 1124 return SDOperand(); 1125 // fold (zext_inreg (extload x)) -> (zextload x) 1126 if (N0.getOpcode() == ISD::EXTLOAD) { 1127 MVT::ValueType EVT = cast<VTSDNode>(N0.getOperand(3))->getVT(); 1128 // If we zero all the possible extended bits, then we can turn this into 1129 // a zextload if we are running before legalize or the operation is legal. 1130 if (TLI.MaskedValueIsZero(N1, ~0ULL << MVT::getSizeInBits(EVT)) && 1131 (!AfterLegalize || TLI.isOperationLegal(ISD::ZEXTLOAD, EVT))) { 1132 SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0), 1133 N0.getOperand(1), N0.getOperand(2), 1134 EVT); 1135 AddToWorkList(N); 1136 CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1)); 1137 return SDOperand(); 1138 } 1139 } 1140 // fold (zext_inreg (sextload x)) -> (zextload x) iff load has one use 1141 if (N0.getOpcode() == ISD::SEXTLOAD && N0.hasOneUse()) { 1142 MVT::ValueType EVT = cast<VTSDNode>(N0.getOperand(3))->getVT(); 1143 // If we zero all the possible extended bits, then we can turn this into 1144 // a zextload if we are running before legalize or the operation is legal. 1145 if (TLI.MaskedValueIsZero(N1, ~0ULL << MVT::getSizeInBits(EVT)) && 1146 (!AfterLegalize || TLI.isOperationLegal(ISD::ZEXTLOAD, EVT))) { 1147 SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0), 1148 N0.getOperand(1), N0.getOperand(2), 1149 EVT); 1150 AddToWorkList(N); 1151 CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1)); 1152 return SDOperand(); 1153 } 1154 } 1155 1156 // fold (and (load x), 255) -> (zextload x, i8) 1157 // fold (and (extload x, i16), 255) -> (zextload x, i8) 1158 if (N1C && 1159 (N0.getOpcode() == ISD::LOAD || N0.getOpcode() == ISD::EXTLOAD || 1160 N0.getOpcode() == ISD::ZEXTLOAD) && 1161 N0.hasOneUse()) { 1162 MVT::ValueType EVT, LoadedVT; 1163 if (N1C->getValue() == 255) 1164 EVT = MVT::i8; 1165 else if (N1C->getValue() == 65535) 1166 EVT = MVT::i16; 1167 else if (N1C->getValue() == ~0U) 1168 EVT = MVT::i32; 1169 else 1170 EVT = MVT::Other; 1171 1172 LoadedVT = N0.getOpcode() == ISD::LOAD ? VT : 1173 cast<VTSDNode>(N0.getOperand(3))->getVT(); 1174 if (EVT != MVT::Other && LoadedVT > EVT) { 1175 MVT::ValueType PtrType = N0.getOperand(1).getValueType(); 1176 // For big endian targets, we need to add an offset to the pointer to load 1177 // the correct bytes. For little endian systems, we merely need to read 1178 // fewer bytes from the same pointer. 1179 unsigned PtrOff = 1180 (MVT::getSizeInBits(LoadedVT) - MVT::getSizeInBits(EVT)) / 8; 1181 SDOperand NewPtr = N0.getOperand(1); 1182 if (!TLI.isLittleEndian()) 1183 NewPtr = DAG.getNode(ISD::ADD, PtrType, NewPtr, 1184 DAG.getConstant(PtrOff, PtrType)); 1185 AddToWorkList(NewPtr.Val); 1186 SDOperand Load = 1187 DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0), NewPtr, 1188 N0.getOperand(2), EVT); 1189 AddToWorkList(N); 1190 CombineTo(N0.Val, Load, Load.getValue(1)); 1191 return SDOperand(); 1192 } 1193 } 1194 1195 return SDOperand(); 1196} 1197 1198SDOperand DAGCombiner::visitOR(SDNode *N) { 1199 SDOperand N0 = N->getOperand(0); 1200 SDOperand N1 = N->getOperand(1); 1201 SDOperand LL, LR, RL, RR, CC0, CC1; 1202 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1203 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1204 MVT::ValueType VT = N1.getValueType(); 1205 unsigned OpSizeInBits = MVT::getSizeInBits(VT); 1206 1207 // fold (or c1, c2) -> c1|c2 1208 if (N0C && N1C) 1209 return DAG.getNode(ISD::OR, VT, N0, N1); 1210 // canonicalize constant to RHS 1211 if (N0C && !N1C) 1212 return DAG.getNode(ISD::OR, VT, N1, N0); 1213 // fold (or x, 0) -> x 1214 if (N1C && N1C->isNullValue()) 1215 return N0; 1216 // fold (or x, -1) -> -1 1217 if (N1C && N1C->isAllOnesValue()) 1218 return N1; 1219 // fold (or x, c) -> c iff (x & ~c) == 0 1220 if (N1C && 1221 TLI.MaskedValueIsZero(N0,~N1C->getValue() & (~0ULL>>(64-OpSizeInBits)))) 1222 return N1; 1223 // reassociate or 1224 SDOperand ROR = ReassociateOps(ISD::OR, N0, N1); 1225 if (ROR.Val != 0) 1226 return ROR; 1227 // Canonicalize (or (and X, c1), c2) -> (and (or X, c2), c1|c2) 1228 if (N1C && N0.getOpcode() == ISD::AND && N0.Val->hasOneUse() && 1229 isa<ConstantSDNode>(N0.getOperand(1))) { 1230 ConstantSDNode *C1 = cast<ConstantSDNode>(N0.getOperand(1)); 1231 return DAG.getNode(ISD::AND, VT, DAG.getNode(ISD::OR, VT, N0.getOperand(0), 1232 N1), 1233 DAG.getConstant(N1C->getValue() | C1->getValue(), VT)); 1234 } 1235 // fold (or (setcc x), (setcc y)) -> (setcc (or x, y)) 1236 if (isSetCCEquivalent(N0, LL, LR, CC0) && isSetCCEquivalent(N1, RL, RR, CC1)){ 1237 ISD::CondCode Op0 = cast<CondCodeSDNode>(CC0)->get(); 1238 ISD::CondCode Op1 = cast<CondCodeSDNode>(CC1)->get(); 1239 1240 if (LR == RR && isa<ConstantSDNode>(LR) && Op0 == Op1 && 1241 MVT::isInteger(LL.getValueType())) { 1242 // fold (X != 0) | (Y != 0) -> (X|Y != 0) 1243 // fold (X < 0) | (Y < 0) -> (X|Y < 0) 1244 if (cast<ConstantSDNode>(LR)->getValue() == 0 && 1245 (Op1 == ISD::SETNE || Op1 == ISD::SETLT)) { 1246 SDOperand ORNode = DAG.getNode(ISD::OR, LR.getValueType(), LL, RL); 1247 AddToWorkList(ORNode.Val); 1248 return DAG.getSetCC(VT, ORNode, LR, Op1); 1249 } 1250 // fold (X != -1) | (Y != -1) -> (X&Y != -1) 1251 // fold (X > -1) | (Y > -1) -> (X&Y > -1) 1252 if (cast<ConstantSDNode>(LR)->isAllOnesValue() && 1253 (Op1 == ISD::SETNE || Op1 == ISD::SETGT)) { 1254 SDOperand ANDNode = DAG.getNode(ISD::AND, LR.getValueType(), LL, RL); 1255 AddToWorkList(ANDNode.Val); 1256 return DAG.getSetCC(VT, ANDNode, LR, Op1); 1257 } 1258 } 1259 // canonicalize equivalent to ll == rl 1260 if (LL == RR && LR == RL) { 1261 Op1 = ISD::getSetCCSwappedOperands(Op1); 1262 std::swap(RL, RR); 1263 } 1264 if (LL == RL && LR == RR) { 1265 bool isInteger = MVT::isInteger(LL.getValueType()); 1266 ISD::CondCode Result = ISD::getSetCCOrOperation(Op0, Op1, isInteger); 1267 if (Result != ISD::SETCC_INVALID) 1268 return DAG.getSetCC(N0.getValueType(), LL, LR, Result); 1269 } 1270 } 1271 // fold (or (zext x), (zext y)) -> (zext (or x, y)) 1272 if (N0.getOpcode() == ISD::ZERO_EXTEND && 1273 N1.getOpcode() == ISD::ZERO_EXTEND && 1274 N0.getOperand(0).getValueType() == N1.getOperand(0).getValueType()) { 1275 SDOperand ORNode = DAG.getNode(ISD::OR, N0.getOperand(0).getValueType(), 1276 N0.getOperand(0), N1.getOperand(0)); 1277 AddToWorkList(ORNode.Val); 1278 return DAG.getNode(ISD::ZERO_EXTEND, VT, ORNode); 1279 } 1280 // fold (or (shl/srl/sra x), (shl/srl/sra y)) -> (shl/srl/sra (or x, y)) 1281 if (((N0.getOpcode() == ISD::SHL && N1.getOpcode() == ISD::SHL) || 1282 (N0.getOpcode() == ISD::SRL && N1.getOpcode() == ISD::SRL) || 1283 (N0.getOpcode() == ISD::SRA && N1.getOpcode() == ISD::SRA)) && 1284 N0.getOperand(1) == N1.getOperand(1)) { 1285 SDOperand ORNode = DAG.getNode(ISD::OR, N0.getOperand(0).getValueType(), 1286 N0.getOperand(0), N1.getOperand(0)); 1287 AddToWorkList(ORNode.Val); 1288 return DAG.getNode(N0.getOpcode(), VT, ORNode, N0.getOperand(1)); 1289 } 1290 // canonicalize shl to left side in a shl/srl pair, to match rotate 1291 if (N0.getOpcode() == ISD::SRL && N1.getOpcode() == ISD::SHL) 1292 std::swap(N0, N1); 1293 // check for rotl, rotr 1294 if (N0.getOpcode() == ISD::SHL && N1.getOpcode() == ISD::SRL && 1295 N0.getOperand(0) == N1.getOperand(0) && 1296 TLI.isOperationLegal(ISD::ROTL, VT) && TLI.isTypeLegal(VT)) { 1297 // fold (or (shl x, C1), (srl x, C2)) -> (rotl x, C1) 1298 if (N0.getOperand(1).getOpcode() == ISD::Constant && 1299 N1.getOperand(1).getOpcode() == ISD::Constant) { 1300 uint64_t c1val = cast<ConstantSDNode>(N0.getOperand(1))->getValue(); 1301 uint64_t c2val = cast<ConstantSDNode>(N1.getOperand(1))->getValue(); 1302 if ((c1val + c2val) == OpSizeInBits) 1303 return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0), N0.getOperand(1)); 1304 } 1305 // fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotl x, y) 1306 if (N1.getOperand(1).getOpcode() == ISD::SUB && 1307 N0.getOperand(1) == N1.getOperand(1).getOperand(1)) 1308 if (ConstantSDNode *SUBC = 1309 dyn_cast<ConstantSDNode>(N1.getOperand(1).getOperand(0))) 1310 if (SUBC->getValue() == OpSizeInBits) 1311 return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0), N0.getOperand(1)); 1312 // fold (or (shl x, (sub 32, y)), (srl x, r)) -> (rotr x, y) 1313 if (N0.getOperand(1).getOpcode() == ISD::SUB && 1314 N1.getOperand(1) == N0.getOperand(1).getOperand(1)) 1315 if (ConstantSDNode *SUBC = 1316 dyn_cast<ConstantSDNode>(N0.getOperand(1).getOperand(0))) 1317 if (SUBC->getValue() == OpSizeInBits) { 1318 if (TLI.isOperationLegal(ISD::ROTR, VT) && TLI.isTypeLegal(VT)) 1319 return DAG.getNode(ISD::ROTR, VT, N0.getOperand(0), 1320 N1.getOperand(1)); 1321 else 1322 return DAG.getNode(ISD::ROTL, VT, N0.getOperand(0), 1323 N0.getOperand(1)); 1324 } 1325 } 1326 return SDOperand(); 1327} 1328 1329SDOperand DAGCombiner::visitXOR(SDNode *N) { 1330 SDOperand N0 = N->getOperand(0); 1331 SDOperand N1 = N->getOperand(1); 1332 SDOperand LHS, RHS, CC; 1333 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1334 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1335 MVT::ValueType VT = N0.getValueType(); 1336 1337 // fold (xor c1, c2) -> c1^c2 1338 if (N0C && N1C) 1339 return DAG.getNode(ISD::XOR, VT, N0, N1); 1340 // canonicalize constant to RHS 1341 if (N0C && !N1C) 1342 return DAG.getNode(ISD::XOR, VT, N1, N0); 1343 // fold (xor x, 0) -> x 1344 if (N1C && N1C->isNullValue()) 1345 return N0; 1346 // reassociate xor 1347 SDOperand RXOR = ReassociateOps(ISD::XOR, N0, N1); 1348 if (RXOR.Val != 0) 1349 return RXOR; 1350 // fold !