CGStmt.cpp revision ba0513de93d2fab6db5ab30b6927209fcc883078
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::GotoStmtClass: 83 case Stmt::BreakStmtClass: 84 case Stmt::ContinueStmtClass: 85 case Stmt::DefaultStmtClass: 86 case Stmt::CaseStmtClass: 87 llvm_unreachable("should have emitted these statements as simple"); 88 89#define STMT(Type, Base) 90#define ABSTRACT_STMT(Op) 91#define EXPR(Type, Base) \ 92 case Stmt::Type##Class: 93#include "clang/AST/StmtNodes.inc" 94 { 95 // Remember the block we came in on. 96 llvm::BasicBlock *incoming = Builder.GetInsertBlock(); 97 assert(incoming && "expression emission must have an insertion point"); 98 99 EmitIgnoredExpr(cast<Expr>(S)); 100 101 llvm::BasicBlock *outgoing = Builder.GetInsertBlock(); 102 assert(outgoing && "expression emission cleared block!"); 103 104 // The expression emitters assume (reasonably!) that the insertion 105 // point is always set. To maintain that, the call-emission code 106 // for noreturn functions has to enter a new block with no 107 // predecessors. We want to kill that block and mark the current 108 // insertion point unreachable in the common case of a call like 109 // "exit();". Since expression emission doesn't otherwise create 110 // blocks with no predecessors, we can just test for that. 111 // However, we must be careful not to do this to our incoming 112 // block, because *statement* emission does sometimes create 113 // reachable blocks which will have no predecessors until later in 114 // the function. This occurs with, e.g., labels that are not 115 // reachable by fallthrough. 116 if (incoming != outgoing && outgoing->use_empty()) { 117 outgoing->eraseFromParent(); 118 Builder.ClearInsertionPoint(); 119 } 120 break; 121 } 122 123 case Stmt::IndirectGotoStmtClass: 124 EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break; 125 126 case Stmt::IfStmtClass: EmitIfStmt(cast<IfStmt>(*S)); break; 127 case Stmt::WhileStmtClass: EmitWhileStmt(cast<WhileStmt>(*S)); break; 128 case Stmt::DoStmtClass: EmitDoStmt(cast<DoStmt>(*S)); break; 129 case Stmt::ForStmtClass: EmitForStmt(cast<ForStmt>(*S)); break; 130 131 case Stmt::ReturnStmtClass: EmitReturnStmt(cast<ReturnStmt>(*S)); break; 132 133 case Stmt::SwitchStmtClass: EmitSwitchStmt(cast<SwitchStmt>(*S)); break; 134 case Stmt::AsmStmtClass: EmitAsmStmt(cast<AsmStmt>(*S)); break; 135 136 case Stmt::ObjCAtTryStmtClass: 137 EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S)); 138 break; 139 case Stmt::ObjCAtCatchStmtClass: 140 llvm_unreachable( 141 "@catch statements should be handled by EmitObjCAtTryStmt"); 142 case Stmt::ObjCAtFinallyStmtClass: 143 llvm_unreachable( 144 "@finally statements should be handled by EmitObjCAtTryStmt"); 145 case Stmt::ObjCAtThrowStmtClass: 146 EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S)); 147 break; 148 case Stmt::ObjCAtSynchronizedStmtClass: 149 EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S)); 150 break; 151 case Stmt::ObjCForCollectionStmtClass: 152 EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S)); 153 break; 154 case Stmt::ObjCAutoreleasePoolStmtClass: 155 EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S)); 156 break; 157 158 case Stmt::CXXTryStmtClass: 159 EmitCXXTryStmt(cast<CXXTryStmt>(*S)); 160 break; 161 case Stmt::CXXForRangeStmtClass: 162 EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S)); 163 case Stmt::SEHTryStmtClass: 164 // FIXME Not yet implemented 165 break; 166 } 167} 168 169bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) { 170 switch (S->getStmtClass()) { 171 default: return false; 172 case Stmt::NullStmtClass: break; 173 case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break; 174 case Stmt::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break; 175 case Stmt::LabelStmtClass: EmitLabelStmt(cast<LabelStmt>(*S)); break; 176 case Stmt::GotoStmtClass: EmitGotoStmt(cast<GotoStmt>(*S)); break; 177 case Stmt::BreakStmtClass: EmitBreakStmt(cast<BreakStmt>(*S)); break; 178 case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break; 179 case Stmt::DefaultStmtClass: EmitDefaultStmt(cast<DefaultStmt>(*S)); break; 180 case Stmt::CaseStmtClass: EmitCaseStmt(cast<CaseStmt>(*S)); break; 181 } 182 183 return true; 184} 185 186/// EmitCompoundStmt - Emit a compound statement {..} node. If GetLast is true, 187/// this captures the expression result of the last sub-statement and returns it 188/// (for use by the statement expression extension). 189RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast, 190 AggValueSlot AggSlot) { 191 PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(), 192 "LLVM IR generation of compound statement ('{}')"); 193 194 CGDebugInfo *DI = getDebugInfo(); 195 if (DI) 196 DI->EmitLexicalBlockStart(Builder, S.getLBracLoc()); 197 198 // Keep track of the current cleanup stack depth. 199 RunCleanupsScope Scope(*this); 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 if (DI) 206 DI->EmitLexicalBlockEnd(Builder, S.getRBracLoc()); 207 208 RValue RV; 209 if (!GetLast) 210 RV = RValue::get(0); 211 else { 212 // We have to special case labels here. They are statements, but when put 213 // at the end of a statement expression, they yield the value of their 214 // subexpression. Handle this by walking through all labels we encounter, 215 // emitting them before we evaluate the subexpr. 