CGStmt.cpp revision b992259f7790d3fb9fc5c2eb7182d7af9d64f9ac
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 DI->setLocation(S.getLBracLoc()); 152 DI->EmitRegionStart(CurFn, Builder); 153 } 154 155 // Keep track of the current cleanup stack depth. 156 CleanupScope Scope(*this); 157 158 for (CompoundStmt::const_body_iterator I = S.body_begin(), 159 E = S.body_end()-GetLast; I != E; ++I) 160 EmitStmt(*I); 161 162 if (DI) { 163 DI->setLocation(S.getLBracLoc()); 164 DI->EmitRegionEnd(CurFn, Builder); 165 } 166 167 RValue RV; 168 if (!GetLast) 169 RV = RValue::get(0); 170 else { 171 // We have to special case labels here. They are statements, but when put 172 // at the end of a statement expression, they yield the value of their 173 // subexpression. Handle this by walking through all labels we encounter, 174 // emitting them before we evaluate the subexpr. 175 const Stmt *LastStmt = S.body_back(); 176 while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { 177 EmitLabel(*LS); 178 LastStmt = LS->getSubStmt(); 179 } 180 181 EnsureInsertPoint(); 182 183 RV = EmitAnyExpr(cast<Expr>(LastStmt), AggLoc); 184 } 185 186 return RV; 187} 188 189void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { 190 llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); 191 192 // If there is a cleanup stack, then we it isn't worth trying to 193 // simplify this block (we would need to remove it from the scope map 194 // and cleanup entry). 195 if (!CleanupEntries.empty()) 196 return; 197 198 // Can only simplify direct branches. 199 if (!BI || !BI->isUnconditional()) 200 return; 201 202 BB->replaceAllUsesWith(BI->getSuccessor(0)); 203 BI->eraseFromParent(); 204 BB->eraseFromParent(); 205} 206 207void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { 208 // Fall out of the current block (if necessary). 209 EmitBranch(BB); 210 211 if (IsFinished && BB->use_empty()) { 212 delete BB; 213 return; 214 } 215 216 // If necessary, associate the block with the cleanup stack size. 217 if (!CleanupEntries.empty()) { 218 // Check if the basic block has already been inserted. 219 BlockScopeMap::iterator I = BlockScopes.find(BB); 220 if (I != BlockScopes.end()) { 221 assert(I->second == CleanupEntries.size() - 1); 222 } else { 223 BlockScopes[BB] = CleanupEntries.size() - 1; 224 CleanupEntries.back().Blocks.push_back(BB); 225 } 226 } 227 228 CurFn->getBasicBlockList().push_back(BB); 229 Builder.SetInsertPoint(BB); 230} 231 232void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { 233 // Emit a branch from the current block to the target one if this 234 // was a real block. If this was just a fall-through block after a 235 // terminator, don't emit it. 236 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 237 238 if (!CurBB || CurBB->getTerminator()) { 239 // If there is no insert point or the previous block is already 240 // terminated, don't touch it. 241 } else { 242 // Otherwise, create a fall-through branch. 243 Builder.CreateBr(Target); 244 } 245 246 Builder.ClearInsertionPoint(); 247} 248 249void CodeGenFunction::EmitLabel(const LabelStmt &S) { 250 EmitBlock(getBasicBlockForLabel(&S)); 251} 252 253 254void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { 255 EmitLabel(S); 256 EmitStmt(S.getSubStmt()); 257} 258 259void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { 260 // If this code is reachable then emit a stop point (if generating 261 // debug info). We have to do this ourselves because we are on the 262 // "simple" statement path. 263 if (HaveInsertPoint()) 264 EmitStopPoint(&S); 265 266 EmitBranchThroughCleanup(getBasicBlockForLabel(S.getLabel())); 267} 268 269 270void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { 271 // Ensure that we have an i8* for our PHI node. 272 llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()), 273 llvm::Type::getInt8PtrTy(VMContext), 274 "addr"); 275 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 276 277 278 // Get the basic block for the indirect goto. 279 llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock(); 280 281 // The first instruction in the block has to be the PHI for the switch dest, 282 // add an entry for this branch. 