CGStmt.cpp revision 5be92de217a1940d0e109abd0f401df4480c1a4b
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 "TargetInfo.h" 18#include "clang/AST/StmtVisitor.h" 19#include "clang/Basic/PrettyStackTrace.h" 20#include "clang/Basic/TargetInfo.h" 21#include "llvm/ADT/StringExtras.h" 22#include "llvm/InlineAsm.h" 23#include "llvm/Intrinsics.h" 24#include "llvm/Target/TargetData.h" 25using namespace clang; 26using namespace CodeGen; 27 28//===----------------------------------------------------------------------===// 29// Statement Emission 30//===----------------------------------------------------------------------===// 31 32void CodeGenFunction::EmitStopPoint(const Stmt *S) { 33 if (CGDebugInfo *DI = getDebugInfo()) { 34 SourceLocation Loc; 35 if (isa<DeclStmt>(S)) 36 Loc = S->getLocEnd(); 37 else 38 Loc = S->getLocStart(); 39 DI->EmitLocation(Builder, Loc); 40 } 41} 42 43void CodeGenFunction::EmitStmt(const Stmt *S) { 44 assert(S && "Null statement?"); 45 46 // These statements have their own debug info handling. 47 if (EmitSimpleStmt(S)) 48 return; 49 50 // Check if we are generating unreachable code. 51 if (!HaveInsertPoint()) { 52 // If so, and the statement doesn't contain a label, then we do not need to 53 // generate actual code. This is safe because (1) the current point is 54 // unreachable, so we don't need to execute the code, and (2) we've already 55 // handled the statements which update internal data structures (like the 56 // local variable map) which could be used by subsequent statements. 57 if (!ContainsLabel(S)) { 58 // Verify that any decl statements were handled as simple, they may be in 59 // scope of subsequent reachable statements. 60 assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!"); 61 return; 62 } 63 64 // Otherwise, make a new block to hold the code. 65 EnsureInsertPoint(); 66 } 67 68 // Generate a stoppoint if we are emitting debug info. 69 EmitStopPoint(S); 70 71 switch (S->getStmtClass()) { 72 case Stmt::NoStmtClass: 73 case Stmt::CXXCatchStmtClass: 74 case Stmt::SEHExceptStmtClass: 75 case Stmt::SEHFinallyStmtClass: 76 case Stmt::MSDependentExistsStmtClass: 77 llvm_unreachable("invalid statement class to emit generically"); 78 case Stmt::NullStmtClass: 79 case Stmt::CompoundStmtClass: 80 case Stmt::DeclStmtClass: 81 case Stmt::LabelStmtClass: 82 case Stmt::AttributedStmtClass: 83 case Stmt::GotoStmtClass: 84 case Stmt::BreakStmtClass: 85 case Stmt::ContinueStmtClass: 86 case Stmt::DefaultStmtClass: 87 case Stmt::CaseStmtClass: 88 llvm_unreachable("should have emitted these statements as simple"); 89 90#define STMT(Type, Base) 91#define ABSTRACT_STMT(Op) 92#define EXPR(Type, Base) \ 93 case Stmt::Type##Class: 94#include "clang/AST/StmtNodes.inc" 95 { 96 // Remember the block we came in on. 97 llvm::BasicBlock *incoming = Builder.GetInsertBlock(); 98 assert(incoming && "expression emission must have an insertion point"); 99 100 EmitIgnoredExpr(cast<Expr>(S)); 101 102 llvm::BasicBlock *outgoing = Builder.GetInsertBlock(); 103 assert(outgoing && "expression emission cleared block!"); 104 105 // The expression emitters assume (reasonably!) that the insertion 106 // point is always set. To maintain that, the call-emission code 107 // for noreturn functions has to enter a new block with no 108 // predecessors. We want to kill that block and mark the current 109 // insertion point unreachable in the common case of a call like 110 // "exit();". Since expression emission doesn't otherwise create 111 // blocks with no predecessors, we can just test for that. 112 // However, we must be careful not to do this to our incoming 113 // block, because *statement* emission does sometimes create 114 // reachable blocks which will have no predecessors until later in 115 // the function. This occurs with, e.g., labels that are not 116 // reachable by fallthrough. 117 if (incoming != outgoing && outgoing->use_empty()) { 118 outgoing->eraseFromParent(); 119 Builder.ClearInsertionPoint(); 120 } 121 break; 122 } 123 124 case Stmt::IndirectGotoStmtClass: 125 EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break; 126 127 case Stmt::IfStmtClass: EmitIfStmt(cast<IfStmt>(*S)); break; 128 case Stmt::WhileStmtClass: EmitWhileStmt(cast<WhileStmt>(*S)); break; 129 case Stmt::DoStmtClass: EmitDoStmt(cast<DoStmt>(*S)); break; 130 case Stmt::ForStmtClass: EmitForStmt(cast<ForStmt>(*S)); break; 131 132 case Stmt::ReturnStmtClass: EmitReturnStmt(cast<ReturnStmt>(*S)); break; 133 134 case Stmt::SwitchStmtClass: EmitSwitchStmt(cast<SwitchStmt>(*S)); break; 135 case Stmt::GCCAsmStmtClass: // Intentional fall-through. 136 case Stmt::MSAsmStmtClass: EmitAsmStmt(cast<AsmStmt>(*S)); break; 137 138 case Stmt::ObjCAtTryStmtClass: 139 EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S)); 140 break; 141 case Stmt::ObjCAtCatchStmtClass: 142 llvm_unreachable( 143 "@catch statements should be handled by EmitObjCAtTryStmt"); 144 case Stmt::ObjCAtFinallyStmtClass: 145 llvm_unreachable( 146 "@finally statements should be handled by EmitObjCAtTryStmt"); 147 case Stmt::ObjCAtThrowStmtClass: 148 EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S)); 149 break; 150 case Stmt::ObjCAtSynchronizedStmtClass: 151 EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S)); 152 break; 153 case Stmt::ObjCForCollectionStmtClass: 154 EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S)); 155 break; 156 case Stmt::ObjCAutoreleasePoolStmtClass: 157 EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S)); 158 break; 159 160 case Stmt::CXXTryStmtClass: 161 EmitCXXTryStmt(cast<CXXTryStmt>(*S)); 162 break; 163 case Stmt::CXXForRangeStmtClass: 164 EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S)); 165 case Stmt::SEHTryStmtClass: 166 case Stmt::SEHLeaveStmtClass: 167 // FIXME Not yet implemented 168 break; 169 } 170} 171 172bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) { 173 switch (S->getStmtClass()) { 174 default: return false; 175 case Stmt::NullStmtClass: break; 176 case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break; 177 case Stmt::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break; 178 case Stmt::LabelStmtClass: EmitLabelStmt(cast<LabelStmt>(*S)); break; 179 case Stmt::AttributedStmtClass: 180 EmitAttributedStmt(cast<AttributedStmt>(*S)); break; 181 case Stmt::GotoStmtClass: EmitGotoStmt(cast<GotoStmt>(*S)); break; 182 case Stmt::BreakStmtClass: EmitBreakStmt(cast<BreakStmt>(*S)); break; 183 case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break; 184 case Stmt::DefaultStmtClass: EmitDefaultStmt(cast<DefaultStmt>(*S)); break; 185 case Stmt::CaseStmtClass: EmitCaseStmt(cast<CaseStmt>(*S)); break; 186 } 187 188 return true; 189} 190 191/// EmitCompoundStmt - Emit a compound statement {..} node. If GetLast is true, 192/// this captures the expression result of the last sub-statement and returns it 193/// (for use by the statement expression extension). 194RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast, 195 AggValueSlot AggSlot) { 196 PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(), 197 "LLVM IR generation of compound statement ('{}')"); 198 199 // Keep track of the current cleanup stack depth, including debug scopes. 200 LexicalScope Scope(*this, S.getSourceRange()); 201 202 for (CompoundStmt::const_body_iterator I = S.body_begin(), 203 E = S.body_end()-GetLast; I != E; ++I) 204 EmitStmt(*I); 205 206 RValue RV; 207 if (!GetLast) 208 RV = RValue::get(0); 209 else { 210 // We have to special case labels here. They are statements, but when put 211 // at the end of a statement expression, they yield the value of their 212 // subexpression. Handle this by walking through all labels we encounter, 213 // emitting them before we evaluate the subexpr. 