216 const Stmt *LastStmt = S.body_back(); 217 while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { 218 EmitLabel(LS->getDecl()); 219 LastStmt = LS->getSubStmt(); 220 } 221 222 EnsureInsertPoint(); 223 224 RV = EmitAnyExpr(cast<Expr>(LastStmt), AggSlot); 225 } 226 227 return RV; 228} 229 230void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { 231 llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); 232 233 // If there is a cleanup stack, then we it isn't worth trying to 234 // simplify this block (we would need to remove it from the scope map 235 // and cleanup entry). 236 if (!EHStack.empty()) 237 return; 238 239 // Can only simplify direct branches. 240 if (!BI || !BI->isUnconditional()) 241 return; 242 243 BB->replaceAllUsesWith(BI->getSuccessor(0)); 244 BI->eraseFromParent(); 245 BB->eraseFromParent(); 246} 247 248void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { 249 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 250 251 // Fall out of the current block (if necessary). 252 EmitBranch(BB); 253 254 if (IsFinished && BB->use_empty()) { 255 delete BB; 256 return; 257 } 258 259 // Place the block after the current block, if possible, or else at 260 // the end of the function. 261 if (CurBB && CurBB->getParent()) 262 CurFn->getBasicBlockList().insertAfter(CurBB, BB); 263 else 264 CurFn->getBasicBlockList().push_back(BB); 265 Builder.SetInsertPoint(BB); 266} 267 268void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { 269 // Emit a branch from the current block to the target one if this 270 // was a real block. If this was just a fall-through block after a 271 // terminator, don't emit it. 272 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 273 274 if (!CurBB || CurBB->getTerminator()) { 275 // If there is no insert point or the previous block is already 276 // terminated, don't touch it. 277 } else { 278 // Otherwise, create a fall-through branch. 279 Builder.CreateBr(Target); 280 } 281 282 Builder.ClearInsertionPoint(); 283} 284 285void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) { 286 bool inserted = false; 287 for (llvm::BasicBlock::use_iterator 288 i = block->use_begin(), e = block->use_end(); i != e; ++i) { 289 if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(*i)) { 290 CurFn->getBasicBlockList().insertAfter(insn->getParent(), block); 291 inserted = true; 292 break; 293 } 294 } 295 296 if (!inserted) 297 CurFn->getBasicBlockList().push_back(block); 298 299 Builder.SetInsertPoint(block); 300} 301 302CodeGenFunction::JumpDest 303CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) { 304 JumpDest &Dest = LabelMap[D]; 305 if (Dest.isValid()) return Dest; 306 307 // Create, but don't insert, the new block. 308 Dest = JumpDest(createBasicBlock(D->getName()), 309 EHScopeStack::stable_iterator::invalid(), 310 NextCleanupDestIndex++); 311 return Dest; 312} 313 314void CodeGenFunction::EmitLabel(const LabelDecl *D) { 315 JumpDest &Dest = LabelMap[D]; 316 317 // If we didn't need a forward reference to this label, just go 318 // ahead and create a destination at the current scope. 319 if (!Dest.isValid()) { 320 Dest = getJumpDestInCurrentScope(D->getName()); 321 322 // Otherwise, we need to give this label a target depth and remove 323 // it from the branch-fixups list. 324 } else { 325 assert(!Dest.getScopeDepth().isValid() && "already emitted label!"); 326 Dest = JumpDest(Dest.getBlock(), 327 EHStack.stable_begin(), 328 Dest.getDestIndex()); 329 330 ResolveBranchFixups(Dest.getBlock()); 331 } 332 333 EmitBlock(Dest.getBlock()); 334} 335 336 337void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { 338 EmitLabel(S.getDecl()); 339 EmitStmt(S.getSubStmt()); 340} 341 342void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { 343 // If this code is reachable then emit a stop point (if generating 344 // debug info). We have to do this ourselves because we are on the 345 // "simple" statement path. 346 if (HaveInsertPoint()) 347 EmitStopPoint(&S); 348 349 EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel())); 350} 351 352 353void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { 354 if (const LabelDecl *Target = S.getConstantTarget()) { 355 EmitBranchThroughCleanup(getJumpDestForLabel(Target)); 356 return; 357 } 358 359 // Ensure that we have an i8* for our PHI node. 360 llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()), 361 Int8PtrTy, "addr"); 362 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 363 364 365 // 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 375void 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 441void 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 518void 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 565void 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 658void 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 728void 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 :). 