(x cc y) -> (x !cc y) 1351 if (N1C && N1C->getValue() == 1 && isSetCCEquivalent(N0, LHS, RHS, CC)) { 1352 bool isInt = MVT::isInteger(LHS.getValueType()); 1353 ISD::CondCode NotCC = ISD::getSetCCInverse(cast<CondCodeSDNode>(CC)->get(), 1354 isInt); 1355 if (N0.getOpcode() == ISD::SETCC) 1356 return DAG.getSetCC(VT, LHS, RHS, NotCC); 1357 if (N0.getOpcode() == ISD::SELECT_CC) 1358 return DAG.getSelectCC(LHS, RHS, N0.getOperand(2),N0.getOperand(3),NotCC); 1359 assert(0 && "Unhandled SetCC Equivalent!"); 1360 abort(); 1361 } 1362 // fold !(x or y) -> (!x and !y) iff x or y are setcc 1363 if (N1C && N1C->getValue() == 1 && 1364 (N0.getOpcode() == ISD::OR || N0.getOpcode() == ISD::AND)) { 1365 SDOperand LHS = N0.getOperand(0), RHS = N0.getOperand(1); 1366 if (isOneUseSetCC(RHS) || isOneUseSetCC(LHS)) { 1367 unsigned NewOpcode = N0.getOpcode() == ISD::AND ? ISD::OR : ISD::AND; 1368 LHS = DAG.getNode(ISD::XOR, VT, LHS, N1); // RHS = ~LHS 1369 RHS = DAG.getNode(ISD::XOR, VT, RHS, N1); // RHS = ~RHS 1370 AddToWorkList(LHS.Val); AddToWorkList(RHS.Val); 1371 return DAG.getNode(NewOpcode, VT, LHS, RHS); 1372 } 1373 } 1374 // fold !(x or y) -> (!x and !y) iff x or y are constants 1375 if (N1C && N1C->isAllOnesValue() && 1376 (N0.getOpcode() == ISD::OR || N0.getOpcode() == ISD::AND)) { 1377 SDOperand LHS = N0.getOperand(0), RHS = N0.getOperand(1); 1378 if (isa<ConstantSDNode>(RHS) || isa<ConstantSDNode>(LHS)) { 1379 unsigned NewOpcode = N0.getOpcode() == ISD::AND ? ISD::OR : ISD::AND; 1380 LHS = DAG.getNode(ISD::XOR, VT, LHS, N1); // RHS = ~LHS 1381 RHS = DAG.getNode(ISD::XOR, VT, RHS, N1); // RHS = ~RHS 1382 AddToWorkList(LHS.Val); AddToWorkList(RHS.Val); 1383 return DAG.getNode(NewOpcode, VT, LHS, RHS); 1384 } 1385 } 1386 // fold (xor (xor x, c1), c2) -> (xor x, c1^c2) 1387 if (N1C && N0.getOpcode() == ISD::XOR) { 1388 ConstantSDNode *N00C = dyn_cast<ConstantSDNode>(N0.getOperand(0)); 1389 ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1)); 1390 if (N00C) 1391 return DAG.getNode(ISD::XOR, VT, N0.getOperand(1), 1392 DAG.getConstant(N1C->getValue()^N00C->getValue(), VT)); 1393 if (N01C) 1394 return DAG.getNode(ISD::XOR, VT, N0.getOperand(0), 1395 DAG.getConstant(N1C->getValue()^N01C->getValue(), VT)); 1396 } 1397 // fold (xor x, x) -> 0 1398 if (N0 == N1) 1399 return DAG.getConstant(0, VT); 1400 // fold (xor (zext x), (zext y)) -> (zext (xor x, y)) 1401 if (N0.getOpcode() == ISD::ZERO_EXTEND && 1402 N1.getOpcode() == ISD::ZERO_EXTEND && 1403 N0.getOperand(0).getValueType() == N1.getOperand(0).getValueType()) { 1404 SDOperand XORNode = DAG.getNode(ISD::XOR, N0.getOperand(0).getValueType(), 1405 N0.getOperand(0), N1.getOperand(0)); 1406 AddToWorkList(XORNode.Val); 1407 return DAG.getNode(ISD::ZERO_EXTEND, VT, XORNode); 1408 } 1409 // fold (xor (shl/srl/sra x), (shl/srl/sra y)) -> (shl/srl/sra (xor x, y)) 1410 if (((N0.getOpcode() == ISD::SHL && N1.getOpcode() == ISD::SHL) || 1411 (N0.getOpcode() == ISD::SRL && N1.getOpcode() == ISD::SRL) || 1412 (N0.getOpcode() == ISD::SRA && N1.getOpcode() == ISD::SRA)) && 1413 N0.getOperand(1) == N1.getOperand(1)) { 1414 SDOperand XORNode = DAG.getNode(ISD::XOR, N0.getOperand(0).getValueType(), 1415 N0.getOperand(0), N1.getOperand(0)); 1416 AddToWorkList(XORNode.Val); 1417 return DAG.getNode(N0.getOpcode(), VT, XORNode, N0.getOperand(1)); 1418 } 1419 return SDOperand(); 1420} 1421 1422SDOperand DAGCombiner::visitSHL(SDNode *N) { 1423 SDOperand N0 = N->getOperand(0); 1424 SDOperand N1 = N->getOperand(1); 1425 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1426 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1427 MVT::ValueType VT = N0.getValueType(); 1428 unsigned OpSizeInBits = MVT::getSizeInBits(VT); 1429 1430 // fold (shl c1, c2) -> c1<<c2 1431 if (N0C && N1C) 1432 return DAG.getNode(ISD::SHL, VT, N0, N1); 1433 // fold (shl 0, x) -> 0 1434 if (N0C && N0C->isNullValue()) 1435 return N0; 1436 // fold (shl x, c >= size(x)) -> undef 1437 if (N1C && N1C->getValue() >= OpSizeInBits) 1438 return DAG.getNode(ISD::UNDEF, VT); 1439 // fold (shl x, 0) -> x 1440 if (N1C && N1C->isNullValue()) 1441 return N0; 1442 // if (shl x, c) is known to be zero, return 0 1443 if (TLI.MaskedValueIsZero(SDOperand(N, 0), MVT::getIntVTBitMask(VT))) 1444 return DAG.getConstant(0, VT); 1445 if (SimplifyDemandedBits(SDOperand(N, 0))) 1446 return SDOperand(); 1447 // fold (shl (shl x, c1), c2) -> 0 or (shl x, c1+c2) 1448 if (N1C && N0.getOpcode() == ISD::SHL && 1449 N0.getOperand(1).getOpcode() == ISD::Constant) { 1450 uint64_t c1 = cast<ConstantSDNode>(N0.getOperand(1))->getValue(); 1451 uint64_t c2 = N1C->getValue(); 1452 if (c1 + c2 > OpSizeInBits) 1453 return DAG.getConstant(0, VT); 1454 return DAG.getNode(ISD::SHL, VT, N0.getOperand(0), 1455 DAG.getConstant(c1 + c2, N1.getValueType())); 1456 } 1457 // fold (shl (srl x, c1), c2) -> (shl (and x, -1 << c1), c2-c1) or 1458 // (srl (and x, -1 << c1), c1-c2) 1459 if (N1C && N0.getOpcode() == ISD::SRL && 1460 N0.getOperand(1).getOpcode() == ISD::Constant) { 1461 uint64_t c1 = cast<ConstantSDNode>(N0.getOperand(1))->getValue(); 1462 uint64_t c2 = N1C->getValue(); 1463 SDOperand Mask = DAG.getNode(ISD::AND, VT, N0.getOperand(0), 1464 DAG.getConstant(~0ULL << c1, VT)); 1465 if (c2 > c1) 1466 return DAG.getNode(ISD::SHL, VT, Mask, 1467 DAG.getConstant(c2-c1, N1.getValueType())); 1468 else 1469 return DAG.getNode(ISD::SRL, VT, Mask, 1470 DAG.getConstant(c1-c2, N1.getValueType())); 1471 } 1472 // fold (shl (sra x, c1), c1) -> (and x, -1 << c1) 1473 if (N1C && N0.getOpcode() == ISD::SRA && N1 == N0.getOperand(1)) 1474 return DAG.getNode(ISD::AND, VT, N0.getOperand(0), 1475 DAG.getConstant(~0ULL << N1C->getValue(), VT)); 1476 // fold (shl (add x, c1), c2) -> (add (shl x, c2), c1<<c2) 1477 if (N1C && N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse() && 1478 isa<ConstantSDNode>(N0.getOperand(1))) { 1479 return DAG.getNode(ISD::ADD, VT, 1480 DAG.getNode(ISD::SHL, VT, N0.getOperand(0), N1), 1481 DAG.getNode(ISD::SHL, VT, N0.getOperand(1), N1)); 1482 } 1483 return SDOperand(); 1484} 1485 1486SDOperand DAGCombiner::visitSRA(SDNode *N) { 1487 SDOperand N0 = N->getOperand(0); 1488 SDOperand N1 = N->getOperand(1); 1489 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1490 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1491 MVT::ValueType VT = N0.getValueType(); 1492 1493 // fold (sra c1, c2) -> c1>>c2 1494 if (N0C && N1C) 1495 return DAG.getNode(ISD::SRA, VT, N0, N1); 1496 // fold (sra 0, x) -> 0 1497 if (N0C && N0C->isNullValue()) 1498 return N0; 1499 // fold (sra -1, x) -> -1 1500 if (N0C && N0C->isAllOnesValue()) 1501 return N0; 1502 // fold (sra x, c >= size(x)) -> undef 1503 if (N1C && N1C->getValue() >= MVT::getSizeInBits(VT)) 1504 return DAG.getNode(ISD::UNDEF, VT); 1505 // fold (sra x, 0) -> x 1506 if (N1C && N1C->isNullValue()) 1507 return N0; 1508 // fold (sra (shl x, c1), c1) -> sext_inreg for some c1 and target supports 1509 // sext_inreg. 1510 if (N1C && N0.getOpcode() == ISD::SHL && N1 == N0.getOperand(1)) { 1511 unsigned LowBits = MVT::getSizeInBits(VT) - (unsigned)N1C->getValue(); 1512 MVT::ValueType EVT; 1513 switch (LowBits) { 1514 default: EVT = MVT::Other; break; 1515 case 1: EVT = MVT::i1; break; 1516 case 8: EVT = MVT::i8; break; 1517 case 16: EVT = MVT::i16; break; 1518 case 32: EVT = MVT::i32; break; 1519 } 1520 if (EVT > MVT::Other && TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, EVT)) 1521 return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0), 1522 DAG.getValueType(EVT)); 1523 } 1524 1525 // fold (sra (sra x, c1), c2) -> (sra x, c1+c2) 1526 if (N1C && N0.getOpcode() == ISD::SRA) { 1527 if (ConstantSDNode *C1 = dyn_cast<ConstantSDNode>(N0.getOperand(1))) { 1528 unsigned Sum = N1C->getValue() + C1->getValue(); 1529 if (Sum >= MVT::getSizeInBits(VT)) Sum = MVT::getSizeInBits(VT)-1; 1530 return DAG.getNode(ISD::SRA, VT, N0.getOperand(0), 1531 DAG.getConstant(Sum, N1C->getValueType(0))); 1532 } 1533 } 1534 1535 // If the sign bit is known to be zero, switch this to a SRL. 1536 if (TLI.MaskedValueIsZero(N0, MVT::getIntVTSignBit(VT))) 1537 return DAG.getNode(ISD::SRL, VT, N0, N1); 1538 return SDOperand(); 1539} 1540 1541SDOperand DAGCombiner::visitSRL(SDNode *N) { 1542 SDOperand N0 = N->getOperand(0); 1543 SDOperand N1 = N->getOperand(1); 1544 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1545 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1546 MVT::ValueType VT = N0.getValueType(); 1547 unsigned OpSizeInBits = MVT::getSizeInBits(VT); 1548 1549 // fold (srl c1, c2) -> c1 >>u c2 1550 if (N0C && N1C) 1551 return DAG.getNode(ISD::SRL, VT, N0, N1); 1552 // fold (srl 0, x) -> 0 1553 if (N0C && N0C->isNullValue()) 1554 return N0; 1555 // fold (srl x, c >= size(x)) -> undef 1556 if (N1C && N1C->getValue() >= OpSizeInBits) 1557 return DAG.getNode(ISD::UNDEF, VT); 1558 // fold (srl x, 0) -> x 1559 if (N1C && N1C->isNullValue()) 1560 return N0; 1561 // if (srl x, c) is known to be zero, return 0 1562 if (N1C && TLI.MaskedValueIsZero(SDOperand(N, 0), ~0ULL >> (64-OpSizeInBits))) 1563 return DAG.getConstant(0, VT); 1564 // fold (srl (srl x, c1), c2) -> 0 or (srl x, c1+c2) 1565 if (N1C && N0.getOpcode() == ISD::SRL && 1566 N0.getOperand(1).getOpcode() == ISD::Constant) { 1567 uint64_t c1 = cast<ConstantSDNode>(N0.getOperand(1))->getValue(); 1568 uint64_t c2 = N1C->getValue(); 1569 if (c1 + c2 > OpSizeInBits) 1570 return DAG.getConstant(0, VT); 1571 return DAG.getNode(ISD::SRL, VT, N0.getOperand(0), 1572 DAG.getConstant(c1 + c2, N1.getValueType())); 1573 } 1574 return SDOperand(); 1575} 1576 1577SDOperand DAGCombiner::visitCTLZ(SDNode *N) { 1578 SDOperand N0 = N->getOperand(0); 1579 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1580 MVT::ValueType VT = N->getValueType(0); 1581 1582 // fold (ctlz c1) -> c2 1583 if (N0C) 1584 return DAG.getNode(ISD::CTLZ, VT, N0); 1585 return SDOperand(); 1586} 1587 1588SDOperand DAGCombiner::visitCTTZ(SDNode *N) { 1589 SDOperand N0 = N->getOperand(0); 1590 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1591 MVT::ValueType VT = N->getValueType(0); 1592 1593 // fold (cttz c1) -> c2 1594 if (N0C) 1595 return DAG.getNode(ISD::CTTZ, VT, N0); 1596 return SDOperand(); 1597} 1598 1599SDOperand DAGCombiner::visitCTPOP(SDNode *N) { 1600 SDOperand N0 = N->getOperand(0); 1601 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1602 MVT::ValueType VT = N->getValueType(0); 1603 1604 // fold (ctpop c1) -> c2 1605 if (N0C) 1606 return DAG.getNode(ISD::CTPOP, VT, N0); 1607 return SDOperand(); 1608} 1609 1610SDOperand DAGCombiner::visitSELECT(SDNode *N) { 1611 SDOperand N0 = N->getOperand(0); 1612 SDOperand N1 = N->getOperand(1); 1613 SDOperand N2 = N->getOperand(2); 1614 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1615 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1616 ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2); 1617 MVT::ValueType VT = N->getValueType(0); 1618 1619 // fold select C, X, X -> X 1620 if (N1 == N2) 1621 return N1; 1622 // fold select true, X, Y -> X 1623 if (N0C && !N0C->isNullValue()) 1624 return N1; 1625 // fold select false, X, Y -> Y 1626 if (N0C && N0C->isNullValue()) 1627 return N2; 1628 // fold select C, 1, X -> C | X 1629 if (MVT::i1 == VT && N1C && N1C->getValue() == 1) 1630 return DAG.getNode(ISD::OR, VT, N0, N2); 1631 // fold select C, 0, X -> ~C & X 1632 // FIXME: this should check for C type == X type, not i1? 