1 //===--- CGStmt.cpp - Emit LLVM Code from Statements ----------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This contains code to emit Stmt nodes as LLVM code. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "CGDebugInfo.h" 15 #include "CodeGenModule.h" 16 #include "CodeGenFunction.h" 17 #include "TargetInfo.h" 18 #include "clang/AST/StmtVisitor.h" 19 #include "clang/Basic/PrettyStackTrace.h" 20 #include "clang/Basic/TargetInfo.h" 21 #include "llvm/ADT/StringExtras.h" 22 #include "llvm/InlineAsm.h" 23 #include "llvm/Intrinsics.h" 24 #include "llvm/Target/TargetData.h" 25 using namespace clang; 26 using namespace CodeGen; 27 28 //===----------------------------------------------------------------------===// 29 // Statement Emission 30 //===----------------------------------------------------------------------===// 31 32 void CodeGenFunction::EmitStopPoint(const Stmt *S) { 33 if (CGDebugInfo *DI = getDebugInfo()) { 34 SourceLocation Loc; 35 if (isa<DeclStmt>(S)) 36 Loc = S->getLocEnd(); 37 else 38 Loc = S->getLocStart(); 39 DI->EmitLocation(Builder, Loc); 40 } 41 } 42 43 void CodeGenFunction::EmitStmt(const Stmt *S) { 44 assert(S && "Null statement?"); 45 46 // These statements have their own debug info handling. 47 if (EmitSimpleStmt(S)) 48 return; 49 50 // Check if we are generating unreachable code. 51 if (!HaveInsertPoint()) { 52 // If so, and the statement doesn't contain a label, then we do not need to 53 // generate actual code. This is safe because (1) the current point is 54 // unreachable, so we don't need to execute the code, and (2) we've already 55 // handled the statements which update internal data structures (like the 56 // local variable map) which could be used by subsequent statements. 57 if (!ContainsLabel(S)) { 58 // Verify that any decl statements were handled as simple, they may be in 59 // scope of subsequent reachable statements. 60 assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!"); 61 return; 62 } 63 64 // Otherwise, make a new block to hold the code. 65 EnsureInsertPoint(); 66 } 67 68 // Generate a stoppoint if we are emitting debug info. 69 EmitStopPoint(S); 70 71 switch (S->getStmtClass()) { 72 case Stmt::NoStmtClass: 73 case Stmt::CXXCatchStmtClass: 74 case Stmt::SEHExceptStmtClass: 75 case Stmt::SEHFinallyStmtClass: 76 llvm_unreachable("invalid statement class to emit generically"); 77 case Stmt::NullStmtClass: 78 case Stmt::CompoundStmtClass: 79 case Stmt::DeclStmtClass: 80 case Stmt::LabelStmtClass: 81 case Stmt::GotoStmtClass: 82 case Stmt::BreakStmtClass: 83 case Stmt::ContinueStmtClass: 84 case Stmt::DefaultStmtClass: 85 case Stmt::CaseStmtClass: 86 llvm_unreachable("should have emitted these statements as simple"); 87 88 #define STMT(Type, Base) 89 #define ABSTRACT_STMT(Op) 90 #define EXPR(Type, Base) \ 91 case Stmt::Type##Class: 92 #include "clang/AST/StmtNodes.inc" 93 { 94 // Remember the block we came in on. 95 llvm::BasicBlock *incoming = Builder.GetInsertBlock(); 96 assert(incoming && "expression emission must have an insertion point"); 97 98 EmitIgnoredExpr(cast<Expr>(S)); 99 100 llvm::BasicBlock *outgoing = Builder.GetInsertBlock(); 101 assert(outgoing && "expression emission cleared block!"); 102 103 // The expression emitters assume (reasonably!) that the insertion 104 // point is always set. To maintain that, the call-emission code 105 // for noreturn functions has to enter a new block with no 106 // predecessors. We want to kill that block and mark the current 107 // insertion point unreachable in the common case of a call like 108 // "exit();". Since expression emission doesn't otherwise create 109 // blocks with no predecessors, we can just test for that. 110 // However, we must be careful not to do this to our incoming 111 // block, because *statement* emission does sometimes create 112 // reachable blocks which will have no predecessors until later in 113 // the function. This occurs with, e.g., labels that are not 114 // reachable by fallthrough. 115 if (incoming != outgoing && outgoing->use_empty()) { 116 outgoing->eraseFromParent(); 117 Builder.ClearInsertionPoint(); 118 } 119 break; 120 } 121 122 case Stmt::IndirectGotoStmtClass: 123 EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break; 124 125 case Stmt::IfStmtClass: EmitIfStmt(cast<IfStmt>(*S)); break; 126 case Stmt::WhileStmtClass: EmitWhileStmt(cast<WhileStmt>(*S)); break; 127 case Stmt::DoStmtClass: EmitDoStmt(cast<DoStmt>(*S)); break; 128 case Stmt::ForStmtClass: EmitForStmt(cast<ForStmt>(*S)); break; 129 130 case Stmt::ReturnStmtClass: EmitReturnStmt(cast<ReturnStmt>(*S)); break; 131 132 case Stmt::SwitchStmtClass: EmitSwitchStmt(cast<SwitchStmt>(*S)); break; 133 case Stmt::AsmStmtClass: EmitAsmStmt(cast<AsmStmt>(*S)); break; 134 135 case Stmt::ObjCAtTryStmtClass: 136 EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S)); 137 break; 138 case Stmt::ObjCAtCatchStmtClass: 139 llvm_unreachable( 140 "@catch statements should be handled by EmitObjCAtTryStmt"); 141 case Stmt::ObjCAtFinallyStmtClass: 142 llvm_unreachable( 143 "@finally statements should be handled by EmitObjCAtTryStmt"); 144 case Stmt::ObjCAtThrowStmtClass: 145 EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S)); 146 break; 147 case Stmt::ObjCAtSynchronizedStmtClass: 148 EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S)); 149 break; 150 case Stmt::ObjCForCollectionStmtClass: 151 EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S)); 152 break; 153 case Stmt::ObjCAutoreleasePoolStmtClass: 154 EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S)); 155 break; 156 157 case Stmt::CXXTryStmtClass: 158 EmitCXXTryStmt(cast<CXXTryStmt>(*S)); 159 break; 160 case Stmt::CXXForRangeStmtClass: 161 EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S)); 162 case Stmt::SEHTryStmtClass: 163 // FIXME Not yet implemented 164 break; 165 } 166 } 167 168 bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) { 169 switch (S->getStmtClass()) { 170 default: return false; 171 case Stmt::NullStmtClass: break; 172 case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break; 173 case Stmt::DeclStmtClass: EmitDeclStmt(cast<DeclStmt>(*S)); break; 174 case Stmt::LabelStmtClass: EmitLabelStmt(cast<LabelStmt>(*S)); break; 175 case Stmt::GotoStmtClass: EmitGotoStmt(cast<GotoStmt>(*S)); break; 176 case Stmt::BreakStmtClass: EmitBreakStmt(cast<BreakStmt>(*S)); break; 177 case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break; 178 case Stmt::DefaultStmtClass: EmitDefaultStmt(cast<DefaultStmt>(*S)); break; 179 case Stmt::CaseStmtClass: EmitCaseStmt(cast<CaseStmt>(*S)); break; 180 } 181 182 return true; 183 } 184 185 /// EmitCompoundStmt - Emit a compound statement {..} node. If GetLast is true, 186 /// this captures the expression result of the last sub-statement and returns it 187 /// (for use by the statement expression extension). 188 RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast, 189 AggValueSlot AggSlot) { 190 PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(), 191 "LLVM IR generation of compound statement ('{}')"); 192 193 CGDebugInfo *DI = getDebugInfo(); 194 if (DI) 195 DI->EmitLexicalBlockStart(Builder, S.getLBracLoc()); 196 197 // Keep track of the current cleanup stack depth. 198 RunCleanupsScope Scope(*this); 199 200 for (CompoundStmt::const_body_iterator I = S.body_begin(), 201 E = S.body_end()-GetLast; I != E; ++I) 202 EmitStmt(*I); 203 204 if (DI) 205 DI->EmitLexicalBlockEnd(Builder, S.getRBracLoc()); 206 207 RValue RV; 208 if (!GetLast) 209 RV = RValue::get(0); 210 else { 211 // We have to special case labels here. They are statements, but when put 212 // at the end of a statement expression, they yield the value of their 213 // subexpression. Handle this by walking through all labels we encounter, 214 // emitting them before we evaluate the subexpr. 