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"
17 #include "CGDebugInfo.h"
18 #include "CGException.h"
19 #include "clang/Basic/TargetInfo.h"
20 #include "clang/AST/APValue.h"
21 #include "clang/AST/ASTContext.h"
22 #include "clang/AST/Decl.h"
23 #include "clang/AST/DeclCXX.h"
24 #include "clang/AST/StmtCXX.h"
25 #include "clang/Frontend/CodeGenOptions.h"
26 #include "llvm/Target/TargetData.h"
27 #include "llvm/Intrinsics.h"
28 using namespace clang;
29 using namespace CodeGen;
31 CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
32 : CodeGenTypeCache(cgm), CGM(cgm),
33 Target(CGM.getContext().Target), Builder(cgm.getModule().getContext()),
34 AutoreleaseResult(false), BlockInfo(0), BlockPointer(0),
35 NormalCleanupDest(0), EHCleanupDest(0), NextCleanupDestIndex(1),
36 ExceptionSlot(0), EHSelectorSlot(0),
37 DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false),
38 IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0),
39 CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0),
40 OutermostConditional(0), TerminateLandingPad(0), TerminateHandler(0),
43 CatchUndefined = getContext().getLangOptions().CatchUndefined;
44 CGM.getCXXABI().getMangleContext().startNewFunction();
48 llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
49 return CGM.getTypes().ConvertTypeForMem(T);
52 llvm::Type *CodeGenFunction::ConvertType(QualType T) {
53 return CGM.getTypes().ConvertType(T);
56 bool CodeGenFunction::hasAggregateLLVMType(QualType type) {
57 switch (type.getCanonicalType()->getTypeClass()) {
58 #define TYPE(name, parent)
59 #define ABSTRACT_TYPE(name, parent)
60 #define NON_CANONICAL_TYPE(name, parent) case Type::name:
61 #define DEPENDENT_TYPE(name, parent) case Type::name:
62 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name:
63 #include "clang/AST/TypeNodes.def"
64 llvm_unreachable("non-canonical or dependent type in IR-generation");
68 case Type::BlockPointer:
69 case Type::LValueReference:
70 case Type::RValueReference:
71 case Type::MemberPointer:
74 case Type::FunctionProto:
75 case Type::FunctionNoProto:
77 case Type::ObjCObjectPointer:
80 // Complexes, arrays, records, and Objective-C objects.
82 case Type::ConstantArray:
83 case Type::IncompleteArray:
84 case Type::VariableArray:
86 case Type::ObjCObject:
87 case Type::ObjCInterface:
90 llvm_unreachable("unknown type kind!");
93 void CodeGenFunction::EmitReturnBlock() {
94 // For cleanliness, we try to avoid emitting the return block for
96 llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
99 assert(!CurBB->getTerminator() && "Unexpected terminated block.");
101 // We have a valid insert point, reuse it if it is empty or there are no
102 // explicit jumps to the return block.
103 if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) {
104 ReturnBlock.getBlock()->replaceAllUsesWith(CurBB);
105 delete ReturnBlock.getBlock();
107 EmitBlock(ReturnBlock.getBlock());
111 // Otherwise, if the return block is the target of a single direct
112 // branch then we can just put the code in that block instead. This
113 // cleans up functions which started with a unified return block.
114 if (ReturnBlock.getBlock()->hasOneUse()) {
115 llvm::BranchInst *BI =
116 dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin());
117 if (BI && BI->isUnconditional() &&
118 BI->getSuccessor(0) == ReturnBlock.getBlock()) {
119 // Reset insertion point and delete the branch.
120 Builder.SetInsertPoint(BI->getParent());
121 BI->eraseFromParent();
122 delete ReturnBlock.getBlock();
127 // FIXME: We are at an unreachable point, there is no reason to emit the block
128 // unless it has uses. However, we still need a place to put the debug
129 // region.end for now.
131 EmitBlock(ReturnBlock.getBlock());
134 static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) {
136 if (!BB->use_empty())
137 return CGF.CurFn->getBasicBlockList().push_back(BB);
141 void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
142 assert(BreakContinueStack.empty() &&
143 "mismatched push/pop in break/continue stack!");
145 // Pop any cleanups that might have been associated with the
146 // parameters. Do this in whatever block we're currently in; it's
147 // important to do this before we enter the return block or return
148 // edges will be *really* confused.