1633 if (MVT::i1 == VT && N1C && N1C->isNullValue()) { 1634 SDOperand XORNode = DAG.getNode(ISD::XOR, VT, N0, DAG.getConstant(1, VT)); 1635 AddToWorkList(XORNode.Val); 1636 return DAG.getNode(ISD::AND, VT, XORNode, N2); 1637 } 1638 // fold select C, X, 1 -> ~C | X 1639 if (MVT::i1 == VT && N2C && N2C->getValue() == 1) { 1640 SDOperand XORNode = DAG.getNode(ISD::XOR, VT, N0, DAG.getConstant(1, VT)); 1641 AddToWorkList(XORNode.Val); 1642 return DAG.getNode(ISD::OR, VT, XORNode, N1); 1643 } 1644 // fold select C, X, 0 -> C & X 1645 // FIXME: this should check for C type == X type, not i1? 1646 if (MVT::i1 == VT && N2C && N2C->isNullValue()) 1647 return DAG.getNode(ISD::AND, VT, N0, N1); 1648 // fold X ? X : Y --> X ? 1 : Y --> X | Y 1649 if (MVT::i1 == VT && N0 == N1) 1650 return DAG.getNode(ISD::OR, VT, N0, N2); 1651 // fold X ? Y : X --> X ? Y : 0 --> X & Y 1652 if (MVT::i1 == VT && N0 == N2) 1653 return DAG.getNode(ISD::AND, VT, N0, N1); 1654 // If we can fold this based on the true/false value, do so. 1655 if (SimplifySelectOps(N, N1, N2)) 1656 return SDOperand(); 1657 // fold selects based on a setcc into other things, such as min/max/abs 1658 if (N0.getOpcode() == ISD::SETCC) 1659 // FIXME: 1660 // Check against MVT::Other for SELECT_CC, which is a workaround for targets 1661 // having to say they don't support SELECT_CC on every type the DAG knows 1662 // about, since there is no way to mark an opcode illegal at all value types 1663 if (TLI.isOperationLegal(ISD::SELECT_CC, MVT::Other)) 1664 return DAG.getNode(ISD::SELECT_CC, VT, N0.getOperand(0), N0.getOperand(1), 1665 N1, N2, N0.getOperand(2)); 1666 else 1667 return SimplifySelect(N0, N1, N2); 1668 return SDOperand(); 1669} 1670 1671SDOperand DAGCombiner::visitSELECT_CC(SDNode *N) { 1672 SDOperand N0 = N->getOperand(0); 1673 SDOperand N1 = N->getOperand(1); 1674 SDOperand N2 = N->getOperand(2); 1675 SDOperand N3 = N->getOperand(3); 1676 SDOperand N4 = N->getOperand(4); 1677 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1678 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 1679 ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2); 1680 ISD::CondCode CC = cast<CondCodeSDNode>(N4)->get(); 1681 1682 // Determine if the condition we're dealing with is constant 1683 SDOperand SCC = SimplifySetCC(TLI.getSetCCResultTy(), N0, N1, CC, false); 1684 ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val); 1685 1686 // fold select_cc lhs, rhs, x, x, cc -> x 1687 if (N2 == N3) 1688 return N2; 1689 1690 // If we can fold this based on the true/false value, do so. 1691 if (SimplifySelectOps(N, N2, N3)) 1692 return SDOperand(); 1693 1694 // fold select_cc into other things, such as min/max/abs 1695 return SimplifySelectCC(N0, N1, N2, N3, CC); 1696} 1697 1698SDOperand DAGCombiner::visitSETCC(SDNode *N) { 1699 return SimplifySetCC(N->getValueType(0), N->getOperand(0), N->getOperand(1), 1700 cast<CondCodeSDNode>(N->getOperand(2))->get()); 1701} 1702 1703SDOperand DAGCombiner::visitSIGN_EXTEND(SDNode *N) { 1704 SDOperand N0 = N->getOperand(0); 1705 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1706 MVT::ValueType VT = N->getValueType(0); 1707 1708 // fold (sext c1) -> c1 1709 if (N0C) 1710 return DAG.getNode(ISD::SIGN_EXTEND, VT, N0); 1711 // fold (sext (sext x)) -> (sext x) 1712 if (N0.getOpcode() == ISD::SIGN_EXTEND) 1713 return DAG.getNode(ISD::SIGN_EXTEND, VT, N0.getOperand(0)); 1714 // fold (sext (truncate x)) -> (sextinreg x) iff x size == sext size. 1715 if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&& 1716 (!AfterLegalize || 1717 TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, N0.getValueType()))) 1718 return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0), 1719 DAG.getValueType(N0.getValueType())); 1720 // fold (sext (load x)) -> (sext (truncate (sextload x))) 1721 if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse() && 1722 (!AfterLegalize||TLI.isOperationLegal(ISD::SEXTLOAD, N0.getValueType()))){ 1723 SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, N0.getOperand(0), 1724 N0.getOperand(1), N0.getOperand(2), 1725 N0.getValueType()); 1726 CombineTo(N, ExtLoad); 1727 CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad), 1728 ExtLoad.getValue(1)); 1729 return SDOperand(); 1730 } 1731 1732 // fold (sext (sextload x)) -> (sext (truncate (sextload x))) 1733 // fold (sext ( extload x)) -> (sext (truncate (sextload x))) 1734 if ((N0.getOpcode() == ISD::SEXTLOAD || N0.getOpcode() == ISD::EXTLOAD) && 1735 N0.hasOneUse()) { 1736 SDOperand ExtLoad = DAG.getNode(ISD::SEXTLOAD, VT, N0.getOperand(0), 1737 N0.getOperand(1), N0.getOperand(2), 1738 N0.getOperand(3)); 1739 CombineTo(N, ExtLoad); 1740 CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad), 1741 ExtLoad.getValue(1)); 1742 return SDOperand(); 1743 } 1744 1745 return SDOperand(); 1746} 1747 1748SDOperand DAGCombiner::visitZERO_EXTEND(SDNode *N) { 1749 SDOperand N0 = N->getOperand(0); 1750 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1751 MVT::ValueType VT = N->getValueType(0); 1752 1753 // fold (zext c1) -> c1 1754 if (N0C) 1755 return DAG.getNode(ISD::ZERO_EXTEND, VT, N0); 1756 // fold (zext (zext x)) -> (zext x) 1757 if (N0.getOpcode() == ISD::ZERO_EXTEND) 1758 return DAG.getNode(ISD::ZERO_EXTEND, VT, N0.getOperand(0)); 1759 // fold (zext (truncate x)) -> (zextinreg x) iff x size == zext size. 1760 if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&& 1761 (!AfterLegalize || TLI.isOperationLegal(ISD::AND, N0.getValueType()))) 1762 return DAG.getZeroExtendInReg(N0.getOperand(0), N0.getValueType()); 1763 // fold (zext (load x)) -> (zext (truncate (zextload x))) 1764 if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse() && 1765 (!AfterLegalize||TLI.isOperationLegal(ISD::ZEXTLOAD, N0.getValueType()))){ 1766 SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0), 1767 N0.getOperand(1), N0.getOperand(2), 1768 N0.getValueType()); 1769 CombineTo(N, ExtLoad); 1770 CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad), 1771 ExtLoad.getValue(1)); 1772 return SDOperand(); 1773 } 1774 1775 // fold (zext (zextload x)) -> (zext (truncate (zextload x))) 1776 // fold (zext ( extload x)) -> (zext (truncate (zextload x))) 1777 if ((N0.getOpcode() == ISD::ZEXTLOAD || N0.getOpcode() == ISD::EXTLOAD) && 1778 N0.hasOneUse()) { 1779 SDOperand ExtLoad = DAG.getNode(ISD::ZEXTLOAD, VT, N0.getOperand(0), 1780 N0.getOperand(1), N0.getOperand(2), 1781 N0.getOperand(3)); 1782 CombineTo(N, ExtLoad); 1783 CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad), 1784 ExtLoad.getValue(1)); 1785 return SDOperand(); 1786 } 1787 return SDOperand(); 1788} 1789 1790SDOperand DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) { 1791 SDOperand N0 = N->getOperand(0); 1792 SDOperand N1 = N->getOperand(1); 1793 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1794 MVT::ValueType VT = N->getValueType(0); 1795 MVT::ValueType EVT = cast<VTSDNode>(N1)->getVT(); 1796 unsigned EVTBits = MVT::getSizeInBits(EVT); 1797 1798 // fold (sext_in_reg c1) -> c1 1799 if (N0C) { 1800 SDOperand Truncate = DAG.getConstant(N0C->getValue(), EVT); 1801 return DAG.getNode(ISD::SIGN_EXTEND, VT, Truncate); 1802 } 1803 // fold (sext_in_reg (sext_in_reg x, VT2), VT1) -> (sext_in_reg x, minVT) pt1 1804 if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG && 1805 cast<VTSDNode>(N0.getOperand(1))->getVT() <= EVT) { 1806 return N0; 1807 } 1808 // fold (sext_in_reg (sext_in_reg x, VT2), VT1) -> (sext_in_reg x, minVT) pt2 1809 if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG && 1810 EVT < cast<VTSDNode>(N0.getOperand(1))->getVT()) { 1811 return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0), N1); 1812 } 1813 // fold (sext_in_reg (assert_sext x)) -> (assert_sext x) 1814 if (N0.getOpcode() == ISD::AssertSext && 1815 cast<VTSDNode>(N0.getOperand(1))->getVT() <= EVT) { 1816 return N0; 1817 } 1818 // fold (sext_in_reg (sextload x)) -> (sextload x) 1819 if (N0.getOpcode() == ISD::SEXTLOAD && 1820 cast<VTSDNode>(N0.getOperand(3))->getVT() <= EVT) { 1821 return N0; 1822 } 1823 // fold (sext_in_reg (setcc x)) -> setcc x iff (setcc x) == 0 or -1 1824 if (N0.getOpcode() == ISD::SETCC && 1825 TLI.getSetCCResultContents() == 1826 TargetLowering::ZeroOrNegativeOneSetCCResult) 1827 return N0; 1828 // fold (sext_in_reg x) -> (zext_in_reg x) if the