CGStmt.cpp revision d9becd1846e2c72bf6ad283faa1b048f33dd3afe
1//===--- CGStmt.cpp - Emit LLVM Code from Statements ----------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This contains code to emit Stmt nodes as LLVM code. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CGDebugInfo.h" 15#include "CodeGenModule.h" 16#include "CodeGenFunction.h" 17#include "clang/AST/StmtVisitor.h" 18#include "clang/Basic/PrettyStackTrace.h" 19#include "clang/Basic/TargetInfo.h" 20#include "llvm/ADT/StringExtras.h" 21#include "llvm/InlineAsm.h" 22#include "llvm/Intrinsics.h" 23#include "llvm/Target/TargetData.h" 24using namespace clang; 25using namespace CodeGen; 26 27//===----------------------------------------------------------------------===// 28// Statement Emission 29//===----------------------------------------------------------------------===// 30 31void CodeGenFunction::EmitStopPoint(const Stmt *S) { 32 if (CGDebugInfo *DI = getDebugInfo()) { 33 DI->setLocation(S->getLocStart()); 34 DI->EmitStopPoint(CurFn, Builder); 35 } 36} 37 38void CodeGenFunction::EmitStmt(const Stmt *S) { 39 assert(S && "Null statement?"); 40 41 // Check if we can handle this without bothering to generate an 42 // insert point or debug info. 43 if (EmitSimpleStmt(S)) 44 return; 45 46 // Check if we are generating unreachable code. 47 if (!HaveInsertPoint()) { 48 // If so, and the statement doesn't contain a label, then we do not need to 49 // generate actual code. This is safe because (1) the current point is 50 // unreachable, so we don't need to execute the code, and (2) we've already 51 // handled the statements which update internal data structures (like the 52 // local variable map) which could be used by subsequent statements. 53 if (!ContainsLabel(S)) { 54 // Verify that any decl statements were handled as simple, they may be in 55 // scope of subsequent reachable statements. 56 assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!"); 57 return; 58 } 59 60 // Otherwise, make a new block to hold the code. 61 EnsureInsertPoint(); 62 } 63 64 // Generate a stoppoint if we are emitting debug info. 65 EmitStopPoint(S); 66 67 switch (S->getStmtClass()) { 68 default: 69 // Must be an expression in a stmt context. Emit the value (to get 70 // side-effects) and ignore the result. 71 if (!isa<Expr>(S)) 72 ErrorUnsupported(S, "statement"); 73 74 EmitAnyExpr(cast<Expr>(S), 0, false, true); 75 76 // Expression emitters don't handle unreachable blocks yet, so look for one 77 // explicitly here. This handles the common case of a call to a noreturn 78 // function. 79 if (llvm::BasicBlock *CurBB = Builder.GetInsertBlock()) { 80 if (CurBB->empty() && CurBB->use_empty()) { 81 CurBB->eraseFromParent(); 82 Builder.ClearInsertionPoint(); 83 } 84 } 85 break; 86 case Stmt::IndirectGotoStmtClass: 87 EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break; 88 89 case Stmt::IfStmtClass: EmitIfStmt(cast<IfStmt>(*S)); break; 90 case Stmt::WhileStmtClass: EmitWhileStmt(cast<WhileStmt>(*S)); break; 91 case Stmt::DoStmtClass: EmitDoStmt(cast<DoStmt>(*S)); break; 92 case Stmt::ForStmtClass: EmitForStmt(cast<ForStmt>(*S)); break; 93 94 case Stmt::ReturnStmtClass: EmitReturnStmt(cast<ReturnStmt>(*S)); break; 95 96 case Stmt::SwitchStmtClass: EmitSwitchStmt(cast<SwitchStmt>(*S)); break; 97 case Stmt::AsmStmtClass: EmitAsmStmt(cast<AsmStmt>(*S)); break; 98 99 case Stmt::ObjCAtTryStmtClass: 100 EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S)); 101 break; 102 case Stmt::ObjCAtCatchStmtClass: 103 assert(0 && "@catch statements should be handled by EmitObjCAtTryStmt"); 104 break; 105 case Stmt::ObjCAtFinallyStmtClass: 106 assert(0 && "@finally statements should be handled by EmitObjCAtTryStmt"); 107 break; 108 case Stmt::ObjCAtThrowStmtClass: 109 EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S)); 110 break; 111 case Stmt::ObjCAtSynchronizedStmtClass: 112 EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S)); 113 break; 114 case Stmt::ObjCForCollectionStmtClass: 115 EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S)); 116 break; 117 118 case Stmt::CXXTryStmtClass: 119 EmitCXXTryStmt(cast<CXXTryStmt>(*S)); 120 break; 121 } 122} 123 124bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) { 125 switch (S->getStmtClass()) { 126 default: return false; 127 case Stmt::NullStmtClass: break; 128 case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break; 129 case Stmt::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break; 130 case Stmt::LabelStmtClass: EmitLabelStmt(cast<LabelStmt>(*S)); break; 131 case Stmt::GotoStmtClass: EmitGotoStmt(cast<GotoStmt>(*S)); break; 132 case Stmt::BreakStmtClass: EmitBreakStmt(cast<BreakStmt>(*S)); break; 133 case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break; 134 case Stmt::DefaultStmtClass: EmitDefaultStmt(cast<DefaultStmt>(*S)); break; 135 case Stmt::CaseStmtClass: EmitCaseStmt(cast<CaseStmt>(*S)); break; 136 } 137 138 return true; 139} 140 141/// EmitCompoundStmt - Emit a compound statement {..