CGStmt.cpp revision c07833795aa6e569de5bb90945f5017b9969288d
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 // Keep track of the current cleanup stack depth, including debug scopes. 195 LexicalScope Scope(*this, S.getSourceRange()); 196 197 for (CompoundStmt::const_body_iterator I = S.body_begin(), 198 E = S.body_end()-GetLast; I != E; ++I) 199 EmitStmt(*I); 200 201 RValue RV; 202 if (!GetLast) 203 RV = RValue::get(0); 204 else { 205 // We have to special case labels here. They are statements, but when put 206 // at the end of a statement expression, they yield the value of their 207 // subexpression. Handle this by walking through all labels we encounter, 208 // emitting them before we evaluate the subexpr. 209 const Stmt *LastStmt = S.body_back(); 210 while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { 211 EmitLabel(LS->getDecl()); 212 LastStmt = LS->getSubStmt(); 213 } 214 215 EnsureInsertPoint(); 216 217 RV = EmitAnyExpr(cast<Expr>(LastStmt), AggSlot); 218 } 219 220 return RV; 221} 222 223void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { 224 llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); 225 226 // If there is a cleanup stack, then we it isn't worth trying to 227 // simplify this block (we would need to remove it from the scope map 228 // and cleanup entry). 229 if (!EHStack.empty()) 230 return; 231 232 // Can only simplify direct branches. 233 if (!BI || !BI->isUnconditional()) 234 return; 235 236 BB->replaceAllUsesWith(BI->getSuccessor(0)); 237 BI->eraseFromParent(); 238 BB->eraseFromParent(); 239} 240 241void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { 242 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 243 244 // Fall out of the current block (if necessary). 245 EmitBranch(BB); 246 247 if (IsFinished && BB->use_empty()) { 248 delete BB; 249 return; 250 } 251 252 // Place the block after the current block, if possible, or else at 253 // the end of the function. 254 if (CurBB && CurBB->getParent()) 255 CurFn->getBasicBlockList().insertAfter(CurBB, BB); 256 else 257 CurFn->getBasicBlockList().push_back(BB); 258 Builder.SetInsertPoint(BB); 259} 260 261void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { 262 // Emit a branch from the current block to the target one if this 263 // was a real block. If this was just a fall-through block after a 264 // terminator, don't emit it. 265 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 266 267 if (!CurBB || CurBB->getTerminator()) { 268 // If there is no insert point or the previous block is already 269 // terminated, don't touch it. 270 } else { 271 // Otherwise, create a fall-through branch. 272 Builder.CreateBr(Target); 273 } 274 275 Builder.ClearInsertionPoint(); 276} 277 278void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) { 279 bool inserted = false; 280 for (llvm::BasicBlock::use_iterator 281 i = block->use_begin(), e = block->use_end(); i != e; ++i) { 282 if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(*i)) { 283 CurFn->getBasicBlockList().insertAfter(insn->getParent(), block); 284 inserted = true; 285 break; 286 } 287 } 288 289 if (!inserted) 290 CurFn->getBasicBlockList().push_back(block); 291 292 Builder.SetInsertPoint(block); 293} 294 295CodeGenFunction::JumpDest 296CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) { 297 JumpDest &Dest = LabelMap[D]; 298 if (Dest.isValid()) return Dest; 299 300 // Create, but don't insert, the new block. 301 Dest = JumpDest(createBasicBlock(D->getName()), 302 EHScopeStack::stable_iterator::invalid(), 303 NextCleanupDestIndex++); 304 return Dest; 305} 306 307void CodeGenFunction::EmitLabel(const LabelDecl *D) { 308 JumpDest &Dest = LabelMap[D]; 309 310 // If we didn't need a forward reference to this label, just go 311 // ahead and create a destination at the current scope. 312 if (!Dest.isValid()) { 313 Dest = getJumpDestInCurrentScope(D->getName()); 314 315 // Otherwise, we need to give this label a target depth and remove 316 // it from the branch-fixups list. 317 } else { 318 assert(!Dest.getScopeDepth().isValid() && "already emitted label!"); 319 Dest = JumpDest(Dest.getBlock(), 320 EHStack.stable_begin(), 321 Dest.getDestIndex()); 322 323 ResolveBranchFixups(Dest.getBlock()); 324 } 325 326 EmitBlock(Dest.getBlock()); 327} 328 329 330void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { 331 EmitLabel(S.getDecl()); 332 EmitStmt(S.getSubStmt()); 333} 334 335void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { 336 // If this code is reachable then emit a stop point (if generating 337 // debug info). We have to do this ourselves because we are on the 338 // "simple" statement path. 339 if (HaveInsertPoint()) 340 EmitStopPoint(&S); 341 342 EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel())); 343} 344 345 346void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { 347 if (const LabelDecl *Target = S.getConstantTarget()) { 348 EmitBranchThroughCleanup(getJumpDestForLabel(Target)); 349 return; 350 } 351 352 // Ensure that we have an i8* for our PHI node. 353 llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()), 354 Int8PtrTy, "addr"); 355 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 356 357 358 // Get the basic block for the indirect goto. 359 llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock(); 360 361 // The first instruction in the block has to be the PHI for the switch dest, 362 // add an entry for this branch. 363 cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB); 364 365 EmitBranch(IndGotoBB); 366} 367 368void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 369 // C99 6.8.4.1: The first substatement is executed if the expression compares 370 // unequal to 0. The condition must be a scalar type. 371 RunCleanupsScope ConditionScope(*this); 372 373 if (S.getConditionVariable()) 374 EmitAutoVarDecl(*S.getConditionVariable()); 375 376 // If the condition constant folds and can be elided, try to avoid emitting 377 // the condition and the dead arm of the if/else. 378 bool CondConstant; 379 if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant)) { 380 // Figure out which block (then or else) is executed. 381 const Stmt *Executed = S.getThen(); 382 const Stmt *Skipped = S.getElse(); 383 if (!CondConstant) // Condition false? 384 std::swap(Executed, Skipped); 385 386 // If the skipped block has no labels in it, just emit the executed block. 387 // This avoids emitting dead code and simplifies the CFG substantially. 388 if (!ContainsLabel(Skipped)) { 389 if (Executed) { 390 RunCleanupsScope ExecutedScope(*this); 391 EmitStmt(Executed); 392 } 393 return; 394 } 395 } 396 397 // Otherwise, the condition did not fold, or we couldn't elide it. Just emit 398 // the conditional branch. 