742void 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 EmitAggExpr(RV, AggValueSlot::forAddr(ReturnValue, Qualifiers(), 776 AggValueSlot::IsDestructed, 777 AggValueSlot::DoesNotNeedGCBarriers, 778 AggValueSlot::IsNotAliased)); 779 } 780 781 EmitBranchThroughCleanup(ReturnBlock); 782} 783 784void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { 785 // As long as debug info is modeled with instructions, we have to ensure we 786 // have a place to insert here and write the stop point here. 787 if (getDebugInfo() && HaveInsertPoint()) 788 EmitStopPoint(&S); 789 790 for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); 791 I != E; ++I) 792 EmitDecl(**I); 793} 794 795void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { 796 assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); 797 798 // If this code is reachable then emit a stop point (if generating 799 // debug info). We have to do this ourselves because we are on the 800 // "simple" statement path. 801 if (HaveInsertPoint()) 802 EmitStopPoint(&S); 803 804 JumpDest Block = BreakContinueStack.back().BreakBlock; 805 EmitBranchThroughCleanup(Block); 806} 807 808void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { 809 assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); 810 811 // If this code is reachable then emit a stop point (if generating 812 // debug info). We have to do this ourselves because we are on the 813 // "simple" statement path. 814 if (HaveInsertPoint()) 815 EmitStopPoint(&S); 816 817 JumpDest Block = BreakContinueStack.back().ContinueBlock; 818 EmitBranchThroughCleanup(Block); 819} 820 821/// EmitCaseStmtRange - If case statement range is not too big then 822/// add multiple cases to switch instruction, one for each value within 823/// the range. If range is too big then emit "if" condition check. 824void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { 825 assert(S.getRHS() && "Expected RHS value in CaseStmt"); 826 827 llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext()); 828 llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext()); 829 830 // Emit the code for this case. We do this first to make sure it is 831 // properly chained from our predecessor before generating the 832 // switch machinery to enter this block. 833 EmitBlock(createBasicBlock("sw.bb")); 834 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 835 EmitStmt(S.getSubStmt()); 836 837 // If range is empty, do nothing. 838 if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) 839 return; 840 841 llvm::APInt Range = RHS - LHS; 842 // FIXME: parameters such as this should not be hardcoded. 843 if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { 844 // Range is small enough to add multiple switch instruction cases. 845 for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { 846 SwitchInsn->addCase(Builder.getInt(LHS), CaseDest); 847 LHS++; 848 } 849 return; 850 } 851 852 // The range is too big. Emit "if" condition into a new block, 853 // making sure to save and restore the current insertion point. 854 llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); 855 856 // Push this test onto the chain of range checks (which terminates 857 // in the default basic block). The switch's default will be changed 858 // to the top of this chain after switch emission is complete. 859 llvm::BasicBlock *FalseDest = CaseRangeBlock; 860 CaseRangeBlock = createBasicBlock("sw.caserange"); 861 862 CurFn->getBasicBlockList().push_back(CaseRangeBlock); 863 Builder.SetInsertPoint(CaseRangeBlock); 864 865 // Emit range check. 866 llvm::Value *Diff = 867 Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS)); 868 llvm::Value *Cond = 869 Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds"); 870 Builder.CreateCondBr(Cond, CaseDest, FalseDest); 871 872 // Restore the appropriate insertion point. 873 if (RestoreBB) 874 Builder.SetInsertPoint(RestoreBB); 875 else 876 Builder.ClearInsertionPoint(); 877} 878 879void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { 880 // Handle case ranges. 881 if (S.getRHS()) { 882 EmitCaseStmtRange(S); 883 return; 884 } 885 886 llvm::ConstantInt *CaseVal = 887 Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext())); 888 889 // If the body of the case is just a 'break', and if there was no fallthrough, 890 // try to not emit an empty block. 891 if (isa<BreakStmt>(S.getSubStmt())) { 892 JumpDest Block = BreakContinueStack.back().BreakBlock; 893 894 // Only do this optimization if there are no cleanups that need emitting. 895 if (isObviouslyBranchWithoutCleanups(Block)) { 896 SwitchInsn->addCase(CaseVal, Block.getBlock()); 897 898 // If there was a fallthrough into this case, make sure to redirect it to 899 // the end of the switch as well. 900 if (Builder.GetInsertBlock()) { 901 Builder.CreateBr(Block.getBlock()); 902 Builder.ClearInsertionPoint(); 903 } 904 return; 905 } 906 } 907 908 EmitBlock(createBasicBlock("sw.bb")); 909 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 910 SwitchInsn->addCase(CaseVal, CaseDest); 911 912 // Recursively emitting the statement is acceptable, but is not wonderful for 913 // code where we have many case statements nested together, i.e.: 914 // case 1: 915 // case 2: 916 // case 3: etc. 917 // Handling this recursively will create a new block for each case statement 918 // that falls through to the next case which is IR intensive. It also causes 919 // deep recursion which can run into stack depth limitations. Handle 920 // sequential non-range case statements specially. 921 const CaseStmt *CurCase = &S; 922 const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); 923 924 // Otherwise, iteratively add consecutive cases to this switch stmt. 925 while (NextCase && NextCase->getRHS() == 0) { 926 CurCase = NextCase; 927 llvm::ConstantInt *CaseVal = 928 Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext())); 929 SwitchInsn->addCase(CaseVal, CaseDest); 930 NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); 931 } 932 933 // Normal default recursion for non-cases. 