149 if (EHStack.stable_begin() != PrologueCleanupDepth)
150 PopCleanupBlocks(PrologueCleanupDepth);
152 // Emit function epilog (to return).
155 if (ShouldInstrumentFunction())
156 EmitFunctionInstrumentation("__cyg_profile_func_exit");
158 // Emit debug descriptor for function end.
159 if (CGDebugInfo *DI = getDebugInfo()) {
160 DI->setLocation(EndLoc);
161 DI->EmitFunctionEnd(Builder);
164 EmitFunctionEpilog(*CurFnInfo);
165 EmitEndEHSpec(CurCodeDecl);
167 assert(EHStack.empty() &&
168 "did not remove all scopes from cleanup stack!");
170 // If someone did an indirect goto, emit the indirect goto block at the end of
172 if (IndirectBranch) {
173 EmitBlock(IndirectBranch->getParent());
174 Builder.ClearInsertionPoint();
177 // Remove the AllocaInsertPt instruction, which is just a convenience for us.
178 llvm::Instruction *Ptr = AllocaInsertPt;
180 Ptr->eraseFromParent();
182 // If someone took the address of a label but never did an indirect goto, we
183 // made a zero entry PHI node, which is illegal, zap it now.
184 if (IndirectBranch) {
185 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
186 if (PN->getNumIncomingValues() == 0) {
187 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
188 PN->eraseFromParent();
192 EmitIfUsed(*this, RethrowBlock.getBlock());
193 EmitIfUsed(*this, TerminateLandingPad);
194 EmitIfUsed(*this, TerminateHandler);
195 EmitIfUsed(*this, UnreachableBlock);
197 if (CGM.getCodeGenOpts().EmitDeclMetadata)
201 /// ShouldInstrumentFunction - Return true if the current function should be
202 /// instrumented with __cyg_profile_func_* calls
203 bool CodeGenFunction::ShouldInstrumentFunction() {
204 if (!CGM.getCodeGenOpts().InstrumentFunctions)
206 if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
211 /// EmitFunctionInstrumentation - Emit LLVM code to call the specified
212 /// instrumentation function with the current function and the call site, if
213 /// function instrumentation is enabled.
214 void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) {
215 // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site);
216 llvm::PointerType *PointerTy = Int8PtrTy;
217 llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy };
218 const llvm::FunctionType *FunctionTy =
219 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()),
220 ProfileFuncArgs, false);
222 llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn);
223 llvm::CallInst *CallSite = Builder.CreateCall(
224 CGM.getIntrinsic(llvm::Intrinsic::returnaddress),
225 llvm::ConstantInt::get(Int32Ty, 0),
228 Builder.CreateCall2(F,
229 llvm::ConstantExpr::getBitCast(CurFn, PointerTy),
233 void CodeGenFunction::EmitMCountInstrumentation() {
234 llvm::FunctionType *FTy =
235 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), false);
237 llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy,
238 Target.getMCountName());
239 Builder.CreateCall(MCountFn);
242 void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
244 const CGFunctionInfo &FnInfo,
245 const FunctionArgList &Args,
246 SourceLocation StartLoc) {
247 const Decl *D = GD.getDecl();
249 DidCallStackSave = false;
250 CurCodeDecl = CurFuncDecl = D;
254 assert(CurFn->isDeclaration() && "Function already has body?");
256 // Pass inline keyword to optimizer if it appears explicitly on any
258 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
259 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(),
260 RE = FD->redecls_end(); RI != RE; ++RI)
261 if (RI->isInlineSpecified()) {
262 Fn->addFnAttr(llvm::Attribute::InlineHint);
266 if (getContext().getLangOptions().OpenCL) {
267 // Add metadata for a kernel function.