} node. If GetLast is true, 142/// this captures the expression result of the last sub-statement and returns it 143/// (for use by the statement expression extension). 144RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast, 145 llvm::Value *AggLoc, bool isAggVol) { 146 PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(), 147 "LLVM IR generation of compound statement ('{}')"); 148 149 CGDebugInfo *DI = getDebugInfo(); 150 if (DI) { 151#ifdef ATTACH_DEBUG_INFO_TO_AN_INSN 152 DI->setLocation(S.getLBracLoc()); 153 DI->EmitRegionStart(CurFn, Builder); 154#else 155 EnsureInsertPoint(); 156 DI->setLocation(S.getLBracLoc()); 157#endif 158 } 159 160 // Keep track of the current cleanup stack depth. 161 size_t CleanupStackDepth = CleanupEntries.size(); 162 bool OldDidCallStackSave = DidCallStackSave; 163 DidCallStackSave = false; 164 165 for (CompoundStmt::const_body_iterator I = S.body_begin(), 166 E = S.body_end()-GetLast; I != E; ++I) 167 EmitStmt(*I); 168 169 if (DI) { 170#ifdef ATTACH_DEBUG_INFO_TO_AN_INSN 171 DI->setLocation(S.getLBracLoc()); 172 DI->EmitRegionEnd(CurFn, Builder); 173#else 174 EnsureInsertPoint(); 175 DI->setLocation(S.getLBracLoc()); 176#endif 177 } 178 179 RValue RV; 180 if (!GetLast) 181 RV = RValue::get(0); 182 else { 183 // We have to special case labels here. They are statements, but when put 184 // at the end of a statement expression, they yield the value of their 185 // subexpression. Handle this by walking through all labels we encounter, 186 // emitting them before we evaluate the subexpr. 187 const Stmt *LastStmt = S.body_back(); 188 while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { 189 EmitLabel(*LS); 190 LastStmt = LS->getSubStmt(); 191 } 192 193 EnsureInsertPoint(); 194 195 RV = EmitAnyExpr(cast<Expr>(LastStmt), AggLoc); 196 } 197 198 DidCallStackSave = OldDidCallStackSave; 199 200 EmitCleanupBlocks(CleanupStackDepth); 201 202 return RV; 203} 204 205void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { 206 llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); 207 208 // If there is a cleanup stack, then we it isn't worth trying to 209 // simplify this block (we would need to remove it from the scope map 210 // and cleanup entry). 211 if (!CleanupEntries.empty()) 212 return; 213 214 // Can only simplify direct branches. 215 if (!BI || !BI->isUnconditional()) 216 return; 217 218 BB->replaceAllUsesWith(BI->getSuccessor(0)); 219 BI->eraseFromParent(); 220 BB->eraseFromParent(); 221} 222 223void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { 224 // Fall out of the current block (if necessary). 225 EmitBranch(BB); 226 227 if (IsFinished && BB->use_empty()) { 228 delete BB; 229 return; 230 } 231 232 // If necessary, associate the block with the cleanup stack size. 233 if (!CleanupEntries.empty()) { 234 // Check if the basic block has already been inserted. 235 BlockScopeMap::iterator I = BlockScopes.find(BB); 236 if (I != BlockScopes.end()) { 237 assert(I->second == CleanupEntries.size() - 1); 238 } else { 239 BlockScopes[BB] = CleanupEntries.size() - 1; 240 CleanupEntries.back().Blocks.push_back(BB); 241 } 242 } 243 244 CurFn->getBasicBlockList().push_back(BB); 245 Builder.SetInsertPoint(BB); 246} 247 248void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { 249 // Emit a branch from the current block to the target one if this 250 // was a real block. If this was just a fall-through block after a 251 // terminator, don't emit it. 252 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 253 254 if (!CurBB || CurBB->getTerminator()) { 255 // If there is no insert point or the previous block is already 256 // terminated, don't touch it. 257 } else { 258 // Otherwise, create a fall-through branch. 259 Builder.CreateBr(Target); 260 } 261 262 Builder.ClearInsertionPoint(); 263} 264 265void CodeGenFunction::EmitLabel(const LabelStmt &S) { 266 EmitBlock(getBasicBlockForLabel(&S)); 267} 268 269 270void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { 271 EmitLabel(S); 272 EmitStmt(S.getSubStmt()); 273} 274 275void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { 276 // If this code is reachable then emit a stop point (if generating 277 // debug info). We have to do this ourselves because we are on the 278 // "simple" statement path. 279 if (HaveInsertPoint()) 280 EmitStopPoint(&S); 281 282 EmitBranchThroughCleanup(getBasicBlockForLabel(S.getLabel())); 283} 284 285 286void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { 287 // Emit initial switch which will be patched up later by 288 // EmitIndirectSwitches(). We need a default dest, so we use the 289 // current BB, but this is overwritten. 