215 const Stmt *LastStmt = S.body_back(); 216 while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) { 217 EmitLabel(LS->getDecl()); 218 LastStmt = LS->getSubStmt(); 219 } 220 221 EnsureInsertPoint(); 222 223 RV = EmitAnyExpr(cast<Expr>(LastStmt), AggSlot); 224 } 225 226 return RV; 227 } 228 229 void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) { 230 llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator()); 231 232 // If there is a cleanup stack, then we it isn't worth trying to 233 // simplify this block (we would need to remove it from the scope map 234 // and cleanup entry). 235 if (!EHStack.empty()) 236 return; 237 238 // Can only simplify direct branches. 239 if (!BI || !BI->isUnconditional()) 240 return; 241 242 BB->replaceAllUsesWith(BI->getSuccessor(0)); 243 BI->eraseFromParent(); 244 BB->eraseFromParent(); 245 } 246 247 void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) { 248 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 249 250 // Fall out of the current block (if necessary). 251 EmitBranch(BB); 252 253 if (IsFinished && BB->use_empty()) { 254 delete BB; 255 return; 256 } 257 258 // Place the block after the current block, if possible, or else at 259 // the end of the function. 260 if (CurBB && CurBB->getParent()) 261 CurFn->getBasicBlockList().insertAfter(CurBB, BB); 262 else 263 CurFn->getBasicBlockList().push_back(BB); 264 Builder.SetInsertPoint(BB); 265 } 266 267 void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) { 268 // Emit a branch from the current block to the target one if this 269 // was a real block. If this was just a fall-through block after a 270 // terminator, don't emit it. 271 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 272 273 if (!CurBB || CurBB->getTerminator()) { 274 // If there is no insert point or the previous block is already 275 // terminated, don't touch it. 276 } else { 277 // Otherwise, create a fall-through branch. 278 Builder.CreateBr(Target); 279 } 280 281 Builder.ClearInsertionPoint(); 282 } 283 284 void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) { 285 bool inserted = false; 286 for (llvm::BasicBlock::use_iterator 287 i = block->use_begin(), e = block->use_end(); i != e; ++i) { 288 if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(*i)) { 289 CurFn->getBasicBlockList().insertAfter(insn->getParent(), block); 290 inserted = true; 291 break; 292 } 293 } 294 295 if (!inserted) 296 CurFn->getBasicBlockList().push_back(block); 297 298 Builder.SetInsertPoint(block); 299 } 300 301 CodeGenFunction::JumpDest 302 CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) { 303 JumpDest &Dest = LabelMap[D]; 304 if (Dest.isValid()) return Dest; 305 306 // Create, but don't insert, the new block. 307 Dest = JumpDest(createBasicBlock(D->getName()), 308 EHScopeStack::stable_iterator::invalid(), 309 NextCleanupDestIndex++); 310 return Dest; 311 } 312 313 void CodeGenFunction::EmitLabel(const LabelDecl *D) { 314 JumpDest &Dest = LabelMap[D]; 315 316 // If we didn't need a forward reference to this label, just go 317 // ahead and create a destination at the current scope. 318 if (!Dest.isValid()) { 319 Dest = getJumpDestInCurrentScope(D->getName()); 320 321 // Otherwise, we need to give this label a target depth and remove 322 // it from the branch-fixups list. 323 } else { 324 assert(!Dest.getScopeDepth().isValid() && "already emitted label!"); 325 Dest = JumpDest(Dest.getBlock(), 326 EHStack.stable_begin(), 327 Dest.getDestIndex()); 328 329 ResolveBranchFixups(Dest.getBlock()); 330 } 331 332 EmitBlock(Dest.getBlock()); 333 } 334 335 336 void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) { 337 EmitLabel(S.getDecl()); 338 EmitStmt(S.getSubStmt()); 339 } 340 341 void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) { 342 // If this code is reachable then emit a stop point (if generating 343 // debug info). We have to do this ourselves because we are on the 344 // "simple" statement path. 345 if (HaveInsertPoint()) 346 EmitStopPoint(&S); 347 348 EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel())); 349 } 350 351 352 void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) { 353 if (const LabelDecl *Target = S.getConstantTarget()) { 354 EmitBranchThroughCleanup(getJumpDestForLabel(Target)); 355 return; 356 } 357 358 // Ensure that we have an i8* for our PHI node. 359 llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()), 360 Int8PtrTy, "addr"); 361 llvm::BasicBlock *CurBB = Builder.GetInsertBlock(); 362 363 364 // Get the basic block for the indirect goto. 365 llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock(); 366 367 // The first instruction in the block has to be the PHI for the switch dest, 368 // add an entry for this branch. 369 cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB); 370 371 EmitBranch(IndGotoBB); 372 } 373 374 void CodeGenFunction::EmitIfStmt(const IfStmt &S) { 375 // C99 6.8.4.1: The first substatement is executed if the expression compares 376 // unequal to 0. The condition must be a scalar type. 377 RunCleanupsScope ConditionScope(*this); 378 379 if (S.getConditionVariable()) 380 EmitAutoVarDecl(*S.getConditionVariable()); 381 382 // If the condition constant folds and can be elided, try to avoid emitting 383 // the condition and the dead arm of the if/else. 384 bool CondConstant; 385 if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant)) { 386 // Figure out which block (then or else) is executed. 387 const Stmt *Executed = S.getThen(); 388 const Stmt *Skipped = S.getElse(); 389 if (!CondConstant) // Condition false? 390 std::swap(Executed, Skipped); 391 392 // If the skipped block has no labels in it, just emit the executed block. 393 // This avoids emitting dead code and simplifies the CFG substantially. 394 if (!ContainsLabel(Skipped)) { 395 if (Executed) { 396 RunCleanupsScope ExecutedScope(*this); 397 EmitStmt(Executed); 398 } 399 return; 400 } 401 } 402 403 // Otherwise, the condition did not fold, or we couldn't elide it. Just emit 404 // the conditional branch. 405 llvm::BasicBlock *ThenBlock = createBasicBlock("if.then"); 406 llvm::BasicBlock *ContBlock = createBasicBlock("if.end"); 407 llvm::BasicBlock *ElseBlock = ContBlock; 408 if (S.getElse()) 409 ElseBlock = createBasicBlock("if.else"); 410 EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock); 411 412 // Emit the 'then' code. 413 EmitBlock(ThenBlock); 414 { 415 RunCleanupsScope ThenScope(*this); 416 EmitStmt(S.getThen()); 417 } 418 EmitBranch(ContBlock); 419 420 // Emit the 'else' code if present. 421 if (const Stmt *Else = S.getElse()) { 422 // There is no need to emit line number for unconditional branch. 423 if (getDebugInfo()) 424 Builder.SetCurrentDebugLocation(llvm::DebugLoc()); 425 EmitBlock(ElseBlock); 426 { 427 RunCleanupsScope ElseScope(*this); 428 EmitStmt(Else); 429 } 430 // There is no need to emit line number for unconditional branch. 431 if (getDebugInfo()) 432 Builder.SetCurrentDebugLocation(llvm::DebugLoc()); 433 EmitBranch(ContBlock); 434 } 435 436 // Emit the continuation block for code after the if. 437 EmitBlock(ContBlock, true); 438 } 439 440 void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) { 441 // Emit the header for the loop, which will also become 442 // the continue target. 