283 cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB); 284 285 EmitBranch(IndGotoBB); 286} 287 288void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 289 // C99 6.8.4.1: The first substatement is executed if the expression compares 290 // unequal to 0. The condition must be a scalar type. 291 CleanupScope ConditionScope(*this); 292 293 if (S.getConditionVariable()) 294 EmitLocalBlockVarDecl(*S.getConditionVariable()); 295 296 // If the condition constant folds and can be elided, try to avoid emitting 297 // the condition and the dead arm of the if/else. 298 if (int Cond = ConstantFoldsToSimpleInteger(S.getCond())) { 299 // Figure out which block (then or else) is executed. 300 const Stmt *Executed = S.getThen(), *Skipped = S.getElse(); 301 if (Cond == -1) // Condition false? 302 std::swap(Executed, Skipped); 303 304 // If the skipped block has no labels in it, just emit the executed block. 305 // This avoids emitting dead code and simplifies the CFG substantially. 306 if (!ContainsLabel(Skipped)) { 307 if (Executed) { 308 CleanupScope ExecutedScope(*this); 309 EmitStmt(Executed); 310 } 311 return; 312 } 313 } 314 315 // Otherwise, the condition did not fold, or we couldn't elide it. Just emit 316 // the conditional branch. 317 llvm::BasicBlock *ThenBlock = createBasicBlock("if.then"); 318 llvm::BasicBlock *ContBlock = createBasicBlock("if.end"); 319 llvm::BasicBlock *ElseBlock = ContBlock; 320 if (S.getElse()) 321 ElseBlock = createBasicBlock("if.else"); 322 EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock); 323 324 // Emit the 'then' code. 325 EmitBlock(ThenBlock); 326 { 327 CleanupScope ThenScope(*this); 328 EmitStmt(S.getThen()); 329 } 330 EmitBranch(ContBlock); 331 332 // Emit the 'else' code if present. 333 if (const Stmt *Else = S.getElse()) { 334 EmitBlock(ElseBlock); 335 { 336 CleanupScope ElseScope(*this); 337 EmitStmt(Else); 338 } 339 EmitBranch(ContBlock); 340 } 341 342 // Emit the continuation block for code after the if. 343 EmitBlock(ContBlock, true); 344} 345 346void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) { 347 // Emit the header for the loop, insert it, which will create an uncond br to 348 // it. 349 llvm::BasicBlock *LoopHeader = createBasicBlock("while.cond"); 350 EmitBlock(LoopHeader); 351 352 // Create an exit block for when the condition fails, create a block for the 353 // body of the loop. 354 llvm::BasicBlock *ExitBlock = createBasicBlock("while.end"); 355 llvm::BasicBlock *LoopBody = createBasicBlock("while.body"); 356 llvm::BasicBlock *CleanupBlock = 0; 357 llvm::BasicBlock *EffectiveExitBlock = ExitBlock; 358 359 // Store the blocks to use for break and continue. 360 BreakContinueStack.push_back(BreakContinue(ExitBlock, LoopHeader)); 361 362 // C++ [stmt.while]p2: 363 // When the condition of a while statement is a declaration, the 364 // scope of the variable that is declared extends from its point 365 // of declaration (3.3.2) to the end of the while statement. 366 // [...] 367 // The object created in a condition is destroyed and created 368 // with each iteration of the loop. 369 CleanupScope ConditionScope(*this); 370 371 if (S.getConditionVariable()) { 372 EmitLocalBlockVarDecl(*S.getConditionVariable()); 373 374 // If this condition variable requires cleanups, create a basic 375 // block to handle those cleanups. 376 if (ConditionScope.requiresCleanups()) { 377 CleanupBlock = createBasicBlock("while.cleanup"); 378 EffectiveExitBlock = CleanupBlock; 379 } 380 } 381 382 // Evaluate the conditional in the while header. C99 6.8.5.1: The 383 // evaluation of the controlling expression takes place before each 384 // execution of the loop body. 385 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 386 387 // while(1) is common, avoid extra exit blocks. Be sure 388 // to correctly handle break/continue though. 389 bool EmitBoolCondBranch = true; 390 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 391 if (C->isOne()) 392 EmitBoolCondBranch = false; 393 394 // As long as the condition is true, go to the loop body. 395 if (EmitBoolCondBranch) 396 Builder.CreateCondBr(BoolCondVal, LoopBody, EffectiveExitBlock); 397 398 // Emit the loop body. 399 { 400 CleanupScope BodyScope(*this); 401 EmitBlock(LoopBody); 402 EmitStmt(S.getBody()); 403 } 404 405 BreakContinueStack.pop_back(); 406 407 if (CleanupBlock) { 408 // If we have a cleanup block, jump there to perform cleanups 409 // before looping. 