290#ifndef USEINDIRECTBRANCH 291 llvm::Value *V = Builder.CreatePtrToInt(EmitScalarExpr(S.getTarget()), 292 llvm::Type::getInt32Ty(VMContext), 293#else 294 llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()), 295 llvm::Type::getInt8PtrTy(VMContext), 296#endif 297 "addr"); 298 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 299 300 301 // Get the basic block for the indirect goto. 302 llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock(); 303 304 // The first instruction in the block has to be the PHI for the switch dest, 305 // add an entry for this branch. 306 cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB); 307 308 EmitBranch(IndGotoBB); 309} 310 311void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 312 // C99 6.8.4.1: The first substatement is executed if the expression compares 313 // unequal to 0. The condition must be a scalar type. 314 315 // If the condition constant folds and can be elided, try to avoid emitting 316 // the condition and the dead arm of the if/else. 317 if (int Cond = ConstantFoldsToSimpleInteger(S.getCond())) { 318 // Figure out which block (then or else) is executed. 319 const Stmt *Executed = S.getThen(), *Skipped = S.getElse(); 320 if (Cond == -1) // Condition false? 321 std::swap(Executed, Skipped); 322 323 // If the skipped block has no labels in it, just emit the executed block. 324 // This avoids emitting dead code and simplifies the CFG substantially. 325 if (!ContainsLabel(Skipped)) { 326 if (Executed) 327 EmitStmt(Executed); 328 return; 329 } 330 } 331 332 // Otherwise, the condition did not fold, or we couldn't elide it. Just emit 333 // the conditional branch. 334 llvm::BasicBlock *ThenBlock = createBasicBlock("if.then"); 335 llvm::BasicBlock *ContBlock = createBasicBlock("if.end"); 336 llvm::BasicBlock *ElseBlock = ContBlock; 337 if (S.getElse()) 338 ElseBlock = createBasicBlock("if.else"); 339 EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock); 340 341 // Emit the 'then' code. 342 EmitBlock(ThenBlock); 343 EmitStmt(S.getThen()); 344 EmitBranch(ContBlock); 345 346 // Emit the 'else' code if present. 347 if (const Stmt *Else = S.getElse()) { 348 EmitBlock(ElseBlock); 349 EmitStmt(Else); 350 EmitBranch(ContBlock); 351 } 352 353 // Emit the continuation block for code after the if. 354 EmitBlock(ContBlock, true); 355} 356 357void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) { 358 // Emit the header for the loop, insert it, which will create an uncond br to 359 // it. 360 llvm::BasicBlock *LoopHeader = createBasicBlock("while.cond"); 361 EmitBlock(LoopHeader); 362 363 // Create an exit block for when the condition fails, create a block for the 364 // body of the loop. 365 llvm::BasicBlock *ExitBlock = createBasicBlock("while.end"); 366 llvm::BasicBlock *LoopBody = createBasicBlock("while.body"); 367 368 // Store the blocks to use for break and continue. 369 BreakContinueStack.push_back(BreakContinue(ExitBlock, LoopHeader)); 370 371 // Evaluate the conditional in the while header. C99 6.8.5.1: The 372 // evaluation of the controlling expression takes place before each 373 // execution of the loop body. 374 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 375 376 // while(1) is common, avoid extra exit blocks. Be sure 377 // to correctly handle break/continue though. 378 bool EmitBoolCondBranch = true; 379 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 380 if (C->isOne()) 381 EmitBoolCondBranch = false; 382 383 // As long as the condition is true, go to the loop body. 384 if (EmitBoolCondBranch) 385 Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock); 386 387 // Emit the loop body. 388 EmitBlock(LoopBody); 389 EmitStmt(S.getBody()); 390 391 BreakContinueStack.pop_back(); 392 393 // Cycle to the condition. 394 EmitBranch(LoopHeader); 395 396 // Emit the exit block. 397 EmitBlock(ExitBlock, true); 398 399 // The LoopHeader typically is just a branch if we skipped emitting 400 // a branch, try to erase it. 401 if (!EmitBoolCondBranch) 402 SimplifyForwardingBlocks(LoopHeader); 403} 404 405void CodeGenFunction::EmitDoStmt(const DoStmt &S) { 406 // Emit the body for the loop, insert it, which will create an uncond br to 407 // it. 408 llvm::BasicBlock *LoopBody = createBasicBlock("do.body"); 409 llvm::BasicBlock *AfterDo = createBasicBlock("do.end"); 410 EmitBlock(LoopBody); 411 412 llvm::BasicBlock *DoCond = createBasicBlock("do.cond"); 413 414 // Store the blocks to use for break and continue. 