1 //===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This coordinates the per-function state used while generating code.
12 //===----------------------------------------------------------------------===//
14 #include "CodeGenFunction.h"
15 #include "CodeGenModule.h"
16 #include "CGCUDARuntime.h"
18 #include "CGDebugInfo.h"
19 #include "CGException.h"
20 #include "clang/Basic/TargetInfo.h"
21 #include "clang/AST/APValue.h"
22 #include "clang/AST/ASTContext.h"
23 #include "clang/AST/Decl.h"
24 #include "clang/AST/DeclCXX.h"
25 #include "clang/AST/StmtCXX.h"
26 #include "clang/Frontend/CodeGenOptions.h"
27 #include "llvm/Target/TargetData.h"
28 #include "llvm/Intrinsics.h"
29 using namespace clang;
30 using namespace CodeGen;
32 CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
33 : CodeGenTypeCache(cgm), CGM(cgm),
34 Target(CGM.getContext().getTargetInfo()), Builder(cgm.getModule().getContext()),
35 AutoreleaseResult(false), BlockInfo(0), BlockPointer(0),
36 NormalCleanupDest(0), NextCleanupDestIndex(1),
37 EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0),
38 DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false),
39 IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0),
40 CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0),
41 OutermostConditional(0), TerminateLandingPad(0), TerminateHandler(0),
44 CatchUndefined = getContext().getLangOptions().CatchUndefined;
45 CGM.getCXXABI().getMangleContext().startNewFunction();
49 llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
50 return CGM.getTypes().ConvertTypeForMem(T);
53 llvm::Type *CodeGenFunction::ConvertType(QualType T) {
54 return CGM.getTypes().ConvertType(T);
57 bool CodeGenFunction::hasAggregateLLVMType(QualType type) {
58 switch (type.getCanonicalType()->getTypeClass()) {
59 #define TYPE(name, parent)
60 #define ABSTRACT_TYPE(name, parent)
61 #define NON_CANONICAL_TYPE(name, parent) case Type::name:
62 #define DEPENDENT_TYPE(name, parent) case Type::name:
63 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name:
64 #include "clang/AST/TypeNodes.def"
65 llvm_unreachable("non-canonical or dependent type in IR-generation");
69 case Type::BlockPointer:
70 case Type::LValueReference:
71 case Type::RValueReference:
72 case Type::MemberPointer:
75 case Type::FunctionProto:
76 case Type::FunctionNoProto:
78 case Type::ObjCObjectPointer:
81 // Complexes, arrays, records, and Objective-C objects.
83 case Type::ConstantArray:
84 case Type::IncompleteArray:
85 case Type::VariableArray:
87 case Type::ObjCObject:
88 case Type::ObjCInterface:
91 // In IRGen, atomic types are just the underlying type
93 return hasAggregateLLVMType(type->getAs<AtomicType>()->getValueType());
95 llvm_unreachable("unknown type kind!");
98 void CodeGenFunction::EmitReturnBlock() {
99 // For cleanliness, we try to avoid emitting the return block for
101 llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
104 assert(!CurBB->getTerminator() && "Unexpected terminated block.");
106 // We have a valid insert point, reuse it if it is empty or there are no
107 // explicit jumps to the return block.
108 if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) {
109 ReturnBlock.getBlock()->replaceAllUsesWith(CurBB);
110 delete ReturnBlock.getBlock();
112 EmitBlock(ReturnBlock.getBlock());
116 // Otherwise, if the return block is the target of a single direct
117 // branch then we can just put the code in that block instead. This
118 // cleans up functions which started with a unified return block.
119 if (ReturnBlock.getBlock()->hasOneUse()) {
120 llvm::BranchInst *BI =
121 dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin());
122 if (BI && BI->isUnconditional() &&
123 BI->getSuccessor(0) == ReturnBlock.getBlock()) {
124 // Reset insertion point, including debug location, and delete the branch.