sign bit is zero 1829 if (TLI.MaskedValueIsZero(N0, 1ULL << (EVTBits-1))) 1830 return DAG.getZeroExtendInReg(N0, EVT); 1831 // fold (sext_in_reg (srl x)) -> sra x 1832 if (N0.getOpcode() == ISD::SRL && 1833 N0.getOperand(1).getOpcode() == ISD::Constant && 1834 cast<ConstantSDNode>(N0.getOperand(1))->getValue() == EVTBits) { 1835 return DAG.getNode(ISD::SRA, N0.getValueType(), N0.getOperand(0), 1836 N0.getOperand(1)); 1837 } 1838 // fold (sext_inreg (extload x)) -> (sextload x) 1839 if (N0.getOpcode() == ISD::EXTLOAD && 1840 EVT == cast<VTSDNode>(N0.getOperand(3))->getVT() && 1841 (!AfterLegalize || TLI.isOperationLegal(ISD::SEXTLOAD, EVT))) { 1842 SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, N0.getOperand(0), 1843 N0.getOperand(1), N0.getOperand(2), 1844 EVT); 1845 CombineTo(N, ExtLoad); 1846 CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1)); 1847 return SDOperand(); 1848 } 1849 // fold (sext_inreg (zextload x)) -> (sextload x) iff load has one use 1850 if (N0.getOpcode() == ISD::ZEXTLOAD && N0.hasOneUse() && 1851 EVT == cast<VTSDNode>(N0.getOperand(3))->getVT() && 1852 (!AfterLegalize || TLI.isOperationLegal(ISD::SEXTLOAD, EVT))) { 1853 SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, N0.getOperand(0), 1854 N0.getOperand(1), N0.getOperand(2), 1855 EVT); 1856 CombineTo(N, ExtLoad); 1857 CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1)); 1858 return SDOperand(); 1859 } 1860 return SDOperand(); 1861} 1862 1863SDOperand DAGCombiner::visitTRUNCATE(SDNode *N) { 1864 SDOperand N0 = N->getOperand(0); 1865 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 1866 MVT::ValueType VT = N->getValueType(0); 1867 1868 // noop truncate 1869 if (N0.getValueType() == N->getValueType(0)) 1870 return N0; 1871 // fold (truncate c1) -> c1 1872 if (N0C) 1873 return DAG.getNode(ISD::TRUNCATE, VT, N0); 1874 // fold (truncate (truncate x)) -> (truncate x) 1875 if (N0.getOpcode() == ISD::TRUNCATE) 1876 return DAG.getNode(ISD::TRUNCATE, VT, N0.getOperand(0)); 1877 // fold (truncate (ext x)) -> (ext x) or (truncate x) or x 1878 if (N0.getOpcode() == ISD::ZERO_EXTEND || N0.getOpcode() == ISD::SIGN_EXTEND){ 1879 if (N0.getValueType() < VT) 1880 // if the source is smaller than the dest, we still need an extend 1881 return DAG.getNode(N0.getOpcode(), VT, N0.getOperand(0)); 1882 else if (N0.getValueType() > VT) 1883 // if the source is larger than the dest, than we just need the truncate 1884 return DAG.getNode(ISD::TRUNCATE, VT, N0.getOperand(0)); 1885 else 1886 // if the source and dest are the same type, we can drop both the extend 1887 // and the truncate 1888 return N0.getOperand(0); 1889 } 1890 // fold (truncate (load x)) -> (smaller load x) 1891 if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse()) { 1892 assert(MVT::getSizeInBits(N0.getValueType()) > MVT::getSizeInBits(VT) && 1893 "Cannot truncate to larger type!"); 1894 MVT::ValueType PtrType = N0.getOperand(1).getValueType(); 1895 // For big endian targets, we need to add an offset to the pointer to load 1896 // the correct bytes. For little endian systems, we merely need to read 1897 // fewer bytes from the same pointer. 1898 uint64_t PtrOff = 1899 (MVT::getSizeInBits(N0.getValueType()) - MVT::getSizeInBits(VT)) / 8; 1900 SDOperand NewPtr = TLI.isLittleEndian() ? N0.getOperand(1) : 1901 DAG.getNode(ISD::ADD, PtrType, N0.getOperand(1), 1902 DAG.getConstant(PtrOff, PtrType)); 1903 AddToWorkList(NewPtr.Val); 1904 SDOperand Load = DAG.getLoad(VT, N0.getOperand(0), NewPtr,N0.getOperand(2)); 1905 AddToWorkList(N); 1906 CombineTo(N0.Val, Load, Load.getValue(1)); 1907 return SDOperand(); 1908 } 1909 return SDOperand(); 1910} 1911 1912SDOperand DAGCombiner::visitBIT_CONVERT(SDNode *N) { 1913 SDOperand N0 = N->getOperand(0); 1914 MVT::ValueType VT = N->getValueType(0); 1915 1916 // If the input is a constant, let getNode() fold it. 1917 if (isa<ConstantSDNode>(N0) || isa<ConstantFPSDNode>(N0)) { 1918 SDOperand Res = DAG.getNode(ISD::BIT_CONVERT, VT, N0); 1919 if (Res.Val != N) return Res; 1920 } 1921 1922 if (N0.getOpcode() == ISD::BIT_CONVERT) // conv(conv(x,t1),t2) -> conv(x,t2) 1923 return DAG.getNode(ISD::BIT_CONVERT, VT, N0.getOperand(0)); 1924 1925 // fold (conv (load x)) -> (load (conv*)x) 1926 // FIXME: These xforms need to know that the resultant load doesn't need a 1927 // higher alignment than the original! 1928 if (0 && N0.getOpcode() == ISD::LOAD && N0.hasOneUse()) { 1929 SDOperand Load = DAG.getLoad(VT, N0.getOperand(0), N0.getOperand(1), 1930 N0.getOperand(2)); 1931 AddToWorkList(N); 1932 CombineTo(N0.Val, DAG.getNode(ISD::BIT_CONVERT, N0.getValueType(), Load), 1933 Load.getValue(1)); 1934 return Load; 1935 } 1936 1937 return SDOperand(); 1938} 1939 1940SDOperand DAGCombiner::visitFADD(SDNode *N) { 1941 SDOperand N0 = N->getOperand(0); 1942 SDOperand N1 = N->getOperand(1); 1943 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 1944 ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1); 1945 MVT::ValueType VT = N->getValueType(0); 1946 1947 // fold (fadd c1, c2) -> c1+c2 1948 if (N0CFP && N1CFP) 1949 return DAG.getNode(ISD::FADD, VT, N0, N1); 1950 // canonicalize constant to RHS 1951 if (N0CFP && !N1CFP) 1952 return DAG.getNode(ISD::FADD, VT, N1, N0); 1953 // fold (A + (-B)) -> A-B 1954 if (N1.getOpcode() == ISD::FNEG) 1955 return DAG.getNode(ISD::FSUB, VT, N0, N1.getOperand(0)); 1956 // fold ((-A) + B) -> B-A 1957 if (N0.getOpcode() == ISD::FNEG) 1958 return DAG.getNode(ISD::FSUB, VT, N1, N0.getOperand(0)); 1959 return SDOperand(); 1960} 1961 1962SDOperand DAGCombiner::visitFSUB(SDNode *N) { 1963 SDOperand N0 = N->getOperand(0); 1964 SDOperand N1 = N->getOperand(1); 1965 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 1966 ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1); 1967 MVT::ValueType VT = N->getValueType(0); 1968 1969 // fold (fsub c1, c2) -> c1-c2 1970 if (N0CFP && N1CFP) 1971 return DAG.getNode(ISD::FSUB, VT, N0, N1); 1972 // fold (A-(-B)) -> A+B 1973 if (N1.getOpcode() == ISD::FNEG) 1974 return DAG.getNode(ISD::FADD, VT, N0, N1.getOperand(0)); 1975 return SDOperand(); 1976} 1977 1978SDOperand DAGCombiner::visitFMUL(SDNode *N) { 1979 SDOperand N0 = N->getOperand(0); 1980 SDOperand N1 = N->getOperand(1); 1981 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 1982 ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1); 1983 MVT::ValueType VT = N->getValueType(0); 1984 1985 // fold (fmul c1, c2) -> c1*c2 1986 if (N0CFP && N1CFP) 1987 return DAG.getNode(ISD::FMUL, VT, N0, N1); 1988 // canonicalize constant to RHS 1989 if (N0CFP && !N1CFP) 1990 return DAG.getNode(ISD::FMUL, VT, N1, N0); 1991 // fold (fmul X, 2.0) -> (fadd X, X) 1992 if (N1CFP && N1CFP->isExactlyValue(+2.0)) 1993 return DAG.getNode(ISD::FADD, VT, N0, N0); 1994 return SDOperand(); 1995} 1996 1997SDOperand DAGCombiner::visitFDIV(SDNode *N) { 1998 SDOperand N0 = N->getOperand(0); 1999 SDOperand N1 = N->getOperand(1); 2000 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2001 ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1); 2002 MVT::ValueType VT = N->getValueType(0); 2003 2004 // fold (fdiv c1, c2) -> c1/c2 2005 if (N0CFP && N1CFP) 2006 return DAG.getNode(ISD::FDIV, VT, N0, N1); 2007 return SDOperand(); 2008} 2009 2010SDOperand DAGCombiner::visitFREM(SDNode *N) { 2011 SDOperand N0 = N->getOperand(0); 2012 SDOperand N1 = N->getOperand(1); 2013 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2014 ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1); 2015 MVT::ValueType VT = N->getValueType(0); 2016 2017 // fold (frem c1, c2) -> fmod(c1,c2) 2018 if (N0CFP && N1CFP) 2019 return DAG.getNode(ISD::FREM, VT, N0, N1); 2020 return SDOperand(); 2021} 2022 2023SDOperand DAGCombiner::visitFCOPYSIGN(SDNode *N) { 2024 SDOperand N0 = N->getOperand(0); 2025 SDOperand N1 = N->getOperand(1); 2026 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2027 ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1); 2028 MVT::ValueType VT = N->getValueType(0); 2029 2030 if (N0CFP && N1CFP) // Constant fold 2031 return DAG.getNode(ISD::FCOPYSIGN, VT, N0, N1); 2032 2033 if (N1CFP) { 2034 // copysign(x, c1) -> fabs(x) iff ispos(c1) 2035 // copysign(x, c1) -> fneg(fabs(x)) iff isneg(c1) 2036 union { 2037 double d; 2038 int64_t i; 2039 } u; 2040 u.d = N1CFP->getValue(); 2041 if (u.i >= 0) 2042 return DAG.getNode(ISD::FABS, VT, N0); 2043 else 2044 return DAG.getNode(ISD::FNEG, VT, DAG.getNode(ISD::FABS, VT, N0)); 2045 } 2046 2047 // copysign(fabs(x), y) -> copysign(x, y) 2048 // copysign(fneg(x), y) -> copysign(x, y) 2049 // copysign(copysign(x,z), y) -> copysign(x, y) 2050 if (N0.getOpcode() == ISD::FABS || N0.getOpcode() == ISD::FNEG || 2051 N0.getOpcode() == ISD::FCOPYSIGN) 2052 return DAG.getNode(ISD::FCOPYSIGN, VT, N0.getOperand(0), N1); 2053 2054 // copysign(x, abs(y)) -> abs(x) 2055 if (N1.getOpcode() == ISD::FABS) 2056 return DAG.getNode(ISD::FABS, VT, N0); 2057 2058 // copysign(x, copysign(y,z)) -> copysign(x, z) 2059 if (N1.getOpcode() == ISD::FCOPYSIGN) 2060 return DAG.getNode(ISD::FCOPYSIGN, VT, N0, N1.getOperand(1)); 2061 2062 // copysign(x, fp_extend(y)) -> copysign(x, y) 2063 // copysign(x, fp_round(y)) -> copysign(x, y) 2064 if (N1.getOpcode() == ISD::FP_EXTEND || N1.getOpcode() == ISD::FP_ROUND) 2065 return DAG.getNode(ISD::FCOPYSIGN, VT, N0, N1.getOperand(0)); 2066 2067 return SDOperand(); 2068} 2069 2070 2071 2072SDOperand DAGCombiner::visitSINT_TO_FP(SDNode *N) { 2073 SDOperand N0 = N->getOperand(0); 2074 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 2075 MVT::ValueType VT = N->getValueType(0); 2076 2077 // fold (sint_to_fp c1) -> c1fp 2078 if (N0C) 2079 return DAG.getNode(ISD::SINT_TO_FP, VT, N0); 2080 return SDOperand(); 2081} 2082 2083SDOperand DAGCombiner::visitUINT_TO_FP(SDNode *N) { 2084 SDOperand N0 = N->getOperand(0); 2085 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0); 2086 MVT::ValueType VT = N->getValueType(0); 2087 2088 // fold (uint_to_fp c1) -> c1fp 2089 if (N0C) 2090 return DAG.getNode(ISD::UINT_TO_FP, VT, N0); 2091 return SDOperand(); 2092} 2093 2094SDOperand DAGCombiner::visitFP_TO_SINT(SDNode *N) { 2095 SDOperand N0 = N->getOperand(0); 2096 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2097 MVT::ValueType VT = N->getValueType(0); 2098 2099 // fold (fp_to_sint c1fp) -> c1 2100 if (N0CFP) 2101 return DAG.getNode(ISD::FP_TO_SINT, VT, N0); 2102 return SDOperand(); 2103} 2104 2105SDOperand DAGCombiner::visitFP_TO_UINT(SDNode *N) { 2106 SDOperand N0 = N->getOperand(0); 2107 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2108 MVT::ValueType VT = N->getValueType(0); 2109 2110 // fold (fp_to_uint c1fp) -> c1 2111 if (N0CFP) 2112 return DAG.getNode(ISD::FP_TO_UINT, VT, N0); 2113 return SDOperand(); 2114} 2115 2116SDOperand DAGCombiner::visitFP_ROUND(SDNode *N) { 2117 SDOperand N0 = N->getOperand(0); 2118 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2119 MVT::ValueType VT = N->getValueType(0); 2120 2121 // fold (fp_round c1fp) -> c1fp 2122 if (N0CFP) 2123 return DAG.getNode(ISD::FP_ROUND, VT, N0); 2124 2125 // fold (fp_round (fp_extend x)) -> x 2126 if (N0.getOpcode() == ISD::FP_EXTEND && VT == N0.getOperand(0).getValueType()) 2127 return N0.getOperand(0); 2128 2129 // fold (fp_round (copysign X, Y)) -> (copysign (fp_round X), Y) 2130 if (N0.getOpcode() == ISD::FCOPYSIGN && N0.Val->hasOneUse()) { 2131 SDOperand Tmp = DAG.getNode(ISD::FP_ROUND, VT, N0.getOperand(0)); 2132 AddToWorkList(Tmp.Val); 2133 return DAG.getNode(ISD::FCOPYSIGN, VT, Tmp, N0.getOperand(1)); 2134 } 2135 2136 return SDOperand(); 2137} 2138 2139SDOperand DAGCombiner::visitFP_ROUND_INREG(SDNode *N) { 2140 SDOperand N0 = N->getOperand(0); 2141 MVT::ValueType VT = N->getValueType(0); 2142 MVT::ValueType EVT = cast<VTSDNode>(N->getOperand(1))->getVT(); 2143 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2144 2145 // fold (fp_round_inreg c1fp) -> c1fp 2146 if (N0CFP) { 2147 SDOperand Round = DAG.getConstantFP(N0CFP->getValue(), EVT); 2148 return DAG.getNode(ISD::FP_EXTEND, VT, Round); 2149 } 2150 return SDOperand(); 2151} 2152 2153SDOperand DAGCombiner::visitFP_EXTEND(SDNode *N) { 2154 SDOperand N0 = N->getOperand(0); 2155 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2156 MVT::ValueType VT = N->getValueType(0); 2157 2158 // fold (fp_extend c1fp) -> c1fp 2159 if (N0CFP) 2160 return DAG.getNode(ISD::FP_EXTEND, VT, N0); 2161 return SDOperand(); 2162} 2163 2164SDOperand DAGCombiner::visitFNEG(SDNode *N) { 2165 SDOperand N0 = N->getOperand(0); 2166 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2167 MVT::ValueType VT = N->getValueType(0); 2168 2169 // fold (fneg c1) -> -c1 2170 if (N0CFP) 2171 return DAG.getNode(ISD::FNEG, VT, N0); 2172 // fold (fneg (sub x, y)) -> (sub y, x) 2173 if (N0.getOpcode() == ISD::SUB) 2174 return DAG.getNode(ISD::SUB, VT, N0.getOperand(1), N0.getOperand(0)); 2175 // fold (fneg (fneg x)) -> x 2176 if (N0.getOpcode() == ISD::FNEG) 2177 return N0.getOperand(0); 2178 return SDOperand(); 2179} 2180 2181SDOperand DAGCombiner::visitFABS(SDNode *N) { 2182 SDOperand N0 = N->getOperand(0); 2183 ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0); 2184 MVT::ValueType VT = N->getValueType(0); 2185 2186 // fold (fabs c1) -> fabs(c1) 2187 if (N0CFP) 2188 return DAG.getNode(ISD::FABS, VT, N0); 2189 // fold (fabs (fabs x)) -> (fabs x) 2190 if (N0.getOpcode() == ISD::FABS) 2191 return N->getOperand(0); 2192 // fold (fabs (fneg x)) -> (fabs x) 2193 // fold (fabs (fcopysign x, y)) -> (fabs x) 2194 if (N0.getOpcode() == ISD::FNEG || N0.getOpcode() == ISD::FCOPYSIGN) 2195 return DAG.getNode(ISD::FABS, VT, N0.getOperand(0)); 2196 2197 return SDOperand(); 2198} 2199 2200SDOperand DAGCombiner::visitBRCOND(SDNode *N) { 2201 SDOperand Chain = N->getOperand(0); 2202 SDOperand N1 = N->getOperand(1); 2203 SDOperand N2 = N->getOperand(2); 2204 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1); 2205 2206 // never taken branch, fold to chain 2207 if (N1C && N1C->isNullValue()) 2208 return Chain; 2209 // unconditional branch 2210 if (N1C && N1C->getValue() == 1) 2211 return DAG.getNode(ISD::BR, MVT::Other, Chain, N2); 2212 // fold a brcond with a setcc condition into a BR_CC node if BR_CC is legal 2213 // on the target. 2214 if (N1.getOpcode() == ISD::SETCC && 2215 TLI.isOperationLegal(ISD::BR_CC, MVT::Other)) { 2216 return DAG.getNode(ISD::BR_CC, MVT::Other, Chain, N1.getOperand(2), 2217 N1.getOperand(0), N1.getOperand(1), N2); 2218 } 2219 return SDOperand(); 2220} 2221 2222// Operand List for BR_CC: Chain, CondCC, CondLHS, CondRHS, DestBB. 2223// 2224SDOperand DAGCombiner::visitBR_CC(SDNode *N) { 2225 CondCodeSDNode *CC = cast<CondCodeSDNode>(N->getOperand(1)); 2226 SDOperand CondLHS = N->getOperand(2), CondRHS = N->getOperand(3); 2227 2228 // Use SimplifySetCC to simplify SETCC's. 2229 SDOperand Simp = SimplifySetCC(MVT::i1, CondLHS, CondRHS, CC->get(), false); 2230 ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(Simp.Val); 2231 2232 // fold br_cc true, dest -> br dest (unconditional branch) 2233 if (SCCC && SCCC->getValue()) 2234 return DAG.getNode(ISD::BR, MVT::Other, N->getOperand(0), 2235 N->getOperand(4)); 2236 // fold br_cc false, dest -> unconditional fall through 2237 if (SCCC && SCCC->isNullValue()) 2238 return N->getOperand(0); 2239 // fold to a simpler setcc 2240 if (Simp.Val && Simp.getOpcode() == ISD::SETCC) 2241 return DAG.getNode(ISD::BR_CC, MVT::Other, N->getOperand(0), 2242 Simp.getOperand(2), Simp.getOperand(0), 2243 Simp.getOperand(1), N->getOperand(4)); 2244 return SDOperand(); 2245} 2246 2247SDOperand DAGCombiner::visitLOAD(SDNode *N) { 2248 SDOperand Chain = N->getOperand(0); 2249 SDOperand Ptr = N->getOperand(1); 2250 SDOperand SrcValue = N->getOperand(2); 2251 2252 // If this load is directly stored, replace the load value with the stored 2253 // value. 2254 // TODO: Handle store large -> read small portion. 2255 // TODO: Handle TRUNCSTORE/EXTLOAD 2256 if (Chain.getOpcode() == ISD::STORE && Chain.getOperand(2) == Ptr && 2257 Chain.getOperand(1).getValueType() == N->getValueType(0)) 2258 return CombineTo(N, Chain.getOperand(1), Chain); 2259 2260 return SDOperand(); 2261} 2262 2263SDOperand DAGCombiner::visitSTORE(SDNode *N) { 2264 SDOperand Chain = N->getOperand(0); 2265 SDOperand Value = N->getOperand(1); 2266 SDOperand Ptr = N->getOperand(2); 2267 SDOperand SrcValue = N->getOperand(3); 2268 2269 // If this is a store that kills a previous store, remove the previous store. 2270 if (Chain.getOpcode() == ISD::STORE && Chain.getOperand(2) == Ptr && 2271 Chain.Val->hasOneUse() /* Avoid introducing DAG cycles */ && 2272 // Make sure that these stores are the same value type: 2273 // FIXME: we really care that the second store is >= size of the first. 2274 Value.getValueType() == Chain.getOperand(1).getValueType()) { 2275 // Create a new store of Value that replaces both stores. 2276 SDNode *PrevStore = Chain.Val; 2277 if (PrevStore->getOperand(1) == Value) // Same value multiply stored. 2278 return Chain; 2279 SDOperand NewStore = DAG.getNode(ISD::STORE, MVT::Other, 2280 PrevStore->getOperand(0), Value, Ptr, 2281 SrcValue); 2282 CombineTo(N, NewStore); // Nuke this store. 2283 CombineTo(PrevStore, NewStore); // Nuke the previous store. 2284 return SDOperand(N, 0); 2285 } 2286 2287 // If this is a store of a bit convert, store the input value. 2288 // FIXME: This needs to know that the resultant store does not need a 2289 // higher alignment than the original. 2290 if (0 && Value.getOpcode() == ISD::BIT_CONVERT) 2291 return DAG.getNode(ISD::STORE, MVT::Other, Chain, Value.getOperand(0), 2292 Ptr, SrcValue); 2293 2294 return SDOperand(); 2295} 2296 2297SDOperand DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) { 2298 SDOperand InVec = N->getOperand(0); 2299 SDOperand InVal = N->getOperand(1); 2300 SDOperand EltNo = N->getOperand(2); 2301 2302 // If the invec is a BUILD_VECTOR and if EltNo is a constant, build a new 2303 // vector with the inserted element. 2304 if (InVec.getOpcode() == ISD::BUILD_VECTOR && isa<ConstantSDNode>(EltNo)) { 2305 unsigned Elt = cast<ConstantSDNode>(EltNo)->getValue(); 2306 std::vector<SDOperand> Ops(InVec.Val->op_begin(), InVec.Val->op_end()); 2307 if (Elt < Ops.size()) 2308 Ops[Elt] = InVal; 2309 return DAG.getNode(ISD::BUILD_VECTOR, InVec.getValueType(), Ops); 2310 } 2311 2312 return SDOperand(); 2313} 2314 2315SDOperand DAGCombiner::visitVINSERT_VECTOR_ELT(SDNode *N) { 2316 SDOperand InVec = N->getOperand(0); 2317 SDOperand InVal = N->getOperand(1); 2318 SDOperand EltNo = N->getOperand(2); 2319 SDOperand NumElts = N->getOperand(3); 2320 SDOperand EltType = N->getOperand(4); 2321 2322 // If the invec is a VBUILD_VECTOR and if EltNo is a constant, build a new 2323 // vector with the inserted element. 2324 if (InVec.getOpcode() == ISD::VBUILD_VECTOR && isa<ConstantSDNode>(EltNo)) { 2325 unsigned Elt = cast<ConstantSDNode>(EltNo)->getValue(); 2326 std::vector<SDOperand> Ops(InVec.Val->op_begin(), InVec.Val->op_end()); 2327 if (Elt < Ops.size()-2) 2328 Ops[Elt] = InVal; 2329 return DAG.getNode(ISD::VBUILD_VECTOR, InVec.getValueType(), Ops); 2330 } 2331 2332 return SDOperand(); 2333} 2334 2335SDOperand DAGCombiner::SimplifySelect(SDOperand N0, SDOperand N1, SDOperand N2){ 2336 assert(N0.getOpcode() ==ISD::SETCC && "First argument must be a SetCC node!"); 2337 2338 SDOperand SCC = SimplifySelectCC(N0.getOperand(0), N0.getOperand(1), N1, N2, 2339 cast<CondCodeSDNode>(N0.getOperand(2))->get()); 2340 // If we got a simplified select_cc node back from SimplifySelectCC, then 2341 // break it down into a new SETCC node, and a new SELECT node, and then return 2342 // the SELECT node, since we were called with a SELECT node. 2343 if (SCC.Val) { 2344 // Check to see if we got a select_cc back (to turn into setcc/select). 