415 BreakContinueStack.push_back(BreakContinue(AfterDo, DoCond)); 416 417 // Emit the body of the loop into the block. 418 EmitStmt(S.getBody()); 419 420 BreakContinueStack.pop_back(); 421 422 EmitBlock(DoCond); 423 424 // C99 6.8.5.2: "The evaluation of the controlling expression takes place 425 // after each execution of the loop body." 426 427 // Evaluate the conditional in the while header. 428 // C99 6.8.5p2/p4: The first substatement is executed if the expression 429 // compares unequal to 0. The condition must be a scalar type. 430 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 431 432 // "do {} while (0)" is common in macros, avoid extra blocks. Be sure 433 // to correctly handle break/continue though. 434 bool EmitBoolCondBranch = true; 435 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 436 if (C->isZero()) 437 EmitBoolCondBranch = false; 438 439 // As long as the condition is true, iterate the loop. 440 if (EmitBoolCondBranch) 441 Builder.CreateCondBr(BoolCondVal, LoopBody, AfterDo); 442 443 // Emit the exit block. 444 EmitBlock(AfterDo); 445 446 // The DoCond block typically is just a branch if we skipped 447 // emitting a branch, try to erase it. 448 if (!EmitBoolCondBranch) 449 SimplifyForwardingBlocks(DoCond); 450} 451 452void CodeGenFunction::EmitForStmt(const ForStmt &S) { 453 // FIXME: What do we do if the increment (f.e.) contains a stmt expression, 454 // which contains a continue/break? 455 456 // Evaluate the first part before the loop. 457 if (S.getInit()) 458 EmitStmt(S.getInit()); 459 460 // Start the loop with a block that tests the condition. 461 llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); 462 llvm::BasicBlock *AfterFor = createBasicBlock("for.end"); 463 464 EmitBlock(CondBlock); 465 466 // Evaluate the condition if present. If not, treat it as a 467 // non-zero-constant according to 6.8.5.3p2, aka, true. 468 if (S.getCond()) { 469 // As long as the condition is true, iterate the loop. 470 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 471 472 // C99 6.8.5p2/p4: The first substatement is executed if the expression 473 // compares unequal to 0. The condition must be a scalar type. 474 EmitBranchOnBoolExpr(S.getCond(), ForBody, AfterFor); 475 476 EmitBlock(ForBody); 477 } else { 478 // Treat it as a non-zero constant. Don't even create a new block for the 479 // body, just fall into it. 480 } 481 482 // If the for loop doesn't have an increment we can just use the 483 // condition as the continue block. 484 llvm::BasicBlock *ContinueBlock; 485 if (S.getInc()) 486 ContinueBlock = createBasicBlock("for.inc"); 487 else 488 ContinueBlock = CondBlock; 489 490 // Store the blocks to use for break and continue. 491 BreakContinueStack.push_back(BreakContinue(AfterFor, ContinueBlock)); 492 493 // If the condition is true, execute the body of the for stmt. 494#ifdef ATTACH_DEBUG_INFO_TO_AN_INSN 495 CGDebugInfo *DI = getDebugInfo(); 496 if (DI) { 497 DI->setLocation(S.getSourceRange().getBegin()); 498 DI->EmitRegionStart(CurFn, Builder); 499 } 500#endif 501 EmitStmt(S.getBody()); 502 503 BreakContinueStack.pop_back(); 504 505 // If there is an increment, emit it next. 506 if (S.getInc()) { 507 EmitBlock(ContinueBlock); 508 EmitStmt(S.getInc()); 509 } 510 511 // Finally, branch back up to the condition for the next iteration. 512 EmitBranch(CondBlock); 513#ifdef ATTACH_DEBUG_INFO_TO_AN_INSN 514 if (DI) { 515 DI->setLocation(S.getSourceRange().getEnd()); 516 DI->EmitRegionEnd(CurFn, Builder); 517 } 518#endif 519 520 // Emit the fall-through block. 521 EmitBlock(AfterFor, true); 522} 523 524void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { 525 if (RV.isScalar()) { 526 Builder.CreateStore(RV.getScalarVal(), ReturnValue); 527 } else if (RV.isAggregate()) { 528 EmitAggregateCopy(ReturnValue, RV.getAggregateAddr(), Ty); 529 } else { 530 StoreComplexToAddr(RV.getComplexVal(), ReturnValue, false); 531 } 532 EmitBranchThroughCleanup(ReturnBlock); 533} 534 535/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand 536/// if the function returns void, or may be missing one if the function returns 537/// non-void. Fun stuff :). 538void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { 539 // Emit the result value, even if unused, to evalute the side effects. 540 const Expr *RV = S.getRetValue(); 541 542 // FIXME: Clean this up by using an LValue for ReturnTemp, 543 // EmitStoreThroughLValue, and EmitAnyExpr. 544 if (!ReturnValue) { 545 // Make sure not to return anything, but evaluate the expression 546 // for side effects. 547 if (RV) 548 EmitAnyExpr(RV); 549 } else if (RV == 0) { 550 // Do nothing (return value is left uninitialized) 551 } else if (FnRetTy->isReferenceType()) { 552 // If this function returns a reference, take the address of the expression 553 // rather than the value. 