399 llvm::BasicBlock *ThenBlock = createBasicBlock("if.then"); 400 llvm::BasicBlock *ContBlock = createBasicBlock("if.end"); 401 llvm::BasicBlock *ElseBlock = ContBlock; 402 if (S.getElse()) 403 ElseBlock = createBasicBlock("if.else"); 404 EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock); 405 406 // Emit the 'then' code. 407 EmitBlock(ThenBlock); 408 { 409 RunCleanupsScope ThenScope(*this); 410 EmitStmt(S.getThen()); 411 } 412 EmitBranch(ContBlock); 413 414 // Emit the 'else' code if present. 415 if (const Stmt *Else = S.getElse()) { 416 // There is no need to emit line number for unconditional branch. 417 if (getDebugInfo()) 418 Builder.SetCurrentDebugLocation(llvm::DebugLoc()); 419 EmitBlock(ElseBlock); 420 { 421 RunCleanupsScope ElseScope(*this); 422 EmitStmt(Else); 423 } 424 // There is no need to emit line number for unconditional branch. 425 if (getDebugInfo()) 426 Builder.SetCurrentDebugLocation(llvm::DebugLoc()); 427 EmitBranch(ContBlock); 428 } 429 430 // Emit the continuation block for code after the if. 431 EmitBlock(ContBlock, true); 432} 433 434void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) { 435 // Emit the header for the loop, which will also become 436 // the continue target. 437 JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond"); 438 EmitBlock(LoopHeader.getBlock()); 439 440 // Create an exit block for when the condition fails, which will 441 // also become the break target. 442 JumpDest LoopExit = getJumpDestInCurrentScope("while.end"); 443 444 // Store the blocks to use for break and continue. 445 BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader)); 446 447 // C++ [stmt.while]p2: 448 // When the condition of a while statement is a declaration, the 449 // scope of the variable that is declared extends from its point 450 // of declaration (3.3.2) to the end of the while statement. 451 // [...] 452 // The object created in a condition is destroyed and created 453 // with each iteration of the loop. 454 RunCleanupsScope ConditionScope(*this); 455 456 if (S.getConditionVariable()) 457 EmitAutoVarDecl(*S.getConditionVariable()); 458 459 // Evaluate the conditional in the while header. C99 6.8.5.1: The 460 // evaluation of the controlling expression takes place before each 461 // execution of the loop body. 462 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 463 464 // while(1) is common, avoid extra exit blocks. Be sure 465 // to correctly handle break/continue though. 466 bool EmitBoolCondBranch = true; 467 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 468 if (C->isOne()) 469 EmitBoolCondBranch = false; 470 471 // As long as the condition is true, go to the loop body. 472 llvm::BasicBlock *LoopBody = createBasicBlock("while.body"); 473 if (EmitBoolCondBranch) { 474 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 475 if (ConditionScope.requiresCleanups()) 476 ExitBlock = createBasicBlock("while.exit"); 477 478 Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock); 479 480 if (ExitBlock != LoopExit.getBlock()) { 481 EmitBlock(ExitBlock); 482 EmitBranchThroughCleanup(LoopExit); 483 } 484 } 485 486 // Emit the loop body. We have to emit this in a cleanup scope 487 // because it might be a singleton DeclStmt. 488 { 489 RunCleanupsScope BodyScope(*this); 490 EmitBlock(LoopBody); 491 EmitStmt(S.getBody()); 492 } 493 494 BreakContinueStack.pop_back(); 495 496 // Immediately force cleanup. 497 ConditionScope.ForceCleanup(); 498 499 // Branch to the loop header again. 500 EmitBranch(LoopHeader.getBlock()); 501 502 // Emit the exit block. 503 EmitBlock(LoopExit.getBlock(), true); 504 505 // The LoopHeader typically is just a branch if we skipped emitting 506 // a branch, try to erase it. 507 if (!EmitBoolCondBranch) 508 SimplifyForwardingBlocks(LoopHeader.getBlock()); 509} 510 511void CodeGenFunction::EmitDoStmt(const DoStmt &S) { 512 JumpDest LoopExit = getJumpDestInCurrentScope("do.end"); 513 JumpDest LoopCond = getJumpDestInCurrentScope("do.cond"); 514 515 // Store the blocks to use for break and continue. 516 BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond)); 517 518 // Emit the body of the loop. 519 llvm::BasicBlock *LoopBody = createBasicBlock("do.body"); 520 EmitBlock(LoopBody); 521 { 522 RunCleanupsScope BodyScope(*this); 523 EmitStmt(S.getBody()); 524 } 525 526 BreakContinueStack.pop_back(); 527 528 EmitBlock(LoopCond.getBlock()); 529 530 // C99 6.8.5.2: "The evaluation of the controlling expression takes place 531 // after each execution of the loop body." 532 533 // Evaluate the conditional in the while header. 534 // C99 6.8.5p2/p4: The first substatement is executed if the expression 535 // compares unequal to 0. The condition must be a scalar type. 536 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 537 538 // "do {} while (0)" is common in macros, avoid extra blocks. Be sure 539 // to correctly handle break/continue though. 540 bool EmitBoolCondBranch = true; 541 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 542 if (C->isZero()) 543 EmitBoolCondBranch = false; 544 545 // As long as the condition is true, iterate the loop. 546 if (EmitBoolCondBranch) 547 Builder.CreateCondBr(BoolCondVal, LoopBody, LoopExit.getBlock()); 548 549 // Emit the exit block. 550 EmitBlock(LoopExit.getBlock()); 551 552 // The DoCond block typically is just a branch if we skipped 553 // emitting a branch, try to erase it. 554 if (!EmitBoolCondBranch) 555 SimplifyForwardingBlocks(LoopCond.getBlock()); 556} 557 558void CodeGenFunction::EmitForStmt(const ForStmt &S) { 559 JumpDest LoopExit = getJumpDestInCurrentScope("for.end"); 560 561 RunCleanupsScope ForScope(*this); 562 563 CGDebugInfo *DI = getDebugInfo(); 564 if (DI) 565 DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin()); 566 567 // Evaluate the first part before the loop. 568 if (S.getInit()) 569 EmitStmt(S.getInit()); 570 571 // Start the loop with a block that tests the condition. 572 // If there's an increment, the continue scope will be overwritten 573 // later. 574 JumpDest Continue = getJumpDestInCurrentScope("for.cond"); 575 llvm::BasicBlock *CondBlock = Continue.getBlock(); 576 EmitBlock(CondBlock); 577 578 // Create a cleanup scope for the condition variable cleanups. 579 RunCleanupsScope ConditionScope(*this); 580 581 llvm::Value *BoolCondVal = 0; 582 if (S.getCond()) { 583 // If the for statement has a condition scope, emit the local variable 584 // declaration. 585 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 586 if (S.getConditionVariable()) { 587 EmitAutoVarDecl(*S.getConditionVariable()); 588 } 589 590 // If there are any cleanups between here and the loop-exit scope, 591 // create a block to stage a loop exit along. 