268 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
269 if (FD->hasAttr<OpenCLKernelAttr>()) {
270 llvm::LLVMContext &Context = getLLVMContext();
271 llvm::NamedMDNode *OpenCLMetadata =
272 CGM.getModule().getOrInsertNamedMetadata("opencl.kernels");
274 llvm::Value *Op = Fn;
275 OpenCLMetadata->addOperand(llvm::MDNode::get(Context, Op));
279 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
281 // Create a marker to make it easy to insert allocas into the entryblock
282 // later. Don't create this with the builder, because we don't want it
284 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
285 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
286 if (Builder.isNamePreserving())
287 AllocaInsertPt->setName("allocapt");
289 ReturnBlock = getJumpDestInCurrentScope("return");
291 Builder.SetInsertPoint(EntryBB);
293 // Emit subprogram debug descriptor.
294 if (CGDebugInfo *DI = getDebugInfo()) {
295 // FIXME: what is going on here and why does it ignore all these
296 // interesting type properties?
298 getContext().getFunctionType(RetTy, 0, 0,
299 FunctionProtoType::ExtProtoInfo());
301 DI->setLocation(StartLoc);
302 DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
305 if (ShouldInstrumentFunction())
306 EmitFunctionInstrumentation("__cyg_profile_func_enter");
308 if (CGM.getCodeGenOpts().InstrumentForProfiling)
309 EmitMCountInstrumentation();
311 if (RetTy->isVoidType()) {
312 // Void type; nothing to return.
314 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
315 hasAggregateLLVMType(CurFnInfo->getReturnType())) {
316 // Indirect aggregate return; emit returned value directly into sret slot.
317 // This reduces code size, and affects correctness in C++.
318 ReturnValue = CurFn->arg_begin();
320 ReturnValue = CreateIRTemp(RetTy, "retval");
322 // Tell the epilog emitter to autorelease the result. We do this
323 // now so that various specialized functions can suppress it
324 // during their IR-generation.
325 if (getLangOptions().ObjCAutoRefCount &&
326 !CurFnInfo->isReturnsRetained() &&
327 RetTy->isObjCRetainableType())
328 AutoreleaseResult = true;
331 EmitStartEHSpec(CurCodeDecl);
333 PrologueCleanupDepth = EHStack.stable_begin();
334 EmitFunctionProlog(*CurFnInfo, CurFn, Args);
336 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance())
337 CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
339 // If any of the arguments have a variably modified type, make sure to
340 // emit the type size.
341 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
343 QualType Ty = (*i)->getType();
345 if (Ty->isVariablyModifiedType())
346 EmitVariablyModifiedType(Ty);
350 void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
351 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
352 assert(FD->getBody());
353 EmitStmt(FD->getBody());
356 /// Tries to mark the given function nounwind based on the
357 /// non-existence of any throwing calls within it. We believe this is
358 /// lightweight enough to do at -O0.
359 static void TryMarkNoThrow(llvm::Function *F) {
360 // LLVM treats 'nounwind' on a function as part of the type, so we
361 // can't do this on functions that can be overwritten.
362 if (F->mayBeOverridden()) return;
364 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI)
365 for (llvm::BasicBlock::iterator
366 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI)
367 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI))
368 if (!Call->doesNotThrow())
370 F->setDoesNotThrow(true);
373 void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
374 const CGFunctionInfo &FnInfo) {
375 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
377 // Check if we should generate debug info for this function.
378 if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>())
379 DebugInfo = CGM.getModuleDebugInfo();
381 FunctionArgList Args;
382 QualType ResTy = FD->getResultType();
385 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance())
386 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args);
388 if (FD->getNumParams())
389 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
390 Args.push_back(FD->getParamDecl(i));
392 SourceRange BodyRange;
393 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
395 // Emit the standard function prologue.
396 StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin());
398 // Generate the body of the function.
399 if (isa<CXXDestructorDecl>(FD))
400 EmitDestructorBody(Args);
401 else if (isa<CXXConstructorDecl>(FD))
402 EmitConstructorBody(Args);
404 EmitFunctionBody(Args);
406 // Emit the standard function epilogue.
407 FinishFunction(BodyRange.getEnd());
409 // If we haven't marked the function nothrow through other means, do
410 // a quick pass now to see if we can.