554 Builder.CreateStore(EmitLValue(RV).getAddress(), ReturnValue); 555 } else if (!hasAggregateLLVMType(RV->getType())) { 556 Builder.CreateStore(EmitScalarExpr(RV), ReturnValue); 557 } else if (RV->getType()->isAnyComplexType()) { 558 EmitComplexExprIntoAddr(RV, ReturnValue, false); 559 } else { 560 EmitAggExpr(RV, ReturnValue, false); 561 } 562 563 EmitBranchThroughCleanup(ReturnBlock); 564} 565 566void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { 567 // As long as debug info is modeled with instructions, we have to ensure we 568 // have a place to insert here and write the stop point here. 569 if (getDebugInfo()) { 570 EnsureInsertPoint(); 571 EmitStopPoint(&S); 572 } 573 574 for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); 575 I != E; ++I) 576 EmitDecl(**I); 577} 578 579void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { 580 assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); 581 582 // If this code is reachable then emit a stop point (if generating 583 // debug info). We have to do this ourselves because we are on the 584 // "simple" statement path. 585 if (HaveInsertPoint()) 586 EmitStopPoint(&S); 587 588 llvm::BasicBlock *Block = BreakContinueStack.back().BreakBlock; 589 EmitBranchThroughCleanup(Block); 590} 591 592void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { 593 assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); 594 595 // If this code is reachable then emit a stop point (if generating 596 // debug info). We have to do this ourselves because we are on the 597 // "simple" statement path. 598 if (HaveInsertPoint()) 599 EmitStopPoint(&S); 600 601 llvm::BasicBlock *Block = BreakContinueStack.back().ContinueBlock; 602 EmitBranchThroughCleanup(Block); 603} 604 605/// EmitCaseStmtRange - If case statement range is not too big then 606/// add multiple cases to switch instruction, one for each value within 607/// the range. If range is too big then emit "if" condition check. 608void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { 609 assert(S.getRHS() && "Expected RHS value in CaseStmt"); 610 611 llvm::APSInt LHS = S.getLHS()->EvaluateAsInt(getContext()); 612 llvm::APSInt RHS = S.getRHS()->EvaluateAsInt(getContext()); 613 614 // Emit the code for this case. We do this first to make sure it is 615 // properly chained from our predecessor before generating the 616 // switch machinery to enter this block. 617 EmitBlock(createBasicBlock("sw.bb")); 618 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 619 EmitStmt(S.getSubStmt()); 620 621 // If range is empty, do nothing. 622 if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) 623 return; 624 625 llvm::APInt Range = RHS - LHS; 626 // FIXME: parameters such as this should not be hardcoded. 627 if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { 628 // Range is small enough to add multiple switch instruction cases. 629 for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { 630 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, LHS), CaseDest); 631 LHS++; 632 } 633 return; 634 } 635 636 // The range is too big. Emit "if" condition into a new block, 637 // making sure to save and restore the current insertion point. 638 llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); 639 640 // Push this test onto the chain of range checks (which terminates 641 // in the default basic block). The switch's default will be changed 642 // to the top of this chain after switch emission is complete. 643 llvm::BasicBlock *FalseDest = CaseRangeBlock; 644 CaseRangeBlock = createBasicBlock("sw.caserange"); 645 646 CurFn->getBasicBlockList().push_back(CaseRangeBlock); 647 Builder.SetInsertPoint(CaseRangeBlock); 648 649 // Emit range check. 650 llvm::Value *Diff = 651 Builder.CreateSub(SwitchInsn->getCondition(), 652 llvm::ConstantInt::get(VMContext, LHS), "tmp"); 653 llvm::Value *Cond = 654 Builder.CreateICmpULE(Diff, 655 llvm::ConstantInt::get(VMContext, Range), "tmp"); 656 Builder.CreateCondBr(Cond, CaseDest, FalseDest); 657 658 // Restore the appropriate insertion point. 659 if (RestoreBB) 660 Builder.SetInsertPoint(RestoreBB); 661 else 662 Builder.ClearInsertionPoint(); 663} 664 665void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { 666 if (S.getRHS()) { 667 EmitCaseStmtRange(S); 668 return; 669 } 670 671 EmitBlock(createBasicBlock("sw.bb")); 672 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 673 llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext()); 674 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, CaseVal), CaseDest); 675 676 // Recursively emitting the statement is acceptable, but is not wonderful for 677 // code where we have many case statements nested together, i.e.: 678 // case 1: 679 // case 2: 680 // case 3: etc. 681 // Handling this recursively will create a new block for each case statement 682 // that falls through to the next case which is IR intensive. It also causes 683 // deep recursion which can run into stack depth limitations. Handle 684 // sequential non-range case statements specially. 