2345 // Otherwise, just return whatever node we got back, like fabs. 2346 if (SCC.getOpcode() == ISD::SELECT_CC) { 2347 SDOperand SETCC = DAG.getNode(ISD::SETCC, N0.getValueType(), 2348 SCC.getOperand(0), SCC.getOperand(1), 2349 SCC.getOperand(4)); 2350 AddToWorkList(SETCC.Val); 2351 return DAG.getNode(ISD::SELECT, SCC.getValueType(), SCC.getOperand(2), 2352 SCC.getOperand(3), SETCC); 2353 } 2354 return SCC; 2355 } 2356 return SDOperand(); 2357} 2358 2359/// SimplifySelectOps - Given a SELECT or a SELECT_CC node, where LHS and RHS 2360/// are the two values being selected between, see if we can simplify the 2361/// select. 2362/// 2363bool DAGCombiner::SimplifySelectOps(SDNode *TheSelect, SDOperand LHS, 2364 SDOperand RHS) { 2365 2366 // If this is a select from two identical things, try to pull the operation 2367 // through the select. 2368 if (LHS.getOpcode() == RHS.getOpcode() && LHS.hasOneUse() && RHS.hasOneUse()){ 2369#if 0 2370 std::cerr << "SELECT: ["; LHS.Val->dump(); 2371 std::cerr << "] ["; RHS.Val->dump(); 2372 std::cerr << "]\n"; 2373#endif 2374 2375 // If this is a load and the token chain is identical, replace the select 2376 // of two loads with a load through a select of the address to load from. 2377 // This triggers in things like "select bool X, 10.0, 123.0" after the FP 2378 // constants have been dropped into the constant pool. 2379 if ((LHS.getOpcode() == ISD::LOAD || 2380 LHS.getOpcode() == ISD::EXTLOAD || 2381 LHS.getOpcode() == ISD::ZEXTLOAD || 2382 LHS.getOpcode() == ISD::SEXTLOAD) && 2383 // Token chains must be identical. 2384 LHS.getOperand(0) == RHS.getOperand(0) && 2385 // If this is an EXTLOAD, the VT's must match. 2386 (LHS.getOpcode() == ISD::LOAD || 2387 LHS.getOperand(3) == RHS.getOperand(3))) { 2388 // FIXME: this conflates two src values, discarding one. This is not 2389 // the right thing to do, but nothing uses srcvalues now. When they do, 2390 // turn SrcValue into a list of locations. 2391 SDOperand Addr; 2392 if (TheSelect->getOpcode() == ISD::SELECT) 2393 Addr = DAG.getNode(ISD::SELECT, LHS.getOperand(1).getValueType(), 2394 TheSelect->getOperand(0), LHS.getOperand(1), 2395 RHS.getOperand(1)); 2396 else 2397 Addr = DAG.getNode(ISD::SELECT_CC, LHS.getOperand(1).getValueType(), 2398 TheSelect->getOperand(0), 2399 TheSelect->getOperand(1), 2400 LHS.getOperand(1), RHS.getOperand(1), 2401 TheSelect->getOperand(4)); 2402 2403 SDOperand Load; 2404 if (LHS.getOpcode() == ISD::LOAD) 2405 Load = DAG.getLoad(TheSelect->getValueType(0), LHS.getOperand(0), 2406 Addr, LHS.getOperand(2)); 2407 else 2408 Load = DAG.getExtLoad(LHS.getOpcode(), TheSelect->getValueType(0), 2409 LHS.getOperand(0), Addr, LHS.getOperand(2), 2410 cast<VTSDNode>(LHS.getOperand(3))->getVT()); 2411 // Users of the select now use the result of the load. 2412 CombineTo(TheSelect, Load); 2413 2414 // Users of the old loads now use the new load's chain. We know the 2415 // old-load value is dead now. 2416 CombineTo(LHS.Val, Load.getValue(0), Load.getValue(1)); 2417 CombineTo(RHS.Val, Load.getValue(0), Load.getValue(1)); 2418 return true; 2419 } 2420 } 2421 2422 return false; 2423} 2424 2425SDOperand DAGCombiner::SimplifySelectCC(SDOperand N0, SDOperand N1, 2426 SDOperand N2, SDOperand N3, 2427 ISD::CondCode CC) { 2428 2429 MVT::ValueType VT = N2.getValueType(); 2430 ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val); 2431 ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val); 2432 ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2.Val); 2433 ConstantSDNode *N3C = dyn_cast<ConstantSDNode>(N3.Val); 2434 2435 // Determine if the condition we're dealing with is constant 2436 SDOperand SCC = SimplifySetCC(TLI.getSetCCResultTy(), N0, N1, CC, false); 2437 ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val); 2438 2439 // fold select_cc true, x, y -> x 2440 if (SCCC && SCCC->getValue()) 2441 return N2; 2442 // fold select_cc false, x, y -> y 2443 if (SCCC && SCCC->getValue() == 0) 2444 return N3; 2445 2446 // Check to see if we can simplify the select into an fabs node 2447 if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N1)) { 2448 // Allow either -0.0 or 0.0 2449 if (CFP->getValue() == 0.0) { 2450 // select (setg[te] X, +/-0.0), X, fneg(X) -> fabs 2451 if ((CC == ISD::SETGE || CC == ISD::SETGT) && 2452 N0 == N2 && N3.getOpcode() == ISD::FNEG && 2453 N2 == N3.getOperand(0)) 2454 return DAG.getNode(ISD::FABS, VT, N0); 2455 2456 // select (setl[te] X, +/-0.0), fneg(X), X -> fabs 2457 if ((CC == ISD::SETLT || CC == ISD::SETLE) && 2458 N0 == N3 && N2.getOpcode() == ISD::FNEG && 2459 N2.getOperand(0) == N3) 2460 return DAG.getNode(ISD::FABS, VT, N3); 2461 } 2462 } 2463 2464 // Check to see if we can perform the "gzip trick", transforming 2465 // select_cc setlt X, 0, A, 0 -> and (sra X, size(X)-1), A 2466 if (N1C && N1C->isNullValue() && N3C && N3C->isNullValue() && 2467 MVT::isInteger(N0.getValueType()) && 2468 MVT::isInteger(N2.getValueType()) && CC == ISD::SETLT) { 2469 MVT::ValueType XType = N0.getValueType(); 2470 MVT::ValueType AType = N2.getValueType(); 2471 if (XType >= AType) { 2472 // and (sra X, size(X)-1, A) -> "and (srl X, C2), A" iff A is a 2473 // single-bit constant. 2474 if (N2C && ((N2C->getValue() & (N2C->getValue()-1)) == 0)) { 2475 unsigned ShCtV = Log2_64(N2C->getValue()); 2476 ShCtV = MVT::getSizeInBits(XType)-ShCtV-1; 2477 SDOperand ShCt = DAG.getConstant(ShCtV, TLI.getShiftAmountTy()); 2478 SDOperand Shift = DAG.getNode(ISD::SRL, XType, N0, ShCt); 2479 AddToWorkList(Shift.Val); 2480 if (XType > AType) { 2481 Shift = DAG.getNode(ISD::TRUNCATE, AType, Shift); 2482 AddToWorkList(Shift.Val); 2483 } 2484 return DAG.getNode(ISD::AND, AType, Shift, N2); 2485 } 2486 SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0, 2487 DAG.getConstant(MVT::getSizeInBits(XType)-1, 2488 TLI.getShiftAmountTy())); 2489 AddToWorkList(Shift.Val); 2490 if (XType > AType) { 2491 Shift = DAG.getNode(ISD::TRUNCATE, AType, Shift); 2492 AddToWorkList(Shift.Val); 2493 } 2494 return DAG.getNode(ISD::AND, AType, Shift, N2); 2495 } 2496 } 2497 2498 // fold select C, 16, 0 -> shl C, 4 2499 if (N2C && N3C && N3C->isNullValue() && isPowerOf2_64(N2C->getValue()) && 2500 TLI.getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult) { 2501 // Get a SetCC of the condition 2502 // FIXME: Should probably make sure that setcc is legal if we ever have a 2503 // target where it isn't. 2504 SDOperand Temp, SCC; 2505 // cast from setcc result type to select result type 2506 if (AfterLegalize) { 2507 SCC = DAG.getSetCC(TLI.getSetCCResultTy(), N0, N1, CC); 2508 Temp = DAG.getZeroExtendInReg(SCC, N2.getValueType()); 2509 } else { 2510 SCC = DAG.getSetCC(MVT::i1, N0, N1, CC); 2511 Temp = DAG.getNode(ISD::ZERO_EXTEND, N2.getValueType(), SCC); 2512 } 2513 AddToWorkList(SCC.Val); 2514 AddToWorkList(Temp.Val); 2515 // shl setcc result by log2 n2c 2516 return DAG.getNode(ISD::SHL, N2.getValueType(), Temp, 2517 DAG.getConstant(Log2_64(N2C->getValue()), 2518 TLI.getShiftAmountTy())); 2519 } 2520 2521 // Check to see if this is the equivalent of setcc 2522 // FIXME: Turn all of these into setcc if setcc if setcc is legal 2523 // otherwise, go ahead with the folds. 2524 if (0 && N3C && N3C->isNullValue() && N2C && (N2C->getValue() == 1ULL)) { 2525 MVT::ValueType XType = N0.getValueType(); 2526 if (TLI.isOperationLegal(ISD::SETCC, TLI.getSetCCResultTy())) { 2527 SDOperand Res = DAG.getSetCC(TLI.getSetCCResultTy(), N0, N1, CC); 2528 if (Res.getValueType() != VT) 2529 Res = DAG.getNode(ISD::ZERO_EXTEND, VT, Res); 2530 return Res; 2531 } 2532 2533 // seteq X, 0 -> srl (ctlz X, log2(size(X))) 2534 if (N1C && N1C->isNullValue() && CC == ISD::SETEQ && 2535 TLI.isOperationLegal(ISD::CTLZ, XType)) { 2536 SDOperand Ctlz = DAG.getNode(ISD::CTLZ, XType, N0); 2537 return DAG.getNode(ISD::SRL, XType, Ctlz, 2538 DAG.getConstant(Log2_32(MVT::getSizeInBits(XType)), 2539 TLI.getShiftAmountTy())); 2540 } 2541 // setgt X, 0 -> srl (and (-X, ~X), size(X)-1) 2542 if (N1C && N1C->isNullValue() && CC == ISD::SETGT) { 2543 SDOperand NegN0 = DAG.getNode(ISD::SUB, XType, DAG.getConstant(0, XType), 2544 N0); 2545 SDOperand NotN0 = DAG.getNode(ISD::XOR, XType, N0, 2546 DAG.getConstant(~0ULL, XType)); 2547 return DAG.getNode(ISD::SRL, XType, 2548 DAG.getNode(ISD::AND, XType, NegN0, NotN0), 2549 DAG.getConstant(MVT::getSizeInBits(XType)-1, 2550 TLI.getShiftAmountTy())); 2551 } 2552 // setgt X, -1 -> xor (srl (X, size(X)-1), 1) 2553 if (N1C && N1C->isAllOnesValue() && CC == ISD::SETGT) { 2554 SDOperand Sign = DAG.getNode(ISD::SRL, XType, N0, 2555 DAG.getConstant(MVT::getSizeInBits(XType)-1, 2556 TLI.getShiftAmountTy())); 2557 return DAG.getNode(ISD::XOR, XType, Sign, DAG.getConstant(1, XType)); 2558 } 2559 } 2560 2561 // Check to see if this is an integer abs. select_cc setl[te] X, 0, -X, X -> 2562 // Y = sra (X, size(X)-1); xor (add (X, Y), Y) 2563 if (N1C && N1C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE) && 2564 N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1)) { 2565 if (ConstantSDNode *SubC = dyn_cast<ConstantSDNode>(N2.getOperand(0))) { 2566 MVT::ValueType XType = N0.getValueType(); 2567 if (SubC->isNullValue() && MVT::isInteger(XType)) { 2568 SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0, 2569 DAG.getConstant(MVT::getSizeInBits(XType)-1, 2570 TLI.getShiftAmountTy())); 2571 SDOperand Add = DAG.getNode(ISD::ADD, XType, N0, Shift); 2572 AddToWorkList(Shift.Val); 2573 AddToWorkList(Add.Val); 2574 return DAG.getNode(ISD::XOR, XType, Add, Shift); 