214 const Stmt *LastStmt = S.body_back(); 215 while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { 216 EmitLabel(LS->getDecl()); 217 LastStmt = LS->getSubStmt(); 218 } 219 220 EnsureInsertPoint(); 221 222 RV = EmitAnyExpr(cast<Expr>(LastStmt), AggSlot); 223 } 224 225 return RV; 226} 227 228void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { 229 llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); 230 231 // If there is a cleanup stack, then we it isn't worth trying to 232 // simplify this block (we would need to remove it from the scope map 233 // and cleanup entry). 234 if (!EHStack.empty()) 235 return; 236 237 // Can only simplify direct branches. 238 if (!BI || !BI->isUnconditional()) 239 return; 240 241 BB->replaceAllUsesWith(BI->getSuccessor(0)); 242 BI->eraseFromParent(); 243 BB->eraseFromParent(); 244} 245 246void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { 247 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 248 249 // Fall out of the current block (if necessary). 250 EmitBranch(BB); 251 252 if (IsFinished && BB->use_empty()) { 253 delete BB; 254 return; 255 } 256 257 // Place the block after the current block, if possible, or else at 258 // the end of the function. 259 if (CurBB && CurBB->getParent()) 260 CurFn->getBasicBlockList().insertAfter(CurBB, BB); 261 else 262 CurFn->getBasicBlockList().push_back(BB); 263 Builder.SetInsertPoint(BB); 264} 265 266void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { 267 // Emit a branch from the current block to the target one if this 268 // was a real block. If this was just a fall-through block after a 269 // terminator, don't emit it. 270 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 271 272 if (!CurBB || CurBB->getTerminator()) { 273 // If there is no insert point or the previous block is already 274 // terminated, don't touch it. 275 } else { 276 // Otherwise, create a fall-through branch. 277 Builder.CreateBr(Target); 278 } 279 280 Builder.ClearInsertionPoint(); 281} 282 283void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) { 284 bool inserted = false; 285 for (llvm::BasicBlock::use_iterator 286 i = block->use_begin(), e = block->use_end(); i != e; ++i) { 287 if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(*i)) { 288 CurFn->getBasicBlockList().insertAfter(insn->getParent(), block); 289 inserted = true; 290 break; 291 } 292 } 293 294 if (!inserted) 295 CurFn->getBasicBlockList().push_back(block); 296 297 Builder.SetInsertPoint(block); 298} 299 300CodeGenFunction::JumpDest 301CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) { 302 JumpDest &Dest = LabelMap[D]; 303 if (Dest.isValid()) return Dest; 304 305 // Create, but don't insert, the new block. 306 Dest = JumpDest(createBasicBlock(D->getName()), 307 EHScopeStack::stable_iterator::invalid(), 308 NextCleanupDestIndex++); 309 return Dest; 310} 311 312void CodeGenFunction::EmitLabel(const LabelDecl *D) { 313 JumpDest &Dest = LabelMap[D]; 314 315 // If we didn't need a forward reference to this label, just go 316 // ahead and create a destination at the current scope. 317 if (!Dest.isValid()) { 318 Dest = getJumpDestInCurrentScope(D->getName()); 319 320 // Otherwise, we need to give this label a target depth and remove 321 // it from the branch-fixups list. 322 } else { 323 assert(!Dest.getScopeDepth().isValid() && "already emitted label!"); 324 Dest = JumpDest(Dest.getBlock(), 325 EHStack.stable_begin(), 326 Dest.getDestIndex()); 327 328 ResolveBranchFixups(Dest.getBlock()); 329 } 330 331 EmitBlock(Dest.getBlock()); 332} 333 334 335void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { 336 EmitLabel(S.getDecl()); 337 EmitStmt(S.getSubStmt()); 338} 339 340void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) { 341 EmitStmt(S.getSubStmt()); 342} 343 344void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { 345 // If this code is reachable then emit a stop point (if generating 346 // debug info). We have to do this ourselves because we are on the 347 // "simple" statement path. 348 if (HaveInsertPoint()) 349 EmitStopPoint(&S); 350 351 EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel())); 352} 353 354 355void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { 356 if (const LabelDecl *Target = S.getConstantTarget()) { 357 EmitBranchThroughCleanup(getJumpDestForLabel(Target)); 358 return; 359 } 360 361 // Ensure that we have an i8* for our PHI node. 362 llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()), 363 Int8PtrTy, "addr"); 364 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 365 366 // Get the basic block for the indirect goto. 367 llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock(); 368 369 // The first instruction in the block has to be the PHI for the switch dest, 370 // add an entry for this branch. 371 cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB); 372 373 EmitBranch(IndGotoBB); 374} 375 376void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 377 // C99 6.8.4.1: The first substatement is executed if the expression compares 378 // unequal to 0. The condition must be a scalar type. 379 RunCleanupsScope ConditionScope(*this); 380 381 if (S.getConditionVariable()) 382 EmitAutoVarDecl(*S.getConditionVariable()); 383 384 // If the condition constant folds and can be elided, try to avoid emitting 385 // the condition and the dead arm of the if/else. 386 bool CondConstant; 387 if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant)) { 388 // Figure out which block (then or else) is executed. 389 const Stmt *Executed = S.getThen(); 390 const Stmt *Skipped = S.getElse(); 391 if (!CondConstant) // Condition false? 392 std::swap(Executed, Skipped); 393 394 // If the skipped block has no labels in it, just emit the executed block. 395 // This avoids emitting dead code and simplifies the CFG substantially. 396 if (!ContainsLabel(Skipped)) { 397 if (Executed) { 398 RunCleanupsScope ExecutedScope(*this); 399 EmitStmt(Executed); 400 } 401 return; 402 } 403 } 404 405 // Otherwise, the condition did not fold, or we couldn't elide it. Just emit 406 // the conditional branch. 407 llvm::BasicBlock *ThenBlock = createBasicBlock("if.then"); 408 llvm::BasicBlock *ContBlock = createBasicBlock("if.end"); 409 llvm::BasicBlock *ElseBlock = ContBlock; 410 if (S.getElse()) 411 ElseBlock = createBasicBlock("if.else"); 412 EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock); 413 414 // Emit the 'then' code. 415 EmitBlock(ThenBlock); 416 { 417 RunCleanupsScope ThenScope(*this); 418 EmitStmt(S.getThen()); 419 } 420 EmitBranch(ContBlock); 421 422 // Emit the 'else' code if present. 423 if (const Stmt *Else = S.getElse()) { 424 // There is no need to emit line number for unconditional branch. 425 if (getDebugInfo()) 426 Builder.SetCurrentDebugLocation(llvm::DebugLoc()); 427 EmitBlock(ElseBlock); 428 { 429 RunCleanupsScope ElseScope(*this); 430 EmitStmt(Else); 431 } 432 // There is no need to emit line number for unconditional branch. 433 if (getDebugInfo()) 434 Builder.SetCurrentDebugLocation(llvm::DebugLoc()); 435 EmitBranch(ContBlock); 436 } 437 438 // Emit the continuation block for code after the if. 439 EmitBlock(ContBlock, true); 440} 441 442void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) { 443 // Emit the header for the loop, which will also become 444 // the continue target. 445 JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond"); 446 EmitBlock(LoopHeader.getBlock()); 447 448 // Create an exit block for when the condition fails, which will 449 // also become the break target. 