410 EmitBranch(CleanupBlock); 411 412 // Emit the cleanup block, performing cleanups for the condition 413 // and then jumping to either the loop header or the exit block. 414 EmitBlock(CleanupBlock); 415 ConditionScope.ForceCleanup(); 416 Builder.CreateCondBr(BoolCondVal, LoopHeader, ExitBlock); 417 } else { 418 // Cycle to the condition. 419 EmitBranch(LoopHeader); 420 } 421 422 // Emit the exit block. 423 EmitBlock(ExitBlock, true); 424 425 426 // The LoopHeader typically is just a branch if we skipped emitting 427 // a branch, try to erase it. 428 if (!EmitBoolCondBranch && !CleanupBlock) 429 SimplifyForwardingBlocks(LoopHeader); 430} 431 432void CodeGenFunction::EmitDoStmt(const DoStmt &S) { 433 // Emit the body for the loop, insert it, which will create an uncond br to 434 // it. 435 llvm::BasicBlock *LoopBody = createBasicBlock("do.body"); 436 llvm::BasicBlock *AfterDo = createBasicBlock("do.end"); 437 EmitBlock(LoopBody); 438 439 llvm::BasicBlock *DoCond = createBasicBlock("do.cond"); 440 441 // Store the blocks to use for break and continue. 442 BreakContinueStack.push_back(BreakContinue(AfterDo, DoCond)); 443 444 // Emit the body of the loop into the block. 445 EmitStmt(S.getBody()); 446 447 BreakContinueStack.pop_back(); 448 449 EmitBlock(DoCond); 450 451 // C99 6.8.5.2: "The evaluation of the controlling expression takes place 452 // after each execution of the loop body." 453 454 // Evaluate the conditional in the while header. 455 // C99 6.8.5p2/p4: The first substatement is executed if the expression 456 // compares unequal to 0. The condition must be a scalar type. 457 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 458 459 // "do {} while (0)" is common in macros, avoid extra blocks. Be sure 460 // to correctly handle break/continue though. 461 bool EmitBoolCondBranch = true; 462 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 463 if (C->isZero()) 464 EmitBoolCondBranch = false; 465 466 // As long as the condition is true, iterate the loop. 467 if (EmitBoolCondBranch) 468 Builder.CreateCondBr(BoolCondVal, LoopBody, AfterDo); 469 470 // Emit the exit block. 471 EmitBlock(AfterDo); 472 473 // The DoCond block typically is just a branch if we skipped 474 // emitting a branch, try to erase it. 475 if (!EmitBoolCondBranch) 476 SimplifyForwardingBlocks(DoCond); 477} 478 479void CodeGenFunction::EmitForStmt(const ForStmt &S) { 480 // FIXME: What do we do if the increment (f.e.) contains a stmt expression, 481 // which contains a continue/break? 482 CleanupScope ForScope(*this); 483 484 // Evaluate the first part before the loop. 485 if (S.getInit()) 486 EmitStmt(S.getInit()); 487 488 // Start the loop with a block that tests the condition. 489 llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); 490 llvm::BasicBlock *AfterFor = createBasicBlock("for.end"); 491 llvm::BasicBlock *IncBlock = 0; 492 llvm::BasicBlock *CondCleanup = 0; 493 llvm::BasicBlock *EffectiveExitBlock = AfterFor; 494 EmitBlock(CondBlock); 495 496 // Create a cleanup scope for the condition variable cleanups. 497 CleanupScope ConditionScope(*this); 498 499 llvm::Value *BoolCondVal = 0; 500 if (S.getCond()) { 501 // If the for statement has a condition scope, emit the local variable 502 // declaration. 503 if (S.getConditionVariable()) { 504 EmitLocalBlockVarDecl(*S.getConditionVariable()); 505 506 if (ConditionScope.requiresCleanups()) { 507 CondCleanup = createBasicBlock("for.cond.cleanup"); 508 EffectiveExitBlock = CondCleanup; 509 } 510 } 511 512 // As long as the condition is true, iterate the loop. 513 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 514 515 // C99 6.8.5p2/p4: The first substatement is executed if the expression 516 // compares unequal to 0. The condition must be a scalar type. 517 BoolCondVal = EvaluateExprAsBool(S.getCond()); 518 Builder.CreateCondBr(BoolCondVal, ForBody, EffectiveExitBlock); 519 520 EmitBlock(ForBody); 521 } else { 522 // Treat it as a non-zero constant. Don't even create a new block for the 523 // body, just fall into it. 524 } 525 526 // If the for loop doesn't have an increment we can just use the 527 // condition as the continue block. 528 llvm::BasicBlock *ContinueBlock; 529 if (S.getInc()) 530 ContinueBlock = IncBlock = createBasicBlock("for.inc"); 531 else 532 ContinueBlock = CondBlock; 533 534 // Store the blocks to use for break and continue. 