125 Builder.SetCurrentDebugLocation(BI->getDebugLoc());
126 Builder.SetInsertPoint(BI->getParent());
127 BI->eraseFromParent();
128 delete ReturnBlock.getBlock();
133 // FIXME: We are at an unreachable point, there is no reason to emit the block
134 // unless it has uses. However, we still need a place to put the debug
135 // region.end for now.
137 EmitBlock(ReturnBlock.getBlock());
140 static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) {
142 if (!BB->use_empty())
143 return CGF.CurFn->getBasicBlockList().push_back(BB);
147 void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
148 assert(BreakContinueStack.empty() &&
149 "mismatched push/pop in break/continue stack!");
151 // Pop any cleanups that might have been associated with the
152 // parameters. Do this in whatever block we're currently in; it's
153 // important to do this before we enter the return block or return
154 // edges will be *really* confused.
155 if (EHStack.stable_begin() != PrologueCleanupDepth)
156 PopCleanupBlocks(PrologueCleanupDepth);
158 // Emit function epilog (to return).
161 if (ShouldInstrumentFunction())
162 EmitFunctionInstrumentation("__cyg_profile_func_exit");
164 // Emit debug descriptor for function end.
165 if (CGDebugInfo *DI = getDebugInfo()) {
166 DI->setLocation(EndLoc);
167 DI->EmitFunctionEnd(Builder);
170 EmitFunctionEpilog(*CurFnInfo);
171 EmitEndEHSpec(CurCodeDecl);
173 assert(EHStack.empty() &&
174 "did not remove all scopes from cleanup stack!");
176 // If someone did an indirect goto, emit the indirect goto block at the end of
178 if (IndirectBranch) {
179 EmitBlock(IndirectBranch->getParent());
180 Builder.ClearInsertionPoint();
183 // Remove the AllocaInsertPt instruction, which is just a convenience for us.
184 llvm::Instruction *Ptr = AllocaInsertPt;
186 Ptr->eraseFromParent();
188 // If someone took the address of a label but never did an indirect goto, we
189 // made a zero entry PHI node, which is illegal, zap it now.
190 if (IndirectBranch) {
191 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
192 if (PN->getNumIncomingValues() == 0) {
193 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
194 PN->eraseFromParent();
198 EmitIfUsed(*this, EHResumeBlock);
199 EmitIfUsed(*this, TerminateLandingPad);
200 EmitIfUsed(*this, TerminateHandler);
201 EmitIfUsed(*this, UnreachableBlock);
203 if (CGM.getCodeGenOpts().EmitDeclMetadata)
207 /// ShouldInstrumentFunction - Return true if the current function should be
208 /// instrumented with __cyg_profile_func_* calls
209 bool CodeGenFunction::ShouldInstrumentFunction() {
210 if (!CGM.getCodeGenOpts().InstrumentFunctions)
212 if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
217 /// EmitFunctionInstrumentation - Emit LLVM code to call the specified
218 /// instrumentation function with the current function and the call site, if
219 /// function instrumentation is enabled.
220 void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) {
221 // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site);
222 llvm::PointerType *PointerTy = Int8PtrTy;
223 llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy };
224 llvm::FunctionType *FunctionTy =
225 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()),
226 ProfileFuncArgs, false);
228 llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn);
229 llvm::CallInst *CallSite = Builder.CreateCall(
230 CGM.getIntrinsic(llvm::Intrinsic::returnaddress),
231 llvm::ConstantInt::get(Int32Ty, 0),
234 Builder.CreateCall2(F,
235 llvm::ConstantExpr::getBitCast(CurFn, PointerTy),
239 void CodeGenFunction::EmitMCountInstrumentation() {
240 llvm::FunctionType *FTy =
241 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), false);
243 llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy,
244 Target.getMCountName());
245 Builder.CreateCall(MCountFn);
248 void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
250 const CGFunctionInfo &FnInfo,
251 const FunctionArgList &Args,
252 SourceLocation StartLoc) {
253 const Decl *D = GD.getDecl();
255 DidCallStackSave = false;
256 CurCodeDecl = CurFuncDecl = D;
260 assert(CurFn->isDeclaration() && "Function already has body?");
262 // Pass inline keyword to optimizer if it appears explicitly on any
264 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
265 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(),
266 RE = FD->redecls_end(); RI != RE; ++RI)
267 if (RI->isInlineSpecified()) {
268 Fn->addFnAttr(llvm::Attribute::InlineHint);
272 if (getContext().getLangOptions().OpenCL) {
273 // Add metadata for a kernel function.