592 if (ForScope.requiresCleanups()) 593 ExitBlock = createBasicBlock("for.cond.cleanup"); 594 595 // As long as the condition is true, iterate the loop. 596 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 597 598 // C99 6.8.5p2/p4: The first substatement is executed if the expression 599 // compares unequal to 0. The condition must be a scalar type. 600 BoolCondVal = EvaluateExprAsBool(S.getCond()); 601 Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock); 602 603 if (ExitBlock != LoopExit.getBlock()) { 604 EmitBlock(ExitBlock); 605 EmitBranchThroughCleanup(LoopExit); 606 } 607 608 EmitBlock(ForBody); 609 } else { 610 // Treat it as a non-zero constant. Don't even create a new block for the 611 // body, just fall into it. 612 } 613 614 // If the for loop doesn't have an increment we can just use the 615 // condition as the continue block. Otherwise we'll need to create 616 // a block for it (in the current scope, i.e. in the scope of the 617 // condition), and that we will become our continue block. 618 if (S.getInc()) 619 Continue = getJumpDestInCurrentScope("for.inc"); 620 621 // Store the blocks to use for break and continue. 622 BreakContinueStack.push_back(BreakContinue(LoopExit, Continue)); 623 624 { 625 // Create a separate cleanup scope for the body, in case it is not 626 // a compound statement. 627 RunCleanupsScope BodyScope(*this); 628 EmitStmt(S.getBody()); 629 } 630 631 // If there is an increment, emit it next. 632 if (S.getInc()) { 633 EmitBlock(Continue.getBlock()); 634 EmitStmt(S.getInc()); 635 } 636 637 BreakContinueStack.pop_back(); 638 639 ConditionScope.ForceCleanup(); 640 EmitBranch(CondBlock); 641 642 ForScope.ForceCleanup(); 643 644 if (DI) 645 DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd()); 646 647 // Emit the fall-through block. 648 EmitBlock(LoopExit.getBlock(), true); 649} 650 651void CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S) { 652 JumpDest LoopExit = getJumpDestInCurrentScope("for.end"); 653 654 RunCleanupsScope ForScope(*this); 655 656 CGDebugInfo *DI = getDebugInfo(); 657 if (DI) 658 DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin()); 659 660 // Evaluate the first pieces before the loop. 661 EmitStmt(S.getRangeStmt()); 662 EmitStmt(S.getBeginEndStmt()); 663 664 // Start the loop with a block that tests the condition. 665 // If there's an increment, the continue scope will be overwritten 666 // later. 667 llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); 668 EmitBlock(CondBlock); 669 670 // If there are any cleanups between here and the loop-exit scope, 671 // create a block to stage a loop exit along. 672 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 673 if (ForScope.requiresCleanups()) 674 ExitBlock = createBasicBlock("for.cond.cleanup"); 675 676 // The loop body, consisting of the specified body and the loop variable. 677 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 678 679 // The body is executed if the expression, contextually converted 680 // to bool, is true. 681 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 682 Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock); 683 684 if (ExitBlock != LoopExit.getBlock()) { 685 EmitBlock(ExitBlock); 686 EmitBranchThroughCleanup(LoopExit); 687 } 688 689 EmitBlock(ForBody); 690 691 // Create a block for the increment. In case of a 'continue', we jump there. 692 JumpDest Continue = getJumpDestInCurrentScope("for.inc"); 693 694 // Store the blocks to use for break and continue. 695 BreakContinueStack.push_back(BreakContinue(LoopExit, Continue)); 696 697 { 698 // Create a separate cleanup scope for the loop variable and body. 699 RunCleanupsScope BodyScope(*this); 700 EmitStmt(S.getLoopVarStmt()); 701 EmitStmt(S.getBody()); 702 } 703 704 // If there is an increment, emit it next. 705 EmitBlock(Continue.getBlock()); 706 EmitStmt(S.getInc()); 707 708 BreakContinueStack.pop_back(); 709 710 EmitBranch(CondBlock); 711 712 ForScope.ForceCleanup(); 713 714 if (DI) 715 DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd()); 716 717 // Emit the fall-through block. 718 EmitBlock(LoopExit.getBlock(), true); 719} 720 721void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { 722 if (RV.isScalar()) { 723 Builder.CreateStore(RV.getScalarVal(), ReturnValue); 724 } else if (RV.isAggregate()) { 725 EmitAggregateCopy(ReturnValue, RV.getAggregateAddr(), Ty); 726 } else { 727 StoreComplexToAddr(RV.getComplexVal(), ReturnValue, false); 728 } 729 EmitBranchThroughCleanup(ReturnBlock); 730} 731 732/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand 733/// if the function returns void, or may be missing one if the function returns 734/// non-void. Fun stuff :). 735void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { 736 // Emit the result value, even if unused, to evalute the side effects. 737 const Expr *RV = S.getRetValue(); 738 739 // FIXME: Clean this up by using an LValue for ReturnTemp, 740 // EmitStoreThroughLValue, and EmitAnyExpr. 741 if (S.getNRVOCandidate() && S.getNRVOCandidate()->isNRVOVariable() && 742 !Target.useGlobalsForAutomaticVariables()) { 743 // Apply the named return value optimization for this return statement, 744 // which means doing nothing: the appropriate result has already been 745 // constructed into the NRVO variable. 746 747 // If there is an NRVO flag for this variable, set it to 1 into indicate 748 // that the cleanup code should not destroy the variable. 749 if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()]) 750 Builder.CreateStore(Builder.getTrue(), NRVOFlag); 751 } else if (!ReturnValue) { 752 // Make sure not to return anything, but evaluate the expression 753 // for side effects. 754 if (RV) 755 EmitAnyExpr(RV); 756 } else if (RV == 0) { 757 // Do nothing (return value is left uninitialized) 758 } else if (FnRetTy->isReferenceType()) { 759 // If this function returns a reference, take the address of the expression 760 // rather than the value. 