535 BreakContinueStack.push_back(BreakContinue(AfterFor, ContinueBlock)); 536 537 // If the condition is true, execute the body of the for stmt. 538 CGDebugInfo *DI = getDebugInfo(); 539 if (DI) { 540 DI->setLocation(S.getSourceRange().getBegin()); 541 DI->EmitRegionStart(CurFn, Builder); 542 } 543 544 { 545 // Create a separate cleanup scope for the body, in case it is not 546 // a compound statement. 547 CleanupScope BodyScope(*this); 548 EmitStmt(S.getBody()); 549 } 550 551 BreakContinueStack.pop_back(); 552 553 // If there is an increment, emit it next. 554 if (S.getInc()) { 555 EmitBlock(IncBlock); 556 EmitStmt(S.getInc()); 557 } 558 559 // Finally, branch back up to the condition for the next iteration. 560 if (CondCleanup) { 561 // Branch to the cleanup block. 562 EmitBranch(CondCleanup); 563 564 // Emit the cleanup block, which branches back to the loop body or 565 // outside of the for statement once it is done. 566 EmitBlock(CondCleanup); 567 ConditionScope.ForceCleanup(); 568 Builder.CreateCondBr(BoolCondVal, CondBlock, AfterFor); 569 } else 570 EmitBranch(CondBlock); 571 if (DI) { 572 DI->setLocation(S.getSourceRange().getEnd()); 573 DI->EmitRegionEnd(CurFn, Builder); 574 } 575 576 // Emit the fall-through block. 577 EmitBlock(AfterFor, true); 578} 579 580void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { 581 if (RV.isScalar()) { 582 Builder.CreateStore(RV.getScalarVal(), ReturnValue); 583 } else if (RV.isAggregate()) { 584 EmitAggregateCopy(ReturnValue, RV.getAggregateAddr(), Ty); 585 } else { 586 StoreComplexToAddr(RV.getComplexVal(), ReturnValue, false); 587 } 588 EmitBranchThroughCleanup(ReturnBlock); 589} 590 591/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand 592/// if the function returns void, or may be missing one if the function returns 593/// non-void. Fun stuff :). 594void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { 595 // Emit the result value, even if unused, to evalute the side effects. 596 const Expr *RV = S.getRetValue(); 597 598 // FIXME: Clean this up by using an LValue for ReturnTemp, 599 // EmitStoreThroughLValue, and EmitAnyExpr. 600 if (!ReturnValue) { 601 // Make sure not to return anything, but evaluate the expression 602 // for side effects. 603 if (RV) 604 EmitAnyExpr(RV); 605 } else if (RV == 0) { 606 // Do nothing (return value is left uninitialized) 607 } else if (FnRetTy->isReferenceType()) { 608 // If this function returns a reference, take the address of the expression 609 // rather than the value. 610 Builder.CreateStore(EmitLValue(RV).getAddress(), ReturnValue); 611 } else if (!hasAggregateLLVMType(RV->getType())) { 612 Builder.CreateStore(EmitScalarExpr(RV), ReturnValue); 613 } else if (RV->getType()->isAnyComplexType()) { 614 EmitComplexExprIntoAddr(RV, ReturnValue, false); 615 } else { 616 EmitAggExpr(RV, ReturnValue, false); 617 } 618 619 EmitBranchThroughCleanup(ReturnBlock); 620} 621 622void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { 623 // As long as debug info is modeled with instructions, we have to ensure we 624 // have a place to insert here and write the stop point here. 625 if (getDebugInfo()) { 626 EnsureInsertPoint(); 627 EmitStopPoint(&S); 628 } 629 630 for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); 631 I != E; ++I) 632 EmitDecl(**I); 633} 634 635void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { 636 assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); 637 638 // If this code is reachable then emit a stop point (if generating 639 // debug info). We have to do this ourselves because we are on the 640 // "simple" statement path. 641 if (HaveInsertPoint()) 642 EmitStopPoint(&S); 643 644 llvm::BasicBlock *Block = BreakContinueStack.back().BreakBlock; 645 EmitBranchThroughCleanup(Block); 646} 647 648void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { 649 assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); 650 651 // If this code is reachable then emit a stop point (if generating 652 // debug info). We have to do this ourselves because we are on the 653 // "simple" statement path. 654 if (HaveInsertPoint()) 655 EmitStopPoint(&S); 656 657 llvm::BasicBlock *Block = BreakContinueStack.back().ContinueBlock; 658 EmitBranchThroughCleanup(Block); 659} 660 661/// EmitCaseStmtRange - If case statement range is not too big then 662/// add multiple cases to switch instruction, one for each value within 663/// the range. If range is too big then emit "if" condition check. 