274 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
275 if (FD->hasAttr<OpenCLKernelAttr>()) {
276 llvm::LLVMContext &Context = getLLVMContext();
277 llvm::NamedMDNode *OpenCLMetadata =
278 CGM.getModule().getOrInsertNamedMetadata("opencl.kernels");
280 llvm::Value *Op = Fn;
281 OpenCLMetadata->addOperand(llvm::MDNode::get(Context, Op));
285 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
287 // Create a marker to make it easy to insert allocas into the entryblock
288 // later. Don't create this with the builder, because we don't want it
290 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
291 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
292 if (Builder.isNamePreserving())
293 AllocaInsertPt->setName("allocapt");
295 ReturnBlock = getJumpDestInCurrentScope("return");
297 Builder.SetInsertPoint(EntryBB);
299 // Emit subprogram debug descriptor.
300 if (CGDebugInfo *DI = getDebugInfo()) {
301 // FIXME: what is going on here and why does it ignore all these
302 // interesting type properties?
304 getContext().getFunctionType(RetTy, 0, 0,
305 FunctionProtoType::ExtProtoInfo());
307 DI->setLocation(StartLoc);
308 DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
311 if (ShouldInstrumentFunction())
312 EmitFunctionInstrumentation("__cyg_profile_func_enter");
314 if (CGM.getCodeGenOpts().InstrumentForProfiling)
315 EmitMCountInstrumentation();
317 if (RetTy->isVoidType()) {
318 // Void type; nothing to return.
320 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
321 hasAggregateLLVMType(CurFnInfo->getReturnType())) {
322 // Indirect aggregate return; emit returned value directly into sret slot.
323 // This reduces code size, and affects correctness in C++.
324 ReturnValue = CurFn->arg_begin();
326 ReturnValue = CreateIRTemp(RetTy, "retval");
328 // Tell the epilog emitter to autorelease the result. We do this
329 // now so that various specialized functions can suppress it
330 // during their IR-generation.
331 if (getLangOptions().ObjCAutoRefCount &&
332 !CurFnInfo->isReturnsRetained() &&
333 RetTy->isObjCRetainableType())
334 AutoreleaseResult = true;
337 EmitStartEHSpec(CurCodeDecl);
339 PrologueCleanupDepth = EHStack.stable_begin();
340 EmitFunctionProlog(*CurFnInfo, CurFn, Args);
342 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance())
343 CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
345 // If any of the arguments have a variably modified type, make sure to
346 // emit the type size.
347 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
349 QualType Ty = (*i)->getType();
351 if (Ty->isVariablyModifiedType())
352 EmitVariablyModifiedType(Ty);
354 // Emit a location at the end of the prologue.
355 if (CGDebugInfo *DI = getDebugInfo())
356 DI->EmitLocation(Builder, StartLoc);
359 void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
360 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
361 assert(FD->getBody());
362 EmitStmt(FD->getBody());
365 /// Tries to mark the given function nounwind based on the
366 /// non-existence of any throwing calls within it. We believe this is
367 /// lightweight enough to do at -O0.
368 static void TryMarkNoThrow(llvm::Function *F) {
369 // LLVM treats 'nounwind' on a function as part of the type, so we
370 // can't do this on functions that can be overwritten.
371 if (F->mayBeOverridden()) return;
373 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI)
374 for (llvm::BasicBlock::iterator
375 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI)
376 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) {
377 if (!Call->doesNotThrow())
379 } else if (isa<llvm::ResumeInst>(&*BI)) {
382 F->setDoesNotThrow(true);
385 void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
386 const CGFunctionInfo &FnInfo) {
387 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
389 // Check if we should generate debug info for this function.