934 EmitStmt(CurCase->getSubStmt()); 935} 936 937void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { 938 llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); 939 assert(DefaultBlock->empty() && 940 "EmitDefaultStmt: Default block already defined?"); 941 EmitBlock(DefaultBlock); 942 EmitStmt(S.getSubStmt()); 943} 944 945/// CollectStatementsForCase - Given the body of a 'switch' statement and a 946/// constant value that is being switched on, see if we can dead code eliminate 947/// the body of the switch to a simple series of statements to emit. Basically, 948/// on a switch (5) we want to find these statements: 949/// case 5: 950/// printf(...); <-- 951/// ++i; <-- 952/// break; 953/// 954/// and add them to the ResultStmts vector. If it is unsafe to do this 955/// transformation (for example, one of the elided statements contains a label 956/// that might be jumped to), return CSFC_Failure. If we handled it and 'S' 957/// should include statements after it (e.g. the printf() line is a substmt of 958/// the case) then return CSFC_FallThrough. If we handled it and found a break 959/// statement, then return CSFC_Success. 960/// 961/// If Case is non-null, then we are looking for the specified case, checking 962/// that nothing we jump over contains labels. If Case is null, then we found 963/// the case and are looking for the break. 964/// 965/// If the recursive walk actually finds our Case, then we set FoundCase to 966/// true. 967/// 968enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success }; 969static CSFC_Result CollectStatementsForCase(const Stmt *S, 970 const SwitchCase *Case, 971 bool &FoundCase, 972 SmallVectorImpl<const Stmt*> &ResultStmts) { 973 // If this is a null statement, just succeed. 974 if (S == 0) 975 return Case ? CSFC_Success : CSFC_FallThrough; 976 977 // If this is the switchcase (case 4: or default) that we're looking for, then 978 // we're in business. Just add the substatement. 979 if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) { 980 if (S == Case) { 981 FoundCase = true; 982 return CollectStatementsForCase(SC->getSubStmt(), 0, FoundCase, 983 ResultStmts); 984 } 985 986 // Otherwise, this is some other case or default statement, just ignore it. 987 return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase, 988 ResultStmts); 989 } 990 991 // If we are in the live part of the code and we found our break statement, 992 // return a success! 993 if (Case == 0 && isa<BreakStmt>(S)) 994 return CSFC_Success; 995 996 // If this is a switch statement, then it might contain the SwitchCase, the 997 // break, or neither. 998 if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) { 999 // Handle this as two cases: we might be looking for the SwitchCase (if so 1000 // the skipped statements must be skippable) or we might already have it. 1001 CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end(); 1002 if (Case) { 1003 // Keep track of whether we see a skipped declaration. The code could be 1004 // using the declaration even if it is skipped, so we can't optimize out 1005 // the decl if the kept statements might refer to it. 1006 bool HadSkippedDecl = false; 1007 1008 // If we're looking for the case, just see if we can skip each of the 1009 // substatements. 1010 for (; Case && I != E; ++I) { 1011 HadSkippedDecl |= isa<DeclStmt>(*I); 1012 1013 switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) { 1014 case CSFC_Failure: return CSFC_Failure; 1015 case CSFC_Success: 1016 // A successful result means that either 1) that the statement doesn't 1017 // have the case and is skippable, or 2) does contain the case value 1018 // and also contains the break to exit the switch. In the later case, 1019 // we just verify the rest of the statements are elidable. 1020 if (FoundCase) { 1021 // If we found the case and skipped declarations, we can't do the 1022 // optimization. 1023 if (HadSkippedDecl) 1024 return CSFC_Failure; 1025 1026 for (++I; I != E; ++I) 1027 if (CodeGenFunction::ContainsLabel(*I, true)) 1028 return CSFC_Failure; 1029 return CSFC_Success; 1030 } 1031 break; 1032 case CSFC_FallThrough: 1033 // If we have a fallthrough condition, then we must have found the 1034 // case started to include statements. Consider the rest of the 1035 // statements in the compound statement as candidates for inclusion. 1036 assert(FoundCase && "Didn't find case but returned fallthrough?"); 1037 // We recursively found Case, so we're not looking for it anymore. 1038 Case = 0; 1039 1040 // If we found the case and skipped declarations, we can't do the 1041 // optimization. 1042 if (HadSkippedDecl) 1043 return CSFC_Failure; 1044 break; 1045 } 1046 } 1047 } 1048 1049 // If we have statements in our range, then we know that the statements are 1050 // live and need to be added to the set of statements we're tracking. 1051 for (; I != E; ++I) { 1052 switch (CollectStatementsForCase(*I, 0, FoundCase, ResultStmts)) { 1053 case CSFC_Failure: return CSFC_Failure; 1054 case CSFC_FallThrough: 1055 // A fallthrough result means that the statement was simple and just 1056 // included in ResultStmt, keep adding them afterwards. 1057 break; 1058 case CSFC_Success: 1059 // A successful result means that we found the break statement and 1060 // stopped statement inclusion. We just ensure that any leftover stmts 1061 // are skippable and return success ourselves. 