685 const CaseStmt *CurCase = &S; 686 const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); 687 688 // Otherwise, iteratively add consequtive cases to this switch stmt. 689 while (NextCase && NextCase->getRHS() == 0) { 690 CurCase = NextCase; 691 CaseVal = CurCase->getLHS()->EvaluateAsInt(getContext()); 692 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, CaseVal), CaseDest); 693 694 NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); 695 } 696 697 // Normal default recursion for non-cases. 698 EmitStmt(CurCase->getSubStmt()); 699} 700 701void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { 702 llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); 703 assert(DefaultBlock->empty() && 704 "EmitDefaultStmt: Default block already defined?"); 705 EmitBlock(DefaultBlock); 706 EmitStmt(S.getSubStmt()); 707} 708 709void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { 710 llvm::Value *CondV = EmitScalarExpr(S.getCond()); 711 712 // Handle nested switch statements. 713 llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; 714 llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; 715 716 // Create basic block to hold stuff that comes after switch 717 // statement. We also need to create a default block now so that 718 // explicit case ranges tests can have a place to jump to on 719 // failure. 720 llvm::BasicBlock *NextBlock = createBasicBlock("sw.epilog"); 721 llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); 722 SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); 723 CaseRangeBlock = DefaultBlock; 724 725 // Clear the insertion point to indicate we are in unreachable code. 726 Builder.ClearInsertionPoint(); 727 728 // All break statements jump to NextBlock. If BreakContinueStack is non empty 729 // then reuse last ContinueBlock. 730 llvm::BasicBlock *ContinueBlock = 0; 731 if (!BreakContinueStack.empty()) 732 ContinueBlock = BreakContinueStack.back().ContinueBlock; 733 734 // Ensure any vlas created between there and here, are undone 735 BreakContinueStack.push_back(BreakContinue(NextBlock, ContinueBlock)); 736 737 // Emit switch body. 738 EmitStmt(S.getBody()); 739 740 BreakContinueStack.pop_back(); 741 742 // Update the default block in case explicit case range tests have 743 // been chained on top. 744 SwitchInsn->setSuccessor(0, CaseRangeBlock); 745 746 // If a default was never emitted then reroute any jumps to it and 747 // discard. 748 if (!DefaultBlock->getParent()) { 749 DefaultBlock->replaceAllUsesWith(NextBlock); 750 delete DefaultBlock; 751 } 752 753 // Emit continuation. 754 EmitBlock(NextBlock, true); 755 756 SwitchInsn = SavedSwitchInsn; 757 CaseRangeBlock = SavedCRBlock; 758} 759 760static std::string 761SimplifyConstraint(const char *Constraint, TargetInfo &Target, 762 llvm::SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { 763 std::string Result; 764 765 while (*Constraint) { 766 switch (*Constraint) { 767 default: 768 Result += Target.convertConstraint(*Constraint); 769 break; 770 // Ignore these 771 case '*': 772 case '?': 773 case '!': 774 break; 775 case 'g': 776 Result += "imr"; 777 break; 778 case '[': { 779 assert(OutCons && 780 "Must pass output names to constraints with a symbolic name"); 781 unsigned Index; 782 bool result = Target.resolveSymbolicName(Constraint, 783 &(*OutCons)[0], 784 OutCons->size(), Index); 785 assert(result && "Could not resolve symbolic name"); result=result; 786 Result += llvm::utostr(Index); 787 break; 788 } 789 } 790 791 Constraint++; 792 } 793 794 return Result; 795} 796 797llvm::Value* CodeGenFunction::EmitAsmInput(const AsmStmt &S, 798 const TargetInfo::ConstraintInfo &Info, 799 const Expr *InputExpr, 800 std::string &ConstraintStr) { 801 llvm::Value *Arg; 802 if (Info.allowsRegister() || !Info.allowsMemory()) { 803 const llvm::Type *Ty = ConvertType(InputExpr->getType()); 804 805 if (Ty->isSingleValueType()) { 806 Arg = EmitScalarExpr(InputExpr); 807 } else { 808 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 809 LValue Dest = EmitLValue(InputExpr); 810 811 uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); 812 if (Size <= 64 && llvm::isPowerOf2_64(Size)) { 813 Ty = llvm::IntegerType::get(VMContext, Size); 814 Ty = llvm::PointerType::getUnqual(Ty); 815 816 Arg = Builder.CreateLoad(Builder.CreateBitCast(Dest.getAddress(), Ty)); 817 } else { 818 Arg = Dest.getAddress(); 819 ConstraintStr += '*'; 820 } 821 } 822 } else { 823 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 824 LValue Dest = EmitLValue(InputExpr); 825 Arg = Dest.getAddress(); 826 ConstraintStr += '*'; 827 } 828 829 return Arg; 830} 831 832void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { 833 // Analyze the asm string to decompose it into its pieces. We know that Sema 834 // has already done this, so it is guaranteed to be successful. 