443 JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond"); 444 EmitBlock(LoopHeader.getBlock()); 445 446 // Create an exit block for when the condition fails, which will 447 // also become the break target. 448 JumpDest LoopExit = getJumpDestInCurrentScope("while.end"); 449 450 // Store the blocks to use for break and continue. 451 BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader)); 452 453 // C++ [stmt.while]p2: 454 // When the condition of a while statement is a declaration, the 455 // scope of the variable that is declared extends from its point 456 // of declaration (3.3.2) to the end of the while statement. 457 // [...] 458 // The object created in a condition is destroyed and created 459 // with each iteration of the loop. 460 RunCleanupsScope ConditionScope(*this); 461 462 if (S.getConditionVariable()) 463 EmitAutoVarDecl(*S.getConditionVariable()); 464 465 // Evaluate the conditional in the while header. C99 6.8.5.1: The 466 // evaluation of the controlling expression takes place before each 467 // execution of the loop body. 468 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 469 470 // while(1) is common, avoid extra exit blocks. Be sure 471 // to correctly handle break/continue though. 472 bool EmitBoolCondBranch = true; 473 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 474 if (C->isOne()) 475 EmitBoolCondBranch = false; 476 477 // As long as the condition is true, go to the loop body. 478 llvm::BasicBlock *LoopBody = createBasicBlock("while.body"); 479 if (EmitBoolCondBranch) { 480 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 481 if (ConditionScope.requiresCleanups()) 482 ExitBlock = createBasicBlock("while.exit"); 483 484 Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock); 485 486 if (ExitBlock != LoopExit.getBlock()) { 487 EmitBlock(ExitBlock); 488 EmitBranchThroughCleanup(LoopExit); 489 } 490 } 491 492 // Emit the loop body. We have to emit this in a cleanup scope 493 // because it might be a singleton DeclStmt. 494 { 495 RunCleanupsScope BodyScope(*this); 496 EmitBlock(LoopBody); 497 EmitStmt(S.getBody()); 498 } 499 500 BreakContinueStack.pop_back(); 501 502 // Immediately force cleanup. 503 ConditionScope.ForceCleanup(); 504 505 // Branch to the loop header again. 506 EmitBranch(LoopHeader.getBlock()); 507 508 // Emit the exit block. 509 EmitBlock(LoopExit.getBlock(), true); 510 511 // The LoopHeader typically is just a branch if we skipped emitting 512 // a branch, try to erase it. 513 if (!EmitBoolCondBranch) 514 SimplifyForwardingBlocks(LoopHeader.getBlock()); 515 } 516 517 void CodeGenFunction::EmitDoStmt(const DoStmt &S) { 518 JumpDest LoopExit = getJumpDestInCurrentScope("do.end"); 519 JumpDest LoopCond = getJumpDestInCurrentScope("do.cond"); 520 521 // Store the blocks to use for break and continue. 522 BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond)); 523 524 // Emit the body of the loop. 525 llvm::BasicBlock *LoopBody = createBasicBlock("do.body"); 526 EmitBlock(LoopBody); 527 { 528 RunCleanupsScope BodyScope(*this); 529 EmitStmt(S.getBody()); 530 } 531 532 BreakContinueStack.pop_back(); 533 534 EmitBlock(LoopCond.getBlock()); 535 536 // C99 6.8.5.2: "The evaluation of the controlling expression takes place 537 // after each execution of the loop body." 538 539 // Evaluate the conditional in the while header. 540 // C99 6.8.5p2/p4: The first substatement is executed if the expression 541 // compares unequal to 0. The condition must be a scalar type. 542 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 543 544 // "do {} while (0)" is common in macros, avoid extra blocks. Be sure 545 // to correctly handle break/continue though. 546 bool EmitBoolCondBranch = true; 547 if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) 548 if (C->isZero()) 549 EmitBoolCondBranch = false; 550 551 // As long as the condition is true, iterate the loop. 552 if (EmitBoolCondBranch) 553 Builder.CreateCondBr(BoolCondVal, LoopBody, LoopExit.getBlock()); 554 555 // Emit the exit block. 556 EmitBlock(LoopExit.getBlock()); 557 558 // The DoCond block typically is just a branch if we skipped 559 // emitting a branch, try to erase it. 560 if (!EmitBoolCondBranch) 561 SimplifyForwardingBlocks(LoopCond.getBlock()); 562 } 563 564 void CodeGenFunction::EmitForStmt(const ForStmt &S) { 565 JumpDest LoopExit = getJumpDestInCurrentScope("for.end"); 566 567 RunCleanupsScope ForScope(*this); 568 569 CGDebugInfo *DI = getDebugInfo(); 570 if (DI) 571 DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin()); 572 573 // Evaluate the first part before the loop. 574 if (S.getInit()) 575 EmitStmt(S.getInit()); 576 577 // Start the loop with a block that tests the condition. 578 // If there's an increment, the continue scope will be overwritten 579 // later. 580 JumpDest Continue = getJumpDestInCurrentScope("for.cond"); 581 llvm::BasicBlock *CondBlock = Continue.getBlock(); 582 EmitBlock(CondBlock); 583 584 // Create a cleanup scope for the condition variable cleanups. 585 RunCleanupsScope ConditionScope(*this); 586 587 llvm::Value *BoolCondVal = 0; 588 if (S.getCond()) { 589 // If the for statement has a condition scope, emit the local variable 590 // declaration. 591 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 592 if (S.getConditionVariable()) { 593 EmitAutoVarDecl(*S.getConditionVariable()); 594 } 595 596 // If there are any cleanups between here and the loop-exit scope, 597 // create a block to stage a loop exit along. 598 if (ForScope.requiresCleanups()) 599 ExitBlock = createBasicBlock("for.cond.cleanup"); 600 601 // As long as the condition is true, iterate the loop. 602 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 603 604 // C99 6.8.5p2/p4: The first substatement is executed if the expression 605 // compares unequal to 0. The condition must be a scalar type. 606 BoolCondVal = EvaluateExprAsBool(S.getCond()); 607 Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock); 608 609 if (ExitBlock != LoopExit.getBlock()) { 610 EmitBlock(ExitBlock); 611 EmitBranchThroughCleanup(LoopExit); 612 } 613 614 EmitBlock(ForBody); 615 } else { 616 // Treat it as a non-zero constant. Don't even create a new block for the 617 // body, just fall into it. 618 } 619 620 // If the for loop doesn't have an increment we can just use the 621 // condition as the continue block. Otherwise we'll need to create 622 // a block for it (in the current scope, i.e. in the scope of the 623 // condition), and that we will become our continue block. 624 if (S.getInc()) 625 Continue = getJumpDestInCurrentScope("for.inc"); 626 627 // Store the blocks to use for break and continue. 628 BreakContinueStack.push_back(BreakContinue(LoopExit, Continue)); 629 630 { 631 // Create a separate cleanup scope for the body, in case it is not 632 // a compound statement. 633 RunCleanupsScope BodyScope(*this); 634 EmitStmt(S.getBody()); 635 } 636 637 // If there is an increment, emit it next. 638 if (S.getInc()) { 639 EmitBlock(Continue.getBlock()); 640 EmitStmt(S.getInc()); 641 } 642 643 BreakContinueStack.pop_back(); 644 645 ConditionScope.ForceCleanup(); 646 EmitBranch(CondBlock); 647 648 ForScope.ForceCleanup(); 649 650 if (DI) 651 DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd()); 652 653 // Emit the fall-through block. 654 EmitBlock(LoopExit.getBlock(), true); 655 } 656 657 void CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S) { 658 JumpDest LoopExit = getJumpDestInCurrentScope("for.end"); 659 660 RunCleanupsScope ForScope(*this); 661 662 CGDebugInfo *DI = getDebugInfo(); 663 if (DI) 664 DI->EmitLexicalBlockStart(Builder, S.getSourceRange().getBegin()); 665 666 // Evaluate the first pieces before the loop. 667 EmitStmt(S.getRangeStmt()); 668 EmitStmt(S.getBeginEndStmt()); 669 670 // Start the loop with a block that tests the condition. 