450 JumpDest LoopExit = getJumpDestInCurrentScope("while.end"); 451 452 // Store the blocks to use for break and continue. 453 BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader)); 454 455 // C++ [stmt.while]p2: 456 // When the condition of a while statement is a declaration, the 457 // scope of the variable that is declared extends from its point 458 // of declaration (3.3.2) to the end of the while statement. 459 // [...] 460 // The object created in a condition is destroyed and created 461 // with each iteration of the loop. 462 RunCleanupsScope ConditionScope(*this); 463 464 if (S.getConditionVariable()) 465 EmitAutoVarDecl(*S.getConditionVariable()); 466 467 // Evaluate the conditional in the while header. C99 6.8.5.1: The 468 // evaluation of the controlling expression takes place before each 469 // execution of the loop body. 470 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 471 472 // while(1) is common, avoid extra exit blocks. Be sure 473 // to correctly handle break/continue though. 474 bool EmitBoolCondBranch = true; 475 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 476 if (C->isOne()) 477 EmitBoolCondBranch = false; 478 479 // As long as the condition is true, go to the loop body. 480 llvm::BasicBlock *LoopBody = createBasicBlock("while.body"); 481 if (EmitBoolCondBranch) { 482 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 483 if (ConditionScope.requiresCleanups()) 484 ExitBlock = createBasicBlock("while.exit"); 485 486 Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock); 487 488 if (ExitBlock != LoopExit.getBlock()) { 489 EmitBlock(ExitBlock); 490 EmitBranchThroughCleanup(LoopExit); 491 } 492 } 493 494 // Emit the loop body. We have to emit this in a cleanup scope 495 // because it might be a singleton DeclStmt. 496 { 497 RunCleanupsScope BodyScope(*this); 498 EmitBlock(LoopBody); 499 EmitStmt(S.getBody()); 500 } 501 502 BreakContinueStack.pop_back(); 503 504 // Immediately force cleanup. 505 ConditionScope.ForceCleanup(); 506 507 // Branch to the loop header again. 508 EmitBranch(LoopHeader.getBlock()); 509 510 // Emit the exit block. 511 EmitBlock(LoopExit.getBlock(), true); 512 513 // The LoopHeader typically is just a branch if we skipped emitting 514 // a branch, try to erase it. 515 if (!EmitBoolCondBranch) 516 SimplifyForwardingBlocks(LoopHeader.getBlock()); 517} 518 519void CodeGenFunction::EmitDoStmt(const DoStmt &S) { 520 JumpDest LoopExit = getJumpDestInCurrentScope("do.end"); 521 JumpDest LoopCond = getJumpDestInCurrentScope("do.cond"); 522 523 // Store the blocks to use for break and continue. 524 BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond)); 525 526 // Emit the body of the loop. 527 llvm::BasicBlock *LoopBody = createBasicBlock("do.body"); 528 EmitBlock(LoopBody); 529 { 530 RunCleanupsScope BodyScope(*this); 531 EmitStmt(S.getBody()); 532 } 533 534 BreakContinueStack.pop_back(); 535 536 EmitBlock(LoopCond.getBlock()); 537 538 // C99 6.8.5.2: "The evaluation of the controlling expression takes place 539 // after each execution of the loop body." 540 541 // Evaluate the conditional in the while header. 542 // C99 6.8.5p2/p4: The first substatement is executed if the expression 543 // compares unequal to 0. The condition must be a scalar type. 544 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 545 546 // "do {} while (0)" is common in macros, avoid extra blocks. Be sure 547 // to correctly handle break/continue though. 548 bool EmitBoolCondBranch = true; 549 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 550 if (C->isZero()) 551 EmitBoolCondBranch = false; 552 553 // As long as the condition is true, iterate the loop. 554 if (EmitBoolCondBranch) 555 Builder.CreateCondBr(BoolCondVal, LoopBody, LoopExit.getBlock()); 556 557 // Emit the exit block. 558 EmitBlock(LoopExit.getBlock()); 559 560 // The DoCond block typically is just a branch if we skipped 561 // emitting a branch, try to erase it. 562 if (!EmitBoolCondBranch) 563 SimplifyForwardingBlocks(LoopCond.getBlock()); 564} 565 566void CodeGenFunction::EmitForStmt(const ForStmt &S) { 567 JumpDest LoopExit = getJumpDestInCurrentScope("for.end"); 568 569 RunCleanupsScope ForScope(*this); 570 571 CGDebugInfo *DI = getDebugInfo(); 572 if (DI) 573 DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin()); 574 575 // Evaluate the first part before the loop. 576 if (S.getInit()) 577 EmitStmt(S.getInit()); 578 579 // Start the loop with a block that tests the condition. 580 // If there's an increment, the continue scope will be overwritten 581 // later. 582 JumpDest Continue = getJumpDestInCurrentScope("for.cond"); 583 llvm::BasicBlock *CondBlock = Continue.getBlock(); 584 EmitBlock(CondBlock); 585 586 // Create a cleanup scope for the condition variable cleanups. 587 RunCleanupsScope ConditionScope(*this); 588 589 llvm::Value *BoolCondVal = 0; 590 if (S.getCond()) { 591 // If the for statement has a condition scope, emit the local variable 592 // declaration. 593 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 594 if (S.getConditionVariable()) { 595 EmitAutoVarDecl(*S.getConditionVariable()); 596 } 597 598 // If there are any cleanups between here and the loop-exit scope, 599 // create a block to stage a loop exit along. 600 if (ForScope.requiresCleanups()) 601 ExitBlock = createBasicBlock("for.cond.cleanup"); 602 603 // As long as the condition is true, iterate the loop. 604 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 605 606 // C99 6.8.5p2/p4: The first substatement is executed if the expression 607 // compares unequal to 0. The condition must be a scalar type. 608 BoolCondVal = EvaluateExprAsBool(S.getCond()); 609 Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock); 610 611 if (ExitBlock != LoopExit.getBlock()) { 612 EmitBlock(ExitBlock); 613 EmitBranchThroughCleanup(LoopExit); 614 } 615 616 EmitBlock(ForBody); 617 } else { 618 // Treat it as a non-zero constant. Don't even create a new block for the 619 // body, just fall into it. 620 } 621 622 // If the for loop doesn't have an increment we can just use the 623 // condition as the continue block. Otherwise we'll need to create 624 // a block for it (in the current scope, i.e. in the scope of the 625 // condition), and that we will become our continue block. 626 if (S.getInc()) 627 Continue = getJumpDestInCurrentScope("for.inc"); 628 629 // Store the blocks to use for break and continue. 630 BreakContinueStack.push_back(BreakContinue(LoopExit, Continue)); 631 632 { 633 // Create a separate cleanup scope for the body, in case it is not 634 // a compound statement. 635 RunCleanupsScope BodyScope(*this); 636 EmitStmt(S.getBody()); 637 } 638 639 // If there is an increment, emit it next. 640 if (S.getInc()) { 641 EmitBlock(Continue.getBlock()); 642 EmitStmt(S.getInc()); 643 } 644 645 BreakContinueStack.pop_back(); 646 647 ConditionScope.ForceCleanup(); 648 EmitBranch(CondBlock); 649 650 ForScope.ForceCleanup(); 651 652 if (DI) 653 DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd()); 654 655 // Emit the fall-through block. 656 EmitBlock(LoopExit.getBlock(), true); 657} 658 659void CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S) { 660 JumpDest LoopExit = getJumpDestInCurrentScope("for.end"); 661 662 RunCleanupsScope ForScope(*this); 663 664 CGDebugInfo *DI = getDebugInfo(); 665 if (DI) 666 DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin()); 667 668 // Evaluate the first pieces before the loop. 669 EmitStmt(S.getRangeStmt()); 670 EmitStmt(S.getBeginEndStmt()); 671 672 // Start the loop with a block that tests the condition. 