1062 for (++I; I != E; ++I) 1063 if (CodeGenFunction::ContainsLabel(*I, true)) 1064 return CSFC_Failure; 1065 return CSFC_Success; 1066 } 1067 } 1068 1069 return Case ? CSFC_Success : CSFC_FallThrough; 1070 } 1071 1072 // Okay, this is some other statement that we don't handle explicitly, like a 1073 // for statement or increment etc. If we are skipping over this statement, 1074 // just verify it doesn't have labels, which would make it invalid to elide. 1075 if (Case) { 1076 if (CodeGenFunction::ContainsLabel(S, true)) 1077 return CSFC_Failure; 1078 return CSFC_Success; 1079 } 1080 1081 // Otherwise, we want to include this statement. Everything is cool with that 1082 // so long as it doesn't contain a break out of the switch we're in. 1083 if (CodeGenFunction::containsBreak(S)) return CSFC_Failure; 1084 1085 // Otherwise, everything is great. Include the statement and tell the caller 1086 // that we fall through and include the next statement as well. 1087 ResultStmts.push_back(S); 1088 return CSFC_FallThrough; 1089} 1090 1091/// FindCaseStatementsForValue - Find the case statement being jumped to and 1092/// then invoke CollectStatementsForCase to find the list of statements to emit 1093/// for a switch on constant. See the comment above CollectStatementsForCase 1094/// for more details. 1095static bool FindCaseStatementsForValue(const SwitchStmt &S, 1096 const llvm::APInt &ConstantCondValue, 1097 SmallVectorImpl<const Stmt*> &ResultStmts, 1098 ASTContext &C) { 1099 // First step, find the switch case that is being branched to. We can do this 1100 // efficiently by scanning the SwitchCase list. 1101 const SwitchCase *Case = S.getSwitchCaseList(); 1102 const DefaultStmt *DefaultCase = 0; 1103 1104 for (; Case; Case = Case->getNextSwitchCase()) { 1105 // It's either a default or case. Just remember the default statement in 1106 // case we're not jumping to any numbered cases. 1107 if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) { 1108 DefaultCase = DS; 1109 continue; 1110 } 1111 1112 // Check to see if this case is the one we're looking for. 1113 const CaseStmt *CS = cast<CaseStmt>(Case); 1114 // Don't handle case ranges yet. 1115 if (CS->getRHS()) return false; 1116 1117 // If we found our case, remember it as 'case'. 1118 if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue) 1119 break; 1120 } 1121 1122 // If we didn't find a matching case, we use a default if it exists, or we 1123 // elide the whole switch body! 1124 if (Case == 0) { 1125 // It is safe to elide the body of the switch if it doesn't contain labels 1126 // etc. If it is safe, return successfully with an empty ResultStmts list. 1127 if (DefaultCase == 0) 1128 return !CodeGenFunction::ContainsLabel(&S); 1129 Case = DefaultCase; 1130 } 1131 1132 // Ok, we know which case is being jumped to, try to collect all the 1133 // statements that follow it. This can fail for a variety of reasons. Also, 1134 // check to see that the recursive walk actually found our case statement. 1135 // Insane cases like this can fail to find it in the recursive walk since we 1136 // don't handle every stmt kind: 1137 // switch (4) { 1138 // while (1) { 1139 // case 4: ... 1140 bool FoundCase = false; 1141 return CollectStatementsForCase(S.getBody(), Case, FoundCase, 1142 ResultStmts) != CSFC_Failure && 1143 FoundCase; 1144} 1145 1146void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { 1147 JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog"); 1148 1149 RunCleanupsScope ConditionScope(*this); 1150 1151 if (S.getConditionVariable()) 1152 EmitAutoVarDecl(*S.getConditionVariable()); 1153 1154 // See if we can constant fold the condition of the switch and therefore only 1155 // emit the live case statement (if any) of the switch. 1156 llvm::APInt ConstantCondValue; 1157 if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) { 1158 SmallVector<const Stmt*, 4> CaseStmts; 1159 if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts, 1160 getContext())) { 1161 RunCleanupsScope ExecutedScope(*this); 1162 1163 // Okay, we can dead code eliminate everything except this case. Emit the 1164 // specified series of statements and we're good. 1165 for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i) 1166 EmitStmt(CaseStmts[i]); 1167 return; 1168 } 1169 } 1170 1171 llvm::Value *CondV = EmitScalarExpr(S.getCond()); 1172 1173 // Handle nested switch statements. 1174 llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; 1175 llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; 1176 1177 // Create basic block to hold stuff that comes after switch 1178 // statement. We also need to create a default block now so that 1179 // explicit case ranges tests can have a place to jump to on 1180 // failure. 1181 llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); 1182 SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); 1183 CaseRangeBlock = DefaultBlock; 1184 1185 // Clear the insertion point to indicate we are in unreachable code. 1186 Builder.ClearInsertionPoint(); 1187 1188 // All break statements jump to NextBlock. If BreakContinueStack is non empty 1189 // then reuse last ContinueBlock. 