390 if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>())
391 DebugInfo = CGM.getModuleDebugInfo();
393 FunctionArgList Args;
394 QualType ResTy = FD->getResultType();
397 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance())
398 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args);
400 if (FD->getNumParams())
401 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
402 Args.push_back(FD->getParamDecl(i));
404 SourceRange BodyRange;
405 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
407 // Emit the standard function prologue.
408 StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin());
410 // Generate the body of the function.
411 if (isa<CXXDestructorDecl>(FD))
412 EmitDestructorBody(Args);
413 else if (isa<CXXConstructorDecl>(FD))
414 EmitConstructorBody(Args);
415 else if (getContext().getLangOptions().CUDA &&
416 !CGM.getCodeGenOpts().CUDAIsDevice &&
417 FD->hasAttr<CUDAGlobalAttr>())
418 CGM.getCUDARuntime().EmitDeviceStubBody(*this, Args);
420 EmitFunctionBody(Args);
422 // Emit the standard function epilogue.
423 FinishFunction(BodyRange.getEnd());
425 // If we haven't marked the function nothrow through other means, do
426 // a quick pass now to see if we can.
427 if (!CurFn->doesNotThrow())
428 TryMarkNoThrow(CurFn);
431 /// ContainsLabel - Return true if the statement contains a label in it. If
432 /// this statement is not executed normally, it not containing a label means
433 /// that we can just remove the code.
434 bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
435 // Null statement, not a label!
436 if (S == 0) return false;
438 // If this is a label, we have to emit the code, consider something like:
439 // if (0) { ... foo: bar(); } goto foo;
441 // TODO: If anyone cared, we could track __label__'s, since we know that you
442 // can't jump to one from outside their declared region.
443 if (isa<LabelStmt>(S))
446 // If this is a case/default statement, and we haven't seen a switch, we have
448 if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
451 // If this is a switch statement, we want to ignore cases below it.
452 if (isa<SwitchStmt>(S))
453 IgnoreCaseStmts = true;
455 // Scan subexpressions for verboten labels.
456 for (Stmt::const_child_range I = S->children(); I; ++I)
457 if (ContainsLabel(*I, IgnoreCaseStmts))
463 /// containsBreak - Return true if the statement contains a break out of it.
464 /// If the statement (recursively) contains a switch or loop with a break
465 /// inside of it, this is fine.
466 bool CodeGenFunction::containsBreak(const Stmt *S) {
467 // Null statement, not a label!
468 if (S == 0) return false;
470 // If this is a switch or loop that defines its own break scope, then we can
471 // include it and anything inside of it.
472 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) ||
476 if (isa<BreakStmt>(S))
479 // Scan subexpressions for verboten breaks.
480 for (Stmt::const_child_range I = S->children(); I; ++I)
481 if (containsBreak(*I))
488 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
489 /// to a constant, or if it does but contains a label, return false. If it
490 /// constant folds return true and set the boolean result in Result.
491 bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond,
493 llvm::APInt ResultInt;
494 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt))
497 ResultBool = ResultInt.getBoolValue();
501 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
502 /// to a constant, or if it does but contains a label, return false. If it
503 /// constant folds return true and set the folded value.
504 bool CodeGenFunction::
505 ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) {
506 // FIXME: Rename and handle conversion of other evaluatable things
508 Expr::EvalResult Result;
509 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() ||
510 Result.HasSideEffects)
511 return false; // Not foldable, not integer or not fully evaluatable.
513 if (CodeGenFunction::ContainsLabel(Cond))
514 return false; // Contains a label.
516 ResultInt = Result.Val.getInt();
522 /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
523 /// statement) to the specified blocks. Based on the condition, this might try
524 /// to simplify the codegen of the conditional based on the branch.