673 // If there's an increment, the continue scope will be overwritten 674 // later. 675 llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); 676 EmitBlock(CondBlock); 677 678 // If there are any cleanups between here and the loop-exit scope, 679 // create a block to stage a loop exit along. 680 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 681 if (ForScope.requiresCleanups()) 682 ExitBlock = createBasicBlock("for.cond.cleanup"); 683 684 // The loop body, consisting of the specified body and the loop variable. 685 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 686 687 // The body is executed if the expression, contextually converted 688 // to bool, is true. 689 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 690 Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock); 691 692 if (ExitBlock != LoopExit.getBlock()) { 693 EmitBlock(ExitBlock); 694 EmitBranchThroughCleanup(LoopExit); 695 } 696 697 EmitBlock(ForBody); 698 699 // Create a block for the increment. In case of a 'continue', we jump there. 700 JumpDest Continue = getJumpDestInCurrentScope("for.inc"); 701 702 // Store the blocks to use for break and continue. 703 BreakContinueStack.push_back(BreakContinue(LoopExit, Continue)); 704 705 { 706 // Create a separate cleanup scope for the loop variable and body. 707 RunCleanupsScope BodyScope(*this); 708 EmitStmt(S.getLoopVarStmt()); 709 EmitStmt(S.getBody()); 710 } 711 712 // If there is an increment, emit it next. 713 EmitBlock(Continue.getBlock()); 714 EmitStmt(S.getInc()); 715 716 BreakContinueStack.pop_back(); 717 718 EmitBranch(CondBlock); 719 720 ForScope.ForceCleanup(); 721 722 if (DI) 723 DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd()); 724 725 // Emit the fall-through block. 726 EmitBlock(LoopExit.getBlock(), true); 727} 728 729void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { 730 if (RV.isScalar()) { 731 Builder.CreateStore(RV.getScalarVal(), ReturnValue); 732 } else if (RV.isAggregate()) { 733 EmitAggregateCopy(ReturnValue, RV.getAggregateAddr(), Ty); 734 } else { 735 StoreComplexToAddr(RV.getComplexVal(), ReturnValue, false); 736 } 737 EmitBranchThroughCleanup(ReturnBlock); 738} 739 740/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand 741/// if the function returns void, or may be missing one if the function returns 742/// non-void. Fun stuff :). 743void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { 744 // Emit the result value, even if unused, to evalute the side effects. 745 const Expr *RV = S.getRetValue(); 746 747 // FIXME: Clean this up by using an LValue for ReturnTemp, 748 // EmitStoreThroughLValue, and EmitAnyExpr. 749 if (S.getNRVOCandidate() && S.getNRVOCandidate()->isNRVOVariable() && 750 !Target.useGlobalsForAutomaticVariables()) { 751 // Apply the named return value optimization for this return statement, 752 // which means doing nothing: the appropriate result has already been 753 // constructed into the NRVO variable. 754 755 // If there is an NRVO flag for this variable, set it to 1 into indicate 756 // that the cleanup code should not destroy the variable. 757 if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()]) 758 Builder.CreateStore(Builder.getTrue(), NRVOFlag); 759 } else if (!ReturnValue) { 760 // Make sure not to return anything, but evaluate the expression 761 // for side effects. 762 if (RV) 763 EmitAnyExpr(RV); 764 } else if (RV == 0) { 765 // Do nothing (return value is left uninitialized) 766 } else if (FnRetTy->isReferenceType()) { 767 // If this function returns a reference, take the address of the expression 768 // rather than the value. 769 RValue Result = EmitReferenceBindingToExpr(RV, /*InitializedDecl=*/0); 770 Builder.CreateStore(Result.getScalarVal(), ReturnValue); 771 } else if (!hasAggregateLLVMType(RV->getType())) { 772 Builder.CreateStore(EmitScalarExpr(RV), ReturnValue); 773 } else if (RV->getType()->isAnyComplexType()) { 774 EmitComplexExprIntoAddr(RV, ReturnValue, false); 775 } else { 776 CharUnits Alignment = getContext().getTypeAlignInChars(RV->getType()); 777 EmitAggExpr(RV, AggValueSlot::forAddr(ReturnValue, Alignment, Qualifiers(), 778 AggValueSlot::IsDestructed, 779 AggValueSlot::DoesNotNeedGCBarriers, 780 AggValueSlot::IsNotAliased)); 781 } 782 783 EmitBranchThroughCleanup(ReturnBlock); 784} 785 786void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { 787 // As long as debug info is modeled with instructions, we have to ensure we 788 // have a place to insert here and write the stop point here. 789 if (HaveInsertPoint()) 790 EmitStopPoint(&S); 791 792 for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); 793 I != E; ++I) 794 EmitDecl(**I); 795} 796 797void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { 798 assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); 799 800 // If this code is reachable then emit a stop point (if generating 801 // debug info). We have to do this ourselves because we are on the 802 // "simple" statement path. 803 if (HaveInsertPoint()) 804 EmitStopPoint(&S); 805 806 JumpDest Block = BreakContinueStack.back().BreakBlock; 807 EmitBranchThroughCleanup(Block); 808} 809 810void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { 811 assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); 812 813 // If this code is reachable then emit a stop point (if generating 814 // debug info). We have to do this ourselves because we are on the 815 // "simple" statement path. 816 if (HaveInsertPoint()) 817 EmitStopPoint(&S); 818 819 JumpDest Block = BreakContinueStack.back().ContinueBlock; 820 EmitBranchThroughCleanup(Block); 821} 822 823/// EmitCaseStmtRange - If case statement range is not too big then 824/// add multiple cases to switch instruction, one for each value within 825/// the range. If range is too big then emit "if" condition check. 826void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { 827 assert(S.getRHS() && "Expected RHS value in CaseStmt"); 828 829 llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext()); 830 llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext()); 831 832 // Emit the code for this case. We do this first to make sure it is 833 // properly chained from our predecessor before generating the 834 // switch machinery to enter this block. 835 EmitBlock(createBasicBlock("sw.bb")); 836 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 837 EmitStmt(S.getSubStmt()); 838 839 // If range is empty, do nothing. 840 if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) 841 return; 842 843 llvm::APInt Range = RHS - LHS; 844 // FIXME: parameters such as this should not be hardcoded. 845 if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { 846 // Range is small enough to add multiple switch instruction cases. 847 for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { 848 SwitchInsn->addCase(Builder.getInt(LHS), CaseDest); 849 LHS++; 850 } 851 return; 852 } 853 854 // The range is too big. Emit "if" condition into a new block, 855 // making sure to save and restore the current insertion point. 856 llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); 857 858 // Push this test onto the chain of range checks (which terminates 859 // in the default basic block). The switch's default will be changed 860 // to the top of this chain after switch emission is complete. 861 llvm::BasicBlock *FalseDest = CaseRangeBlock; 862 CaseRangeBlock = createBasicBlock("sw.caserange"); 863 864 CurFn->getBasicBlockList().push_back(CaseRangeBlock); 865 Builder.SetInsertPoint(CaseRangeBlock); 866 867 // Emit range check. 