411 if (!CurFn->doesNotThrow())
412 TryMarkNoThrow(CurFn);
415 /// ContainsLabel - Return true if the statement contains a label in it. If
416 /// this statement is not executed normally, it not containing a label means
417 /// that we can just remove the code.
418 bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
419 // Null statement, not a label!
420 if (S == 0) return false;
422 // If this is a label, we have to emit the code, consider something like:
423 // if (0) { ... foo: bar(); } goto foo;
425 // TODO: If anyone cared, we could track __label__'s, since we know that you
426 // can't jump to one from outside their declared region.
427 if (isa<LabelStmt>(S))
430 // If this is a case/default statement, and we haven't seen a switch, we have
432 if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
435 // If this is a switch statement, we want to ignore cases below it.
436 if (isa<SwitchStmt>(S))
437 IgnoreCaseStmts = true;
439 // Scan subexpressions for verboten labels.
440 for (Stmt::const_child_range I = S->children(); I; ++I)
441 if (ContainsLabel(*I, IgnoreCaseStmts))
447 /// containsBreak - Return true if the statement contains a break out of it.
448 /// If the statement (recursively) contains a switch or loop with a break
449 /// inside of it, this is fine.
450 bool CodeGenFunction::containsBreak(const Stmt *S) {
451 // Null statement, not a label!
452 if (S == 0) return false;
454 // If this is a switch or loop that defines its own break scope, then we can
455 // include it and anything inside of it.
456 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) ||
460 if (isa<BreakStmt>(S))
463 // Scan subexpressions for verboten breaks.
464 for (Stmt::const_child_range I = S->children(); I; ++I)
465 if (containsBreak(*I))
472 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
473 /// to a constant, or if it does but contains a label, return false. If it
474 /// constant folds return true and set the boolean result in Result.
475 bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond,
477 llvm::APInt ResultInt;
478 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt))
481 ResultBool = ResultInt.getBoolValue();
485 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
486 /// to a constant, or if it does but contains a label, return false. If it
487 /// constant folds return true and set the folded value.
488 bool CodeGenFunction::
489 ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) {
490 // FIXME: Rename and handle conversion of other evaluatable things
492 Expr::EvalResult Result;
493 if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() ||
494 Result.HasSideEffects)
495 return false; // Not foldable, not integer or not fully evaluatable.
497 if (CodeGenFunction::ContainsLabel(Cond))
498 return false; // Contains a label.
500 ResultInt = Result.Val.getInt();
506 /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
507 /// statement) to the specified blocks. Based on the condition, this might try
508 /// to simplify the codegen of the conditional based on the branch.
510 void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
511 llvm::BasicBlock *TrueBlock,
512 llvm::BasicBlock *FalseBlock) {
513 Cond = Cond->IgnoreParens();
515 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
516 // Handle X && Y in a condition.
517 if (CondBOp->getOpcode() == BO_LAnd) {
518 // If we have "1 && X", simplify the code. "0 && X" would have constant
519 // folded if the case was simple enough.
520 bool ConstantBool = false;
521 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
523 // br(1 && X) -> br(X).
524 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
527 // If we have "X && 1", simplify the code to use an uncond branch.
528 // "X && 0" would have been constant folded to 0.
529 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
531 // br(X && 1) -> br(X).
532 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
535 // Emit the LHS as a conditional. If the LHS conditional is false, we
536 // want to jump to the FalseBlock.
537 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true");
539 ConditionalEvaluation eval(*this);
540 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
543 // Any temporaries created here are conditional.
545 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
551 if (CondBOp->getOpcode() == BO_LOr) {
552 // If we have "0 || X", simplify the code. "1 || X" would have constant
553 // folded if the case was simple enough.
554 bool ConstantBool = false;
555 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
557 // br(0 || X) -> br(X).
558 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
561 // If we have "X || 0", simplify the code to use an uncond branch.
562 // "X || 1" would have been constant folded to 1.
563 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
565 // br(X || 0) -> br(X).
566 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
569 // Emit the LHS as a conditional. If the LHS conditional is true, we
570 // want to jump to the TrueBlock.
571 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false");
573 ConditionalEvaluation eval(*this);
574 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
577 // Any temporaries created here are conditional.
