X86FloatingPoint.cpp revision e377d4d142d7e2ec9266435087c99ffc43f394aa
1//===-- X86FloatingPoint.cpp - Floating point Reg -> Stack converter ------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines the pass which converts floating point instructions from 11// virtual registers into register stack instructions. This pass uses live 12// variable information to indicate where the FPn registers are used and their 13// lifetimes. 14// 15// This pass is hampered by the lack of decent CFG manipulation routines for 16// machine code. In particular, this wants to be able to split critical edges 17// as necessary, traverse the machine basic block CFG in depth-first order, and 18// allow there to be multiple machine basic blocks for each LLVM basicblock 19// (needed for critical edge splitting). 20// 21// In particular, this pass currently barfs on critical edges. Because of this, 22// it requires the instruction selector to insert FP_REG_KILL instructions on 23// the exits of any basic block that has critical edges going from it, or which 24// branch to a critical basic block. 25// 26// FIXME: this is not implemented yet. The stackifier pass only works on local 27// basic blocks. 28// 29//===----------------------------------------------------------------------===// 30 31#define DEBUG_TYPE "x86-codegen" 32#include "X86.h" 33#include "X86InstrInfo.h" 34#include "llvm/CodeGen/MachineFunctionPass.h" 35#include "llvm/CodeGen/MachineInstrBuilder.h" 36#include "llvm/CodeGen/LiveVariables.h" 37#include "llvm/CodeGen/Passes.h" 38#include "llvm/Target/TargetInstrInfo.h" 39#include "llvm/Target/TargetMachine.h" 40#include "llvm/Support/Debug.h" 41#include "llvm/Support/Compiler.h" 42#include "llvm/ADT/DepthFirstIterator.h" 43#include "llvm/ADT/SmallVector.h" 44#include "llvm/ADT/Statistic.h" 45#include "llvm/ADT/STLExtras.h" 46#include <algorithm> 47#include <set> 48using namespace llvm; 49 50STATISTIC(NumFXCH, "Number of fxch instructions inserted"); 51STATISTIC(NumFP , "Number of floating point instructions"); 52 53namespace { 54 struct VISIBILITY_HIDDEN FPS : public MachineFunctionPass { 55 static char ID; 56 FPS() : MachineFunctionPass((intptr_t)&ID) {} 57 58 virtual bool runOnMachineFunction(MachineFunction &MF); 59 60 virtual const char *getPassName() const { return "X86 FP Stackifier"; } 61 62 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 63 AU.addRequired<LiveVariables>(); 64 MachineFunctionPass::getAnalysisUsage(AU); 65 } 66 private: 67 const TargetInstrInfo *TII; // Machine instruction info. 68 LiveVariables *LV; // Live variable info for current function... 69 MachineBasicBlock *MBB; // Current basic block 70 unsigned Stack[8]; // FP<n> Registers in each stack slot... 71 unsigned RegMap[8]; // Track which stack slot contains each register 72 unsigned StackTop; // The current top of the FP stack. 73 74 void dumpStack() const { 75 cerr << "Stack contents:"; 76 for (unsigned i = 0; i != StackTop; ++i) { 77 cerr << " FP" << Stack[i]; 78 assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!"); 79 } 80 cerr << "\n"; 81 } 82 private: 83 // getSlot - Return the stack slot number a particular register number is 84 // in... 85 unsigned getSlot(unsigned RegNo) const { 86 assert(RegNo < 8 && "Regno out of range!"); 87 return RegMap[RegNo]; 88 } 89 90 // getStackEntry - Return the X86::FP<n> register in register ST(i) 91 unsigned getStackEntry(unsigned STi) const { 92 assert(STi < StackTop && "Access past stack top!"); 93 return Stack[StackTop-1-STi]; 94 } 95 96 // getSTReg - Return the X86::ST(i) register which contains the specified 97 // FP<RegNo> register 98 unsigned getSTReg(unsigned RegNo) const { 99 return StackTop - 1 - getSlot(RegNo) + llvm::X86::ST0; 100 } 101 102 // pushReg - Push the specified FP<n> register onto the stack 103 void pushReg(unsigned Reg) { 104 assert(Reg < 8 && "Register number out of range!"); 105 assert(StackTop < 8 && "Stack overflow!"); 106 Stack[StackTop] = Reg; 107 RegMap[Reg] = StackTop++; 108 } 109 110 bool isAtTop(unsigned RegNo) const { return getSlot(RegNo) == StackTop-1; } 111 void moveToTop(unsigned RegNo, MachineBasicBlock::iterator &I) { 112 