671 // If there's an increment, the continue scope will be overwritten 672 // later. 673 llvm::BasicBlock *CondBlock = createBasicBlock("for.cond"); 674 EmitBlock(CondBlock); 675 676 // If there are any cleanups between here and the loop-exit scope, 677 // create a block to stage a loop exit along. 678 llvm::BasicBlock *ExitBlock = LoopExit.getBlock(); 679 if (ForScope.requiresCleanups()) 680 ExitBlock = createBasicBlock("for.cond.cleanup"); 681 682 // The loop body, consisting of the specified body and the loop variable. 683 llvm::BasicBlock *ForBody = createBasicBlock("for.body"); 684 685 // The body is executed if the expression, contextually converted 686 // to bool, is true. 687 llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond()); 688 Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock); 689 690 if (ExitBlock != LoopExit.getBlock()) { 691 EmitBlock(ExitBlock); 692 EmitBranchThroughCleanup(LoopExit); 693 } 694 695 EmitBlock(ForBody); 696 697 // Create a block for the increment. In case of a 'continue', we jump there. 698 JumpDest Continue = getJumpDestInCurrentScope("for.inc"); 699 700 // Store the blocks to use for break and continue. 701 BreakContinueStack.push_back(BreakContinue(LoopExit, Continue)); 702 703 { 704 // Create a separate cleanup scope for the loop variable and body. 705 RunCleanupsScope BodyScope(*this); 706 EmitStmt(S.getLoopVarStmt()); 707 EmitStmt(S.getBody()); 708 } 709 710 // If there is an increment, emit it next. 711 EmitBlock(Continue.getBlock()); 712 EmitStmt(S.getInc()); 713 714 BreakContinueStack.pop_back(); 715 716 EmitBranch(CondBlock); 717 718 ForScope.ForceCleanup(); 719 720 if (DI) 721 DI->EmitLexicalBlockEnd(Builder, S.getSourceRange().getEnd()); 722 723 // Emit the fall-through block. 724 EmitBlock(LoopExit.getBlock(), true); 725 } 726 727 void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) { 728 if (RV.isScalar()) { 729 Builder.CreateStore(RV.getScalarVal(), ReturnValue); 730 } else if (RV.isAggregate()) { 731 EmitAggregateCopy(ReturnValue, RV.getAggregateAddr(), Ty); 732 } else { 733 StoreComplexToAddr(RV.getComplexVal(), ReturnValue, false); 734 } 735 EmitBranchThroughCleanup(ReturnBlock); 736 } 737 738 /// EmitReturnStmt - Note that due to GCC extensions, this can have an operand 739 /// if the function returns void, or may be missing one if the function returns 740 /// non-void. Fun stuff :). 741 void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { 742 // Emit the result value, even if unused, to evalute the side effects. 743 const Expr *RV = S.getRetValue(); 744 745 // FIXME: Clean this up by using an LValue for ReturnTemp, 746 // EmitStoreThroughLValue, and EmitAnyExpr. 747 if (S.getNRVOCandidate() && S.getNRVOCandidate()->isNRVOVariable() && 748 !Target.useGlobalsForAutomaticVariables()) { 749 // Apply the named return value optimization for this return statement, 750 // which means doing nothing: the appropriate result has already been 751 // constructed into the NRVO variable. 752 753 // If there is an NRVO flag for this variable, set it to 1 into indicate 754 // that the cleanup code should not destroy the variable. 755 if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()]) 756 Builder.CreateStore(Builder.getTrue(), NRVOFlag); 757 } else if (!ReturnValue) { 758 // Make sure not to return anything, but evaluate the expression 759 // for side effects. 760 if (RV) 761 EmitAnyExpr(RV); 762 } else if (RV == 0) { 763 // Do nothing (return value is left uninitialized) 764 } else if (FnRetTy->isReferenceType()) { 765 // If this function returns a reference, take the address of the expression 766 // rather than the value. 767 RValue Result = EmitReferenceBindingToExpr(RV, /*InitializedDecl=*/0); 768 Builder.CreateStore(Result.getScalarVal(), ReturnValue); 769 } else if (!hasAggregateLLVMType(RV->getType())) { 770 Builder.CreateStore(EmitScalarExpr(RV), ReturnValue); 771 } else if (RV->getType()->isAnyComplexType()) { 772 EmitComplexExprIntoAddr(RV, ReturnValue, false); 773 } else { 774 EmitAggExpr(RV, AggValueSlot::forAddr(ReturnValue, Qualifiers(), 775 AggValueSlot::IsDestructed, 776 AggValueSlot::DoesNotNeedGCBarriers, 777 AggValueSlot::IsNotAliased)); 778 } 779 780 EmitBranchThroughCleanup(ReturnBlock); 781 } 782 783 void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) { 784 // As long as debug info is modeled with instructions, we have to ensure we 785 // have a place to insert here and write the stop point here. 786 if (getDebugInfo() && HaveInsertPoint()) 787 EmitStopPoint(&S); 788 789 for (DeclStmt::const_decl_iterator I = S.decl_begin(), E = S.decl_end(); 790 I != E; ++I) 791 EmitDecl(**I); 792 } 793 794 void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) { 795 assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!"); 796 797 // If this code is reachable then emit a stop point (if generating 798 // debug info). We have to do this ourselves because we are on the 799 // "simple" statement path. 800 if (HaveInsertPoint()) 801 EmitStopPoint(&S); 802 803 JumpDest Block = BreakContinueStack.back().BreakBlock; 804 EmitBranchThroughCleanup(Block); 805 } 806 807 void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) { 808 assert(!BreakContinueStack.empty() && "continue stmt not in a loop!"); 809 810 // If this code is reachable then emit a stop point (if generating 811 // debug info). We have to do this ourselves because we are on the 812 // "simple" statement path. 813 if (HaveInsertPoint()) 814 EmitStopPoint(&S); 815 816 JumpDest Block = BreakContinueStack.back().ContinueBlock; 817 EmitBranchThroughCleanup(Block); 818 } 819 820 /// EmitCaseStmtRange - If case statement range is not too big then 821 /// add multiple cases to switch instruction, one for each value within 822 /// the range. If range is too big then emit "if" condition check. 823 void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) { 824 assert(S.getRHS() && "Expected RHS value in CaseStmt"); 825 826 llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext()); 827 llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext()); 828 829 // Emit the code for this case. We do this first to make sure it is 830 // properly chained from our predecessor before generating the 831 // switch machinery to enter this block. 832 EmitBlock(createBasicBlock("sw.bb")); 833 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 834 EmitStmt(S.getSubStmt()); 835 836 // If range is empty, do nothing. 837 if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS)) 838 return; 839 840 llvm::APInt Range = RHS - LHS; 841 // FIXME: parameters such as this should not be hardcoded. 842 if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) { 843 // Range is small enough to add multiple switch instruction cases. 844 for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) { 845 SwitchInsn->addCase(Builder.getInt(LHS), CaseDest); 846 LHS++; 847 } 848 return; 849 } 850 851 // The range is too big. Emit "if" condition into a new block, 852 // making sure to save and restore the current insertion point. 853 llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock(); 854 855 // Push this test onto the chain of range checks (which terminates 856 // in the default basic block). The switch's default will be changed 857 // to the top of this chain after switch emission is complete. 