526 void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
527 llvm::BasicBlock *TrueBlock,
528 llvm::BasicBlock *FalseBlock) {
529 Cond = Cond->IgnoreParens();
531 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
532 // Handle X && Y in a condition.
533 if (CondBOp->getOpcode() == BO_LAnd) {
534 // If we have "1 && X", simplify the code. "0 && X" would have constant
535 // folded if the case was simple enough.
536 bool ConstantBool = false;
537 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
539 // br(1 && X) -> br(X).
540 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
543 // If we have "X && 1", simplify the code to use an uncond branch.
544 // "X && 0" would have been constant folded to 0.
545 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
547 // br(X && 1) -> br(X).
548 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
551 // Emit the LHS as a conditional. If the LHS conditional is false, we
552 // want to jump to the FalseBlock.
553 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true");
555 ConditionalEvaluation eval(*this);
556 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
559 // Any temporaries created here are conditional.
561 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
567 if (CondBOp->getOpcode() == BO_LOr) {
568 // If we have "0 || X", simplify the code. "1 || X" would have constant
569 // folded if the case was simple enough.
570 bool ConstantBool = false;
571 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
573 // br(0 || X) -> br(X).
574 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
577 // If we have "X || 0", simplify the code to use an uncond branch.
578 // "X || 1" would have been constant folded to 1.
579 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
581 // br(X || 0) -> br(X).
582 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
585 // Emit the LHS as a conditional. If the LHS conditional is true, we
586 // want to jump to the TrueBlock.
587 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false");
589 ConditionalEvaluation eval(*this);
590 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
593 // Any temporaries created here are conditional.
595 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
602 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) {
603 // br(!x, t, f) -> br(x, f, t)
604 if (CondUOp->getOpcode() == UO_LNot)
605 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock);
608 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) {
609 // Handle ?: operator.
611 // Just ignore GNU ?: extension.
612 if (CondOp->getLHS()) {
613 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f))
614 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
615 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
617 ConditionalEvaluation cond(*this);
618 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
622 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
627 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
634 // Emit the code with the fully general case.
635 llvm::Value *CondV = EvaluateExprAsBool(Cond);
636 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
639 /// ErrorUnsupported - Print out an error that codegen doesn't support the
640 /// specified stmt yet.
641 void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type,
643 CGM.ErrorUnsupported(S, Type, OmitOnError);
646 /// emitNonZeroVLAInit - Emit the "zero" initialization of a
647 /// variable-length array whose elements have a non-zero bit-pattern.
649 /// \param src - a char* pointing to the bit-pattern for a single
650 /// base element of the array
651 /// \param sizeInChars - the total size of the VLA, in chars
652 /// \param align - the total alignment of the VLA
653 static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType,
654 llvm::Value *dest, llvm::Value *src,
655 llvm::Value *sizeInChars) {
656 std::pair<CharUnits,CharUnits> baseSizeAndAlign
657 = CGF.getContext().getTypeInfoInChars(baseType);
659 CGBuilderTy &Builder = CGF.Builder;
661 llvm::Value *baseSizeInChars
662 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity());
664 llvm::Type *i8p = Builder.getInt8PtrTy();
666 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin");
667 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end");
669 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock();
670 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop");
671 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont");
673 // Make a loop over the VLA. C99 guarantees that the VLA element
674 // count must be nonzero.
675 CGF.EmitBlock(loopBB);
677 llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur");
678 cur->addIncoming(begin, originBB);
680 // memcpy the individual element bit-pattern.
681 Builder.CreateMemCpy(cur, src, baseSizeInChars,
682 baseSizeAndAlign.second.getQuantity(),
685 // Go to the next element.
686 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next");
688 // Leave if that's the end of the VLA.
689 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone");
690 Builder.CreateCondBr(done, contBB, loopBB);
691 cur->addIncoming(next, loopBB);
693 CGF.EmitBlock(contBB);
697 CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
698 // Ignore empty classes in C++.