1190 JumpDest OuterContinue; 1191 if (!BreakContinueStack.empty()) 1192 OuterContinue = BreakContinueStack.back().ContinueBlock; 1193 1194 BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue)); 1195 1196 // Emit switch body. 1197 EmitStmt(S.getBody()); 1198 1199 BreakContinueStack.pop_back(); 1200 1201 // Update the default block in case explicit case range tests have 1202 // been chained on top. 1203 SwitchInsn->setSuccessor(0, CaseRangeBlock); 1204 1205 // If a default was never emitted: 1206 if (!DefaultBlock->getParent()) { 1207 // If we have cleanups, emit the default block so that there's a 1208 // place to jump through the cleanups from. 1209 if (ConditionScope.requiresCleanups()) { 1210 EmitBlock(DefaultBlock); 1211 1212 // Otherwise, just forward the default block to the switch end. 1213 } else { 1214 DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock()); 1215 delete DefaultBlock; 1216 } 1217 } 1218 1219 ConditionScope.ForceCleanup(); 1220 1221 // Emit continuation. 1222 EmitBlock(SwitchExit.getBlock(), true); 1223 1224 SwitchInsn = SavedSwitchInsn; 1225 CaseRangeBlock = SavedCRBlock; 1226} 1227 1228static std::string 1229SimplifyConstraint(const char *Constraint, const TargetInfo &Target, 1230 SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { 1231 std::string Result; 1232 1233 while (*Constraint) { 1234 switch (*Constraint) { 1235 default: 1236 Result += Target.convertConstraint(Constraint); 1237 break; 1238 // Ignore these 1239 case '*': 1240 case '?': 1241 case '!': 1242 case '=': // Will see this and the following in mult-alt constraints. 1243 case '+': 1244 break; 1245 case ',': 1246 Result += "|"; 1247 break; 1248 case 'g': 1249 Result += "imr"; 1250 break; 1251 case '[': { 1252 assert(OutCons && 1253 "Must pass output names to constraints with a symbolic name"); 1254 unsigned Index; 1255 bool result = Target.resolveSymbolicName(Constraint, 1256 &(*OutCons)[0], 1257 OutCons->size(), Index); 1258 assert(result && "Could not resolve symbolic name"); (void)result; 1259 Result += llvm::utostr(Index); 1260 break; 1261 } 1262 } 1263 1264 Constraint++; 1265 } 1266 1267 return Result; 1268} 1269 1270/// AddVariableConstraints - Look at AsmExpr and if it is a variable declared 1271/// as using a particular register add that as a constraint that will be used 1272/// in this asm stmt. 1273static std::string 1274AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr, 1275 const TargetInfo &Target, CodeGenModule &CGM, 1276 const AsmStmt &Stmt) { 1277 const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr); 1278 if (!AsmDeclRef) 1279 return Constraint; 1280 const ValueDecl &Value = *AsmDeclRef->getDecl(); 1281 const VarDecl *Variable = dyn_cast<VarDecl>(&Value); 1282 if (!Variable) 1283 return Constraint; 1284 AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>(); 1285 if (!Attr) 1286 return Constraint; 1287 StringRef Register = Attr->getLabel(); 1288 assert(Target.isValidGCCRegisterName(Register)); 1289 // We're using validateOutputConstraint here because we only care if 1290 // this is a register constraint. 1291 TargetInfo::ConstraintInfo Info(Constraint, ""); 1292 if (Target.validateOutputConstraint(Info) && 1293 !Info.allowsRegister()) { 1294 CGM.ErrorUnsupported(&Stmt, "__asm__"); 1295 return Constraint; 1296 } 1297 // Canonicalize the register here before returning it. 1298 Register = Target.getNormalizedGCCRegisterName(Register); 1299 return "{" + Register.str() + "}"; 1300} 1301 1302llvm::Value* 1303CodeGenFunction::EmitAsmInputLValue(const AsmStmt &S, 1304 const TargetInfo::ConstraintInfo &Info, 1305 LValue InputValue, QualType InputType, 1306 std::string &ConstraintStr) { 1307 llvm::Value *Arg; 1308 if (Info.allowsRegister() || !Info.allowsMemory()) { 1309 if (!CodeGenFunction::hasAggregateLLVMType(InputType)) { 1310 Arg = EmitLoadOfLValue(InputValue).getScalarVal(); 1311 } else { 1312 llvm::Type *Ty = ConvertType(InputType); 1313 uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); 1314 if (Size <= 64 && llvm::isPowerOf2_64(Size)) { 1315 Ty = llvm::IntegerType::get(getLLVMContext(), Size); 1316 Ty = llvm::PointerType::getUnqual(Ty); 1317 1318 Arg = Builder.CreateLoad(Builder.CreateBitCast(InputValue.getAddress(), 1319 Ty)); 1320 } else { 1321 Arg = InputValue.getAddress(); 1322 ConstraintStr += '*'; 1323 } 1324 } 1325 } else { 1326 Arg = InputValue.getAddress(); 1327 ConstraintStr += '*'; 1328 } 1329 1330 return Arg; 1331} 1332 1333llvm::Value* CodeGenFunction::EmitAsmInput(const AsmStmt &S, 1334 const TargetInfo::ConstraintInfo &Info, 1335 const Expr *InputExpr, 1336 std::string &ConstraintStr) { 1337 if (Info.allowsRegister() || !Info.allowsMemory()) 1338 if (!CodeGenFunction::hasAggregateLLVMType(InputExpr->getType())) 1339 return EmitScalarExpr(InputExpr); 1340 1341 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 1342 LValue Dest = EmitLValue(InputExpr); 1343 return EmitAsmInputLValue(S, Info, Dest, InputExpr->getType(), ConstraintStr); 1344} 1345 1346/// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline 1347/// asm call instruction. The !srcloc MDNode contains a list of constant 1348/// integers which are the source locations of the start of each line in the 1349/// asm. 1350static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str, 1351 CodeGenFunction &CGF) { 1352 SmallVector<llvm::Value *, 8> Locs; 1353 // Add the location of the first line to the MDNode. 1354 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1355 Str->getLocStart().getRawEncoding())); 1356 StringRef StrVal = Str->getString(); 1357 if (!StrVal.empty()) { 1358 const SourceManager &SM = CGF.CGM.getContext().getSourceManager(); 1359 const LangOptions &LangOpts = CGF.CGM.getLangOptions(); 1360 1361 // Add the location of the start of each subsequent line of the asm to the 1362 // MDNode. 