858 llvm::BasicBlock *FalseDest = CaseRangeBlock; 859 CaseRangeBlock = createBasicBlock("sw.caserange"); 860 861 CurFn->getBasicBlockList().push_back(CaseRangeBlock); 862 Builder.SetInsertPoint(CaseRangeBlock); 863 864 // Emit range check. 865 llvm::Value *Diff = 866 Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS)); 867 llvm::Value *Cond = 868 Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds"); 869 Builder.CreateCondBr(Cond, CaseDest, FalseDest); 870 871 // Restore the appropriate insertion point. 872 if (RestoreBB) 873 Builder.SetInsertPoint(RestoreBB); 874 else 875 Builder.ClearInsertionPoint(); 876 } 877 878 void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) { 879 // Handle case ranges. 880 if (S.getRHS()) { 881 EmitCaseStmtRange(S); 882 return; 883 } 884 885 llvm::ConstantInt *CaseVal = 886 Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext())); 887 888 // If the body of the case is just a 'break', and if there was no fallthrough, 889 // try to not emit an empty block. 890 if (isa<BreakStmt>(S.getSubStmt())) { 891 JumpDest Block = BreakContinueStack.back().BreakBlock; 892 893 // Only do this optimization if there are no cleanups that need emitting. 894 if (isObviouslyBranchWithoutCleanups(Block)) { 895 SwitchInsn->addCase(CaseVal, Block.getBlock()); 896 897 // If there was a fallthrough into this case, make sure to redirect it to 898 // the end of the switch as well. 899 if (Builder.GetInsertBlock()) { 900 Builder.CreateBr(Block.getBlock()); 901 Builder.ClearInsertionPoint(); 902 } 903 return; 904 } 905 } 906 907 EmitBlock(createBasicBlock("sw.bb")); 908 llvm::BasicBlock *CaseDest = Builder.GetInsertBlock(); 909 SwitchInsn->addCase(CaseVal, CaseDest); 910 911 // Recursively emitting the statement is acceptable, but is not wonderful for 912 // code where we have many case statements nested together, i.e.: 913 // case 1: 914 // case 2: 915 // case 3: etc. 916 // Handling this recursively will create a new block for each case statement 917 // that falls through to the next case which is IR intensive. It also causes 918 // deep recursion which can run into stack depth limitations. Handle 919 // sequential non-range case statements specially. 920 const CaseStmt *CurCase = &S; 921 const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt()); 922 923 // Otherwise, iteratively add consecutive cases to this switch stmt. 924 while (NextCase && NextCase->getRHS() == 0) { 925 CurCase = NextCase; 926 llvm::ConstantInt *CaseVal = 927 Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext())); 928 SwitchInsn->addCase(CaseVal, CaseDest); 929 NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt()); 930 } 931 932 // Normal default recursion for non-cases. 933 EmitStmt(CurCase->getSubStmt()); 934 } 935 936 void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) { 937 llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest(); 938 assert(DefaultBlock->empty() && 939 "EmitDefaultStmt: Default block already defined?"); 940 EmitBlock(DefaultBlock); 941 EmitStmt(S.getSubStmt()); 942 } 943 944 /// CollectStatementsForCase - Given the body of a 'switch' statement and a 945 /// constant value that is being switched on, see if we can dead code eliminate 946 /// the body of the switch to a simple series of statements to emit. Basically, 947 /// on a switch (5) we want to find these statements: 948 /// case 5: 949 /// printf(...); <-- 950 /// ++i; <-- 951 /// break; 952 /// 953 /// and add them to the ResultStmts vector. If it is unsafe to do this 954 /// transformation (for example, one of the elided statements contains a label 955 /// that might be jumped to), return CSFC_Failure. If we handled it and 'S' 956 /// should include statements after it (e.g. the printf() line is a substmt of 957 /// the case) then return CSFC_FallThrough. If we handled it and found a break 958 /// statement, then return CSFC_Success. 959 /// 960 /// If Case is non-null, then we are looking for the specified case, checking 961 /// that nothing we jump over contains labels. If Case is null, then we found 962 /// the case and are looking for the break. 963 /// 964 /// If the recursive walk actually finds our Case, then we set FoundCase to 965 /// true. 966 /// 967 enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success }; 968 static CSFC_Result CollectStatementsForCase(const Stmt *S, 969 const SwitchCase *Case, 970 bool &FoundCase, 971 SmallVectorImpl<const Stmt*> &ResultStmts) { 972 // If this is a null statement, just succeed. 973 if (S == 0) 974 return Case ? CSFC_Success : CSFC_FallThrough; 975 976 // If this is the switchcase (case 4: or default) that we're looking for, then 977 // we're in business. Just add the substatement. 978 if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) { 979 if (S == Case) { 980 FoundCase = true; 981 return CollectStatementsForCase(SC->getSubStmt(), 0, FoundCase, 982 ResultStmts); 983 } 984 985 // Otherwise, this is some other case or default statement, just ignore it. 986 return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase, 987 ResultStmts); 988 } 989 990 // If we are in the live part of the code and we found our break statement, 991 // return a success! 992 if (Case == 0 && isa<BreakStmt>(S)) 993 return CSFC_Success; 994 995 // If this is a switch statement, then it might contain the SwitchCase, the 996 // break, or neither. 997 if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) { 998 // Handle this as two cases: we might be looking for the SwitchCase (if so 999 // the skipped statements must be skippable) or we might already have it. 1000 CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end(); 1001 if (Case) { 1002 // Keep track of whether we see a skipped declaration. The code could be 1003 // using the declaration even if it is skipped, so we can't optimize out 1004 // the decl if the kept statements might refer to it. 1005 bool HadSkippedDecl = false; 1006 1007 // If we're looking for the case, just see if we can skip each of the 1008 // substatements. 1009 for (; Case && I != E; ++I) { 1010 HadSkippedDecl |= isa<DeclStmt>(*I); 1011 1012 switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) { 1013 case CSFC_Failure: return CSFC_Failure; 1014 case CSFC_Success: 1015 // A successful result means that either 1) that the statement doesn't 1016 // have the case and is skippable, or 2) does contain the case value 1017 // and also contains the break to exit the switch. In the later case, 1018 // we just verify the rest of the statements are elidable. 1019 if (FoundCase) { 1020 // If we found the case and skipped declarations, we can't do the 1021 // optimization. 1022 if (HadSkippedDecl) 1023 return CSFC_Failure; 1024 1025 for (++I; I != E; ++I) 1026 if (CodeGenFunction::ContainsLabel(*I, true)) 1027 return CSFC_Failure; 1028 return CSFC_Success; 1029 } 1030 break; 1031 case CSFC_FallThrough: 1032 // If we have a fallthrough condition, then we must have found the 1033 // case started to include statements. Consider the rest of the 1034 // statements in the compound statement as candidates for inclusion. 1035 assert(FoundCase && "Didn't find case but returned fallthrough?"); 1036 // We recursively found Case, so we're not looking for it anymore. 1037 Case = 0; 1038 1039 // If we found the case and skipped declarations, we can't do the 1040 // optimization. 1041 if (HadSkippedDecl) 1042 return CSFC_Failure; 1043 break; 1044 } 1045 } 1046 } 1047 1048 // If we have statements in our range, then we know that the statements are 1049 // live and need to be added to the set of statements we're tracking. 