2575 } 2576 } 2577 } 2578 2579 return SDOperand(); 2580} 2581 2582SDOperand DAGCombiner::SimplifySetCC(MVT::ValueType VT, SDOperand N0, 2583 SDOperand N1, ISD::CondCode Cond, 2584 bool foldBooleans) { 2585 // These setcc operations always fold. 2586 switch (Cond) { 2587 default: break; 2588 case ISD::SETFALSE: 2589 case ISD::SETFALSE2: return DAG.getConstant(0, VT); 2590 case ISD::SETTRUE: 2591 case ISD::SETTRUE2: return DAG.getConstant(1, VT); 2592 } 2593 2594 if (ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val)) { 2595 uint64_t C1 = N1C->getValue(); 2596 if (ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val)) { 2597 uint64_t C0 = N0C->getValue(); 2598 2599 // Sign extend the operands if required 2600 if (ISD::isSignedIntSetCC(Cond)) { 2601 C0 = N0C->getSignExtended(); 2602 C1 = N1C->getSignExtended(); 2603 } 2604 2605 switch (Cond) { 2606 default: assert(0 && "Unknown integer setcc!"); 2607 case ISD::SETEQ: return DAG.getConstant(C0 == C1, VT); 2608 case ISD::SETNE: return DAG.getConstant(C0 != C1, VT); 2609 case ISD::SETULT: return DAG.getConstant(C0 < C1, VT); 2610 case ISD::SETUGT: return DAG.getConstant(C0 > C1, VT); 2611 case ISD::SETULE: return DAG.getConstant(C0 <= C1, VT); 2612 case ISD::SETUGE: return DAG.getConstant(C0 >= C1, VT); 2613 case ISD::SETLT: return DAG.getConstant((int64_t)C0 < (int64_t)C1, VT); 2614 case ISD::SETGT: return DAG.getConstant((int64_t)C0 > (int64_t)C1, VT); 2615 case ISD::SETLE: return DAG.getConstant((int64_t)C0 <= (int64_t)C1, VT); 2616 case ISD::SETGE: return DAG.getConstant((int64_t)C0 >= (int64_t)C1, VT); 2617 } 2618 } else { 2619 // If the LHS is a ZERO_EXTEND, perform the comparison on the input. 2620 if (N0.getOpcode() == ISD::ZERO_EXTEND) { 2621 unsigned InSize = MVT::getSizeInBits(N0.getOperand(0).getValueType()); 2622 2623 // If the comparison constant has bits in the upper part, the 2624 // zero-extended value could never match. 2625 if (C1 & (~0ULL << InSize)) { 2626 unsigned VSize = MVT::getSizeInBits(N0.getValueType()); 2627 switch (Cond) { 2628 case ISD::SETUGT: 2629 case ISD::SETUGE: 2630 case ISD::SETEQ: return DAG.getConstant(0, VT); 2631 case ISD::SETULT: 2632 case ISD::SETULE: 2633 case ISD::SETNE: return DAG.getConstant(1, VT); 2634 case ISD::SETGT: 2635 case ISD::SETGE: 2636 // True if the sign bit of C1 is set. 2637 return DAG.getConstant((C1 & (1ULL << VSize)) != 0, VT); 2638 case ISD::SETLT: 2639 case ISD::SETLE: 2640 // True if the sign bit of C1 isn't set. 2641 return DAG.getConstant((C1 & (1ULL << VSize)) == 0, VT); 2642 default: 2643 break; 2644 } 2645 } 2646 2647 // Otherwise, we can perform the comparison with the low bits. 2648 switch (Cond) { 2649 case ISD::SETEQ: 2650 case ISD::SETNE: 2651 case ISD::SETUGT: 2652 case ISD::SETUGE: 2653 case ISD::SETULT: 2654 case ISD::SETULE: 2655 return DAG.getSetCC(VT, N0.getOperand(0), 2656 DAG.getConstant(C1, N0.getOperand(0).getValueType()), 2657 Cond); 2658 default: 2659 break; // todo, be more careful with signed comparisons 2660 } 2661 } else if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG && 2662 (Cond == ISD::SETEQ || Cond == ISD::SETNE)) { 2663 MVT::ValueType ExtSrcTy = cast<VTSDNode>(N0.getOperand(1))->getVT(); 2664 unsigned ExtSrcTyBits = MVT::getSizeInBits(ExtSrcTy); 2665 MVT::ValueType ExtDstTy = N0.getValueType(); 2666 unsigned ExtDstTyBits = MVT::getSizeInBits(ExtDstTy); 2667 2668 // If the extended part has any inconsistent bits, it cannot ever 2669 // compare equal. In other words, they have to be all ones or all 2670 // zeros. 2671 uint64_t ExtBits = 2672 (~0ULL >> (64-ExtSrcTyBits)) & (~0ULL << (ExtDstTyBits-1)); 2673 if ((C1 & ExtBits) != 0 && (C1 & ExtBits) != ExtBits) 2674 return DAG.getConstant(Cond == ISD::SETNE, VT); 2675 2676 SDOperand ZextOp; 2677 MVT::ValueType Op0Ty = N0.getOperand(0).getValueType(); 2678 if (Op0Ty == ExtSrcTy) { 2679 ZextOp = N0.getOperand(0); 2680 } else { 2681 int64_t Imm = ~0ULL >> (64-ExtSrcTyBits); 2682 ZextOp = DAG.getNode(ISD::AND, Op0Ty, N0.getOperand(0), 2683 DAG.getConstant(Imm, Op0Ty)); 2684 } 2685 AddToWorkList(ZextOp.Val); 2686 // Otherwise, make this a use of a zext. 2687 return DAG.getSetCC(VT, ZextOp, 2688 DAG.getConstant(C1 & (~0ULL>>(64-ExtSrcTyBits)), 2689 ExtDstTy), 2690 Cond); 2691 } else if ((N1C->getValue() == 0 || N1C->getValue() == 1) && 2692 (Cond == ISD::SETEQ || Cond == ISD::SETNE) && 2693 (N0.getOpcode() == ISD::XOR || 2694 (N0.getOpcode() == ISD::AND && 2695 N0.getOperand(0).getOpcode() == ISD::XOR && 2696 N0.getOperand(1) == N0.getOperand(0).getOperand(1))) && 2697 isa<ConstantSDNode>(N0.getOperand(1)) && 2698 cast<ConstantSDNode>(N0.getOperand(1))->getValue() == 1) { 2699 // If this is (X^1) == 0/1, swap the RHS and eliminate the xor. We can 2700 // only do this if the top bits are known zero. 2701 if (TLI.MaskedValueIsZero(N1, 2702 MVT::getIntVTBitMask(N0.getValueType())-1)) { 2703 // Okay, get the un-inverted input value. 2704 SDOperand Val; 2705 if (N0.getOpcode() == ISD::XOR) 2706 Val = N0.getOperand(0); 2707 else { 2708 assert(N0.getOpcode() == ISD::AND && 2709 N0.getOperand(0).getOpcode() == ISD::XOR); 2710 // ((X^1)&1)^1 -> X & 1 2711 Val = DAG.getNode(ISD::AND, N0.getValueType(), 2712 N0.getOperand(0).getOperand(0), N0.getOperand(1)); 2713 } 2714 return DAG.getSetCC(VT, Val, N1, 2715 Cond == ISD::SETEQ ? ISD::SETNE : ISD::SETEQ); 2716 } 2717 } 2718 2719 uint64_t MinVal, MaxVal; 2720 unsigned OperandBitSize = MVT::getSizeInBits(N1C->getValueType(0)); 2721 if (ISD::isSignedIntSetCC(Cond)) { 2722 MinVal = 1ULL << (OperandBitSize-1); 2723 if (OperandBitSize != 1) // Avoid X >> 64, which is undefined. 2724 MaxVal = ~0ULL >> (65-OperandBitSize); 2725 else 2726 MaxVal = 0; 2727 } else { 2728 MinVal = 0; 2729 MaxVal = ~0ULL >> (64-OperandBitSize); 2730 } 2731 2732 // Canonicalize GE/LE comparisons to use GT/LT comparisons. 2733 if (Cond == ISD::SETGE || Cond == ISD::SETUGE) { 2734 if (C1 == MinVal) return DAG.getConstant(1, VT); // X >= MIN --> true 2735 --C1; // X >= C0 --> X > (C0-1) 2736 return DAG.getSetCC(VT, N0, DAG.getConstant(C1, N1.getValueType()), 2737 (Cond == ISD::SETGE) ? ISD::SETGT : ISD::SETUGT); 2738 } 2739 2740 if (Cond == ISD::SETLE || Cond == ISD::SETULE) { 2741 if (C1 == MaxVal) return DAG.getConstant(1, VT); // X <= MAX --> true 2742 ++C1; // X <= C0 --> X < (C0+1) 2743 return DAG.getSetCC(VT, N0, DAG.getConstant(C1, N1.getValueType()), 2744 (Cond == ISD::SETLE) ? ISD::SETLT : ISD::SETULT); 2745 } 2746 2747 if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MinVal) 2748 return DAG.getConstant(0, VT); // X < MIN --> false 2749 2750 // Canonicalize setgt X, Min --> setne X, Min 2751 if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MinVal) 2752 return DAG.getSetCC(VT, N0, N1, ISD::SETNE); 2753 // Canonicalize setlt X, Max --> setne X, Max 2754 if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MaxVal) 2755 return DAG.getSetCC(VT, N0, N1, ISD::SETNE); 2756 2757 // If we have setult X, 1, turn it into seteq X, 0 2758 if ((Cond == ISD::SETLT || Cond == ISD::SETULT) && C1 == MinVal+1) 2759 return DAG.getSetCC(VT, N0, DAG.getConstant(MinVal, N0.getValueType()), 2760 ISD::SETEQ); 2761 // If we have setugt X, Max-1, turn it into seteq X, Max 2762 else if ((Cond == ISD::SETGT || Cond == ISD::SETUGT) && C1 == MaxVal-1) 2763 return DAG.getSetCC(VT, N0, DAG.getConstant(MaxVal, N0.getValueType()), 2764 ISD::SETEQ); 2765 2766 // If we have "setcc X, C0", check to see if we can shrink the immediate 2767 // by changing cc. 2768 2769 // SETUGT X, SINTMAX -> SETLT X, 0 2770 if (Cond == ISD::SETUGT && OperandBitSize != 1 && 2771 C1 == (~0ULL >> (65-OperandBitSize))) 2772 return DAG.getSetCC(VT, N0, DAG.getConstant(0, N1.getValueType()), 2773 ISD::SETLT); 2774 2775 // FIXME: Implement the rest of these. 2776 2777 // Fold bit comparisons when we can. 2778 if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) && 2779 VT == N0.getValueType() && N0.getOpcode() == ISD::AND) 2780 if (ConstantSDNode *AndRHS = 2781 dyn_cast<ConstantSDNode>(N0.getOperand(1))) { 2782 if (Cond == ISD::SETNE && C1 == 0) {// (X & 8) != 0 --> (X & 8) >> 3 2783 // Perform the xform if the AND RHS is a single bit. 2784 if ((AndRHS->getValue() & (AndRHS->getValue()-1)) == 0) { 2785 return DAG.getNode(ISD::SRL, VT, N0, 2786 DAG.getConstant(Log2_64(AndRHS->getValue()), 2787 TLI.getShiftAmountTy())); 2788 } 2789 } else if (Cond == ISD::SETEQ && C1 == AndRHS->getValue()) { 2790 // (X & 8) == 8 --> (X & 8) >> 3 2791 // Perform the xform if C1 is a single bit. 2792 if ((C1 & (C1-1)) == 0) { 2793 return DAG.getNode(ISD::SRL, VT, N0, 2794 DAG.getConstant(Log2_64(C1),TLI.getShiftAmountTy())); 2795 } 2796 } 2797 } 2798 } 2799 } else if (isa<ConstantSDNode>(N0.Val)) { 2800 // Ensure that the constant occurs on the RHS. 2801 return DAG.getSetCC(VT, N1, N0, ISD::getSetCCSwappedOperands(Cond)); 2802 } 2803 2804 if (ConstantFPSDNode *N0C = dyn_cast<ConstantFPSDNode>(N0.Val)) 2805 if (ConstantFPSDNode *N1C = dyn_cast<ConstantFPSDNode>(N1.Val)) { 2806 double C0 = N0C->getValue(), C1 = N1C->getValue(); 2807 2808 switch (Cond) { 2809 default: break; // FIXME: Implement the rest of these! 2810 case ISD::SETEQ: return DAG.getConstant(C0 == C1, VT); 2811 case ISD::SETNE: return DAG.getConstant(C0 != C1, VT); 2812 case ISD::SETLT: return DAG.getConstant(C0 < C1, VT); 2813 case ISD::SETGT: return DAG.getConstant(C0 > C1, VT); 2814 case ISD::SETLE: return DAG.getConstant(C0 <= C1, VT); 2815 case ISD::SETGE: return DAG.getConstant(C0 >= C1, VT); 2816 } 2817 } else { 2818 // Ensure that the constant occurs on the RHS. 2819 return DAG.getSetCC(VT, N1, N0, ISD::getSetCCSwappedOperands(Cond)); 2820 } 2821 2822 if (N0 == N1) { 2823 // We can always fold X == Y for integer setcc's. 2824 if (MVT::isInteger(N0.getValueType())) 2825 return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT); 2826 unsigned UOF = ISD::getUnorderedFlavor(Cond); 2827 if (UOF == 2) // FP operators that are undefined on NaNs. 2828 return DAG.getConstant(ISD::isTrueWhenEqual(Cond), VT); 2829 if (UOF == unsigned(ISD::isTrueWhenEqual(Cond))) 2830 return DAG.getConstant(UOF, VT); 2831 // Otherwise, we can't fold it. However, we can simplify it to SETUO/SETO 2832 // if it is not already. 