761 RValue Result = EmitReferenceBindingToExpr(RV, /*InitializedDecl=*/0); 762 Builder.CreateStore(Result.getScalarVal(), ReturnValue); 763 } else if (!hasAggregateLLVMType(RV->getType())) { 764 Builder.CreateStore(EmitScalarExpr(RV), ReturnValue); 765 } else if (RV->getType()->isAnyComplexType()) { 766 EmitComplexExprIntoAddr(RV, ReturnValue, false); 767 } else { 768 CharUnits Alignment = getContext().getTypeAlignInChars(RV->getType()); 769 EmitAggExpr(RV, AggValueSlot::forAddr(ReturnValue, Alignment, Qualifiers(), 770 AggValueSlot::IsDestructed, 771 AggValueSlot::DoesNotNeedGCBarriers, 772 AggValueSlot::IsNotAliased)); 773 } 774 775 EmitBranchThroughCleanup(ReturnBlock); 776} 777 778void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { 779 // As long as debug info is modeled with instructions, we have to ensure we 780 // have a place to insert here and write the stop point here. 781 if (HaveInsertPoint()) 782 EmitStopPoint(&S); 783 784 for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); 785 I != E; ++I) 786 EmitDecl(**I); 787} 788 789void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { 790 assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); 791 792 // If this code is reachable then emit a stop point (if generating 793 // debug info). We have to do this ourselves because we are on the 794 // "simple" statement path. 795 if (HaveInsertPoint()) 796 EmitStopPoint(&S); 797 798 JumpDest Block = BreakContinueStack.back().BreakBlock; 799 EmitBranchThroughCleanup(Block); 800} 801 802void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { 803 assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); 804 805 // If this code is reachable then emit a stop point (if generating 806 // debug info). We have to do this ourselves because we are on the 807 // "simple" statement path. 808 if (HaveInsertPoint()) 809 EmitStopPoint(&S); 810 811 JumpDest Block = BreakContinueStack.back().ContinueBlock; 812 EmitBranchThroughCleanup(Block); 813} 814 815/// EmitCaseStmtRange - If case statement range is not too big then 816/// add multiple cases to switch instruction, one for each value within 817/// the range. If range is too big then emit "if" condition check. 818void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { 819 assert(S.getRHS() && "Expected RHS value in CaseStmt"); 820 821 llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext()); 822 llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext()); 823 824 // Emit the code for this case. We do this first to make sure it is 825 // properly chained from our predecessor before generating the 826 // switch machinery to enter this block. 827 EmitBlock(createBasicBlock("sw.bb")); 828 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 829 EmitStmt(S.getSubStmt()); 830 831 // If range is empty, do nothing. 832 if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) 833 return; 834 835 llvm::APInt Range = RHS - LHS; 836 // FIXME: parameters such as this should not be hardcoded. 837 if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { 838 // Range is small enough to add multiple switch instruction cases. 839 for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { 840 SwitchInsn->addCase(Builder.getInt(LHS), CaseDest); 841 LHS++; 842 } 843 return; 844 } 845 846 // The range is too big. Emit "if" condition into a new block, 847 // making sure to save and restore the current insertion point. 848 llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); 849 850 // Push this test onto the chain of range checks (which terminates 851 // in the default basic block). The switch's default will be changed 852 // to the top of this chain after switch emission is complete. 853 llvm::BasicBlock *FalseDest = CaseRangeBlock; 854 CaseRangeBlock = createBasicBlock("sw.caserange"); 855 856 CurFn->getBasicBlockList().push_back(CaseRangeBlock); 857 Builder.SetInsertPoint(CaseRangeBlock); 858 859 // Emit range check. 860 llvm::Value *Diff = 861 Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS)); 862 llvm::Value *Cond = 863 Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds"); 864 Builder.CreateCondBr(Cond, CaseDest, FalseDest); 865 866 // Restore the appropriate insertion point. 867 if (RestoreBB) 868 Builder.SetInsertPoint(RestoreBB); 869 else 870 Builder.ClearInsertionPoint(); 871} 872 873void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { 874 // If there is no enclosing switch instance that we're aware of, then this 875 // case statement and its block can be elided. This situation only happens 876 // when we've constant-folded the switch, are emitting the constant case, 877 // and part of the constant case includes another case statement. For 878 // instance: switch (4) { case 4: do { case 5: } while (1); } 879 if (!SwitchInsn) { 880 EmitStmt(S.getSubStmt()); 881 return; 882 } 883 884 // Handle case ranges. 885 if (S.getRHS()) { 886 EmitCaseStmtRange(S); 887 return; 888 } 889 890 llvm::ConstantInt *CaseVal = 891 Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext())); 892 893 // If the body of the case is just a 'break', and if there was no fallthrough, 894 // try to not emit an empty block. 895 if ((CGM.getCodeGenOpts().OptimizationLevel > 0) && isa<BreakStmt>(S.getSubStmt())) { 896 JumpDest Block = BreakContinueStack.back().BreakBlock; 897 898 // Only do this optimization if there are no cleanups that need emitting. 899 if (isObviouslyBranchWithoutCleanups(Block)) { 900 SwitchInsn->addCase(CaseVal, Block.getBlock()); 901 902 // If there was a fallthrough into this case, make sure to redirect it to 903 // the end of the switch as well. 904 if (Builder.GetInsertBlock()) { 905 Builder.CreateBr(Block.getBlock()); 906 Builder.ClearInsertionPoint(); 907 } 908 return; 909 } 910 } 911 912 EmitBlock(createBasicBlock("sw.bb")); 913 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 914 SwitchInsn->addCase(CaseVal, CaseDest); 915 916 // Recursively emitting the statement is acceptable, but is not wonderful for 917 // code where we have many case statements nested together, i.e.: 918 // case 1: 919 // case 2: 920 // case 3: etc. 921 // Handling this recursively will create a new block for each case statement 922 // that falls through to the next case which is IR intensive. It also causes 923 // deep recursion which can run into stack depth limitations. Handle 924 // sequential non-range case statements specially. 925 const CaseStmt *CurCase = &S; 926 const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); 927 928 // Otherwise, iteratively add consecutive cases to this switch stmt. 929 while (NextCase && NextCase->getRHS() == 0) { 930 CurCase = NextCase; 931 llvm::ConstantInt *CaseVal = 932 Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext())); 933 SwitchInsn->addCase(CaseVal, CaseDest); 934 NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); 935 } 936 937 // Normal default recursion for non-cases. 938 EmitStmt(CurCase->getSubStmt()); 939} 940 941void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { 942 llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); 943 assert(DefaultBlock->empty() && 944 "EmitDefaultStmt: Default block already defined?"); 945 EmitBlock(DefaultBlock); 946 EmitStmt(S.getSubStmt()); 947} 948 949/// CollectStatementsForCase - Given the body of a 'switch' statement and a 950/// constant value that is being switched on, see if we can dead code eliminate 951/// the body of the switch to a simple series of statements to emit. Basically, 952/// on a switch (5) we want to find these statements: 953/// case 5: 954/// printf(...); <-- 955/// ++i; <-- 956/// break; 957/// 958/// and add them to the ResultStmts vector. If it is unsafe to do this 959/// transformation (for example, one of the elided statements contains a label 960/// that might be jumped to), return CSFC_Failure. If we handled it and 'S' 961/// should include statements after it (e.g. the printf() line is a substmt of 962/// the case) then return CSFC_FallThrough. If we handled it and found a break 963/// statement, then return CSFC_Success. 