if (!isAtTop(RegNo)) { 113 unsigned STReg = getSTReg(RegNo); 114 unsigned RegOnTop = getStackEntry(0); 115 116 // Swap the slots the regs are in 117 std::swap(RegMap[RegNo], RegMap[RegOnTop]); 118 119 // Swap stack slot contents 120 assert(RegMap[RegOnTop] < StackTop); 121 std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]); 122 123 // Emit an fxch to update the runtime processors version of the state 124 BuildMI(*MBB, I, TII->get(X86::XCH_F)).addReg(STReg); 125 NumFXCH++; 126 } 127 } 128 129 void duplicateToTop(unsigned RegNo, unsigned AsReg, MachineInstr *I) { 130 unsigned STReg = getSTReg(RegNo); 131 pushReg(AsReg); // New register on top of stack 132 133 BuildMI(*MBB, I, TII->get(X86::LD_Frr)).addReg(STReg); 134 } 135 136 // popStackAfter - Pop the current value off of the top of the FP stack 137 // after the specified instruction. 138 void popStackAfter(MachineBasicBlock::iterator &I); 139 140 // freeStackSlotAfter - Free the specified register from the register stack, 141 // so that it is no longer in a register. If the register is currently at 142 // the top of the stack, we just pop the current instruction, otherwise we 143 // store the current top-of-stack into the specified slot, then pop the top 144 // of stack. 145 void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg); 146 147 bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB); 148 149 void handleZeroArgFP(MachineBasicBlock::iterator &I); 150 void handleOneArgFP(MachineBasicBlock::iterator &I); 151 void handleOneArgFPRW(MachineBasicBlock::iterator &I); 152 void handleTwoArgFP(MachineBasicBlock::iterator &I); 153 void handleCompareFP(MachineBasicBlock::iterator &I); 154 void handleCondMovFP(MachineBasicBlock::iterator &I); 155 void handleSpecialFP(MachineBasicBlock::iterator &I); 156 }; 157 char FPS::ID = 0; 158} 159 160FunctionPass *llvm::createX86FloatingPointStackifierPass() { return new FPS(); } 161 162/// runOnMachineFunction - Loop over all of the basic blocks, transforming FP 163/// register references into FP stack references. 164/// 165bool FPS::runOnMachineFunction(MachineFunction &MF) { 166 // We only need to run this pass if there are any FP registers used in this 167 // function. If it is all integer, there is nothing for us to do! 168 bool FPIsUsed = false; 169 170 assert(X86::FP6 == X86::FP0+6 && "Register enums aren't sorted right!"); 171 for (unsigned i = 0; i <= 6; ++i) 172 if (MF.isPhysRegUsed(X86::FP0+i)) { 173 FPIsUsed = true; 174 break; 175 } 176 177 // Early exit. 178 if (!FPIsUsed) return false; 179 180 TII = MF.getTarget().getInstrInfo(); 181 LV = &getAnalysis<LiveVariables>(); 182 StackTop = 0; 183 184 // Process the function in depth first order so that we process at least one 185 // of the predecessors for every reachable block in the function. 186 std::set<MachineBasicBlock*> Processed; 187 MachineBasicBlock *Entry = MF.begin(); 188 189 bool Changed = false; 190 for (df_ext_iterator<MachineBasicBlock*, std::set<MachineBasicBlock*> > 191 I = df_ext_begin(Entry, Processed), E = df_ext_end(Entry, Processed); 192 I != E; ++I) 193 Changed |= processBasicBlock(MF, **I); 194 195 return Changed; 196} 197 198/// processBasicBlock - Loop over all of the instructions in the basic block, 199/// transforming FP instructions into their stack form. 200/// 201bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) { 202 bool Changed = false; 203 MBB = &BB; 204 205 for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) { 206 MachineInstr *MI = I; 207 unsigned Flags = MI->getInstrDescriptor()->TSFlags; 208 if ((Flags & X86II::FPTypeMask) == X86II::NotFP) 209 continue; // Efficiently ignore non-fp insts! 210 211 MachineInstr *PrevMI = 0; 212 if (I != BB.begin()) 213 PrevMI = prior(I); 214 215 ++NumFP; // Keep track of # of pseudo instrs 216 DOUT << "\nFPInst:\t" << *MI; 217 218 // Get dead variables list now because the MI pointer may be deleted as part 219 // of processing! 