2833 ISD::CondCode NewCond = UOF == 0 ? ISD::SETO : ISD::SETUO; 2834 if (NewCond != Cond) 2835 return DAG.getSetCC(VT, N0, N1, NewCond); 2836 } 2837 2838 if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) && 2839 MVT::isInteger(N0.getValueType())) { 2840 if (N0.getOpcode() == ISD::ADD || N0.getOpcode() == ISD::SUB || 2841 N0.getOpcode() == ISD::XOR) { 2842 // Simplify (X+Y) == (X+Z) --> Y == Z 2843 if (N0.getOpcode() == N1.getOpcode()) { 2844 if (N0.getOperand(0) == N1.getOperand(0)) 2845 return DAG.getSetCC(VT, N0.getOperand(1), N1.getOperand(1), Cond); 2846 if (N0.getOperand(1) == N1.getOperand(1)) 2847 return DAG.getSetCC(VT, N0.getOperand(0), N1.getOperand(0), Cond); 2848 if (isCommutativeBinOp(N0.getOpcode())) { 2849 // If X op Y == Y op X, try other combinations. 2850 if (N0.getOperand(0) == N1.getOperand(1)) 2851 return DAG.getSetCC(VT, N0.getOperand(1), N1.getOperand(0), Cond); 2852 if (N0.getOperand(1) == N1.getOperand(0)) 2853 return DAG.getSetCC(VT, N0.getOperand(0), N1.getOperand(1), Cond); 2854 } 2855 } 2856 2857 if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(N1)) { 2858 if (ConstantSDNode *LHSR = dyn_cast<ConstantSDNode>(N0.getOperand(1))) { 2859 // Turn (X+C1) == C2 --> X == C2-C1 2860 if (N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse()) { 2861 return DAG.getSetCC(VT, N0.getOperand(0), 2862 DAG.getConstant(RHSC->getValue()-LHSR->getValue(), 2863 N0.getValueType()), Cond); 2864 } 2865 2866 // Turn (X^C1) == C2 into X == C1^C2 iff X&~C1 = 0. 2867 if (N0.getOpcode() == ISD::XOR) 2868 // If we know that all of the inverted bits are zero, don't bother 2869 // performing the inversion. 2870 if (TLI.MaskedValueIsZero(N0.getOperand(0), ~LHSR->getValue())) 2871 return DAG.getSetCC(VT, N0.getOperand(0), 2872 DAG.getConstant(LHSR->getValue()^RHSC->getValue(), 2873 N0.getValueType()), Cond); 2874 } 2875 2876 // Turn (C1-X) == C2 --> X == C1-C2 2877 if (ConstantSDNode *SUBC = dyn_cast<ConstantSDNode>(N0.getOperand(0))) { 2878 if (N0.getOpcode() == ISD::SUB && N0.Val->hasOneUse()) { 2879 return DAG.getSetCC(VT, N0.getOperand(1), 2880 DAG.getConstant(SUBC->getValue()-RHSC->getValue(), 2881 N0.getValueType()), Cond); 2882 } 2883 } 2884 } 2885 2886 // Simplify (X+Z) == X --> Z == 0 2887 if (N0.getOperand(0) == N1) 2888 return DAG.getSetCC(VT, N0.getOperand(1), 2889 DAG.getConstant(0, N0.getValueType()), Cond); 2890 if (N0.getOperand(1) == N1) { 2891 if (isCommutativeBinOp(N0.getOpcode())) 2892 return DAG.getSetCC(VT, N0.getOperand(0), 2893 DAG.getConstant(0, N0.getValueType()), Cond); 2894 else { 2895 assert(N0.getOpcode() == ISD::SUB && "Unexpected operation!"); 2896 // (Z-X) == X --> Z == X<<1 2897 SDOperand SH = DAG.getNode(ISD::SHL, N1.getValueType(), 2898 N1, 2899 DAG.getConstant(1,TLI.getShiftAmountTy())); 2900 AddToWorkList(SH.Val); 2901 return DAG.getSetCC(VT, N0.getOperand(0), SH, Cond); 2902 } 2903 } 2904 } 2905 2906 if (N1.getOpcode() == ISD::ADD || N1.getOpcode() == ISD::SUB || 2907 N1.getOpcode() == ISD::XOR) { 2908 // Simplify X == (X+Z) --> Z == 0 2909 if (N1.getOperand(0) == N0) { 2910 return DAG.getSetCC(VT, N1.getOperand(1), 2911 DAG.getConstant(0, N1.getValueType()), Cond); 2912 } else if (N1.getOperand(1) == N0) { 2913 if (isCommutativeBinOp(N1.getOpcode())) { 2914 return DAG.getSetCC(VT, N1.getOperand(0), 2915 DAG.getConstant(0, N1.getValueType()), Cond); 2916 } else { 2917 assert(N1.getOpcode() == ISD::SUB && "Unexpected operation!"); 2918 // X == (Z-X) --> X<<1 == Z 2919 SDOperand SH = DAG.getNode(ISD::SHL, N1.getValueType(), N0, 2920 DAG.getConstant(1,TLI.getShiftAmountTy())); 2921 AddToWorkList(SH.Val); 2922 return DAG.getSetCC(VT, SH, N1.getOperand(0), Cond); 2923 } 2924 } 2925 } 2926 } 2927 2928 // Fold away ALL boolean setcc's. 2929 SDOperand Temp; 2930 if (N0.getValueType() == MVT::i1 && foldBooleans) { 2931 switch (Cond) { 2932 default: assert(0 && "Unknown integer setcc!"); 2933 case ISD::SETEQ: // X == Y -> (X^Y)^1 2934 Temp = DAG.getNode(ISD::XOR, MVT::i1, N0, N1); 2935 N0 = DAG.getNode(ISD::XOR, MVT::i1, Temp, DAG.getConstant(1, MVT::i1)); 2936 AddToWorkList(Temp.Val); 2937 break; 2938 case ISD::SETNE: // X != Y --> (X^Y) 2939 N0 = DAG.getNode(ISD::XOR, MVT::i1, N0, N1); 2940 break; 2941 case ISD::SETGT: // X >s Y --> X == 0 & Y == 1 --> X^1 & Y 2942 case ISD::SETULT: // X <u Y --> X == 0 & Y == 1 --> X^1 & Y 2943 Temp = DAG.getNode(ISD::XOR, MVT::i1, N0, DAG.getConstant(1, MVT::i1)); 2944 N0 = DAG.getNode(ISD::AND, MVT::i1, N1, Temp); 2945 AddToWorkList(Temp.Val); 2946 break; 2947 case ISD::SETLT: // X <s Y --> X == 1 & Y == 0 --> Y^1 & X 2948 case ISD::SETUGT: // X >u Y --> X == 1 & Y == 0 --> Y^1 & X 2949 Temp = DAG.getNode(ISD::XOR, MVT::i1, N1, DAG.getConstant(1, MVT::i1)); 2950 N0 = DAG.getNode(ISD::AND, MVT::i1, N0, Temp); 2951 AddToWorkList(Temp.Val); 2952 break; 2953 case ISD::SETULE: // X <=u Y --> X == 0 | Y == 1 --> X^1 | Y 2954 case ISD::SETGE: // X >=s Y --> X == 0 | Y == 1 --> X^1 | Y 2955 Temp = DAG.getNode(ISD::XOR, MVT::i1, N0, DAG.getConstant(1, MVT::i1)); 2956 N0 = DAG.getNode(ISD::OR, MVT::i1, N1, Temp); 2957 AddToWorkList(Temp.Val); 2958 break; 2959 case ISD::SETUGE: // X >=u Y --> X == 1 | Y == 0 --> Y^1 | X 2960 case ISD::SETLE: // X <=s Y --> X == 1 | Y == 0 --> Y^1 | X 2961 Temp = DAG.getNode(ISD::XOR, MVT::i1, N1, DAG.getConstant(1, MVT::i1)); 2962 N0 = DAG.getNode(ISD::OR, MVT::i1, N0, Temp); 2963 break; 2964 } 2965 if (VT != MVT::i1) { 2966 AddToWorkList(N0.Val); 2967 // FIXME: If running after legalize, we probably can't do this. 2968 N0 = DAG.getNode(ISD::ZERO_EXTEND, VT, N0); 2969 } 2970 return N0; 2971 } 2972 2973 // Could not fold it. 2974 return SDOperand(); 2975} 2976 2977/// BuildSDIVSequence - Given an ISD::SDIV node expressing a divide by constant, 2978/// return a DAG expression to select that will generate the same value by 2979/// multiplying by a magic number. See: 2980/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html> 2981SDOperand DAGCombiner::BuildSDIV(SDNode *N) { 2982 MVT::ValueType VT = N->getValueType(0); 2983 2984 // Check to see if we can do this. 2985 if (!TLI.isTypeLegal(VT) || (VT != MVT::i32 && VT != MVT::i64)) 2986 return SDOperand(); // BuildSDIV only operates on i32 or i64 2987 if (!TLI.isOperationLegal(ISD::MULHS, VT)) 2988 return SDOperand(); // Make sure the target supports MULHS. 2989 2990 int64_t d = cast<ConstantSDNode>(N->getOperand(1))->getSignExtended(); 2991 ms magics = (VT == MVT::i32) ? magic32(d) : magic64(d); 2992 2993 // Multiply the numerator (operand 0) by the magic value 2994 SDOperand Q = DAG.getNode(ISD::MULHS, VT, N->getOperand(0), 2995 DAG.getConstant(magics.m, VT)); 2996 // If d > 0 and m < 0, add the numerator 2997 if (d > 0 && magics.m < 0) { 2998 Q = DAG.getNode(ISD::ADD, VT, Q, N->getOperand(0)); 2999 AddToWorkList(Q.Val); 3000 } 3001 // If d < 0 and m > 0, subtract the numerator. 3002 if (d < 0 && magics.m > 0) { 3003 Q = DAG.getNode(ISD::SUB, VT, Q, N->getOperand(0)); 3004 AddToWorkList(Q.Val); 3005 } 3006 // Shift right algebraic if shift value is nonzero 3007 if (magics.s > 0) { 3008 Q = DAG.getNode(ISD::SRA, VT, Q, 3009 DAG.getConstant(magics.s, TLI.getShiftAmountTy())); 3010 AddToWorkList(Q.Val); 3011 } 3012 // Extract the sign bit and add it to the quotient 3013 SDOperand T = 3014 DAG.getNode(ISD::SRL, VT, Q, DAG.getConstant(MVT::getSizeInBits(VT)-1, 3015 TLI.getShiftAmountTy())); 3016 AddToWorkList(T.Val); 3017 return DAG.getNode(ISD::ADD, VT, Q, T); 3018} 3019 3020/// BuildUDIVSequence - Given an ISD::UDIV node expressing a divide by constant, 3021/// return a DAG expression to select that will generate the same value by 3022/// multiplying by a magic number. See: 3023/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html> 3024SDOperand DAGCombiner::BuildUDIV(SDNode *N) { 3025 MVT::ValueType VT = N->getValueType(0); 3026 3027 // Check to see if we can do this. 3028 if (!TLI.isTypeLegal(VT) || (VT != MVT::i32 && VT != MVT::i64)) 3029 return SDOperand(); // BuildUDIV only operates on i32 or i64 3030 if (!TLI.isOperationLegal(ISD::MULHU, VT)) 3031 return SDOperand(); // Make sure the target supports MULHU. 3032 3033 uint64_t d = cast<ConstantSDNode>(N->getOperand(1))->getValue(); 3034 mu magics = (VT == MVT::i32) ? magicu32(d) : magicu64(d); 3035 3036 // Multiply the numerator (operand 0) by the magic value 3037 SDOperand Q = DAG.getNode(ISD::MULHU, VT, N->getOperand(0), 3038 DAG.getConstant(magics.m, VT)); 3039 AddToWorkList(Q.Val); 3040 3041 if (magics.a == 0) { 3042 return DAG.getNode(ISD::SRL, VT, Q, 3043 DAG.getConstant(magics.s, TLI.getShiftAmountTy())); 3044 } else { 3045 SDOperand NPQ = DAG.getNode(ISD::SUB, VT, N->getOperand(0), Q); 3046 AddToWorkList(NPQ.Val); 3047 NPQ = DAG.getNode(ISD::SRL, VT, NPQ, 3048 DAG.getConstant(1, TLI.getShiftAmountTy())); 3049 AddToWorkList(NPQ.Val); 3050 NPQ = DAG.getNode(ISD::ADD, VT, NPQ, Q); 3051 AddToWorkList(NPQ.Val); 3052 return DAG.getNode(ISD::SRL, VT, NPQ, 3053 DAG.getConstant(magics.s-1, TLI.getShiftAmountTy())); 3054 } 3055} 3056 3057// SelectionDAG::Combine - This is the entry point for the file. 3058// 3059void SelectionDAG::Combine(bool RunningAfterLegalize) { 3060 /// run - This is the main entry point to this class. 3061 /// 3062 DAGCombiner(*this).Run(RunningAfterLegalize); 3063} 3064