964/// 965/// If Case is non-null, then we are looking for the specified case, checking 966/// that nothing we jump over contains labels. If Case is null, then we found 967/// the case and are looking for the break. 968/// 969/// If the recursive walk actually finds our Case, then we set FoundCase to 970/// true. 971/// 972enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success }; 973static CSFC_Result CollectStatementsForCase(const Stmt *S, 974 const SwitchCase *Case, 975 bool &FoundCase, 976 SmallVectorImpl<const Stmt*> &ResultStmts) { 977 // If this is a null statement, just succeed. 978 if (S == 0) 979 return Case ? CSFC_Success : CSFC_FallThrough; 980 981 // If this is the switchcase (case 4: or default) that we're looking for, then 982 // we're in business. Just add the substatement. 983 if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) { 984 if (S == Case) { 985 FoundCase = true; 986 return CollectStatementsForCase(SC->getSubStmt(), 0, FoundCase, 987 ResultStmts); 988 } 989 990 // Otherwise, this is some other case or default statement, just ignore it. 991 return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase, 992 ResultStmts); 993 } 994 995 // If we are in the live part of the code and we found our break statement, 996 // return a success! 997 if (Case == 0 && isa<BreakStmt>(S)) 998 return CSFC_Success; 999 1000 // If this is a switch statement, then it might contain the SwitchCase, the 1001 // break, or neither. 1002 if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) { 1003 // Handle this as two cases: we might be looking for the SwitchCase (if so 1004 // the skipped statements must be skippable) or we might already have it. 1005 CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end(); 1006 if (Case) { 1007 // Keep track of whether we see a skipped declaration. The code could be 1008 // using the declaration even if it is skipped, so we can't optimize out 1009 // the decl if the kept statements might refer to it. 1010 bool HadSkippedDecl = false; 1011 1012 // If we're looking for the case, just see if we can skip each of the 1013 // substatements. 1014 for (; Case && I != E; ++I) { 1015 HadSkippedDecl |= isa<DeclStmt>(*I); 1016 1017 switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) { 1018 case CSFC_Failure: return CSFC_Failure; 1019 case CSFC_Success: 1020 // A successful result means that either 1) that the statement doesn't 1021 // have the case and is skippable, or 2) does contain the case value 1022 // and also contains the break to exit the switch. In the later case, 1023 // we just verify the rest of the statements are elidable. 1024 if (FoundCase) { 1025 // If we found the case and skipped declarations, we can't do the 1026 // optimization. 1027 if (HadSkippedDecl) 1028 return CSFC_Failure; 1029 1030 for (++I; I != E; ++I) 1031 if (CodeGenFunction::ContainsLabel(*I, true)) 1032 return CSFC_Failure; 1033 return CSFC_Success; 1034 } 1035 break; 1036 case CSFC_FallThrough: 1037 // If we have a fallthrough condition, then we must have found the 1038 // case started to include statements. Consider the rest of the 1039 // statements in the compound statement as candidates for inclusion. 1040 assert(FoundCase && "Didn't find case but returned fallthrough?"); 1041 // We recursively found Case, so we're not looking for it anymore. 1042 Case = 0; 1043 1044 // If we found the case and skipped declarations, we can't do the 1045 // optimization. 1046 if (HadSkippedDecl) 1047 return CSFC_Failure; 1048 break; 1049 } 1050 } 1051 } 1052 1053 // If we have statements in our range, then we know that the statements are 1054 // live and need to be added to the set of statements we're tracking. 1055 for (; I != E; ++I) { 1056 switch (CollectStatementsForCase(*I, 0, FoundCase, ResultStmts)) { 1057 case CSFC_Failure: return CSFC_Failure; 1058 case CSFC_FallThrough: 1059 // A fallthrough result means that the statement was simple and just 1060 // included in ResultStmt, keep adding them afterwards. 1061 break; 1062 case CSFC_Success: 1063 // A successful result means that we found the break statement and 1064 // stopped statement inclusion. We just ensure that any leftover stmts 1065 // are skippable and return success ourselves. 1066 for (++I; I != E; ++I) 1067 if (CodeGenFunction::ContainsLabel(*I, true)) 1068 return CSFC_Failure; 1069 return CSFC_Success; 1070 } 1071 } 1072 1073 return Case ? CSFC_Success : CSFC_FallThrough; 1074 } 1075 1076 // Okay, this is some other statement that we don't handle explicitly, like a 1077 // for statement or increment etc. If we are skipping over this statement, 1078 // just verify it doesn't have labels, which would make it invalid to elide. 1079 if (Case) { 1080 if (CodeGenFunction::ContainsLabel(S, true)) 1081 return CSFC_Failure; 1082 return CSFC_Success; 1083 } 1084 1085 // Otherwise, we want to include this statement. Everything is cool with that 1086 // so long as it doesn't contain a break out of the switch we're in. 1087 if (CodeGenFunction::containsBreak(S)) return CSFC_Failure; 1088 1089 // Otherwise, everything is great. Include the statement and tell the caller 1090 // that we fall through and include the next statement as well. 1091 ResultStmts.push_back(S); 1092 return CSFC_FallThrough; 1093} 1094 1095/// FindCaseStatementsForValue - Find the case statement being jumped to and 1096/// then invoke CollectStatementsForCase to find the list of statements to emit 1097/// for a switch on constant. See the comment above CollectStatementsForCase 1098/// for more details. 1099static bool FindCaseStatementsForValue(const SwitchStmt &S, 1100 const llvm::APInt &ConstantCondValue, 1101 SmallVectorImpl<const Stmt*> &ResultStmts, 1102 ASTContext &C) { 1103 // First step, find the switch case that is being branched to. We can do this 1104 // efficiently by scanning the SwitchCase list. 1105 const SwitchCase *Case = S.getSwitchCaseList(); 1106 const DefaultStmt *DefaultCase = 0; 1107 1108 for (; Case; Case = Case->getNextSwitchCase()) { 1109 // It's either a default or case. Just remember the default statement in 1110 // case we're not jumping to any numbered cases. 1111 if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) { 1112 DefaultCase = DS; 1113 continue; 1114 } 1115 1116 // Check to see if this case is the one we're looking for. 1117 const CaseStmt *CS = cast<CaseStmt>(Case); 1118 // Don't handle case ranges yet. 1119 if (CS->getRHS()) return false; 1120 1121 // If we found our case, remember it as 'case'. 