1050 for (; I != E; ++I) { 1051 switch (CollectStatementsForCase(*I, 0, FoundCase, ResultStmts)) { 1052 case CSFC_Failure: return CSFC_Failure; 1053 case CSFC_FallThrough: 1054 // A fallthrough result means that the statement was simple and just 1055 // included in ResultStmt, keep adding them afterwards. 1056 break; 1057 case CSFC_Success: 1058 // A successful result means that we found the break statement and 1059 // stopped statement inclusion. We just ensure that any leftover stmts 1060 // are skippable and return success ourselves. 1061 for (++I; I != E; ++I) 1062 if (CodeGenFunction::ContainsLabel(*I, true)) 1063 return CSFC_Failure; 1064 return CSFC_Success; 1065 } 1066 } 1067 1068 return Case ? CSFC_Success : CSFC_FallThrough; 1069 } 1070 1071 // Okay, this is some other statement that we don't handle explicitly, like a 1072 // for statement or increment etc. If we are skipping over this statement, 1073 // just verify it doesn't have labels, which would make it invalid to elide. 1074 if (Case) { 1075 if (CodeGenFunction::ContainsLabel(S, true)) 1076 return CSFC_Failure; 1077 return CSFC_Success; 1078 } 1079 1080 // Otherwise, we want to include this statement. Everything is cool with that 1081 // so long as it doesn't contain a break out of the switch we're in. 1082 if (CodeGenFunction::containsBreak(S)) return CSFC_Failure; 1083 1084 // Otherwise, everything is great. Include the statement and tell the caller 1085 // that we fall through and include the next statement as well. 1086 ResultStmts.push_back(S); 1087 return CSFC_FallThrough; 1088 } 1089 1090 /// FindCaseStatementsForValue - Find the case statement being jumped to and 1091 /// then invoke CollectStatementsForCase to find the list of statements to emit 1092 /// for a switch on constant. See the comment above CollectStatementsForCase 1093 /// for more details. 1094 static bool FindCaseStatementsForValue(const SwitchStmt &S, 1095 const llvm::APInt &ConstantCondValue, 1096 SmallVectorImpl<const Stmt*> &ResultStmts, 1097 ASTContext &C) { 1098 // First step, find the switch case that is being branched to. We can do this 1099 // efficiently by scanning the SwitchCase list. 1100 const SwitchCase *Case = S.getSwitchCaseList(); 1101 const DefaultStmt *DefaultCase = 0; 1102 1103 for (; Case; Case = Case->getNextSwitchCase()) { 1104 // It's either a default or case. Just remember the default statement in 1105 // case we're not jumping to any numbered cases. 1106 if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) { 1107 DefaultCase = DS; 1108 continue; 1109 } 1110 1111 // Check to see if this case is the one we're looking for. 1112 const CaseStmt *CS = cast<CaseStmt>(Case); 1113 // Don't handle case ranges yet. 1114 if (CS->getRHS()) return false; 1115 1116 // If we found our case, remember it as 'case'. 1117 if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue) 1118 break; 1119 } 1120 1121 // If we didn't find a matching case, we use a default if it exists, or we 1122 // elide the whole switch body! 1123 if (Case == 0) { 1124 // It is safe to elide the body of the switch if it doesn't contain labels 1125 // etc. If it is safe, return successfully with an empty ResultStmts list. 1126 if (DefaultCase == 0) 1127 return !CodeGenFunction::ContainsLabel(&S); 1128 Case = DefaultCase; 1129 } 1130 1131 // Ok, we know which case is being jumped to, try to collect all the 1132 // statements that follow it. This can fail for a variety of reasons. Also, 1133 // check to see that the recursive walk actually found our case statement. 1134 // Insane cases like this can fail to find it in the recursive walk since we 1135 // don't handle every stmt kind: 1136 // switch (4) { 1137 // while (1) { 1138 // case 4: ... 1139 bool FoundCase = false; 1140 return CollectStatementsForCase(S.getBody(), Case, FoundCase, 1141 ResultStmts) != CSFC_Failure && 1142 FoundCase; 1143 } 1144 1145 void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) { 1146 JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog"); 1147 1148 RunCleanupsScope ConditionScope(*this); 1149 1150 if (S.getConditionVariable()) 1151 EmitAutoVarDecl(*S.getConditionVariable()); 1152 1153 // See if we can constant fold the condition of the switch and therefore only 1154 // emit the live case statement (if any) of the switch. 1155 llvm::APInt ConstantCondValue; 1156 if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) { 1157 SmallVector<const Stmt*, 4> CaseStmts; 1158 if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts, 1159 getContext())) { 1160 RunCleanupsScope ExecutedScope(*this); 1161 1162 // Okay, we can dead code eliminate everything except this case. Emit the 1163 // specified series of statements and we're good. 1164 for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i) 1165 EmitStmt(CaseStmts[i]); 1166 return; 1167 } 1168 } 1169 1170 llvm::Value *CondV = EmitScalarExpr(S.getCond()); 1171 1172 // Handle nested switch statements. 1173 llvm::SwitchInst *SavedSwitchInsn = SwitchInsn; 1174 llvm::BasicBlock *SavedCRBlock = CaseRangeBlock; 1175 1176 // Create basic block to hold stuff that comes after switch 1177 // statement. We also need to create a default block now so that 1178 // explicit case ranges tests can have a place to jump to on 1179 // failure. 1180 llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default"); 1181 SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock); 1182 CaseRangeBlock = DefaultBlock; 1183 1184 // Clear the insertion point to indicate we are in unreachable code. 1185 Builder.ClearInsertionPoint(); 1186 1187 // All break statements jump to NextBlock. If BreakContinueStack is non empty 1188 // then reuse last ContinueBlock. 1189 JumpDest OuterContinue; 1190 if (!BreakContinueStack.empty()) 1191 OuterContinue = BreakContinueStack.back().ContinueBlock; 1192 1193 BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue)); 1194 1195 // Emit switch body. 1196 EmitStmt(S.getBody()); 1197 1198 BreakContinueStack.pop_back(); 1199 1200 // Update the default block in case explicit case range tests have 1201 // been chained on top. 1202 SwitchInsn->setSuccessor(0, CaseRangeBlock); 1203 1204 // If a default was never emitted: 1205 if (!DefaultBlock->getParent()) { 1206 // If we have cleanups, emit the default block so that there's a 1207 // place to jump through the cleanups from. 1208 if (ConditionScope.requiresCleanups()) { 1209 EmitBlock(DefaultBlock); 1210 1211 // Otherwise, just forward the default block to the switch end. 1212 } else { 1213 DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock()); 1214 delete DefaultBlock; 1215 } 1216 } 1217 1218 ConditionScope.ForceCleanup(); 1219 1220 // Emit continuation. 1221 EmitBlock(SwitchExit.getBlock(), true); 1222 1223 SwitchInsn = SavedSwitchInsn; 1224 CaseRangeBlock = SavedCRBlock; 1225 } 1226 1227 static std::string 1228 SimplifyConstraint(const char *Constraint, const TargetInfo &Target, 1229 SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=0) { 1230 std::string Result; 1231 1232 while (*Constraint) { 1233 switch (*Constraint) { 1234 default: 1235 Result += Target.convertConstraint(Constraint); 1236 break; 1237 // Ignore these 1238 case '*': 1239 case '?': 1240 case '!': 1241 case '=': // Will see this and the following in mult-alt constraints. 