1363 for (unsigned i = 0, e = StrVal.size()-1; i != e; ++i) { 1364 if (StrVal[i] != '\n') continue; 1365 SourceLocation LineLoc = Str->getLocationOfByte(i+1, SM, LangOpts, 1366 CGF.Target); 1367 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1368 LineLoc.getRawEncoding())); 1369 } 1370 } 1371 1372 return llvm::MDNode::get(CGF.getLLVMContext(), Locs); 1373} 1374 1375void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { 1376 // Analyze the asm string to decompose it into its pieces. We know that Sema 1377 // has already done this, so it is guaranteed to be successful. 1378 SmallVector<AsmStmt::AsmStringPiece, 4> Pieces; 1379 unsigned DiagOffs; 1380 S.AnalyzeAsmString(Pieces, getContext(), DiagOffs); 1381 1382 // Assemble the pieces into the final asm string. 1383 std::string AsmString; 1384 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { 1385 if (Pieces[i].isString()) 1386 AsmString += Pieces[i].getString(); 1387 else if (Pieces[i].getModifier() == '\0') 1388 AsmString += '$' + llvm::utostr(Pieces[i].getOperandNo()); 1389 else 1390 AsmString += "${" + llvm::utostr(Pieces[i].getOperandNo()) + ':' + 1391 Pieces[i].getModifier() + '}'; 1392 } 1393 1394 // Get all the output and input constraints together. 1395 SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 1396 SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 1397 1398 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1399 TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), 1400 S.getOutputName(i)); 1401 bool IsValid = Target.validateOutputConstraint(Info); (void)IsValid; 1402 assert(IsValid && "Failed to parse output constraint"); 1403 OutputConstraintInfos.push_back(Info); 1404 } 1405 1406 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1407 TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), 1408 S.getInputName(i)); 1409 bool IsValid = Target.validateInputConstraint(OutputConstraintInfos.data(), 1410 S.getNumOutputs(), Info); 1411 assert(IsValid && "Failed to parse input constraint"); (void)IsValid; 1412 InputConstraintInfos.push_back(Info); 1413 } 1414 1415 std::string Constraints; 1416 1417 std::vector<LValue> ResultRegDests; 1418 std::vector<QualType> ResultRegQualTys; 1419 std::vector<llvm::Type *> ResultRegTypes; 1420 std::vector<llvm::Type *> ResultTruncRegTypes; 1421 std::vector<llvm::Type*> ArgTypes; 1422 std::vector<llvm::Value*> Args; 1423 1424 // Keep track of inout constraints. 1425 std::string InOutConstraints; 1426 std::vector<llvm::Value*> InOutArgs; 1427 std::vector<llvm::Type*> InOutArgTypes; 1428 1429 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1430 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 1431 1432 // Simplify the output constraint. 1433 std::string OutputConstraint(S.getOutputConstraint(i)); 1434 OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); 1435 1436 const Expr *OutExpr = S.getOutputExpr(i); 1437 OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); 1438 1439 OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr, 1440 Target, CGM, S); 1441 1442 LValue Dest = EmitLValue(OutExpr); 1443 if (!Constraints.empty()) 1444 Constraints += ','; 1445 1446 // If this is a register output, then make the inline asm return it 1447 // by-value. If this is a memory result, return the value by-reference. 1448 if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { 1449 Constraints += "=" + OutputConstraint; 1450 ResultRegQualTys.push_back(OutExpr->getType()); 1451 ResultRegDests.push_back(Dest); 1452 ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); 1453 ResultTruncRegTypes.push_back(ResultRegTypes.back()); 1454 1455 // If this output is tied to an input, and if the input is larger, then 1456 // we need to set the actual result type of the inline asm node to be the 1457 // same as the input type. 1458 if (Info.hasMatchingInput()) { 1459 unsigned InputNo; 1460 for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { 1461 TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; 1462 if (Input.hasTiedOperand() && Input.getTiedOperand() == i) 1463 break; 1464 } 1465 assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); 1466 1467 QualType InputTy = S.getInputExpr(InputNo)->getType(); 1468 QualType OutputType = OutExpr->getType(); 1469 1470 uint64_t InputSize = getContext().getTypeSize(InputTy); 1471 if (getContext().getTypeSize(OutputType) < InputSize) { 1472 // Form the asm to return the value as a larger integer or fp type. 1473 ResultRegTypes.back() = ConvertType(InputTy); 1474 } 1475 } 1476 if (llvm::Type* AdjTy = 1477 getTargetHooks().adjustInlineAsmType(*this, OutputConstraint, 1478 ResultRegTypes.back())) 1479 ResultRegTypes.back() = AdjTy; 1480 } else { 1481 ArgTypes.push_back(Dest.getAddress()->getType()); 1482 Args.push_back(Dest.getAddress()); 1483 Constraints += "=*"; 1484 Constraints += OutputConstraint; 1485 } 1486 1487 if (Info.isReadWrite()) { 1488 InOutConstraints += ','; 1489 1490 const Expr *InputExpr = S.getOutputExpr(i); 1491 llvm::Value *Arg = EmitAsmInputLValue(S, Info, Dest, InputExpr->getType(), 1492 InOutConstraints); 1493 1494 if (Info.allowsRegister()) 1495 InOutConstraints += llvm::utostr(i); 1496 else 1497 InOutConstraints += OutputConstraint; 1498 1499 InOutArgTypes.push_back(Arg->getType()); 1500 InOutArgs.push_back(Arg); 1501 } 1502 } 1503 1504 unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); 1505 1506 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1507 const Expr *InputExpr = S.getInputExpr(i); 1508 1509 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 1510 1511 if (!Constraints.empty()) 1512 Constraints += ','; 1513 1514 // Simplify the input constraint. 