1122 if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue) 1123 break; 1124 } 1125 1126 // If we didn't find a matching case, we use a default if it exists, or we 1127 // elide the whole switch body! 1128 if (Case == 0) { 1129 // It is safe to elide the body of the switch if it doesn't contain labels 1130 // etc. If it is safe, return successfully with an empty ResultStmts list. 1131 if (DefaultCase == 0) 1132 return !CodeGenFunction::ContainsLabel(&S); 1133 Case = DefaultCase; 1134 } 1135 1136 // Ok, we know which case is being jumped to, try to collect all the 1137 // statements that follow it. This can fail for a variety of reasons. Also, 1138 // check to see that the recursive walk actually found our case statement. 1139 // Insane cases like this can fail to find it in the recursive walk since we 1140 // don't handle every stmt kind: 1141 // switch (4) { 1142 // while (1) { 1143 // case 4: ... 1144 bool FoundCase = false; 1145 return CollectStatementsForCase(S.getBody(), Case, FoundCase, 1146 ResultStmts) != CSFC_Failure && 1147 FoundCase; 1148} 1149 1150void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { 1151 JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog"); 1152 1153 RunCleanupsScope ConditionScope(*this); 1154 1155 if (S.getConditionVariable()) 1156 EmitAutoVarDecl(*S.getConditionVariable()); 1157 1158 // Handle nested switch statements. 1159 llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; 1160 llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; 1161 1162 // See if we can constant fold the condition of the switch and therefore only 1163 // emit the live case statement (if any) of the switch. 1164 llvm::APInt ConstantCondValue; 1165 if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) { 1166 SmallVector<const Stmt*, 4> CaseStmts; 1167 if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts, 1168 getContext())) { 1169 RunCleanupsScope ExecutedScope(*this); 1170 1171 // At this point, we are no longer "within" a switch instance, so 1172 // we can temporarily enforce this to ensure that any embedded case 1173 // statements are not emitted. 1174 SwitchInsn = 0; 1175 1176 // Okay, we can dead code eliminate everything except this case. Emit the 1177 // specified series of statements and we're good. 1178 for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i) 1179 EmitStmt(CaseStmts[i]); 1180 1181 // Now we want to restore the saved switch instance so that nested 1182 // switches continue to function properly 1183 SwitchInsn = SavedSwitchInsn; 1184 1185 return; 1186 } 1187 } 1188 1189 llvm::Value *CondV = EmitScalarExpr(S.getCond()); 1190 1191 // Create basic block to hold stuff that comes after switch 1192 // statement. We also need to create a default block now so that 1193 // explicit case ranges tests can have a place to jump to on 1194 // failure. 1195 llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); 1196 SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); 1197 CaseRangeBlock = DefaultBlock; 1198 1199 // Clear the insertion point to indicate we are in unreachable code. 1200 Builder.ClearInsertionPoint(); 1201 1202 // All break statements jump to NextBlock. If BreakContinueStack is non empty 1203 // then reuse last ContinueBlock. 1204 JumpDest OuterContinue; 1205 if (!BreakContinueStack.empty()) 1206 OuterContinue = BreakContinueStack.back().ContinueBlock; 1207 1208 BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue)); 1209 1210 // Emit switch body. 1211 EmitStmt(S.getBody()); 1212 1213 BreakContinueStack.pop_back(); 1214 1215 // Update the default block in case explicit case range tests have 1216 // been chained on top. 1217 SwitchInsn->setDefaultDest(CaseRangeBlock); 1218 1219 // If a default was never emitted: 1220 if (!DefaultBlock->getParent()) { 1221 // If we have cleanups, emit the default block so that there's a 1222 // place to jump through the cleanups from. 1223 if (ConditionScope.requiresCleanups()) { 1224 EmitBlock(DefaultBlock); 1225 1226 // Otherwise, just forward the default block to the switch end. 1227 } else { 1228 DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock()); 1229 delete DefaultBlock; 1230 } 1231 } 1232 1233 ConditionScope.ForceCleanup(); 1234 1235 // Emit continuation. 1236 EmitBlock(SwitchExit.getBlock(), true); 1237 1238 SwitchInsn = SavedSwitchInsn; 1239 CaseRangeBlock = SavedCRBlock; 1240} 1241 1242static std::string 1243SimplifyConstraint(const char *Constraint, const TargetInfo &Target, 1244 SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { 1245 std::string Result; 1246 1247 while (*Constraint) { 1248 switch (*Constraint) { 1249 default: 1250 Result += Target.convertConstraint(Constraint); 1251 break; 1252 // Ignore these 1253 case '*': 1254 case '?': 1255 case '!': 1256 case '=': // Will see this and the following in mult-alt constraints. 1257 case '+': 1258 break; 1259 case ',': 1260 Result += "|"; 1261 break; 1262 case 'g': 1263 Result += "imr"; 1264 break; 1265 case '[': { 1266 assert(OutCons && 1267 "Must pass output names to constraints with a symbolic name"); 1268 unsigned Index; 1269 bool result = Target.resolveSymbolicName(Constraint, 1270 &(*OutCons)[0], 1271 OutCons->size(), Index); 1272 assert(result && "Could not resolve symbolic name"); (void)result; 1273 Result += llvm::utostr(Index); 1274 break; 1275 } 1276 } 1277 1278 Constraint++; 1279 } 1280 1281 return Result; 1282} 1283 1284/// AddVariableConstraints - Look at AsmExpr and if it is a variable declared 1285/// as using a particular register add that as a constraint that will be used 1286/// in this asm stmt. 1287static std::string 1288AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr, 1289 const TargetInfo &Target, CodeGenModule &CGM, 1290 const AsmStmt &Stmt) { 1291 const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr); 1292 if (!AsmDeclRef) 1293 return Constraint; 1294 const ValueDecl &Value = *AsmDeclRef->getDecl(); 1295 const VarDecl *Variable = dyn_cast<VarDecl>(&Value); 1296 if (!Variable) 1297 return Constraint; 1298 if (Variable->getStorageClass() != SC_Register) 1299 return Constraint; 1300 AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>(); 1301 if (!Attr) 1302 return Constraint; 1303 StringRef Register = Attr->getLabel(); 1304 assert(Target.isValidGCCRegisterName(Register)); 1305 // We're using validateOutputConstraint here because we only care if 1306 // this is a register constraint. 