699 if (getContext().getLangOptions().CPlusPlus) {
700 if (const RecordType *RT = Ty->getAs<RecordType>()) {
701 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
706 // Cast the dest ptr to the appropriate i8 pointer type.
708 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace();
709 llvm::Type *BP = Builder.getInt8PtrTy(DestAS);
710 if (DestPtr->getType() != BP)
711 DestPtr = Builder.CreateBitCast(DestPtr, BP);
713 // Get size and alignment info for this aggregate.
714 std::pair<CharUnits, CharUnits> TypeInfo =
715 getContext().getTypeInfoInChars(Ty);
716 CharUnits Size = TypeInfo.first;
717 CharUnits Align = TypeInfo.second;
719 llvm::Value *SizeVal;
720 const VariableArrayType *vla;
722 // Don't bother emitting a zero-byte memset.
724 // But note that getTypeInfo returns 0 for a VLA.
725 if (const VariableArrayType *vlaType =
726 dyn_cast_or_null<VariableArrayType>(
727 getContext().getAsArrayType(Ty))) {
729 llvm::Value *numElts;
730 llvm::tie(numElts, eltType) = getVLASize(vlaType);
733 CharUnits eltSize = getContext().getTypeSizeInChars(eltType);
734 if (!eltSize.isOne())
735 SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize));
741 SizeVal = CGM.getSize(Size);
745 // If the type contains a pointer to data member we can't memset it to zero.
746 // Instead, create a null constant and copy it to the destination.
747 // TODO: there are other patterns besides zero that we can usefully memset,
748 // like -1, which happens to be the pattern used by member-pointers.
749 if (!CGM.getTypes().isZeroInitializable(Ty)) {
750 // For a VLA, emit a single element, then splat that over the VLA.
751 if (vla) Ty = getContext().getBaseElementType(vla);
753 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
755 llvm::GlobalVariable *NullVariable =
756 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
758 llvm::GlobalVariable::PrivateLinkage,
759 NullConstant, Twine());
760 llvm::Value *SrcPtr =
761 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy());
763 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal);
765 // Get and call the appropriate llvm.memcpy overload.
766 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false);
770 // Otherwise, just memset the whole thing to zero. This is legal
771 // because in LLVM, all default initializers (other than the ones we just
772 // handled above) are guaranteed to have a bit pattern of all zeros.
773 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal,
774 Align.getQuantity(), false);
777 llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) {
778 // Make sure that there is a block for the indirect goto.
779 if (IndirectBranch == 0)
780 GetIndirectGotoBlock();
782 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock();
784 // Make sure the indirect branch includes all of the address-taken blocks.
785 IndirectBranch->addDestination(BB);
786 return llvm::BlockAddress::get(CurFn, BB);
789 llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() {
790 // If we already made the indirect branch for indirect goto, return its block.
791 if (IndirectBranch) return IndirectBranch->getParent();
793 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto"));
795 // Create the PHI node that indirect gotos will add entries to.
796 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0,
797 "indirect.goto.dest");
799 // Create the indirect branch instruction.
800 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
801 return IndirectBranch->getParent();
804 /// Computes the length of an array in elements, as well as the base
805 /// element type and a properly-typed first element pointer.
806 llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType,
808 llvm::Value *&addr) {
809 const ArrayType *arrayType = origArrayType;
811 // If it's a VLA, we have to load the stored size. Note that
812 // this is the size of the VLA in bytes, not its size in elements.
813 llvm::Value *numVLAElements = 0;
814 if (isa<VariableArrayType>(arrayType)) {
815 numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first;
817 // Walk into all VLAs. This doesn't require changes to addr,
818 // which has type T* where T is the first non-VLA element type.
820 QualType elementType = arrayType->getElementType();
821 arrayType = getContext().getAsArrayType(elementType);
823 // If we only have VLA components, 'addr' requires no adjustment.