868 llvm::Value *Diff = 869 Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS)); 870 llvm::Value *Cond = 871 Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds"); 872 Builder.CreateCondBr(Cond, CaseDest, FalseDest); 873 874 // Restore the appropriate insertion point. 875 if (RestoreBB) 876 Builder.SetInsertPoint(RestoreBB); 877 else 878 Builder.ClearInsertionPoint(); 879} 880 881void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { 882 // If there is no enclosing switch instance that we're aware of, then this 883 // case statement and its block can be elided. This situation only happens 884 // when we've constant-folded the switch, are emitting the constant case, 885 // and part of the constant case includes another case statement. For 886 // instance: switch (4) { case 4: do { case 5: } while (1); } 887 if (!SwitchInsn) { 888 EmitStmt(S.getSubStmt()); 889 return; 890 } 891 892 // Handle case ranges. 893 if (S.getRHS()) { 894 EmitCaseStmtRange(S); 895 return; 896 } 897 898 llvm::ConstantInt *CaseVal = 899 Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext())); 900 901 // If the body of the case is just a 'break', and if there was no fallthrough, 902 // try to not emit an empty block. 903 if ((CGM.getCodeGenOpts().OptimizationLevel > 0) && 904 isa<BreakStmt>(S.getSubStmt())) { 905 JumpDest Block = BreakContinueStack.back().BreakBlock; 906 907 // Only do this optimization if there are no cleanups that need emitting. 908 if (isObviouslyBranchWithoutCleanups(Block)) { 909 SwitchInsn->addCase(CaseVal, Block.getBlock()); 910 911 // If there was a fallthrough into this case, make sure to redirect it to 912 // the end of the switch as well. 913 if (Builder.GetInsertBlock()) { 914 Builder.CreateBr(Block.getBlock()); 915 Builder.ClearInsertionPoint(); 916 } 917 return; 918 } 919 } 920 921 EmitBlock(createBasicBlock("sw.bb")); 922 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 923 SwitchInsn->addCase(CaseVal, CaseDest); 924 925 // Recursively emitting the statement is acceptable, but is not wonderful for 926 // code where we have many case statements nested together, i.e.: 927 // case 1: 928 // case 2: 929 // case 3: etc. 930 // Handling this recursively will create a new block for each case statement 931 // that falls through to the next case which is IR intensive. It also causes 932 // deep recursion which can run into stack depth limitations. Handle 933 // sequential non-range case statements specially. 934 const CaseStmt *CurCase = &S; 935 const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); 936 937 // Otherwise, iteratively add consecutive cases to this switch stmt. 938 while (NextCase && NextCase->getRHS() == 0) { 939 CurCase = NextCase; 940 llvm::ConstantInt *CaseVal = 941 Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext())); 942 SwitchInsn->addCase(CaseVal, CaseDest); 943 NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); 944 } 945 946 // Normal default recursion for non-cases. 947 EmitStmt(CurCase->getSubStmt()); 948} 949 950void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { 951 llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); 952 assert(DefaultBlock->empty() && 953 "EmitDefaultStmt: Default block already defined?"); 954 EmitBlock(DefaultBlock); 955 EmitStmt(S.getSubStmt()); 956} 957 958/// CollectStatementsForCase - Given the body of a 'switch' statement and a 959/// constant value that is being switched on, see if we can dead code eliminate 960/// the body of the switch to a simple series of statements to emit. Basically, 961/// on a switch (5) we want to find these statements: 962/// case 5: 963/// printf(...); <-- 964/// ++i; <-- 965/// break; 966/// 967/// and add them to the ResultStmts vector. If it is unsafe to do this 968/// transformation (for example, one of the elided statements contains a label 969/// that might be jumped to), return CSFC_Failure. If we handled it and 'S' 970/// should include statements after it (e.g. the printf() line is a substmt of 971/// the case) then return CSFC_FallThrough. If we handled it and found a break 972/// statement, then return CSFC_Success. 973/// 974/// If Case is non-null, then we are looking for the specified case, checking 975/// that nothing we jump over contains labels. If Case is null, then we found 976/// the case and are looking for the break. 977/// 978/// If the recursive walk actually finds our Case, then we set FoundCase to 979/// true. 980/// 981enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success }; 982static CSFC_Result CollectStatementsForCase(const Stmt *S, 983 const SwitchCase *Case, 984 bool &FoundCase, 985 SmallVectorImpl<const Stmt*> &ResultStmts) { 986 // If this is a null statement, just succeed. 987 if (S == 0) 988 return Case ? CSFC_Success : CSFC_FallThrough; 989 990 // If this is the switchcase (case 4: or default) that we're looking for, then 991 // we're in business. Just add the substatement. 992 if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) { 993 if (S == Case) { 994 FoundCase = true; 995 return CollectStatementsForCase(SC->getSubStmt(), 0, FoundCase, 996 ResultStmts); 997 } 998 999 // Otherwise, this is some other case or default statement, just ignore it. 1000 return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase, 1001 ResultStmts); 1002 } 1003 1004 // If we are in the live part of the code and we found our break statement, 1005 // return a success! 1006 if (Case == 0 && isa<BreakStmt>(S)) 1007 return CSFC_Success; 1008 1009 // If this is a switch statement, then it might contain the SwitchCase, the 1010 // break, or neither. 1011 if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) { 1012 // Handle this as two cases: we might be looking for the SwitchCase (if so 1013 // the skipped statements must be skippable) or we might already have it. 1014 CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end(); 1015 if (Case) { 1016 // Keep track of whether we see a skipped declaration. The code could be 1017 // using the declaration even if it is skipped, so we can't optimize out 1018 // the decl if the kept statements might refer to it. 1019 bool HadSkippedDecl = false; 1020 1021 // If we're looking for the case, just see if we can skip each of the 1022 // substatements. 1023 for (; Case && I != E; ++I) { 1024 HadSkippedDecl |= isa<DeclStmt>(*I); 1025 1026 switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) { 1027 case CSFC_Failure: return CSFC_Failure; 1028 case CSFC_Success: 1029 // A successful result means that either 1) that the statement doesn't 1030 // have the case and is skippable, or 2) does contain the case value 1031 // and also contains the break to exit the switch. In the later case, 1032 // we just verify the rest of the statements are elidable. 1033 if (FoundCase) { 1034 // If we found the case and skipped declarations, we can't do the 1035 // optimization. 1036 if (HadSkippedDecl) 1037 return CSFC_Failure; 1038 1039 for (++I; I != E; ++I) 1040 if (CodeGenFunction::ContainsLabel(*I, true)) 1041 return CSFC_Failure; 1042 return CSFC_Success; 1043 } 1044 break; 1045 case CSFC_FallThrough: 1046 // If we have a fallthrough condition, then we must have found the 1047 // case started to include statements. Consider the rest of the 1048 // statements in the compound statement as candidates for inclusion. 1049 assert(FoundCase && "Didn't find case but returned fallthrough?"); 1050 // We recursively found Case, so we're not looking for it anymore. 1051 Case = 0; 1052 1053 // If we found the case and skipped declarations, we can't do the 1054 // optimization. 1055 if (HadSkippedDecl) 1056 return CSFC_Failure; 1057 break; 1058 } 1059 } 1060 } 1061 1062 // If we have statements in our range, then we know that the statements are 1063 // live and need to be added to the set of statements we're tracking. 