1307 TargetInfo::ConstraintInfo Info(Constraint, ""); 1308 if (Target.validateOutputConstraint(Info) && 1309 !Info.allowsRegister()) { 1310 CGM.ErrorUnsupported(&Stmt, "__asm__"); 1311 return Constraint; 1312 } 1313 // Canonicalize the register here before returning it. 1314 Register = Target.getNormalizedGCCRegisterName(Register); 1315 return "{" + Register.str() + "}"; 1316} 1317 1318llvm::Value* 1319CodeGenFunction::EmitAsmInputLValue(const AsmStmt &S, 1320 const TargetInfo::ConstraintInfo &Info, 1321 LValue InputValue, QualType InputType, 1322 std::string &ConstraintStr) { 1323 llvm::Value *Arg; 1324 if (Info.allowsRegister() || !Info.allowsMemory()) { 1325 if (!CodeGenFunction::hasAggregateLLVMType(InputType)) { 1326 Arg = EmitLoadOfLValue(InputValue).getScalarVal(); 1327 } else { 1328 llvm::Type *Ty = ConvertType(InputType); 1329 uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); 1330 if (Size <= 64 && llvm::isPowerOf2_64(Size)) { 1331 Ty = llvm::IntegerType::get(getLLVMContext(), Size); 1332 Ty = llvm::PointerType::getUnqual(Ty); 1333 1334 Arg = Builder.CreateLoad(Builder.CreateBitCast(InputValue.getAddress(), 1335 Ty)); 1336 } else { 1337 Arg = InputValue.getAddress(); 1338 ConstraintStr += '*'; 1339 } 1340 } 1341 } else { 1342 Arg = InputValue.getAddress(); 1343 ConstraintStr += '*'; 1344 } 1345 1346 return Arg; 1347} 1348 1349llvm::Value* CodeGenFunction::EmitAsmInput(const AsmStmt &S, 1350 const TargetInfo::ConstraintInfo &Info, 1351 const Expr *InputExpr, 1352 std::string &ConstraintStr) { 1353 if (Info.allowsRegister() || !Info.allowsMemory()) 1354 if (!CodeGenFunction::hasAggregateLLVMType(InputExpr->getType())) 1355 return EmitScalarExpr(InputExpr); 1356 1357 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 1358 LValue Dest = EmitLValue(InputExpr); 1359 return EmitAsmInputLValue(S, Info, Dest, InputExpr->getType(), ConstraintStr); 1360} 1361 1362/// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline 1363/// asm call instruction. The !srcloc MDNode contains a list of constant 1364/// integers which are the source locations of the start of each line in the 1365/// asm. 1366static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str, 1367 CodeGenFunction &CGF) { 1368 SmallVector<llvm::Value *, 8> Locs; 1369 // Add the location of the first line to the MDNode. 1370 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1371 Str->getLocStart().getRawEncoding())); 1372 StringRef StrVal = Str->getString(); 1373 if (!StrVal.empty()) { 1374 const SourceManager &SM = CGF.CGM.getContext().getSourceManager(); 1375 const LangOptions &LangOpts = CGF.CGM.getLangOpts(); 1376 1377 // Add the location of the start of each subsequent line of the asm to the 1378 // MDNode. 1379 for (unsigned i = 0, e = StrVal.size()-1; i != e; ++i) { 1380 if (StrVal[i] != '\n') continue; 1381 SourceLocation LineLoc = Str->getLocationOfByte(i+1, SM, LangOpts, 1382 CGF.Target); 1383 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1384 LineLoc.getRawEncoding())); 1385 } 1386 } 1387 1388 return llvm::MDNode::get(CGF.getLLVMContext(), Locs); 1389} 1390 1391void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { 1392 // Analyze the asm string to decompose it into its pieces. We know that Sema 1393 // has already done this, so it is guaranteed to be successful. 1394 SmallVector<AsmStmt::AsmStringPiece, 4> Pieces; 1395 unsigned DiagOffs; 1396 S.AnalyzeAsmString(Pieces, getContext(), DiagOffs); 1397 1398 // Assemble the pieces into the final asm string. 1399 std::string AsmString; 1400 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { 1401 if (Pieces[i].isString()) 1402 AsmString += Pieces[i].getString(); 1403 else if (Pieces[i].getModifier() == '\0') 1404 AsmString += '$' + llvm::utostr(Pieces[i].getOperandNo()); 1405 else 1406 AsmString += "${" + llvm::utostr(Pieces[i].getOperandNo()) + ':' + 1407 Pieces[i].getModifier() + '}'; 1408 } 1409 1410 // Get all the output and input constraints together. 1411 SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 1412 SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 1413 1414 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1415 TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), 1416 S.getOutputName(i)); 1417 bool IsValid = Target.validateOutputConstraint(Info); (void)IsValid; 1418 assert(IsValid && "Failed to parse output constraint"); 1419 OutputConstraintInfos.push_back(Info); 1420 } 1421 1422 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1423 TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), 1424 S.getInputName(i)); 1425 bool IsValid = Target.validateInputConstraint(OutputConstraintInfos.data(), 1426 S.getNumOutputs(), Info); 1427 assert(IsValid && "Failed to parse input constraint"); (void)IsValid; 1428 InputConstraintInfos.push_back(Info); 1429 } 1430 1431 std::string Constraints; 1432 1433 std::vector<LValue> ResultRegDests; 1434 std::vector<QualType> ResultRegQualTys; 1435 std::vector<llvm::Type *> ResultRegTypes; 1436 std::vector<llvm::Type *> ResultTruncRegTypes; 1437 std::vector<llvm::Type*> ArgTypes; 1438 std::vector<llvm::Value*> Args; 1439 1440 // Keep track of inout constraints. 1441 std::string InOutConstraints; 1442 std::vector<llvm::Value*> InOutArgs; 1443 std::vector<llvm::Type*> InOutArgTypes; 1444 1445 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1446 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 1447 1448 // Simplify the output constraint. 1449 std::string OutputConstraint(S.getOutputConstraint(i)); 1450 OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); 1451 1452 const Expr *OutExpr = S.getOutputExpr(i); 1453 OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); 1454 1455 OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr, 1456 Target, CGM, S); 1457 1458 LValue Dest = EmitLValue(OutExpr); 1459 if (!Constraints.empty()) 1460 Constraints += ','; 1461 1462 // If this is a register output, then make the inline asm return it 1463 // by-value. If this is a memory result, return the value by-reference. 1464 if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { 1465 Constraints += "=" + OutputConstraint; 1466 ResultRegQualTys.push_back(OutExpr->getType()); 1467 ResultRegDests.push_back(Dest); 1468 ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); 1469 ResultTruncRegTypes.push_back(ResultRegTypes.back()); 1470 1471 // If this output is tied to an input, and if the input is larger, then 1472 // we need to set the actual result type of the inline asm node to be the 1473 // same as the input type. 1474 if (Info.hasMatchingInput()) { 1475 unsigned InputNo; 1476 for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { 1477 TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; 1478 if (Input.hasTiedOperand() && Input.getTiedOperand() == i) 1479 break; 1480 } 1481 assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); 1482 1483 QualType InputTy = S.getInputExpr(InputNo)->getType(); 1484 QualType OutputType = OutExpr->getType(); 1485 1486 uint64_t InputSize = getContext().getTypeSize(InputTy); 1487 if (getContext().getTypeSize(OutputType) < InputSize) { 1488 // Form the asm