825 baseType = elementType;
826 return numVLAElements;
828 } while (isa<VariableArrayType>(arrayType));
830 // We get out here only if we find a constant array type
834 // We have some number of constant-length arrays, so addr should
835 // have LLVM type [M x [N x [...]]]*. Build a GEP that walks
836 // down to the first element of addr.
837 SmallVector<llvm::Value*, 8> gepIndices;
839 // GEP down to the array type.
840 llvm::ConstantInt *zero = Builder.getInt32(0);
841 gepIndices.push_back(zero);
843 // It's more efficient to calculate the count from the LLVM
844 // constant-length arrays than to re-evaluate the array bounds.
845 uint64_t countFromCLAs = 1;
847 llvm::ArrayType *llvmArrayType =
848 cast<llvm::ArrayType>(
849 cast<llvm::PointerType>(addr->getType())->getElementType());
851 assert(isa<ConstantArrayType>(arrayType));
852 assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue()
853 == llvmArrayType->getNumElements());
855 gepIndices.push_back(zero);
856 countFromCLAs *= llvmArrayType->getNumElements();
859 dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType());
860 if (!llvmArrayType) break;
862 arrayType = getContext().getAsArrayType(arrayType->getElementType());
863 assert(arrayType && "LLVM and Clang types are out-of-synch");
866 baseType = arrayType->getElementType();
868 // Create the actual GEP.
869 addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin");
871 llvm::Value *numElements
872 = llvm::ConstantInt::get(SizeTy, countFromCLAs);
874 // If we had any VLA dimensions, factor them in.
876 numElements = Builder.CreateNUWMul(numVLAElements, numElements);
881 std::pair<llvm::Value*, QualType>
882 CodeGenFunction::getVLASize(QualType type) {
883 const VariableArrayType *vla = getContext().getAsVariableArrayType(type);
884 assert(vla && "type was not a variable array type!");
885 return getVLASize(vla);
888 std::pair<llvm::Value*, QualType>
889 CodeGenFunction::getVLASize(const VariableArrayType *type) {
890 // The number of elements so far; always size_t.
891 llvm::Value *numElements = 0;
893 QualType elementType;
895 elementType = type->getElementType();
896 llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()];
897 assert(vlaSize && "no size for VLA!");
898 assert(vlaSize->getType() == SizeTy);
901 numElements = vlaSize;
903 // It's undefined behavior if this wraps around, so mark it that way.
904 numElements = Builder.CreateNUWMul(numElements, vlaSize);
906 } while ((type = getContext().getAsVariableArrayType(elementType)));
908 return std::pair<llvm::Value*,QualType>(numElements, elementType);
911 void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
912 assert(type->isVariablyModifiedType() &&
913 "Must pass variably modified type to EmitVLASizes!");
917 // We're going to walk down into the type and look for VLA
919 type = type.getCanonicalType();
921 assert(type->isVariablyModifiedType());
923 const Type *ty = type.getTypePtr();
924 switch (ty->getTypeClass()) {
925 #define TYPE(Class, Base)
926 #define ABSTRACT_TYPE(Class, Base)
927 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
928 #define DEPENDENT_TYPE(Class, Base) case Type::Class:
929 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
930 #include "clang/AST/TypeNodes.def"
931 llvm_unreachable("unexpected dependent or non-canonical type!");
933 // These types are never variably-modified.
937 case Type::ExtVector:
940 case Type::ObjCObject:
941 case Type::ObjCInterface:
942 case Type::ObjCObjectPointer:
943 llvm_unreachable("type class is never variably-modified!");
946 type = cast<PointerType>(ty)->getPointeeType();
949 case Type::BlockPointer:
950 type = cast<BlockPointerType>(ty)->getPointeeType();
953 case Type::LValueReference:
954 case Type::RValueReference:
955 type = cast<ReferenceType>(ty)->getPointeeType();
958 case Type::MemberPointer:
959 type = cast<MemberPointerType>(ty)->getPointeeType();
962 case Type::ConstantArray:
963 case Type::IncompleteArray:
964 // Losing element qualification here is fine.