664void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { 665 assert(S.getRHS() && "Expected RHS value in CaseStmt"); 666 667 llvm::APSInt LHS = S.getLHS()->EvaluateAsInt(getContext()); 668 llvm::APSInt RHS = S.getRHS()->EvaluateAsInt(getContext()); 669 670 // Emit the code for this case. We do this first to make sure it is 671 // properly chained from our predecessor before generating the 672 // switch machinery to enter this block. 673 EmitBlock(createBasicBlock("sw.bb")); 674 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 675 EmitStmt(S.getSubStmt()); 676 677 // If range is empty, do nothing. 678 if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) 679 return; 680 681 llvm::APInt Range = RHS - LHS; 682 // FIXME: parameters such as this should not be hardcoded. 683 if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { 684 // Range is small enough to add multiple switch instruction cases. 685 for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { 686 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, LHS), CaseDest); 687 LHS++; 688 } 689 return; 690 } 691 692 // The range is too big. Emit "if" condition into a new block, 693 // making sure to save and restore the current insertion point. 694 llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); 695 696 // Push this test onto the chain of range checks (which terminates 697 // in the default basic block). The switch's default will be changed 698 // to the top of this chain after switch emission is complete. 699 llvm::BasicBlock *FalseDest = CaseRangeBlock; 700 CaseRangeBlock = createBasicBlock("sw.caserange"); 701 702 CurFn->getBasicBlockList().push_back(CaseRangeBlock); 703 Builder.SetInsertPoint(CaseRangeBlock); 704 705 // Emit range check. 706 llvm::Value *Diff = 707 Builder.CreateSub(SwitchInsn->getCondition(), 708 llvm::ConstantInt::get(VMContext, LHS), "tmp"); 709 llvm::Value *Cond = 710 Builder.CreateICmpULE(Diff, 711 llvm::ConstantInt::get(VMContext, Range), "tmp"); 712 Builder.CreateCondBr(Cond, CaseDest, FalseDest); 713 714 // Restore the appropriate insertion point. 715 if (RestoreBB) 716 Builder.SetInsertPoint(RestoreBB); 717 else 718 Builder.ClearInsertionPoint(); 719} 720 721void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { 722 if (S.getRHS()) { 723 EmitCaseStmtRange(S); 724 return; 725 } 726 727 EmitBlock(createBasicBlock("sw.bb")); 728 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 729 llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext()); 730 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, CaseVal), CaseDest); 731 732 // Recursively emitting the statement is acceptable, but is not wonderful for 733 // code where we have many case statements nested together, i.e.: 734 // case 1: 735 // case 2: 736 // case 3: etc. 737 // Handling this recursively will create a new block for each case statement 738 // that falls through to the next case which is IR intensive. It also causes 739 // deep recursion which can run into stack depth limitations. Handle 740 // sequential non-range case statements specially. 741 const CaseStmt *CurCase = &S; 742 const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); 743 744 // Otherwise, iteratively add consequtive cases to this switch stmt. 745 while (NextCase && NextCase->getRHS() == 0) { 746 CurCase = NextCase; 747 CaseVal = CurCase->getLHS()->EvaluateAsInt(getContext()); 748 SwitchInsn->addCase(llvm::ConstantInt::get(VMContext, CaseVal), CaseDest); 749 750 NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); 751 } 752 753 // Normal default recursion for non-cases. 754 EmitStmt(CurCase->getSubStmt()); 755} 756 757void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { 758 llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); 759 assert(DefaultBlock->empty() && 760 "EmitDefaultStmt: Default block already defined?"); 761 EmitBlock(DefaultBlock); 762 EmitStmt(S.getSubStmt()); 763} 764 765void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { 766 CleanupScope ConditionScope(*this); 767 768 if (S.getConditionVariable()) 769 EmitLocalBlockVarDecl(*S.getConditionVariable()); 770 771 llvm::Value *CondV = EmitScalarExpr(S.getCond()); 772 773 // Handle nested switch statements. 