1515 std::string InputConstraint(S.getInputConstraint(i)); 1516 InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, 1517 &OutputConstraintInfos); 1518 1519 InputConstraint = 1520 AddVariableConstraints(InputConstraint, 1521 *InputExpr->IgnoreParenNoopCasts(getContext()), 1522 Target, CGM, S); 1523 1524 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints); 1525 1526 // If this input argument is tied to a larger output result, extend the 1527 // input to be the same size as the output. The LLVM backend wants to see 1528 // the input and output of a matching constraint be the same size. Note 1529 // that GCC does not define what the top bits are here. We use zext because 1530 // that is usually cheaper, but LLVM IR should really get an anyext someday. 1531 if (Info.hasTiedOperand()) { 1532 unsigned Output = Info.getTiedOperand(); 1533 QualType OutputType = S.getOutputExpr(Output)->getType(); 1534 QualType InputTy = InputExpr->getType(); 1535 1536 if (getContext().getTypeSize(OutputType) > 1537 getContext().getTypeSize(InputTy)) { 1538 // Use ptrtoint as appropriate so that we can do our extension. 1539 if (isa<llvm::PointerType>(Arg->getType())) 1540 Arg = Builder.CreatePtrToInt(Arg, IntPtrTy); 1541 llvm::Type *OutputTy = ConvertType(OutputType); 1542 if (isa<llvm::IntegerType>(OutputTy)) 1543 Arg = Builder.CreateZExt(Arg, OutputTy); 1544 else if (isa<llvm::PointerType>(OutputTy)) 1545 Arg = Builder.CreateZExt(Arg, IntPtrTy); 1546 else { 1547 assert(OutputTy->isFloatingPointTy() && "Unexpected output type"); 1548 Arg = Builder.CreateFPExt(Arg, OutputTy); 1549 } 1550 } 1551 } 1552 if (llvm::Type* AdjTy = 1553 getTargetHooks().adjustInlineAsmType(*this, InputConstraint, 1554 Arg->getType())) 1555 Arg = Builder.CreateBitCast(Arg, AdjTy); 1556 1557 ArgTypes.push_back(Arg->getType()); 1558 Args.push_back(Arg); 1559 Constraints += InputConstraint; 1560 } 1561 1562 // Append the "input" part of inout constraints last. 1563 for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { 1564 ArgTypes.push_back(InOutArgTypes[i]); 1565 Args.push_back(InOutArgs[i]); 1566 } 1567 Constraints += InOutConstraints; 1568 1569 // Clobbers 1570 for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { 1571 StringRef Clobber = S.getClobber(i)->getString(); 1572 1573 if (Clobber != "memory" && Clobber != "cc") 1574 Clobber = Target.getNormalizedGCCRegisterName(Clobber); 1575 1576 if (i != 0 || NumConstraints != 0) 1577 Constraints += ','; 1578 1579 Constraints += "~{"; 1580 Constraints += Clobber; 1581 Constraints += '}'; 1582 } 1583 1584 // Add machine specific clobbers 1585 std::string MachineClobbers = Target.getClobbers(); 1586 if (!MachineClobbers.empty()) { 1587 if (!Constraints.empty()) 1588 Constraints += ','; 1589 Constraints += MachineClobbers; 1590 } 1591 1592 llvm::Type *ResultType; 1593 if (ResultRegTypes.empty()) 1594 ResultType = llvm::Type::getVoidTy(getLLVMContext()); 1595 else if (ResultRegTypes.size() == 1) 1596 ResultType = ResultRegTypes[0]; 1597 else 1598 ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes); 1599 1600 llvm::FunctionType *FTy = 1601 llvm::FunctionType::get(ResultType, ArgTypes, false); 1602 1603 llvm::InlineAsm *IA = 1604 llvm::InlineAsm::get(FTy, AsmString, Constraints, 1605 S.isVolatile() || S.getNumOutputs() == 0); 1606 llvm::CallInst *Result = Builder.CreateCall(IA, Args); 1607 Result->addAttribute(~0, llvm::Attribute::NoUnwind); 1608 1609 // Slap the source location of the inline asm into a !srcloc metadata on the 1610 // call. 1611 Result->setMetadata("srcloc", getAsmSrcLocInfo(S.getAsmString(), *this)); 1612 1613 // Extract all of the register value results from the asm. 1614 std::vector<llvm::Value*> RegResults; 1615 if (ResultRegTypes.size() == 1) { 1616 RegResults.push_back(Result); 1617 } else { 1618 for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { 1619 llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); 1620 RegResults.push_back(Tmp); 1621 } 1622 } 1623 1624 for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { 1625 llvm::Value *Tmp = RegResults[i]; 1626 1627 // If the result type of the LLVM IR asm doesn't match the result type of 1628 // the expression, do the conversion. 1629 if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { 1630 llvm::Type *TruncTy = ResultTruncRegTypes[i]; 1631 1632 // Truncate the integer result to the right size, note that TruncTy can be 1633 // a pointer. 1634 if (TruncTy->isFloatingPointTy()) 1635 Tmp = Builder.CreateFPTrunc(Tmp, TruncTy); 1636 else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) { 1637 uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); 1638 Tmp = Builder.CreateTrunc(Tmp, 1639 llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize)); 1640 Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); 1641 } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) { 1642 uint64_t TmpSize =CGM.getTargetData().getTypeSizeInBits(Tmp->getType()); 1643 Tmp = Builder.CreatePtrToInt(Tmp, 1644 llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize)); 1645 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1646 } else if (TruncTy->isIntegerTy()) { 1647 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1648 } else if (TruncTy->isVectorTy()) { 1649 Tmp = Builder.CreateBitCast(Tmp, TruncTy); 1650 } 1651 } 1652 1653 EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i]); 1654 } 1655} 1656