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