835 llvm::SmallVector<AsmStmt::AsmStringPiece, 4> Pieces; 836 unsigned DiagOffs; 837 S.AnalyzeAsmString(Pieces, getContext(), DiagOffs); 838 839 // Assemble the pieces into the final asm string. 840 std::string AsmString; 841 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { 842 if (Pieces[i].isString()) 843 AsmString += Pieces[i].getString(); 844 else if (Pieces[i].getModifier() == '\0') 845 AsmString += '$' + llvm::utostr(Pieces[i].getOperandNo()); 846 else 847 AsmString += "${" + llvm::utostr(Pieces[i].getOperandNo()) + ':' + 848 Pieces[i].getModifier() + '}'; 849 } 850 851 // Get all the output and input constraints together. 852 llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 853 llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 854 855 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 856 TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), 857 S.getOutputName(i)); 858 bool result = Target.validateOutputConstraint(Info); 859 assert(result && "Failed to parse output constraint"); result=result; 860 OutputConstraintInfos.push_back(Info); 861 } 862 863 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 864 TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), 865 S.getInputName(i)); 866 bool result = Target.validateInputConstraint(OutputConstraintInfos.data(), 867 S.getNumOutputs(), 868 Info); result=result; 869 assert(result && "Failed to parse input constraint"); 870 InputConstraintInfos.push_back(Info); 871 } 872 873 std::string Constraints; 874 875 std::vector<LValue> ResultRegDests; 876 std::vector<QualType> ResultRegQualTys; 877 std::vector<const llvm::Type *> ResultRegTypes; 878 std::vector<const llvm::Type *> ResultTruncRegTypes; 879 std::vector<const llvm::Type*> ArgTypes; 880 std::vector<llvm::Value*> Args; 881 882 // Keep track of inout constraints. 883 std::string InOutConstraints; 884 std::vector<llvm::Value*> InOutArgs; 885 std::vector<const llvm::Type*> InOutArgTypes; 886 887 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 888 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 889 890 // Simplify the output constraint. 891 std::string OutputConstraint(S.getOutputConstraint(i)); 892 OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); 893 894 const Expr *OutExpr = S.getOutputExpr(i); 895 OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); 896 897 LValue Dest = EmitLValue(OutExpr); 898 if (!Constraints.empty()) 899 Constraints += ','; 900 901 // If this is a register output, then make the inline asm return it 902 // by-value. If this is a memory result, return the value by-reference. 903 if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { 904 Constraints += "=" + OutputConstraint; 905 ResultRegQualTys.push_back(OutExpr->getType()); 906 ResultRegDests.push_back(Dest); 907 ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); 908 ResultTruncRegTypes.push_back(ResultRegTypes.back()); 909 910 // If this output is tied to an input, and if the input is larger, then 911 // we need to set the actual result type of the inline asm node to be the 912 // same as the input type. 913 if (Info.hasMatchingInput()) { 914 unsigned InputNo; 915 for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { 916 TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; 917 if (Input.hasTiedOperand() && 918 Input.getTiedOperand() == i) 919 break; 920 } 921 assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); 922 923 QualType InputTy = S.getInputExpr(InputNo)->getType(); 924 QualType OutputTy = OutExpr->getType(); 925 926 uint64_t InputSize = getContext().getTypeSize(InputTy); 927 if (getContext().getTypeSize(OutputTy) < InputSize) { 928 // Form the asm to return the value as a larger integer type. 929 ResultRegTypes.back() = llvm::IntegerType::get(VMContext, (unsigned)InputSize); 930 } 931 } 932 } else { 933 ArgTypes.push_back(Dest.getAddress()->getType()); 934 Args.push_back(Dest.getAddress()); 935 Constraints += "=*"; 936 Constraints += OutputConstraint; 937 } 938 939 if (Info.isReadWrite()) { 940 InOutConstraints += ','; 941 942 const Expr *InputExpr = S.getOutputExpr(i); 943 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, InOutConstraints); 944 945 if (Info.allowsRegister()) 946 InOutConstraints += llvm::utostr(i); 947 else 948 InOutConstraints += OutputConstraint; 949 950 InOutArgTypes.push_back(Arg->getType()); 951 InOutArgs.push_back(Arg); 952 } 953 } 954 955 unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); 956 957 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 958 const Expr *InputExpr = S.getInputExpr(i); 959 960 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 961 962 if (!Constraints.empty()) 963 Constraints += ','; 964 965 // Simplify the input constraint. 