220 SmallVector<unsigned, 8> DeadRegs; 221 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 222 const MachineOperand &MO = MI->getOperand(i); 223 if (MO.isReg() && MO.isDead()) 224 DeadRegs.push_back(MO.getReg()); 225 } 226 227 switch (Flags & X86II::FPTypeMask) { 228 case X86II::ZeroArgFP: handleZeroArgFP(I); break; 229 case X86II::OneArgFP: handleOneArgFP(I); break; // fstp ST(0) 230 case X86II::OneArgFPRW: handleOneArgFPRW(I); break; // ST(0) = fsqrt(ST(0)) 231 case X86II::TwoArgFP: handleTwoArgFP(I); break; 232 case X86II::CompareFP: handleCompareFP(I); break; 233 case X86II::CondMovFP: handleCondMovFP(I); break; 234 case X86II::SpecialFP: handleSpecialFP(I); break; 235 default: assert(0 && "Unknown FP Type!"); 236 } 237 238 // Check to see if any of the values defined by this instruction are dead 239 // after definition. If so, pop them. 240 for (unsigned i = 0, e = DeadRegs.size(); i != e; ++i) { 241 unsigned Reg = DeadRegs[i]; 242 if (Reg >= X86::FP0 && Reg <= X86::FP6) { 243 DOUT << "Register FP#" << Reg-X86::FP0 << " is dead!\n"; 244 freeStackSlotAfter(I, Reg-X86::FP0); 245 } 246 } 247 248 // Print out all of the instructions expanded to if -debug 249 DEBUG( 250 MachineBasicBlock::iterator PrevI(PrevMI); 251 if (I == PrevI) { 252 cerr << "Just deleted pseudo instruction\n"; 253 } else { 254 MachineBasicBlock::iterator Start = I; 255 // Rewind to first instruction newly inserted. 256 while (Start != BB.begin() && prior(Start) != PrevI) --Start; 257 cerr << "Inserted instructions:\n\t"; 258 Start->print(*cerr.stream(), &MF.getTarget()); 259 while (++Start != next(I)); 260 } 261 dumpStack(); 262 ); 263 264 Changed = true; 265 } 266 267 assert(StackTop == 0 && "Stack not empty at end of basic block?"); 268 return Changed; 269} 270 271//===----------------------------------------------------------------------===// 272// Efficient Lookup Table Support 273//===----------------------------------------------------------------------===// 274 275namespace { 276 struct TableEntry { 277 unsigned from; 278 unsigned to; 279 bool operator<(const TableEntry &TE) const { return from < TE.from; } 280 friend bool operator<(const TableEntry &TE, unsigned V) { 281 return TE.from < V; 282 } 283 friend bool operator<(unsigned V, const TableEntry &TE) { 284 return V < TE.from; 285 } 286 }; 287} 288 289static bool TableIsSorted(const TableEntry *Table, unsigned NumEntries) { 290 for (unsigned i = 0; i != NumEntries-1; ++i) 291 if (!(Table[i] < Table[i+1])) return false; 292 return true; 293} 294 295static int Lookup(const TableEntry *Table, unsigned N, unsigned Opcode) { 296 const TableEntry *I = std::lower_bound(Table, Table+N, Opcode); 297 if (I != Table+N && I->from == Opcode) 298 return I->to; 299 return -1; 300} 301 302#define ARRAY_SIZE(TABLE) \ 303 (sizeof(TABLE)/sizeof(TABLE[0])) 304 305#ifdef NDEBUG 306#define ASSERT_SORTED(TABLE) 307#else 308#define ASSERT_SORTED(TABLE) \ 309 { static bool TABLE##Checked = false; \ 310 if (!TABLE##Checked) { \ 311 assert(TableIsSorted(TABLE, ARRAY_SIZE(TABLE)) && \ 312 "All lookup tables must be sorted for efficient access!"); \ 313 TABLE##Checked = true; \ 314 } \ 315 } 316#endif 317 318//===----------------------------------------------------------------------===// 319// Register File -> Register Stack Mapping Methods 320//===----------------------------------------------------------------------===// 321 322// OpcodeTable - Sorted map of register instructions to their stack version. 323// The first element is an register file pseudo instruction, the second is the 324// concrete X86 instruction which uses the register stack. 325// 326static const TableEntry OpcodeTable[] = { 327 { X86::ABS_Fp32 , X86::ABS_F }, 328 { X86::ABS_Fp64 , X86::ABS_F }, 329 { X86::ADD_Fp32m , X86::ADD_F32m }, 330 { X86::ADD_Fp64m , X86::ADD_F64m }, 331 { X86::ADD_FpI16m32 , X86::ADD_FI16m }, 332 { X86::ADD_FpI16m64 , X86::ADD_FI16m }, 333 { X86::ADD_FpI32m32 , X86::ADD_FI32m }, 334 { X86::ADD_FpI32m64 , X86::ADD_FI32m }, 335 { X86::CHS_Fp32 , X86::CHS_F }, 336 { X86::CHS_Fp64 , X86::CHS_F }, 337 { X86::CMOVBE_Fp32 , X86::CMOVBE_F }, 338 { X86::CMOVBE_Fp64 , X86::CMOVBE_F }, 339 { X86::CMOVB_Fp32 , X86::CMOVB_F }, 340 { X86::CMOVB_Fp64 , X86::CMOVB_F }, 341 { X86::CMOVE_Fp32 , X86::CMOVE_F }, 342 { X86::CMOVE_Fp64 , X86::CMOVE_F }, 343 { X86::CMOVNBE_Fp32 , X86::CMOVNBE_F }, 344 { X86::CMOVNBE_Fp64 , X86::CMOVNBE_F }, 345 { X86::CMOVNB_Fp32 , X86::CMOVNB_F }, 346 { X86::CMOVNB_Fp64 , X86::CMOVNB_F }, 347 { X86::CMOVNE_Fp32 , X86::CMOVNE_F }, 348 { X86::CMOVNE_Fp64 , X86::CMOVNE_F }, 349 { X86::CMOVNP_Fp32 , X86::CMOVNP_F }, 350 { X86::CMOVNP_Fp64 , X86::CMOVNP_F }, 351 { X86::CMOVP_Fp32 , X86::CMOVP_F }, 352 { X86::CMOVP_Fp64 , X86::CMOVP_F }, 353 { X86::COS_Fp32 , X86::COS_F }, 354 { X86::COS_Fp64 , X86::COS_F }, 355 { X86::DIVR_Fp32m , X86::DIVR_F32m }, 356 { X86::DIVR_Fp64m , X86::DIVR_F64m }, 357 { X86::DIVR_FpI16m32, X86::DIVR_FI16m}, 358 { X86::DIVR_FpI16m64, X86::DIVR_FI16m}, 359 { X86::DIVR_FpI32m32, X86::DIVR_FI32m}, 360 { X86::DIVR_FpI32m64, X86::DIVR_FI32m}, 361 { X86::DIV_Fp32m , X86::DIV_F32m }, 362 { X86::DIV_Fp64m , X86::DIV_F64m }, 363 { X86::DIV_FpI16m32 , X86::DIV_FI16m }, 364 { X86::DIV_FpI16m64 , X86::DIV_FI16m }, 365 { X86::DIV_FpI32m32 , X86::DIV_FI32m }, 366 { X86::DIV_FpI32m64 , X86::DIV_FI32m }, 367 { X86::ILD_Fp16m32 , X86::ILD_F16m }, 368 { X86::ILD_Fp16m64 , X86::ILD_F16m }, 369 { X86::ILD_Fp32m32 , X86::ILD_F32m }, 370 { X86::ILD_Fp32m64 , X86::ILD_F32m }, 371 { X86::ILD_Fp64m32 , X86::ILD_F64m }, 372 { X86::ILD_Fp64m64 , X86::ILD_F64m }, 373 { X86::ISTT_Fp16m32 , X86::ISTT_FP16m}, 374 { X86::ISTT_Fp16m64 , X86::ISTT_FP16m}, 375 { X86::ISTT_Fp32m32 , X86::ISTT_FP32m}, 376 { X86::ISTT_Fp32m64 , X86::ISTT_FP32m}, 377 { X86::ISTT_Fp64m32 , X86::ISTT_FP64m}, 378 { X86::ISTT_Fp64m64 , X86::ISTT_FP64m}, 379 { X86::IST_Fp16m32 , X86::IST_F16m }, 380 { X86::IST_Fp16m64 , X86::IST_F16m }, 381 { X86::IST_Fp32m32 , X86::IST_F32m }, 382 { X86::IST_Fp32m64 , X86::IST_F32m }, 383 { X86::IST_Fp64m32 , X86::IST_FP64m }, 384 { X86::IST_Fp64m64 , X86::IST_FP64m }, 385 { X86::LD_Fp032 , X86::LD_F0 }, 386 { X86::LD_Fp064 , X86::LD_F0 }, 387 { X86::LD_Fp132 , X86::LD_F1 }, 388 { X86::LD_Fp164 , X86::LD_F1 }, 389 { X86::LD_Fp32m , X86::LD_F32m }, 390 { X86::LD_Fp64m , X86::LD_F64m }, 391 { X86::MUL_Fp32m , X86::MUL_F32m }, 392 { X86::MUL_Fp64m , X86::MUL_F64m }, 393 { X86::MUL_FpI16m32 , X86::MUL_FI16m }, 394 { X86::MUL_FpI16m64 , X86::MUL_FI16m }, 395 { X86::MUL_FpI32m32 , X86::MUL_FI32m }, 396 { X86::MUL_FpI32m64 , X86::MUL_FI32m }, 397 { X86::SIN_Fp32 , X86::SIN_F }, 398 { X86::SIN_Fp64 , X86::SIN_F }, 399 { X86::SQRT_Fp32 , X86::SQRT_F }, 400 { X86::SQRT_Fp64 , X86::SQRT_F }, 401 { X86::ST_Fp32m , X86::ST_F32m }, 402 { X86::ST_Fp64m , X86::ST_F64m }, 403 { X86::ST_Fp64m32 , X86::ST_F32m }, 404 { X86::SUBR_Fp32m , X86::SUBR_F32m }, 405 { X86::SUBR_Fp64m , X86::SUBR_F64m }, 406 { X86::SUBR_FpI16m32, X86::SUBR_FI16m}, 407 { X86::SUBR_FpI16m64, X86::SUBR_FI16m}, 408 { X86::SUBR_FpI32m32, X86::SUBR_FI32m}, 409 { X86::SUBR_FpI32m64, X86::SUBR_FI32m}, 410 { X86::SUB_Fp32m , X86::SUB_F32m }, 411 { X86::SUB_Fp64m , X86::SUB_F64m }, 412 { X86::SUB_FpI16m32 , X86::SUB_FI16m }, 413 { X86::SUB_FpI16m64 , X86::SUB_FI16m }, 414 { X86::SUB_FpI32m32 , X86::SUB_FI32m }, 415 { X86::SUB_FpI32m64 , X86::SUB_FI32m }, 416 { X86::TST_Fp32 , X86::TST_F }, 417 { X86::TST_Fp64 , X86::TST_F }, 418 { X86::UCOM_FpIr32 , X86::UCOM_FIr }, 419 { X86::UCOM_FpIr64 , X86::UCOM_FIr }, 420 { X86::UCOM_Fpr32 , X86::UCOM_Fr }, 421 { X86::UCOM_Fpr64 , X86::UCOM_Fr }, 422}; 423 424static unsigned getConcreteOpcode(unsigned Opcode) { 425 ASSERT_SORTED(OpcodeTable); 426 int Opc = Lookup(OpcodeTable, ARRAY_SIZE(OpcodeTable), Opcode); 427 assert(Opc != -1 && "FP Stack instruction not in OpcodeTable!"); 428 return Opc; 429} 430 431//===----------------------------------------------------------------------===// 432// Helper Methods 433//===----------------------------------------------------------------------===// 434 435// PopTable - Sorted map of instructions to their popping version. The first 436// element is an instruction, the second is the version which pops. 437// 438static const TableEntry PopTable[] = { 439 { X86::ADD_FrST0 , X86::ADD_FPrST0 }, 440 441 { X86::DIVR_FrST0, X86::DIVR_FPrST0 }, 442 { X86::DIV_FrST0 , X86::DIV_FPrST0 }, 443 444 { X86::IST_F16m , X86::IST_FP16m }, 445 { X86::IST_F32m , X86::IST_FP32m }, 446 447 { X86::MUL_FrST0 , X86::MUL_FPrST0 }, 448 449 { X86::ST_F32m , X86::ST_FP32m }, 450 { X86::ST_F64m , X86::ST_FP64m }, 451 { X86::ST_Frr , X86::ST_FPrr }, 452 453 { X86::SUBR_FrST0, X86::SUBR_FPrST0 }, 454 { X86::SUB_FrST0 , X86::SUB_FPrST0 }, 455 456 { X86::UCOM_FIr , X86::UCOM_FIPr }, 457 458 { X86::UCOM_FPr , X86::UCOM_FPPr }, 459 { X86::UCOM_Fr , X86::UCOM_FPr }, 460}; 461 462/// popStackAfter - Pop the current value off of the top of the FP stack after 463/// the specified instruction. This attempts to be sneaky and combine the pop 464/// into the instruction itself if possible. The iterator is left pointing to 465/// the last instruction, be it a new pop instruction inserted, or the old 466/// instruction if it was modified in place. 467/// 468void FPS::popStackAfter(MachineBasicBlock::iterator &I) { 469 ASSERT_SORTED(PopTable); 470 assert(StackTop > 0 && "Cannot pop empty stack!"); 471 RegMap[Stack[--StackTop]] = ~0; // Update state 472 473 // Check to see if there is a popping version of this instruction... 474 int Opcode = Lookup(PopTable, ARRAY_SIZE(PopTable), I->getOpcode()); 475 if (Opcode != -1) { 476 I->setInstrDescriptor(TII->get(Opcode)); 477 if (Opcode == X86::UCOM_FPPr) 478 I->RemoveOperand(0); 479 } else { // Insert an explicit pop 480 I = BuildMI(*MBB, ++I, TII->get(X86::ST_FPrr)).addReg(X86::ST0); 481 } 482} 483 484/// freeStackSlotAfter - Free the specified register from the register stack, so 485/// that it is no longer in a register. If the register is currently at the top 486/// of the stack, we just pop the current instruction, otherwise we store the 487/// current top-of-stack into the specified slot, then pop the top of stack. 488void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) { 489 if (getStackEntry(0) == FPRegNo) { // already at the top of stack? easy. 490 popStackAfter(I); 491 return; 492 } 493 494 // Otherwise, store the top of stack into the dead slot, killing the operand 495 // without having to add in an explicit xchg then pop. 496 // 497 unsigned STReg = getSTReg(FPRegNo); 498 unsigned OldSlot = getSlot(FPRegNo); 499 unsigned TopReg = Stack[StackTop-1]; 500 Stack[OldSlot] = TopReg; 501 RegMap[TopReg] = OldSlot; 502 RegMap[FPRegNo] = ~0; 503 Stack[--StackTop] = ~0; 504 I = BuildMI(*MBB, ++I, TII->get(X86::ST_FPrr)).addReg(STReg); 505} 506 507 508static unsigned getFPReg(const MachineOperand &MO) { 509 assert(MO.isRegister() && "Expected an FP register!"); 510 unsigned Reg = MO.getReg(); 511 assert(Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP register!"); 512 return Reg - X86::FP0; 513} 514 515 516//===----------------------------------------------------------------------===// 517// Instruction transformation implementation 518//===----------------------------------------------------------------------===// 519 520/// handleZeroArgFP - ST(0) = fld0 ST(0) = flds <mem> 521/// 522void FPS::handleZeroArgFP(MachineBasicBlock::iterator &I) { 523 MachineInstr *MI = I; 524 unsigned DestReg = getFPReg(MI->getOperand(0)); 525 526 // Change from the pseudo instruction to the concrete instruction. 527 MI->RemoveOperand(0); // Remove the explicit ST(0) operand 528 MI->setInstrDescriptor(TII->get(getConcreteOpcode(MI->getOpcode()))); 529 530 // Result gets pushed on the stack. 531 pushReg(DestReg); 532} 533 534/// handleOneArgFP - fst <mem>, ST(0) 535/// 536void FPS::handleOneArgFP(MachineBasicBlock::iterator &I) { 537 MachineInstr *MI = I; 538 unsigned NumOps = MI->getInstrDescriptor()->numOperands; 539 assert((NumOps == 5 || NumOps == 1) && 540 "Can only handle fst* & ftst instructions!"); 541 542 // Is this the last use of the source register? 543 unsigned Reg = getFPReg(MI->getOperand(NumOps-1)); 544 bool KillsSrc = LV->KillsRegister(MI, X86::FP0+Reg); 545 546 // FISTP64m is strange because there isn't a non-popping versions. 547 // If we have one _and_ we don't want to pop the operand, duplicate the value 548 // on the stack instead of moving it. This ensure that popping the value is 549 // always ok. 550 // Ditto FISTTP16m, FISTTP32m, FISTTP64m. 551 // 552 if (!KillsSrc && 553 (MI->getOpcode() == X86::IST_Fp64m32 || 554 MI->getOpcode() == X86::ISTT_Fp16m32 || 555 MI->getOpcode() == X86::ISTT_Fp32m32 || 556 MI->getOpcode() == X86::ISTT_Fp64m32 || 557 MI->getOpcode() == X86::IST_Fp64m64 || 558 MI->getOpcode() == X86::ISTT_Fp16m64 || 559 MI->getOpcode() == X86::ISTT_Fp32m64 || 560 MI->getOpcode() == X86::ISTT_Fp64m64)) { 561 duplicateToTop(Reg, 7 /*temp register*/, I); 562 } else { 563 moveToTop(Reg, I); // Move to the top of the stack... 