1064 for (; I != E; ++I) { 1065 switch (CollectStatementsForCase(*I, 0, FoundCase, ResultStmts)) { 1066 case CSFC_Failure: return CSFC_Failure; 1067 case CSFC_FallThrough: 1068 // A fallthrough result means that the statement was simple and just 1069 // included in ResultStmt, keep adding them afterwards. 1070 break; 1071 case CSFC_Success: 1072 // A successful result means that we found the break statement and 1073 // stopped statement inclusion. We just ensure that any leftover stmts 1074 // are skippable and return success ourselves. 1075 for (++I; I != E; ++I) 1076 if (CodeGenFunction::ContainsLabel(*I, true)) 1077 return CSFC_Failure; 1078 return CSFC_Success; 1079 } 1080 } 1081 1082 return Case ? CSFC_Success : CSFC_FallThrough; 1083 } 1084 1085 // Okay, this is some other statement that we don't handle explicitly, like a 1086 // for statement or increment etc. If we are skipping over this statement, 1087 // just verify it doesn't have labels, which would make it invalid to elide. 1088 if (Case) { 1089 if (CodeGenFunction::ContainsLabel(S, true)) 1090 return CSFC_Failure; 1091 return CSFC_Success; 1092 } 1093 1094 // Otherwise, we want to include this statement. Everything is cool with that 1095 // so long as it doesn't contain a break out of the switch we're in. 1096 if (CodeGenFunction::containsBreak(S)) return CSFC_Failure; 1097 1098 // Otherwise, everything is great. Include the statement and tell the caller 1099 // that we fall through and include the next statement as well. 1100 ResultStmts.push_back(S); 1101 return CSFC_FallThrough; 1102} 1103 1104/// FindCaseStatementsForValue - Find the case statement being jumped to and 1105/// then invoke CollectStatementsForCase to find the list of statements to emit 1106/// for a switch on constant. See the comment above CollectStatementsForCase 1107/// for more details. 1108static bool FindCaseStatementsForValue(const SwitchStmt &S, 1109 const llvm::APSInt &ConstantCondValue, 1110 SmallVectorImpl<const Stmt*> &ResultStmts, 1111 ASTContext &C) { 1112 // First step, find the switch case that is being branched to. We can do this 1113 // efficiently by scanning the SwitchCase list. 1114 const SwitchCase *Case = S.getSwitchCaseList(); 1115 const DefaultStmt *DefaultCase = 0; 1116 1117 for (; Case; Case = Case->getNextSwitchCase()) { 1118 // It's either a default or case. Just remember the default statement in 1119 // case we're not jumping to any numbered cases. 1120 if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) { 1121 DefaultCase = DS; 1122 continue; 1123 } 1124 1125 // Check to see if this case is the one we're looking for. 1126 const CaseStmt *CS = cast<CaseStmt>(Case); 1127 // Don't handle case ranges yet. 1128 if (CS->getRHS()) return false; 1129 1130 // If we found our case, remember it as 'case'. 1131 if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue) 1132 break; 1133 } 1134 1135 // If we didn't find a matching case, we use a default if it exists, or we 1136 // elide the whole switch body! 1137 if (Case == 0) { 1138 // It is safe to elide the body of the switch if it doesn't contain labels 1139 // etc. If it is safe, return successfully with an empty ResultStmts list. 1140 if (DefaultCase == 0) 1141 return !CodeGenFunction::ContainsLabel(&S); 1142 Case = DefaultCase; 1143 } 1144 1145 // Ok, we know which case is being jumped to, try to collect all the 1146 // statements that follow it. This can fail for a variety of reasons. Also, 1147 // check to see that the recursive walk actually found our case statement. 1148 // Insane cases like this can fail to find it in the recursive walk since we 1149 // don't handle every stmt kind: 1150 // switch (4) { 1151 // while (1) { 1152 // case 4: ... 1153 bool FoundCase = false; 1154 return CollectStatementsForCase(S.getBody(), Case, FoundCase, 1155 ResultStmts) != CSFC_Failure && 1156 FoundCase; 1157} 1158 1159void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { 1160 JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog"); 1161 1162 RunCleanupsScope ConditionScope(*this); 1163 1164 if (S.getConditionVariable()) 1165 EmitAutoVarDecl(*S.getConditionVariable()); 1166 1167 // Handle nested switch statements. 1168 llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; 1169 llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; 1170 1171 // See if we can constant fold the condition of the switch and therefore only 1172 // emit the live case statement (if any) of the switch. 1173 llvm::APSInt ConstantCondValue; 1174 if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) { 1175 SmallVector<const Stmt*, 4> CaseStmts; 1176 if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts, 1177 getContext())) { 1178 RunCleanupsScope ExecutedScope(*this); 1179 1180 // At this point, we are no longer "within" a switch instance, so 1181 // we can temporarily enforce this to ensure that any embedded case 1182 // statements are not emitted. 1183 SwitchInsn = 0; 1184 1185 // Okay, we can dead code eliminate everything except this case. Emit the 1186 // specified series of statements and we're good. 1187 for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i) 1188 EmitStmt(CaseStmts[i]); 1189 1190 // Now we want to restore the saved switch instance so that nested 1191 // switches continue to function properly 1192 SwitchInsn = SavedSwitchInsn; 1193 1194 return; 1195 } 1196 } 1197 1198 llvm::Value *CondV = EmitScalarExpr(S.getCond()); 1199 1200 // Create basic block to hold stuff that comes after switch 1201 // statement. We also need to create a default block now so that 1202 // explicit case ranges tests can have a place to jump to on 1203 // failure. 1204 llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); 1205 SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); 1206 CaseRangeBlock = DefaultBlock; 1207 1208 // Clear the insertion point to indicate we are in unreachable code. 1209 Builder.ClearInsertionPoint(); 1210 1211 // All break statements jump to NextBlock. If BreakContinueStack is non empty 1212 // then reuse last ContinueBlock. 1213 JumpDest OuterContinue; 1214 if (!BreakContinueStack.empty()) 1215 OuterContinue = BreakContinueStack.back().ContinueBlock; 1216 1217 BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue)); 1218 1219 // Emit switch body. 1220 EmitStmt(S.getBody()); 1221 1222 BreakContinueStack.pop_back(); 1223 1224 // Update the default block in case explicit case range tests have 1225 // been chained on top. 1226 SwitchInsn->setDefaultDest(CaseRangeBlock); 1227 1228 // If a default was never emitted: 1229 if (!DefaultBlock->getParent()) { 1230 // If we have cleanups, emit the default block so that there's a 1231 // place to jump through the cleanups from. 1232 if (ConditionScope.requiresCleanups()) { 1233 EmitBlock(DefaultBlock); 1234 1235 // Otherwise, just forward the default block to the switch end. 1236 } else { 1237 DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock()); 1238 delete DefaultBlock; 1239 } 1240 } 1241 1242 ConditionScope.ForceCleanup(); 1243 1244 // Emit continuation. 1245 EmitBlock(SwitchExit.getBlock(), true); 1246 1247 SwitchInsn = SavedSwitchInsn; 1248 CaseRangeBlock = SavedCRBlock; 1249} 1250 1251static std::string 1252SimplifyConstraint(const char *Constraint, const TargetInfo &Target, 1253 SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { 1254 std::string Result; 1255 1256 while (*Constraint) { 1257 switch (*Constraint) { 1258 default: 1259 Result += Target.convertConstraint(Constraint); 1260 break; 1261 // Ignore these 1262 case '*': 1263 case '?': 1264 case '!': 1265 case '=': // Will see this and the following in mult-alt constraints. 