774 llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; 775 llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; 776 777 // Create basic block to hold stuff that comes after switch 778 // statement. We also need to create a default block now so that 779 // explicit case ranges tests can have a place to jump to on 780 // failure. 781 llvm::BasicBlock *NextBlock = createBasicBlock("sw.epilog"); 782 llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); 783 SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); 784 CaseRangeBlock = DefaultBlock; 785 786 // Clear the insertion point to indicate we are in unreachable code. 787 Builder.ClearInsertionPoint(); 788 789 // All break statements jump to NextBlock. If BreakContinueStack is non empty 790 // then reuse last ContinueBlock. 791 llvm::BasicBlock *ContinueBlock = 0; 792 if (!BreakContinueStack.empty()) 793 ContinueBlock = BreakContinueStack.back().ContinueBlock; 794 795 // Ensure any vlas created between there and here, are undone 796 BreakContinueStack.push_back(BreakContinue(NextBlock, ContinueBlock)); 797 798 // Emit switch body. 799 EmitStmt(S.getBody()); 800 801 BreakContinueStack.pop_back(); 802 803 // Update the default block in case explicit case range tests have 804 // been chained on top. 805 SwitchInsn->setSuccessor(0, CaseRangeBlock); 806 807 // If a default was never emitted then reroute any jumps to it and 808 // discard. 809 if (!DefaultBlock->getParent()) { 810 DefaultBlock->replaceAllUsesWith(NextBlock); 811 delete DefaultBlock; 812 } 813 814 // Emit continuation. 815 EmitBlock(NextBlock, true); 816 817 SwitchInsn = SavedSwitchInsn; 818 CaseRangeBlock = SavedCRBlock; 819} 820 821static std::string 822SimplifyConstraint(const char *Constraint, const TargetInfo &Target, 823 llvm::SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { 824 std::string Result; 825 826 while (*Constraint) { 827 switch (*Constraint) { 828 default: 829 Result += Target.convertConstraint(*Constraint); 830 break; 831 // Ignore these 832 case '*': 833 case '?': 834 case '!': 835 break; 836 case 'g': 837 Result += "imr"; 838 break; 839 case '[': { 840 assert(OutCons && 841 "Must pass output names to constraints with a symbolic name"); 842 unsigned Index; 843 bool result = Target.resolveSymbolicName(Constraint, 844 &(*OutCons)[0], 845 OutCons->size(), Index); 846 assert(result && "Could not resolve symbolic name"); result=result; 847 Result += llvm::utostr(Index); 848 break; 849 } 850 } 851 852 Constraint++; 853 } 854 855 return Result; 856} 857 858llvm::Value* CodeGenFunction::EmitAsmInput(const AsmStmt &S, 859 const TargetInfo::ConstraintInfo &Info, 860 const Expr *InputExpr, 861 std::string &ConstraintStr) { 862 llvm::Value *Arg; 863 if (Info.allowsRegister() || !Info.allowsMemory()) { 864 if (!CodeGenFunction::hasAggregateLLVMType(InputExpr->getType())) { 865 Arg = EmitScalarExpr(InputExpr); 866 } else { 867 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 868 LValue Dest = EmitLValue(InputExpr); 869 870 const llvm::Type *Ty = ConvertType(InputExpr->getType()); 871 uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); 872 if (Size <= 64 && llvm::isPowerOf2_64(Size)) { 873 Ty = llvm::IntegerType::get(VMContext, Size); 874 Ty = llvm::PointerType::getUnqual(Ty); 875 876 Arg = Builder.CreateLoad(Builder.CreateBitCast(Dest.getAddress(), Ty)); 877 } else { 878 Arg = Dest.getAddress(); 879 ConstraintStr += '*'; 880 } 881 } 882 } else { 883 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 884 LValue Dest = EmitLValue(InputExpr); 885 Arg = Dest.getAddress(); 886 ConstraintStr += '*'; 887 } 888 889 return Arg; 890} 891 892void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { 893 // Analyze the asm string to decompose it into its pieces. We know that Sema 894 // has already done this, so it is guaranteed to be successful. 895 llvm::SmallVector<AsmStmt::AsmStringPiece, 4> Pieces; 896 unsigned DiagOffs; 897 S.AnalyzeAsmString(Pieces, getContext(), DiagOffs); 898 899 // Assemble the pieces into the final asm string. 