564 } 565 566 // Convert from the pseudo instruction to the concrete instruction. 567 MI->RemoveOperand(NumOps-1); // Remove explicit ST(0) operand 568 MI->setInstrDescriptor(TII->get(getConcreteOpcode(MI->getOpcode()))); 569 570 if (MI->getOpcode() == X86::IST_FP64m || 571 MI->getOpcode() == X86::ISTT_FP16m || 572 MI->getOpcode() == X86::ISTT_FP32m || 573 MI->getOpcode() == X86::ISTT_FP64m) { 574 assert(StackTop > 0 && "Stack empty??"); 575 --StackTop; 576 } else if (KillsSrc) { // Last use of operand? 577 popStackAfter(I); 578 } 579} 580 581 582/// handleOneArgFPRW: Handle instructions that read from the top of stack and 583/// replace the value with a newly computed value. These instructions may have 584/// non-fp operands after their FP operands. 585/// 586/// Examples: 587/// R1 = fchs R2 588/// R1 = fadd R2, [mem] 589/// 590void FPS::handleOneArgFPRW(MachineBasicBlock::iterator &I) { 591 MachineInstr *MI = I; 592 unsigned NumOps = MI->getInstrDescriptor()->numOperands; 593 assert(NumOps >= 2 && "FPRW instructions must have 2 ops!!"); 594 595 // Is this the last use of the source register? 596 unsigned Reg = getFPReg(MI->getOperand(1)); 597 bool KillsSrc = LV->KillsRegister(MI, X86::FP0+Reg); 598 599 if (KillsSrc) { 600 // If this is the last use of the source register, just make sure it's on 601 // the top of the stack. 602 moveToTop(Reg, I); 603 assert(StackTop > 0 && "Stack cannot be empty!"); 604 --StackTop; 605 pushReg(getFPReg(MI->getOperand(0))); 606 } else { 607 // If this is not the last use of the source register, _copy_ it to the top 608 // of the stack. 609 duplicateToTop(Reg, getFPReg(MI->getOperand(0)), I); 610 } 611 612 // Change from the pseudo instruction to the concrete instruction. 613 MI->RemoveOperand(1); // Drop the source operand. 614 MI->RemoveOperand(0); // Drop the destination operand. 615 MI->setInstrDescriptor(TII->get(getConcreteOpcode(MI->getOpcode()))); 616} 617 618 619//===----------------------------------------------------------------------===// 620// Define tables of various ways to map pseudo instructions 621// 622 623// ForwardST0Table - Map: A = B op C into: ST(0) = ST(0) op ST(i) 624static const TableEntry ForwardST0Table[] = { 625 { X86::ADD_Fp32 , X86::ADD_FST0r }, 626 { X86::ADD_Fp64 , X86::ADD_FST0r }, 627 { X86::DIV_Fp32 , X86::DIV_FST0r }, 628 { X86::DIV_Fp64 , X86::DIV_FST0r }, 629 { X86::MUL_Fp32 , X86::MUL_FST0r }, 630 { X86::MUL_Fp64 , X86::MUL_FST0r }, 631 { X86::SUB_Fp32 , X86::SUB_FST0r }, 632 { X86::SUB_Fp64 , X86::SUB_FST0r }, 633}; 634 635// ReverseST0Table - Map: A = B op C into: ST(0) = ST(i) op ST(0) 636static const TableEntry ReverseST0Table[] = { 637 { X86::ADD_Fp32 , X86::ADD_FST0r }, // commutative 638 { X86::ADD_Fp64 , X86::ADD_FST0r }, // commutative 639 { X86::DIV_Fp32 , X86::DIVR_FST0r }, 640 { X86::DIV_Fp64 , X86::DIVR_FST0r }, 641 { X86::MUL_Fp32 , X86::MUL_FST0r }, // commutative 642 { X86::MUL_Fp64 , X86::MUL_FST0r }, // commutative 643 { X86::SUB_Fp32 , X86::SUBR_FST0r }, 644 { X86::SUB_Fp64 , X86::SUBR_FST0r }, 645}; 646 647// ForwardSTiTable - Map: A = B op C into: ST(i) = ST(0) op ST(i) 648static const TableEntry ForwardSTiTable[] = { 649 { X86::ADD_Fp32 , X86::ADD_FrST0 }, // commutative 650 { X86::ADD_Fp64 , X86::ADD_FrST0 }, // commutative 651 { X86::DIV_Fp32 , X86::DIVR_FrST0 }, 652 { X86::DIV_Fp64 , X86::DIVR_FrST0 }, 653 { X86::MUL_Fp32 , X86::MUL_FrST0 }, // commutative 654 { X86::MUL_Fp64 , X86::MUL_FrST0 }, // commutative 655 { X86::SUB_Fp32 , X86::SUBR_FrST0 }, 656 { X86::SUB_Fp64 , X86::SUBR_FrST0 }, 657}; 658 659// ReverseSTiTable - Map: A = B op C into: ST(i) = ST(i) op ST(0) 660static const TableEntry ReverseSTiTable[] = { 661 { X86::ADD_Fp32 , X86::ADD_FrST0 }, 662 { X86::ADD_Fp64 , X86::ADD_FrST0 }, 663 { X86::DIV_Fp32 , X86::DIV_FrST0 }, 664 { X86::DIV_Fp64 , X86::DIV_FrST0 }, 665 { X86::MUL_Fp32 , X86::MUL_FrST0 }, 666 { X86::MUL_Fp64 , X86::MUL_FrST0 }, 667 { X86::SUB_Fp32 , X86::SUB_FrST0 }, 668 { X86::SUB_Fp64 , X86::SUB_FrST0 }, 669}; 670 671 672/// handleTwoArgFP - Handle instructions like FADD and friends which are virtual 673/// instructions which need to be simplified and possibly transformed. 