966 std::string InputConstraint(S.getInputConstraint(i)); 967 InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, 968 &OutputConstraintInfos); 969 970 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints); 971 972 // If this input argument is tied to a larger output result, extend the 973 // input to be the same size as the output. The LLVM backend wants to see 974 // the input and output of a matching constraint be the same size. Note 975 // that GCC does not define what the top bits are here. We use zext because 976 // that is usually cheaper, but LLVM IR should really get an anyext someday. 977 if (Info.hasTiedOperand()) { 978 unsigned Output = Info.getTiedOperand(); 979 QualType OutputTy = S.getOutputExpr(Output)->getType(); 980 QualType InputTy = InputExpr->getType(); 981 982 if (getContext().getTypeSize(OutputTy) > 983 getContext().getTypeSize(InputTy)) { 984 // Use ptrtoint as appropriate so that we can do our extension. 985 if (isa<llvm::PointerType>(Arg->getType())) 986 Arg = Builder.CreatePtrToInt(Arg, 987 llvm::IntegerType::get(VMContext, LLVMPointerWidth)); 988 unsigned OutputSize = (unsigned)getContext().getTypeSize(OutputTy); 989 Arg = Builder.CreateZExt(Arg, llvm::IntegerType::get(VMContext, OutputSize)); 990 } 991 } 992 993 994 ArgTypes.push_back(Arg->getType()); 995 Args.push_back(Arg); 996 Constraints += InputConstraint; 997 } 998 999 // Append the "input" part of inout constraints last. 1000 for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { 1001 ArgTypes.push_back(InOutArgTypes[i]); 1002 Args.push_back(InOutArgs[i]); 1003 } 1004 Constraints += InOutConstraints; 1005 1006 // Clobbers 1007 for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { 1008 std::string Clobber(S.getClobber(i)->getStrData(), 1009 S.getClobber(i)->getByteLength()); 1010 1011 Clobber = Target.getNormalizedGCCRegisterName(Clobber.c_str()); 1012 1013 if (i != 0 || NumConstraints != 0) 1014 Constraints += ','; 1015 1016 Constraints += "~{"; 1017 Constraints += Clobber; 1018 Constraints += '}'; 1019 } 1020 1021 // Add machine specific clobbers 1022 std::string MachineClobbers = Target.getClobbers(); 1023 if (!MachineClobbers.empty()) { 1024 if (!Constraints.empty()) 1025 Constraints += ','; 1026 Constraints += MachineClobbers; 1027 } 1028 1029 const llvm::Type *ResultType; 1030 if (ResultRegTypes.empty()) 1031 ResultType = llvm::Type::getVoidTy(VMContext); 1032 else if (ResultRegTypes.size() == 1) 1033 ResultType = ResultRegTypes[0]; 1034 else 1035 ResultType = llvm::StructType::get(VMContext, ResultRegTypes); 1036 1037 const llvm::FunctionType *FTy = 1038 llvm::FunctionType::get(ResultType, ArgTypes, false); 1039 1040 llvm::InlineAsm *IA = 1041 llvm::InlineAsm::get(FTy, AsmString, Constraints, 1042 S.isVolatile() || S.getNumOutputs() == 0); 1043 llvm::CallInst *Result = Builder.CreateCall(IA, Args.begin(), Args.end()); 1044 Result->addAttribute(~0, llvm::Attribute::NoUnwind); 1045 1046 1047 // Extract all of the register value results from the asm. 1048 std::vector<llvm::Value*> RegResults; 1049 if (ResultRegTypes.size() == 1) { 1050 RegResults.push_back(Result); 1051 } else { 1052 for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { 1053 llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); 1054 RegResults.push_back(Tmp); 1055 } 1056 } 1057 1058 for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { 1059 llvm::Value *Tmp = RegResults[i]; 1060 1061 // If the result type of the LLVM IR asm doesn't match the result type of 1062 // the expression, do the conversion. 1063 if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { 1064 const llvm::Type *TruncTy = ResultTruncRegTypes[i]; 1065 // Truncate the integer result to the right size, note that 1066 // ResultTruncRegTypes can be a pointer. 1067 uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); 1068 Tmp = Builder.CreateTrunc(Tmp, llvm::IntegerType::get(VMContext, (unsigned)ResSize)); 1069 1070 if (Tmp->getType() != TruncTy) { 1071 assert(isa<llvm::PointerType>(TruncTy)); 1072 Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); 1073 } 1074 } 1075 1076 EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i], 1077 ResultRegQualTys[i]); 1078 } 1079} 1080