900 std::string AsmString; 901 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { 902 if (Pieces[i].isString()) 903 AsmString += Pieces[i].getString(); 904 else if (Pieces[i].getModifier() == '\0') 905 AsmString += '$' + llvm::utostr(Pieces[i].getOperandNo()); 906 else 907 AsmString += "${" + llvm::utostr(Pieces[i].getOperandNo()) + ':' + 908 Pieces[i].getModifier() + '}'; 909 } 910 911 // Get all the output and input constraints together. 912 llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 913 llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 914 915 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 916 TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), 917 S.getOutputName(i)); 918 bool IsValid = Target.validateOutputConstraint(Info); (void)IsValid; 919 assert(IsValid && "Failed to parse output constraint"); 920 OutputConstraintInfos.push_back(Info); 921 } 922 923 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 924 TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), 925 S.getInputName(i)); 926 bool IsValid = Target.validateInputConstraint(OutputConstraintInfos.data(), 927 S.getNumOutputs(), Info); 928 assert(IsValid && "Failed to parse input constraint"); (void)IsValid; 929 InputConstraintInfos.push_back(Info); 930 } 931 932 std::string Constraints; 933 934 std::vector<LValue> ResultRegDests; 935 std::vector<QualType> ResultRegQualTys; 936 std::vector<const llvm::Type *> ResultRegTypes; 937 std::vector<const llvm::Type *> ResultTruncRegTypes; 938 std::vector<const llvm::Type*> ArgTypes; 939 std::vector<llvm::Value*> Args; 940 941 // Keep track of inout constraints. 942 std::string InOutConstraints; 943 std::vector<llvm::Value*> InOutArgs; 944 std::vector<const llvm::Type*> InOutArgTypes; 945 946 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 947 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 948 949 // Simplify the output constraint. 950 std::string OutputConstraint(S.getOutputConstraint(i)); 951 OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); 952 953 const Expr *OutExpr = S.getOutputExpr(i); 954 OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); 955 956 LValue Dest = EmitLValue(OutExpr); 957 if (!Constraints.empty()) 958 Constraints += ','; 959 960 // If this is a register output, then make the inline asm return it 961 // by-value. If this is a memory result, return the value by-reference. 962 if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { 963 Constraints += "=" + OutputConstraint; 964 ResultRegQualTys.push_back(OutExpr->getType()); 965 ResultRegDests.push_back(Dest); 966 ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); 967 ResultTruncRegTypes.push_back(ResultRegTypes.back()); 968 969 // If this output is tied to an input, and if the input is larger, then 970 // we need to set the actual result type of the inline asm node to be the 971 // same as the input type. 972 if (Info.hasMatchingInput()) { 973 unsigned InputNo; 974 for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { 975 TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; 976 if (Input.hasTiedOperand() && 977 Input.getTiedOperand() == i) 978 break; 979 } 980 assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); 981 982 QualType InputTy = S.getInputExpr(InputNo)->getType(); 983 QualType OutputTy = OutExpr->getType(); 984 985 uint64_t InputSize = getContext().getTypeSize(InputTy); 986 if (getContext().getTypeSize(OutputTy) < InputSize) { 987 // Form the asm to return the value as a larger integer type. 988 ResultRegTypes.back() = llvm::IntegerType::get(VMContext, (unsigned)InputSize); 989 } 990 } 991 } else { 992 ArgTypes.push_back(Dest.getAddress()->getType()); 993 Args.push_back(Dest.getAddress()); 994 Constraints += "=*"; 995 Constraints += OutputConstraint; 996 } 997 998 if (Info.isReadWrite()) { 999 InOutConstraints += ','; 1000 1001 const Expr *InputExpr = S.getOutputExpr(i); 1002 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, InOutConstraints); 1003 1004 if (Info.allowsRegister()) 1005 InOutConstraints += llvm::utostr(i); 1006 else 1007 InOutConstraints += OutputConstraint; 1008 1009 InOutArgTypes.push_back(Arg->getType()); 1010 InOutArgs.push_back(Arg); 1011 } 1012 } 1013 1014 unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); 1015 1016 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1017 const Expr *InputExpr = S.getInputExpr(i); 1018 1019 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 1020 1021 if (!Constraints.empty()) 1022 Constraints += ','; 1023 1024 // Simplify the input constraint. 