to return the value as a larger integer or fp type. 1489 ResultRegTypes.back() = ConvertType(InputTy); 1490 } 1491 } 1492 if (llvm::Type* AdjTy = 1493 getTargetHooks().adjustInlineAsmType(*this, OutputConstraint, 1494 ResultRegTypes.back())) 1495 ResultRegTypes.back() = AdjTy; 1496 } else { 1497 ArgTypes.push_back(Dest.getAddress()->getType()); 1498 Args.push_back(Dest.getAddress()); 1499 Constraints += "=*"; 1500 Constraints += OutputConstraint; 1501 } 1502 1503 if (Info.isReadWrite()) { 1504 InOutConstraints += ','; 1505 1506 const Expr *InputExpr = S.getOutputExpr(i); 1507 llvm::Value *Arg = EmitAsmInputLValue(S, Info, Dest, InputExpr->getType(), 1508 InOutConstraints); 1509 1510 if (llvm::Type* AdjTy = 1511 getTargetHooks().adjustInlineAsmType(*this, OutputConstraint, 1512 Arg->getType())) 1513 Arg = Builder.CreateBitCast(Arg, AdjTy); 1514 1515 if (Info.allowsRegister()) 1516 InOutConstraints += llvm::utostr(i); 1517 else 1518 InOutConstraints += OutputConstraint; 1519 1520 InOutArgTypes.push_back(Arg->getType()); 1521 InOutArgs.push_back(Arg); 1522 } 1523 } 1524 1525 unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); 1526 1527 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1528 const Expr *InputExpr = S.getInputExpr(i); 1529 1530 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 1531 1532 if (!Constraints.empty()) 1533 Constraints += ','; 1534 1535 // Simplify the input constraint. 1536 std::string InputConstraint(S.getInputConstraint(i)); 1537 InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, 1538 &OutputConstraintInfos); 1539 1540 InputConstraint = 1541 AddVariableConstraints(InputConstraint, 1542 *InputExpr->IgnoreParenNoopCasts(getContext()), 1543 Target, CGM, S); 1544 1545 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints); 1546 1547 // If this input argument is tied to a larger output result, extend the 1548 // input to be the same size as the output. The LLVM backend wants to see 1549 // the input and output of a matching constraint be the same size. Note 1550 // that GCC does not define what the top bits are here. We use zext because 1551 // that is usually cheaper, but LLVM IR should really get an anyext someday. 1552 if (Info.hasTiedOperand()) { 1553 unsigned Output = Info.getTiedOperand(); 1554 QualType OutputType = S.getOutputExpr(Output)->getType(); 1555 QualType InputTy = InputExpr->getType(); 1556 1557 if (getContext().getTypeSize(OutputType) > 1558 getContext().getTypeSize(InputTy)) { 1559 // Use ptrtoint as appropriate so that we can do our extension. 1560 if (isa<llvm::PointerType>(Arg->getType())) 1561 Arg = Builder.CreatePtrToInt(Arg, IntPtrTy); 1562 llvm::Type *OutputTy = ConvertType(OutputType); 1563 if (isa<llvm::IntegerType>(OutputTy)) 1564 Arg = Builder.CreateZExt(Arg, OutputTy); 1565 else if (isa<llvm::PointerType>(OutputTy)) 1566 Arg = Builder.CreateZExt(Arg, IntPtrTy); 1567 else { 1568 assert(OutputTy->isFloatingPointTy() && "Unexpected output type"); 1569 Arg = Builder.CreateFPExt(Arg, OutputTy); 1570 } 1571 } 1572 } 1573 if (llvm::Type* AdjTy = 1574 getTargetHooks().adjustInlineAsmType(*this, InputConstraint, 1575 Arg->getType())) 1576 Arg = Builder.CreateBitCast(Arg, AdjTy); 1577 1578 ArgTypes.push_back(Arg->getType()); 1579 Args.push_back(Arg); 1580 Constraints += InputConstraint; 1581 } 1582 1583 // Append the "input" part of inout constraints last. 1584 for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { 1585 ArgTypes.push_back(InOutArgTypes[i]); 1586 Args.push_back(InOutArgs[i]); 1587 } 1588 Constraints += InOutConstraints; 1589 1590 // Clobbers 1591 for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { 1592 StringRef Clobber = S.getClobber(i)->getString(); 1593 1594 if (Clobber != "memory" && Clobber != "cc") 1595 Clobber = Target.getNormalizedGCCRegisterName(Clobber); 1596 1597 if (i != 0 || NumConstraints != 0) 1598 Constraints += ','; 1599 1600 Constraints += "~{"; 1601 Constraints += Clobber; 1602 Constraints += '}'; 1603 } 1604 1605 // Add machine specific clobbers 1606 std::string MachineClobbers = Target.getClobbers(); 1607 if (!MachineClobbers.empty()) { 1608 if (!Constraints.empty()) 1609 Constraints += ','; 1610 Constraints += MachineClobbers; 1611 } 1612 1613 llvm::Type *ResultType; 1614 if (ResultRegTypes.empty()) 1615 ResultType = VoidTy; 1616 else if (ResultRegTypes.size() == 1) 1617 ResultType = ResultRegTypes[0]; 1618 else 1619 ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes); 1620 1621 llvm::FunctionType *FTy = 1622 llvm::FunctionType::get(ResultType, ArgTypes, false); 1623 1624 llvm::InlineAsm *IA = 1625 llvm::InlineAsm::get(FTy, AsmString, Constraints, 1626 S.isVolatile() || S.getNumOutputs() == 0); 1627 llvm::CallInst *Result = Builder.CreateCall(IA, Args); 1628 Result->addAttribute(~0, llvm::Attribute::NoUnwind); 1629 1630 // Slap the source location of the inline asm into a !srcloc metadata on the 1631 // call. 1632 Result->setMetadata("srcloc", getAsmSrcLocInfo(S.getAsmString(), *this)); 1633 1634 // Extract all of the register value results from the asm. 1635 std::vector<llvm::Value*> RegResults; 1636 if (ResultRegTypes.size() == 1) { 1637 RegResults.push_back(Result); 1638 } else { 1639 for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { 1640 llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); 1641 RegResults.push_back(Tmp); 1642 } 1643 } 1644 1645 for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { 1646 llvm::Value *Tmp = RegResults[i]; 1647 1648 // If the result type of the LLVM IR asm doesn't match the result type of 1649 // the expression, do the conversion. 1650 if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { 1651 llvm::Type *TruncTy = ResultTruncRegTypes[i]; 1652 1653 // Truncate the integer result to the right size, note that TruncTy can be 1654 // a pointer. 1655 if (TruncTy->isFloatingPointTy()) 1656 Tmp = Builder.CreateFPTrunc(Tmp, TruncTy); 1657 else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) { 1658 uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); 1659 Tmp = Builder.CreateTrunc(Tmp, 1660 llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize)); 1661 Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); 1662 } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) { 1663 uint64_t TmpSize =CGM.getTargetData().getTypeSizeInBits(Tmp->getType()); 1664 Tmp = Builder.CreatePtrToInt(Tmp, 1665 llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize)); 1666 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1667 } else if (TruncTy->isIntegerTy()) { 1668 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1669 } else if (TruncTy->isVectorTy()) { 1670 Tmp = Builder.CreateBitCast(Tmp, TruncTy); 1671 } 1672 } 1673 1674 EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i]); 1675 } 1676} 1677