965 type = cast<ArrayType>(ty)->getElementType();
968 case Type::VariableArray: {
969 // Losing element qualification here is fine.
970 const VariableArrayType *vat = cast<VariableArrayType>(ty);
972 // Unknown size indication requires no size computation.
973 // Otherwise, evaluate and record it.
974 if (const Expr *size = vat->getSizeExpr()) {
975 // It's possible that we might have emitted this already,
976 // e.g. with a typedef and a pointer to it.
977 llvm::Value *&entry = VLASizeMap[size];
979 // Always zexting here would be wrong if it weren't
980 // undefined behavior to have a negative bound.
981 entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy,
985 type = vat->getElementType();
989 case Type::FunctionProto:
990 case Type::FunctionNoProto:
991 type = cast<FunctionType>(ty)->getResultType();
995 type = cast<AtomicType>(ty)->getValueType();
998 } while (type->isVariablyModifiedType());
1001 llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
1002 if (getContext().getBuiltinVaListType()->isArrayType())
1003 return EmitScalarExpr(E);
1004 return EmitLValue(E).getAddress();
1007 void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E,
1008 llvm::Constant *Init) {
1009 assert (Init && "Invalid DeclRefExpr initializer!");
1010 if (CGDebugInfo *Dbg = getDebugInfo())
1011 Dbg->EmitGlobalVariable(E->getDecl(), Init);
1014 CodeGenFunction::PeepholeProtection
1015 CodeGenFunction::protectFromPeepholes(RValue rvalue) {
1016 // At the moment, the only aggressive peephole we do in IR gen
1017 // is trunc(zext) folding, but if we add more, we can easily
1018 // extend this protection.
1020 if (!rvalue.isScalar()) return PeepholeProtection();
1021 llvm::Value *value = rvalue.getScalarVal();
1022 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection();
1024 // Just make an extra bitcast.
1025 assert(HaveInsertPoint());
1026 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "",
1027 Builder.GetInsertBlock());
1029 PeepholeProtection protection;
1030 protection.Inst = inst;
1034 void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) {
1035 if (!protection.Inst) return;
1037 // In theory, we could try to duplicate the peepholes now, but whatever.
1038 protection.Inst->eraseFromParent();
1041 llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Value *AnnotationFn,
1042 llvm::Value *AnnotatedVal,
1043 llvm::StringRef AnnotationStr,
1044 SourceLocation Location) {
1045 llvm::Value *Args[4] = {
1047 Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy),
1048 Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy),
1049 CGM.EmitAnnotationLineNo(Location)
1051 return Builder.CreateCall(AnnotationFn, Args);
1054 void CodeGenFunction::EmitVarAnnotations(const VarDecl *D, llvm::Value *V) {
1055 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
1056 // FIXME We create a new bitcast for every annotation because that's what
1057 // llvm-gcc was doing.
1058 for (specific_attr_iterator<AnnotateAttr>
1059 ai = D->specific_attr_begin<AnnotateAttr>(),
1060 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai)
1061 EmitAnnotationCall(CGM.getIntrinsic(llvm::Intrinsic::var_annotation),
1062 Builder.CreateBitCast(V, CGM.Int8PtrTy, V->getName()),
1063 (*ai)->getAnnotation(), D->getLocation());
1066 llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D,
1068 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
1069 llvm::Type *VTy = V->getType();
1070 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::ptr_annotation,
1073 for (specific_attr_iterator<AnnotateAttr>
1074 ai = D->specific_attr_begin<AnnotateAttr>(),
1075 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) {
1076 // FIXME Always emit the cast inst so we can differentiate between
1077 // annotation on the first field of a struct and annotation on the struct
1079 if (VTy != CGM.Int8PtrTy)
1080 V = Builder.Insert(new llvm::BitCastInst(V, CGM.Int8PtrTy));
1081 V = EmitAnnotationCall(F, V, (*ai)->getAnnotation(), D->getLocation());
1082 V = Builder.CreateBitCast(V, VTy);