1025 std::string InputConstraint(S.getInputConstraint(i)); 1026 InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, 1027 &OutputConstraintInfos); 1028 1029 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints); 1030 1031 // If this input argument is tied to a larger output result, extend the 1032 // input to be the same size as the output. The LLVM backend wants to see 1033 // the input and output of a matching constraint be the same size. Note 1034 // that GCC does not define what the top bits are here. We use zext because 1035 // that is usually cheaper, but LLVM IR should really get an anyext someday. 1036 if (Info.hasTiedOperand()) { 1037 unsigned Output = Info.getTiedOperand(); 1038 QualType OutputTy = S.getOutputExpr(Output)->getType(); 1039 QualType InputTy = InputExpr->getType(); 1040 1041 if (getContext().getTypeSize(OutputTy) > 1042 getContext().getTypeSize(InputTy)) { 1043 // Use ptrtoint as appropriate so that we can do our extension. 1044 if (isa<llvm::PointerType>(Arg->getType())) 1045 Arg = Builder.CreatePtrToInt(Arg, 1046 llvm::IntegerType::get(VMContext, LLVMPointerWidth)); 1047 unsigned OutputSize = (unsigned)getContext().getTypeSize(OutputTy); 1048 Arg = Builder.CreateZExt(Arg, llvm::IntegerType::get(VMContext, OutputSize)); 1049 } 1050 } 1051 1052 1053 ArgTypes.push_back(Arg->getType()); 1054 Args.push_back(Arg); 1055 Constraints += InputConstraint; 1056 } 1057 1058 // Append the "input" part of inout constraints last. 1059 for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { 1060 ArgTypes.push_back(InOutArgTypes[i]); 1061 Args.push_back(InOutArgs[i]); 1062 } 1063 Constraints += InOutConstraints; 1064 1065 // Clobbers 1066 for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { 1067 llvm::StringRef Clobber = S.getClobber(i)->getString(); 1068 1069 Clobber = Target.getNormalizedGCCRegisterName(Clobber); 1070 1071 if (i != 0 || NumConstraints != 0) 1072 Constraints += ','; 1073 1074 Constraints += "~{"; 1075 Constraints += Clobber; 1076 Constraints += '}'; 1077 } 1078 1079 // Add machine specific clobbers 1080 std::string MachineClobbers = Target.getClobbers(); 1081 if (!MachineClobbers.empty()) { 1082 if (!Constraints.empty()) 1083 Constraints += ','; 1084 Constraints += MachineClobbers; 1085 } 1086 1087 const llvm::Type *ResultType; 1088 if (ResultRegTypes.empty()) 1089 ResultType = llvm::Type::getVoidTy(VMContext); 1090 else if (ResultRegTypes.size() == 1) 1091 ResultType = ResultRegTypes[0]; 1092 else 1093 ResultType = llvm::StructType::get(VMContext, ResultRegTypes); 1094 1095 const llvm::FunctionType *FTy = 1096 llvm::FunctionType::get(ResultType, ArgTypes, false); 1097 1098 llvm::InlineAsm *IA = 1099 llvm::InlineAsm::get(FTy, AsmString, Constraints, 1100 S.isVolatile() || S.getNumOutputs() == 0); 1101 llvm::CallInst *Result = Builder.CreateCall(IA, Args.begin(), Args.end()); 1102 Result->addAttribute(~0, llvm::Attribute::NoUnwind); 1103 1104 1105 // Extract all of the register value results from the asm. 1106 std::vector<llvm::Value*> RegResults; 1107 if (ResultRegTypes.size() == 1) { 1108 RegResults.push_back(Result); 1109 } else { 1110 for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { 1111 llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); 1112 RegResults.push_back(Tmp); 1113 } 1114 } 1115 1116 for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { 1117 llvm::Value *Tmp = RegResults[i]; 1118 1119 // If the result type of the LLVM IR asm doesn't match the result type of 1120 // the expression, do the conversion. 1121 if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { 1122 const llvm::Type *TruncTy = ResultTruncRegTypes[i]; 1123 // Truncate the integer result to the right size, note that 1124 // ResultTruncRegTypes can be a pointer. 1125 uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); 1126 Tmp = Builder.CreateTrunc(Tmp, llvm::IntegerType::get(VMContext, (unsigned)ResSize)); 1127 1128 if (Tmp->getType() != TruncTy) { 1129 assert(isa<llvm::PointerType>(TruncTy)); 1130 Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); 1131 } 1132 } 1133 1134 EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i], 1135 ResultRegQualTys[i]); 1136 } 1137} 1138