674/// 675/// Result: ST(0) = fsub ST(0), ST(i) 676/// ST(i) = fsub ST(0), ST(i) 677/// ST(0) = fsubr ST(0), ST(i) 678/// ST(i) = fsubr ST(0), ST(i) 679/// 680void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) { 681 ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table); 682 ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable); 683 MachineInstr *MI = I; 684 685 unsigned NumOperands = MI->getInstrDescriptor()->numOperands; 686 assert(NumOperands == 3 && "Illegal TwoArgFP instruction!"); 687 unsigned Dest = getFPReg(MI->getOperand(0)); 688 unsigned Op0 = getFPReg(MI->getOperand(NumOperands-2)); 689 unsigned Op1 = getFPReg(MI->getOperand(NumOperands-1)); 690 bool KillsOp0 = LV->KillsRegister(MI, X86::FP0+Op0); 691 bool KillsOp1 = LV->KillsRegister(MI, X86::FP0+Op1); 692 693 unsigned TOS = getStackEntry(0); 694 695 // One of our operands must be on the top of the stack. If neither is yet, we 696 // need to move one. 697 if (Op0 != TOS && Op1 != TOS) { // No operand at TOS? 698 // We can choose to move either operand to the top of the stack. If one of 699 // the operands is killed by this instruction, we want that one so that we 700 // can update right on top of the old version. 701 if (KillsOp0) { 702 moveToTop(Op0, I); // Move dead operand to TOS. 703 TOS = Op0; 704 } else if (KillsOp1) { 705 moveToTop(Op1, I); 706 TOS = Op1; 707 } else { 708 // All of the operands are live after this instruction executes, so we 709 // cannot update on top of any operand. Because of this, we must 710 // duplicate one of the stack elements to the top. It doesn't matter 711 // which one we pick. 712 // 713 duplicateToTop(Op0, Dest, I); 714 Op0 = TOS = Dest; 715 KillsOp0 = true; 716 } 717 } else if (!KillsOp0 && !KillsOp1) { 718 // If we DO have one of our operands at the top of the stack, but we don't 719 // have a dead operand, we must duplicate one of the operands to a new slot 720 // on the stack. 721 duplicateToTop(Op0, Dest, I); 722 Op0 = TOS = Dest; 723 KillsOp0 = true; 724 } 725 726 // Now we know that one of our operands is on the top of the stack, and at 727 // least one of our operands is killed by this instruction. 728 assert((TOS == Op0 || TOS == Op1) && (KillsOp0 || KillsOp1) && 729 "Stack conditions not set up right!"); 730 731 // We decide which form to use based on what is on the top of the stack, and 732 // which operand is killed by this instruction. 733 const TableEntry *InstTable; 734 bool isForward = TOS == Op0; 735 bool updateST0 = (TOS == Op0 && !KillsOp1) || (TOS == Op1 && !KillsOp0); 736 if (updateST0) { 737 if (isForward) 738 InstTable = ForwardST0Table; 739 else 740 InstTable = ReverseST0Table; 741 } else { 742 if (isForward) 743 InstTable = ForwardSTiTable; 744 else 745 InstTable = ReverseSTiTable; 746 } 747 748 int Opcode = Lookup(InstTable, ARRAY_SIZE(ForwardST0Table), MI->getOpcode()); 749 assert(Opcode != -1 && "Unknown TwoArgFP pseudo instruction!"); 750 751 // NotTOS - The register which is not on the top of stack... 752 unsigned NotTOS = (TOS == Op0) ? Op1 : Op0; 753 754 // Replace the old instruction with a new instruction 755 MBB->remove(I++); 756 I = BuildMI(*MBB, I, TII->get(Opcode)).addReg(getSTReg(NotTOS)); 757 758 // If both operands are killed, pop one off of the stack in addition to 759 // overwriting the other one. 760 if (KillsOp0 && KillsOp1 && Op0 != Op1) { 761 assert(!updateST0 && "Should have updated other operand!"); 762 popStackAfter(I); // Pop the top of stack 763 } 764 765 // Update stack information so that we know the destination register is now on 766 // the stack. 767 unsigned UpdatedSlot = getSlot(updateST0 ? TOS : NotTOS); 768 assert(UpdatedSlot < StackTop && Dest < 7); 769 Stack[UpdatedSlot] = Dest; 770 RegMap[Dest] = UpdatedSlot; 771 delete MI; // Remove the old instruction 772} 773 774/// handleCompareFP - Handle FUCOM and FUCOMI instructions, which have two FP 775/// register arguments and no explicit destinations. 