1266 case '+': 1267 break; 1268 case ',': 1269 Result += "|"; 1270 break; 1271 case 'g': 1272 Result += "imr"; 1273 break; 1274 case '[': { 1275 assert(OutCons && 1276 "Must pass output names to constraints with a symbolic name"); 1277 unsigned Index; 1278 bool result = Target.resolveSymbolicName(Constraint, 1279 &(*OutCons)[0], 1280 OutCons->size(), Index); 1281 assert(result && "Could not resolve symbolic name"); (void)result; 1282 Result += llvm::utostr(Index); 1283 break; 1284 } 1285 } 1286 1287 Constraint++; 1288 } 1289 1290 return Result; 1291} 1292 1293/// AddVariableConstraints - Look at AsmExpr and if it is a variable declared 1294/// as using a particular register add that as a constraint that will be used 1295/// in this asm stmt. 1296static std::string 1297AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr, 1298 const TargetInfo &Target, CodeGenModule &CGM, 1299 const AsmStmt &Stmt) { 1300 const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr); 1301 if (!AsmDeclRef) 1302 return Constraint; 1303 const ValueDecl &Value = *AsmDeclRef->getDecl(); 1304 const VarDecl *Variable = dyn_cast<VarDecl>(&Value); 1305 if (!Variable) 1306 return Constraint; 1307 if (Variable->getStorageClass() != SC_Register) 1308 return Constraint; 1309 AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>(); 1310 if (!Attr) 1311 return Constraint; 1312 StringRef Register = Attr->getLabel(); 1313 assert(Target.isValidGCCRegisterName(Register)); 1314 // We're using validateOutputConstraint here because we only care if 1315 // this is a register constraint. 1316 TargetInfo::ConstraintInfo Info(Constraint, ""); 1317 if (Target.validateOutputConstraint(Info) && 1318 !Info.allowsRegister()) { 1319 CGM.ErrorUnsupported(&Stmt, "__asm__"); 1320 return Constraint; 1321 } 1322 // Canonicalize the register here before returning it. 1323 Register = Target.getNormalizedGCCRegisterName(Register); 1324 return "{" + Register.str() + "}"; 1325} 1326 1327llvm::Value* 1328CodeGenFunction::EmitAsmInputLValue(const TargetInfo::ConstraintInfo &Info, 1329 LValue InputValue, QualType InputType, 1330 std::string &ConstraintStr) { 1331 llvm::Value *Arg; 1332 if (Info.allowsRegister() || !Info.allowsMemory()) { 1333 if (!CodeGenFunction::hasAggregateLLVMType(InputType)) { 1334 Arg = EmitLoadOfLValue(InputValue).getScalarVal(); 1335 } else { 1336 llvm::Type *Ty = ConvertType(InputType); 1337 uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); 1338 if (Size <= 64 && llvm::isPowerOf2_64(Size)) { 1339 Ty = llvm::IntegerType::get(getLLVMContext(), Size); 1340 Ty = llvm::PointerType::getUnqual(Ty); 1341 1342 Arg = Builder.CreateLoad(Builder.CreateBitCast(InputValue.getAddress(), 1343 Ty)); 1344 } else { 1345 Arg = InputValue.getAddress(); 1346 ConstraintStr += '*'; 1347 } 1348 } 1349 } else { 1350 Arg = InputValue.getAddress(); 1351 ConstraintStr += '*'; 1352 } 1353 1354 return Arg; 1355} 1356 1357llvm::Value* CodeGenFunction::EmitAsmInput( 1358 const TargetInfo::ConstraintInfo &Info, 1359 const Expr *InputExpr, 1360 std::string &ConstraintStr) { 1361 if (Info.allowsRegister() || !Info.allowsMemory()) 1362 if (!CodeGenFunction::hasAggregateLLVMType(InputExpr->getType())) 1363 return EmitScalarExpr(InputExpr); 1364 1365 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 1366 LValue Dest = EmitLValue(InputExpr); 1367 return EmitAsmInputLValue(Info, Dest, InputExpr->getType(), ConstraintStr); 1368} 1369 1370/// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline 1371/// asm call instruction. The !srcloc MDNode contains a list of constant 1372/// integers which are the source locations of the start of each line in the 1373/// asm. 1374static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str, 1375 CodeGenFunction &CGF) { 1376 SmallVector<llvm::Value *, 8> Locs; 1377 // Add the location of the first line to the MDNode. 1378 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1379 Str->getLocStart().getRawEncoding())); 1380 StringRef StrVal = Str->getString(); 1381 if (!StrVal.empty()) { 1382 const SourceManager &SM = CGF.CGM.getContext().getSourceManager(); 1383 const LangOptions &LangOpts = CGF.CGM.getLangOpts(); 1384 1385 // Add the location of the start of each subsequent line of the asm to the 1386 // MDNode. 1387 for (unsigned i = 0, e = StrVal.size()-1; i != e; ++i) { 1388 if (StrVal[i] != '\n') continue; 1389 SourceLocation LineLoc = Str->getLocationOfByte(i+1, SM, LangOpts, 1390 CGF.Target); 1391 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1392 LineLoc.getRawEncoding())); 1393 } 1394 } 1395 1396 return llvm::MDNode::get(CGF.getLLVMContext(), Locs); 1397} 1398 1399void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { 1400 // Assemble the final asm string. 1401 std::string AsmString = S.generateAsmString(getContext()); 1402 1403 // Get all the output and input constraints together. 1404 SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 1405 SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 1406 1407 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1408 TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), 1409 S.getOutputName(i)); 1410 bool IsValid = Target.validateOutputConstraint(Info); (void)IsValid; 1411 assert(IsValid && "Failed to parse output constraint"); 1412 OutputConstraintInfos.push_back(Info); 1413 } 1414 1415 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1416 TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), 1417 S.getInputName(i)); 1418 bool IsValid = Target.validateInputConstraint(OutputConstraintInfos.data(), 1419 S.getNumOutputs(), Info); 1420 assert(IsValid && "Failed to parse input constraint"); (void)IsValid; 1421 InputConstraintInfos.push_back(Info); 1422 } 1423 1424 std::string Constraints; 1425 1426 std::vector<LValue> ResultRegDests; 1427 std::vector<QualType> ResultRegQualTys; 1428 std::vector<llvm::Type *> ResultRegTypes; 1429 std::vector<llvm::Type *> ResultTruncRegTypes; 1430 std::vector<llvm::Type *> ArgTypes; 1431 std::vector<llvm::Value*> Args; 1432 1433 // Keep track of inout constraints. 1434 std::string InOutConstraints; 1435 std::vector<llvm::Value*> InOutArgs; 1436 std::vector<llvm::Type*> InOutArgTypes; 1437 1438 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1439 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 1440 1441 // Simplify the output constraint. 1442 std::string OutputConstraint(S.getOutputConstraint(i)); 1443 OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); 1444 1445 const Expr *OutExpr = S.getOutputExpr(i); 1446 OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); 1447 1448 OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr, 1449 Target, CGM, S); 1450 1451 LValue Dest = EmitLValue(OutExpr); 1452 if (!Constraints.empty()) 1453 Constraints += ','; 1454 1455 // If this is a register output, then make the inline asm return it 1456 // by-value. If this is a memory result, return the value by-reference. 