1242 case '+': 1243 break; 1244 case ',': 1245 Result += "|"; 1246 break; 1247 case 'g': 1248 Result += "imr"; 1249 break; 1250 case '[': { 1251 assert(OutCons && 1252 "Must pass output names to constraints with a symbolic name"); 1253 unsigned Index; 1254 bool result = Target.resolveSymbolicName(Constraint, 1255 &(*OutCons)[0], 1256 OutCons->size(), Index); 1257 assert(result && "Could not resolve symbolic name"); (void)result; 1258 Result += llvm::utostr(Index); 1259 break; 1260 } 1261 } 1262 1263 Constraint++; 1264 } 1265 1266 return Result; 1267 } 1268 1269 /// AddVariableConstraints - Look at AsmExpr and if it is a variable declared 1270 /// as using a particular register add that as a constraint that will be used 1271 /// in this asm stmt. 1272 static std::string 1273 AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr, 1274 const TargetInfo &Target, CodeGenModule &CGM, 1275 const AsmStmt &Stmt) { 1276 const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr); 1277 if (!AsmDeclRef) 1278 return Constraint; 1279 const ValueDecl &Value = *AsmDeclRef->getDecl(); 1280 const VarDecl *Variable = dyn_cast<VarDecl>(&Value); 1281 if (!Variable) 1282 return Constraint; 1283 AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>(); 1284 if (!Attr) 1285 return Constraint; 1286 StringRef Register = Attr->getLabel(); 1287 assert(Target.isValidGCCRegisterName(Register)); 1288 // We're using validateOutputConstraint here because we only care if 1289 // this is a register constraint. 1290 TargetInfo::ConstraintInfo Info(Constraint, ""); 1291 if (Target.validateOutputConstraint(Info) && 1292 !Info.allowsRegister()) { 1293 CGM.ErrorUnsupported(&Stmt, "__asm__"); 1294 return Constraint; 1295 } 1296 // Canonicalize the register here before returning it. 1297 Register = Target.getNormalizedGCCRegisterName(Register); 1298 return "{" + Register.str() + "}"; 1299 } 1300 1301 llvm::Value* 1302 CodeGenFunction::EmitAsmInputLValue(const AsmStmt &S, 1303 const TargetInfo::ConstraintInfo &Info, 1304 LValue InputValue, QualType InputType, 1305 std::string &ConstraintStr) { 1306 llvm::Value *Arg; 1307 if (Info.allowsRegister() || !Info.allowsMemory()) { 1308 if (!CodeGenFunction::hasAggregateLLVMType(InputType)) { 1309 Arg = EmitLoadOfLValue(InputValue).getScalarVal(); 1310 } else { 1311 llvm::Type *Ty = ConvertType(InputType); 1312 uint64_t Size = CGM.getTargetData().getTypeSizeInBits(Ty); 1313 if (Size <= 64 && llvm::isPowerOf2_64(Size)) { 1314 Ty = llvm::IntegerType::get(getLLVMContext(), Size); 1315 Ty = llvm::PointerType::getUnqual(Ty); 1316 1317 Arg = Builder.CreateLoad(Builder.CreateBitCast(InputValue.getAddress(), 1318 Ty)); 1319 } else { 1320 Arg = InputValue.getAddress(); 1321 ConstraintStr += '*'; 1322 } 1323 } 1324 } else { 1325 Arg = InputValue.getAddress(); 1326 ConstraintStr += '*'; 1327 } 1328 1329 return Arg; 1330 } 1331 1332 llvm::Value* CodeGenFunction::EmitAsmInput(const AsmStmt &S, 1333 const TargetInfo::ConstraintInfo &Info, 1334 const Expr *InputExpr, 1335 std::string &ConstraintStr) { 1336 if (Info.allowsRegister() || !Info.allowsMemory()) 1337 if (!CodeGenFunction::hasAggregateLLVMType(InputExpr->getType())) 1338 return EmitScalarExpr(InputExpr); 1339 1340 InputExpr = InputExpr->IgnoreParenNoopCasts(getContext()); 1341 LValue Dest = EmitLValue(InputExpr); 1342 return EmitAsmInputLValue(S, Info, Dest, InputExpr->getType(), ConstraintStr); 1343 } 1344 1345 /// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline 1346 /// asm call instruction. The !srcloc MDNode contains a list of constant 1347 /// integers which are the source locations of the start of each line in the 1348 /// asm. 1349 static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str, 1350 CodeGenFunction &CGF) { 1351 SmallVector<llvm::Value *, 8> Locs; 1352 // Add the location of the first line to the MDNode. 1353 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1354 Str->getLocStart().getRawEncoding())); 1355 StringRef StrVal = Str->getString(); 1356 if (!StrVal.empty()) { 1357 const SourceManager &SM = CGF.CGM.getContext().getSourceManager(); 1358 const LangOptions &LangOpts = CGF.CGM.getLangOptions(); 1359 1360 // Add the location of the start of each subsequent line of the asm to the 1361 // MDNode. 1362 for (unsigned i = 0, e = StrVal.size()-1; i != e; ++i) { 1363 if (StrVal[i] != '\n') continue; 1364 SourceLocation LineLoc = Str->getLocationOfByte(i+1, SM, LangOpts, 1365 CGF.Target); 1366 Locs.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 1367 LineLoc.getRawEncoding())); 1368 } 1369 } 1370 1371 return llvm::MDNode::get(CGF.getLLVMContext(), Locs); 1372 } 1373 1374 void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) { 1375 // Analyze the asm string to decompose it into its pieces. We know that Sema 1376 // has already done this, so it is guaranteed to be successful. 1377 SmallVector<AsmStmt::AsmStringPiece, 4> Pieces; 1378 unsigned DiagOffs; 1379 S.AnalyzeAsmString(Pieces, getContext(), DiagOffs); 1380 1381 // Assemble the pieces into the final asm string. 1382 std::string AsmString; 1383 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { 1384 if (Pieces[i].isString()) 1385 AsmString += Pieces[i].getString(); 1386 else if (Pieces[i].getModifier() == '\0') 1387 AsmString += '$' + llvm::utostr(Pieces[i].getOperandNo()); 1388 else 1389 AsmString += "${" + llvm::utostr(Pieces[i].getOperandNo()) + ':' + 1390 Pieces[i].getModifier() + '}'; 1391 } 1392 1393 // Get all the output and input constraints together. 1394 SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 1395 SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 1396 1397 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1398 TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), 1399 S.getOutputName(i)); 1400 bool IsValid = Target.validateOutputConstraint(Info); (void)IsValid; 1401 assert(IsValid && "Failed to parse output constraint"); 1402 OutputConstraintInfos.push_back(Info); 1403 } 1404 1405 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1406 TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), 1407 S.getInputName(i)); 1408 bool IsValid = Target.validateInputConstraint(OutputConstraintInfos.data(), 1409 S.getNumOutputs(), Info); 1410 assert(IsValid && "Failed to parse input constraint"); (void)IsValid; 1411 InputConstraintInfos.push_back(Info); 1412 } 1413 1414 std::string Constraints; 1415 1416 std::vector<LValue> ResultRegDests; 1417 std::vector<QualType> ResultRegQualTys; 1418 std::vector<llvm::Type *> ResultRegTypes; 1419 std::vector<llvm::Type *> ResultTruncRegTypes; 1420 std::vector<llvm::Type*> ArgTypes; 1421 std::vector<llvm::Value*> Args; 1422 1423 // Keep track of inout constraints. 1424 std::string InOutConstraints; 1425 std::vector<llvm::Value*> InOutArgs; 1426 std::vector<llvm::Type*> InOutArgTypes; 1427 1428 for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) { 1429 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 1430 1431 // Simplify the output constraint. 1432 std::string OutputConstraint(S.getOutputConstraint(i)); 1433 OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1, Target); 1434 1435 const Expr *OutExpr = S.getOutputExpr(i); 1436 OutExpr = OutExpr->IgnoreParenNoopCasts(getContext()); 1437 1438 OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr, 1439 Target, CGM, S); 1440 1441 LValue Dest = EmitLValue(OutExpr); 1442 if (!Constraints.empty()) 1443 Constraints += ','; 1444 1445 // If this is a register output, then make the inline asm return it 1446 // by-value. If this is a memory result, return the value by-reference. 