776/// 777void FPS::handleCompareFP(MachineBasicBlock::iterator &I) { 778 ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table); 779 ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable); 780 MachineInstr *MI = I; 781 782 unsigned NumOperands = MI->getInstrDescriptor()->numOperands; 783 assert(NumOperands == 2 && "Illegal FUCOM* instruction!"); 784 unsigned Op0 = getFPReg(MI->getOperand(NumOperands-2)); 785 unsigned Op1 = getFPReg(MI->getOperand(NumOperands-1)); 786 bool KillsOp0 = LV->KillsRegister(MI, X86::FP0+Op0); 787 bool KillsOp1 = LV->KillsRegister(MI, X86::FP0+Op1); 788 789 // Make sure the first operand is on the top of stack, the other one can be 790 // anywhere. 791 moveToTop(Op0, I); 792 793 // Change from the pseudo instruction to the concrete instruction. 794 MI->getOperand(0).setReg(getSTReg(Op1)); 795 MI->RemoveOperand(1); 796 MI->setInstrDescriptor(TII->get(getConcreteOpcode(MI->getOpcode()))); 797 798 // If any of the operands are killed by this instruction, free them. 799 if (KillsOp0) freeStackSlotAfter(I, Op0); 800 if (KillsOp1 && Op0 != Op1) freeStackSlotAfter(I, Op1); 801} 802 803/// handleCondMovFP - Handle two address conditional move instructions. These 804/// instructions move a st(i) register to st(0) iff a condition is true. These 805/// instructions require that the first operand is at the top of the stack, but 806/// otherwise don't modify the stack at all. 807void FPS::handleCondMovFP(MachineBasicBlock::iterator &I) { 808 MachineInstr *MI = I; 809 810 unsigned Op0 = getFPReg(MI->getOperand(0)); 811 unsigned Op1 = getFPReg(MI->getOperand(2)); 812 bool KillsOp1 = LV->KillsRegister(MI, X86::FP0+Op1); 813 814 // The first operand *must* be on the top of the stack. 815 moveToTop(Op0, I); 816 817 // Change the second operand to the stack register that the operand is in. 818 // Change from the pseudo instruction to the concrete instruction. 819 MI->RemoveOperand(0); 820 MI->RemoveOperand(1); 821 MI->getOperand(0).setReg(getSTReg(Op1)); 822 MI->setInstrDescriptor(TII->get(getConcreteOpcode(MI->getOpcode()))); 823 824 // If we kill the second operand, make sure to pop it from the stack. 825 if (Op0 != Op1 && KillsOp1) { 826 // Get this value off of the register stack. 827 freeStackSlotAfter(I, Op1); 828 } 829} 830 831 832/// handleSpecialFP - Handle special instructions which behave unlike other 833/// floating point instructions. This is primarily intended for use by pseudo 834/// instructions. 835/// 836void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) { 837 MachineInstr *MI = I; 838 switch (MI->getOpcode()) { 839 default: assert(0 && "Unknown SpecialFP instruction!"); 840 case X86::FpGETRESULT32: // Appears immediately after a call returning FP type! 841 case X86::FpGETRESULT64: // Appears immediately after a call returning FP type! 842 assert(StackTop == 0 && "Stack should be empty after a call!"); 843 pushReg(getFPReg(MI->getOperand(0))); 844 break; 845 case X86::FpSETRESULT32: 846 case X86::FpSETRESULT64: 847 assert(StackTop == 1 && "Stack should have one element on it to return!"); 848 --StackTop; // "Forget" we have something on the top of stack! 849 break; 850 case X86::MOV_Fp3232: 851 case X86::MOV_Fp3264: 852 case X86::MOV_Fp6432: 853 case X86::MOV_Fp6464: { 854 unsigned SrcReg = getFPReg(MI->getOperand(1)); 855 unsigned DestReg = getFPReg(MI->getOperand(0)); 856 857 if (LV->KillsRegister(MI, X86::FP0+SrcReg)) { 858 // If the input operand is killed, we can just change the owner of the 859 // incoming stack slot into the result. 860 unsigned Slot = getSlot(SrcReg); 861 assert(Slot < 7 && DestReg < 7 && "FpMOV operands invalid!"); 862 Stack[Slot] = DestReg; 863 RegMap[DestReg] = Slot; 864 865 } else { 866 // For FMOV we just duplicate the specified value to a new stack slot. 867 // This could be made better, but would require substantial changes. 868 duplicateToTop(SrcReg, DestReg, I); 869 } 870 break; 871 } 872 } 873 874 I = MBB->erase(I); // Remove the pseudo instruction 875 --I; 876} 877