1457 if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { 1458 Constraints += "=" + OutputConstraint; 1459 ResultRegQualTys.push_back(OutExpr->getType()); 1460 ResultRegDests.push_back(Dest); 1461 ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); 1462 ResultTruncRegTypes.push_back(ResultRegTypes.back()); 1463 1464 // If this output is tied to an input, and if the input is larger, then 1465 // we need to set the actual result type of the inline asm node to be the 1466 // same as the input type. 1467 if (Info.hasMatchingInput()) { 1468 unsigned InputNo; 1469 for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { 1470 TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; 1471 if (Input.hasTiedOperand() && Input.getTiedOperand() == i) 1472 break; 1473 } 1474 assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); 1475 1476 QualType InputTy = S.getInputExpr(InputNo)->getType(); 1477 QualType OutputType = OutExpr->getType(); 1478 1479 uint64_t InputSize = getContext().getTypeSize(InputTy); 1480 if (getContext().getTypeSize(OutputType) < InputSize) { 1481 // Form the asm to return the value as a larger integer or fp type. 1482 ResultRegTypes.back() = ConvertType(InputTy); 1483 } 1484 } 1485 if (llvm::Type* AdjTy = 1486 getTargetHooks().adjustInlineAsmType(*this, OutputConstraint, 1487 ResultRegTypes.back())) 1488 ResultRegTypes.back() = AdjTy; 1489 } else { 1490 ArgTypes.push_back(Dest.getAddress()->getType()); 1491 Args.push_back(Dest.getAddress()); 1492 Constraints += "=*"; 1493 Constraints += OutputConstraint; 1494 } 1495 1496 if (Info.isReadWrite()) { 1497 InOutConstraints += ','; 1498 1499 const Expr *InputExpr = S.getOutputExpr(i); 1500 llvm::Value *Arg = EmitAsmInputLValue(Info, Dest, InputExpr->getType(), 1501 InOutConstraints); 1502 1503 if (llvm::Type* AdjTy = 1504 getTargetHooks().adjustInlineAsmType(*this, OutputConstraint, 1505 Arg->getType())) 1506 Arg = Builder.CreateBitCast(Arg, AdjTy); 1507 1508 if (Info.allowsRegister()) 1509 InOutConstraints += llvm::utostr(i); 1510 else 1511 InOutConstraints += OutputConstraint; 1512 1513 InOutArgTypes.push_back(Arg->getType()); 1514 InOutArgs.push_back(Arg); 1515 } 1516 } 1517 1518 unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); 1519 1520 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1521 const Expr *InputExpr = S.getInputExpr(i); 1522 1523 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 1524 1525 if (!Constraints.empty()) 1526 Constraints += ','; 1527 1528 // Simplify the input constraint. 1529 std::string InputConstraint(S.getInputConstraint(i)); 1530 InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, 1531 &OutputConstraintInfos); 1532 1533 InputConstraint = 1534 AddVariableConstraints(InputConstraint, 1535 *InputExpr->IgnoreParenNoopCasts(getContext()), 1536 Target, CGM, S); 1537 1538 llvm::Value *Arg = EmitAsmInput(Info, InputExpr, Constraints); 1539 1540 // If this input argument is tied to a larger output result, extend the 1541 // input to be the same size as the output. The LLVM backend wants to see 1542 // the input and output of a matching constraint be the same size. Note 1543 // that GCC does not define what the top bits are here. We use zext because 1544 // that is usually cheaper, but LLVM IR should really get an anyext someday. 1545 if (Info.hasTiedOperand()) { 1546 unsigned Output = Info.getTiedOperand(); 1547 QualType OutputType = S.getOutputExpr(Output)->getType(); 1548 QualType InputTy = InputExpr->getType(); 1549 1550 if (getContext().getTypeSize(OutputType) > 1551 getContext().getTypeSize(InputTy)) { 1552 // Use ptrtoint as appropriate so that we can do our extension. 1553 if (isa<llvm::PointerType>(Arg->getType())) 1554 Arg = Builder.CreatePtrToInt(Arg, IntPtrTy); 1555 llvm::Type *OutputTy = ConvertType(OutputType); 1556 if (isa<llvm::IntegerType>(OutputTy)) 1557 Arg = Builder.CreateZExt(Arg, OutputTy); 1558 else if (isa<llvm::PointerType>(OutputTy)) 1559 Arg = Builder.CreateZExt(Arg, IntPtrTy); 1560 else { 1561 assert(OutputTy->isFloatingPointTy() && "Unexpected output type"); 1562 Arg = Builder.CreateFPExt(Arg, OutputTy); 1563 } 1564 } 1565 } 1566 if (llvm::Type* AdjTy = 1567 getTargetHooks().adjustInlineAsmType(*this, InputConstraint, 1568 Arg->getType())) 1569 Arg = Builder.CreateBitCast(Arg, AdjTy); 1570 1571 ArgTypes.push_back(Arg->getType()); 1572 Args.push_back(Arg); 1573 Constraints += InputConstraint; 1574 } 1575 1576 // Append the "input" part of inout constraints last. 1577 for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { 1578 ArgTypes.push_back(InOutArgTypes[i]); 1579 Args.push_back(InOutArgs[i]); 1580 } 1581 Constraints += InOutConstraints; 1582 1583 // Clobbers 1584 for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { 1585 StringRef Clobber = S.getClobber(i); 1586 1587 if (Clobber != "memory" && Clobber != "cc") 1588 Clobber = Target.getNormalizedGCCRegisterName(Clobber); 1589 1590 if (i != 0 || NumConstraints != 0) 1591 Constraints += ','; 1592 1593 Constraints += "~{"; 1594 Constraints += Clobber; 1595 Constraints += '}'; 1596 } 1597 1598 // Add machine specific clobbers 1599 std::string MachineClobbers = Target.getClobbers(); 1600 if (!MachineClobbers.empty()) { 1601 if (!Constraints.empty()) 1602 Constraints += ','; 1603 Constraints += MachineClobbers; 1604 } 1605 1606 llvm::Type *ResultType; 1607 if (ResultRegTypes.empty()) 1608 ResultType = VoidTy; 1609 else if (ResultRegTypes.size() == 1) 1610 ResultType = ResultRegTypes[0]; 1611 else 1612 ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes); 1613 1614 llvm::FunctionType *FTy = 1615 llvm::FunctionType::get(ResultType, ArgTypes, false); 1616 1617 llvm::InlineAsm *IA = 1618 llvm::InlineAsm::get(FTy, AsmString, Constraints, 1619 S.isVolatile() || S.getNumOutputs() == 0); 1620 llvm::CallInst *Result = Builder.CreateCall(IA, Args); 1621 Result->addAttribute(~0, llvm::Attribute::NoUnwind); 1622 1623 // Add the inline asm non-standard dialect attribute on MS-style inline asms. 1624 if (isa<MSAsmStmt>(&S)) 1625 Result->addAttribute(~0, llvm::Attribute::IANSDialect); 1626 1627 // Slap the source location of the inline asm into a !srcloc metadata on the 1628 // call. FIXME: Handle metadata for MS-style inline asms. 1629 if (const GCCAsmStmt *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S)) 1630 Result->setMetadata("srcloc", getAsmSrcLocInfo(gccAsmStmt->getAsmString(), 1631 *this)); 1632 1633 // Extract all of the register value results from the asm. 1634 std::vector<llvm::Value*> RegResults; 1635 if (ResultRegTypes.size() == 1) { 1636 RegResults.push_back(Result); 1637 } else { 1638 for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { 1639 llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); 1640 RegResults.push_back(Tmp); 1641 } 1642 } 1643 1644 for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { 1645 llvm::Value *Tmp = RegResults[i]; 1646 1647 // If the result type of the LLVM IR asm doesn't match the result type of 1648 // the expression, do the conversion. 1649 if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { 1650 llvm::Type *TruncTy = ResultTruncRegTypes[i]; 1651 1652 // Truncate the integer result to the right size, note that TruncTy can be 1653 // a pointer. 1654 if (TruncTy->isFloatingPointTy()) 1655 Tmp = Builder.CreateFPTrunc(Tmp, TruncTy); 1656 else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) { 1657 uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); 1658 Tmp = Builder.CreateTrunc(Tmp, 1659 llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize)); 1660 Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); 1661 } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) { 1662 uint64_t TmpSize =CGM.getTargetData().getTypeSizeInBits(Tmp->getType()); 1663 Tmp = Builder.CreatePtrToInt(Tmp, 1664 llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize)); 1665 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1666 } else if (TruncTy->isIntegerTy()) { 1667 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1668 } else if (TruncTy->isVectorTy()) { 1669 Tmp = Builder.CreateBitCast(Tmp, TruncTy); 1670 } 1671 } 1672 1673 EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i]); 1674 } 1675} 1676