1447 if (!Info.allowsMemory() && !hasAggregateLLVMType(OutExpr->getType())) { 1448 Constraints += "=" + OutputConstraint; 1449 ResultRegQualTys.push_back(OutExpr->getType()); 1450 ResultRegDests.push_back(Dest); 1451 ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType())); 1452 ResultTruncRegTypes.push_back(ResultRegTypes.back()); 1453 1454 // If this output is tied to an input, and if the input is larger, then 1455 // we need to set the actual result type of the inline asm node to be the 1456 // same as the input type. 1457 if (Info.hasMatchingInput()) { 1458 unsigned InputNo; 1459 for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) { 1460 TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo]; 1461 if (Input.hasTiedOperand() && Input.getTiedOperand() == i) 1462 break; 1463 } 1464 assert(InputNo != S.getNumInputs() && "Didn't find matching input!"); 1465 1466 QualType InputTy = S.getInputExpr(InputNo)->getType(); 1467 QualType OutputType = OutExpr->getType(); 1468 1469 uint64_t InputSize = getContext().getTypeSize(InputTy); 1470 if (getContext().getTypeSize(OutputType) < InputSize) { 1471 // Form the asm to return the value as a larger integer or fp type. 1472 ResultRegTypes.back() = ConvertType(InputTy); 1473 } 1474 } 1475 if (llvm::Type* AdjTy = 1476 getTargetHooks().adjustInlineAsmType(*this, OutputConstraint, 1477 ResultRegTypes.back())) 1478 ResultRegTypes.back() = AdjTy; 1479 } else { 1480 ArgTypes.push_back(Dest.getAddress()->getType()); 1481 Args.push_back(Dest.getAddress()); 1482 Constraints += "=*"; 1483 Constraints += OutputConstraint; 1484 } 1485 1486 if (Info.isReadWrite()) { 1487 InOutConstraints += ','; 1488 1489 const Expr *InputExpr = S.getOutputExpr(i); 1490 llvm::Value *Arg = EmitAsmInputLValue(S, Info, Dest, InputExpr->getType(), 1491 InOutConstraints); 1492 1493 if (Info.allowsRegister()) 1494 InOutConstraints += llvm::utostr(i); 1495 else 1496 InOutConstraints += OutputConstraint; 1497 1498 InOutArgTypes.push_back(Arg->getType()); 1499 InOutArgs.push_back(Arg); 1500 } 1501 } 1502 1503 unsigned NumConstraints = S.getNumOutputs() + S.getNumInputs(); 1504 1505 for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) { 1506 const Expr *InputExpr = S.getInputExpr(i); 1507 1508 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 1509 1510 if (!Constraints.empty()) 1511 Constraints += ','; 1512 1513 // Simplify the input constraint. 1514 std::string InputConstraint(S.getInputConstraint(i)); 1515 InputConstraint = SimplifyConstraint(InputConstraint.c_str(), Target, 1516 &OutputConstraintInfos); 1517 1518 InputConstraint = 1519 AddVariableConstraints(InputConstraint, 1520 *InputExpr->IgnoreParenNoopCasts(getContext()), 1521 Target, CGM, S); 1522 1523 llvm::Value *Arg = EmitAsmInput(S, Info, InputExpr, Constraints); 1524 1525 // If this input argument is tied to a larger output result, extend the 1526 // input to be the same size as the output. The LLVM backend wants to see 1527 // the input and output of a matching constraint be the same size. Note 1528 // that GCC does not define what the top bits are here. We use zext because 1529 // that is usually cheaper, but LLVM IR should really get an anyext someday. 1530 if (Info.hasTiedOperand()) { 1531 unsigned Output = Info.getTiedOperand(); 1532 QualType OutputType = S.getOutputExpr(Output)->getType(); 1533 QualType InputTy = InputExpr->getType(); 1534 1535 if (getContext().getTypeSize(OutputType) > 1536 getContext().getTypeSize(InputTy)) { 1537 // Use ptrtoint as appropriate so that we can do our extension. 1538 if (isa<llvm::PointerType>(Arg->getType())) 1539 Arg = Builder.CreatePtrToInt(Arg, IntPtrTy); 1540 llvm::Type *OutputTy = ConvertType(OutputType); 1541 if (isa<llvm::IntegerType>(OutputTy)) 1542 Arg = Builder.CreateZExt(Arg, OutputTy); 1543 else if (isa<llvm::PointerType>(OutputTy)) 1544 Arg = Builder.CreateZExt(Arg, IntPtrTy); 1545 else { 1546 assert(OutputTy->isFloatingPointTy() && "Unexpected output type"); 1547 Arg = Builder.CreateFPExt(Arg, OutputTy); 1548 } 1549 } 1550 } 1551 if (llvm::Type* AdjTy = 1552 getTargetHooks().adjustInlineAsmType(*this, InputConstraint, 1553 Arg->getType())) 1554 Arg = Builder.CreateBitCast(Arg, AdjTy); 1555 1556 ArgTypes.push_back(Arg->getType()); 1557 Args.push_back(Arg); 1558 Constraints += InputConstraint; 1559 } 1560 1561 // Append the "input" part of inout constraints last. 1562 for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) { 1563 ArgTypes.push_back(InOutArgTypes[i]); 1564 Args.push_back(InOutArgs[i]); 1565 } 1566 Constraints += InOutConstraints; 1567 1568 // Clobbers 1569 for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) { 1570 StringRef Clobber = S.getClobber(i)->getString(); 1571 1572 if (Clobber != "memory" && Clobber != "cc") 1573 Clobber = Target.getNormalizedGCCRegisterName(Clobber); 1574 1575 if (i != 0 || NumConstraints != 0) 1576 Constraints += ','; 1577 1578 Constraints += "~{"; 1579 Constraints += Clobber; 1580 Constraints += '}'; 1581 } 1582 1583 // Add machine specific clobbers 1584 std::string MachineClobbers = Target.getClobbers(); 1585 if (!MachineClobbers.empty()) { 1586 if (!Constraints.empty()) 1587 Constraints += ','; 1588 Constraints += MachineClobbers; 1589 } 1590 1591 llvm::Type *ResultType; 1592 if (ResultRegTypes.empty()) 1593 ResultType = llvm::Type::getVoidTy(getLLVMContext()); 1594 else if (ResultRegTypes.size() == 1) 1595 ResultType = ResultRegTypes[0]; 1596 else 1597 ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes); 1598 1599 llvm::FunctionType *FTy = 1600 llvm::FunctionType::get(ResultType, ArgTypes, false); 1601 1602 llvm::InlineAsm *IA = 1603 llvm::InlineAsm::get(FTy, AsmString, Constraints, 1604 S.isVolatile() || S.getNumOutputs() == 0); 1605 llvm::CallInst *Result = Builder.CreateCall(IA, Args); 1606 Result->addAttribute(~0, llvm::Attribute::NoUnwind); 1607 1608 // Slap the source location of the inline asm into a !srcloc metadata on the 1609 // call. 1610 Result->setMetadata("srcloc", getAsmSrcLocInfo(S.getAsmString(), *this)); 1611 1612 // Extract all of the register value results from the asm. 1613 std::vector<llvm::Value*> RegResults; 1614 if (ResultRegTypes.size() == 1) { 1615 RegResults.push_back(Result); 1616 } else { 1617 for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) { 1618 llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult"); 1619 RegResults.push_back(Tmp); 1620 } 1621 } 1622 1623 for (unsigned i = 0, e = RegResults.size(); i != e; ++i) { 1624 llvm::Value *Tmp = RegResults[i]; 1625 1626 // If the result type of the LLVM IR asm doesn't match the result type of 1627 // the expression, do the conversion. 1628 if (ResultRegTypes[i] != ResultTruncRegTypes[i]) { 1629 llvm::Type *TruncTy = ResultTruncRegTypes[i]; 1630 1631 // Truncate the integer result to the right size, note that TruncTy can be 1632 // a pointer. 1633 if (TruncTy->isFloatingPointTy()) 1634 Tmp = Builder.CreateFPTrunc(Tmp, TruncTy); 1635 else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) { 1636 uint64_t ResSize = CGM.getTargetData().getTypeSizeInBits(TruncTy); 1637 Tmp = Builder.CreateTrunc(Tmp, 1638 llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize)); 1639 Tmp = Builder.CreateIntToPtr(Tmp, TruncTy); 1640 } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) { 1641 uint64_t TmpSize =CGM.getTargetData().getTypeSizeInBits(Tmp->getType()); 1642 Tmp = Builder.CreatePtrToInt(Tmp, 1643 llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize)); 1644 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1645 } else if (TruncTy->isIntegerTy()) { 1646 Tmp = Builder.CreateTrunc(Tmp, TruncTy); 1647 } else if (TruncTy->isVectorTy()) { 1648 Tmp = Builder.CreateBitCast(Tmp, TruncTy); 1649 } 1650 } 1651 1652 EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i]); 1653 } 1654 } 1655