579 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
586 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) {
587 // br(!x, t, f) -> br(x, f, t)
588 if (CondUOp->getOpcode() == UO_LNot)
589 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock);
592 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) {
593 // Handle ?: operator.
595 // Just ignore GNU ?: extension.
596 if (CondOp->getLHS()) {
597 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f))
598 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
599 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
601 ConditionalEvaluation cond(*this);
602 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
606 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
611 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
618 // Emit the code with the fully general case.
619 llvm::Value *CondV = EvaluateExprAsBool(Cond);
620 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
623 /// ErrorUnsupported - Print out an error that codegen doesn't support the
624 /// specified stmt yet.
625 void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type,
627 CGM.ErrorUnsupported(S, Type, OmitOnError);
630 /// emitNonZeroVLAInit - Emit the "zero" initialization of a
631 /// variable-length array whose elements have a non-zero bit-pattern.
633 /// \param src - a char* pointing to the bit-pattern for a single
634 /// base element of the array
635 /// \param sizeInChars - the total size of the VLA, in chars
636 /// \param align - the total alignment of the VLA
637 static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType,
638 llvm::Value *dest, llvm::Value *src,
639 llvm::Value *sizeInChars) {
640 std::pair<CharUnits,CharUnits> baseSizeAndAlign
641 = CGF.getContext().getTypeInfoInChars(baseType);
643 CGBuilderTy &Builder = CGF.Builder;
645 llvm::Value *baseSizeInChars
646 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity());
648 const llvm::Type *i8p = Builder.getInt8PtrTy();
650 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin");
651 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end");
653 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock();
654 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop");
655 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont");
657 // Make a loop over the VLA. C99 guarantees that the VLA element
658 // count must be nonzero.
659 CGF.EmitBlock(loopBB);
661 llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur");
662 cur->addIncoming(begin, originBB);
664 // memcpy the individual element bit-pattern.
665 Builder.CreateMemCpy(cur, src, baseSizeInChars,
666 baseSizeAndAlign.second.getQuantity(),
669 // Go to the next element.
670 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next");
672 // Leave if that's the end of the VLA.
673 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone");
674 Builder.CreateCondBr(done, contBB, loopBB);
675 cur->addIncoming(next, loopBB);
677 CGF.EmitBlock(contBB);
681 CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
682 // Ignore empty classes in C++.
683 if (getContext().getLangOptions().CPlusPlus) {
684 if (const RecordType *RT = Ty->getAs<RecordType>()) {
685 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
690 // Cast the dest ptr to the appropriate i8 pointer type.
692 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace();
693 const llvm::Type *BP = Builder.getInt8PtrTy(DestAS);
694 if (DestPtr->getType() != BP)
695 DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
697 // Get size and alignment info for this aggregate.
698 std::pair<CharUnits, CharUnits> TypeInfo =
699 getContext().getTypeInfoInChars(Ty);
700 CharUnits Size = TypeInfo.first;
701 CharUnits Align = TypeInfo.second;
703 llvm::Value *SizeVal;
704 const VariableArrayType *vla;
706 // Don't bother emitting a zero-byte memset.
708 // But note that getTypeInfo returns 0 for a VLA.
709 if (const VariableArrayType *vlaType =
710 dyn_cast_or_null<VariableArrayType>(
711 getContext().getAsArrayType(Ty))) {
713 llvm::Value *numElts;
714 llvm::tie(numElts, eltType) = getVLASize(vlaType);
717 CharUnits eltSize = getContext().getTypeSizeInChars(eltType);
718 if (!eltSize.isOne())
719 SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize));
725 SizeVal = CGM.getSize(Size);
729 // If the type contains a pointer to data member we can't memset it to zero.
730 // Instead, create a null constant and copy it to the destination.
731 // TODO: there are other patterns besides zero that we can usefully memset,
732 // like -1, which happens to be the pattern used by member-pointers.
733 if (!CGM.getTypes().isZeroInitializable(Ty)) {
734 // For a VLA, emit a single element, then splat that over the VLA.
735 if (vla) Ty = getContext().getBaseElementType(vla);
737 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
739 llvm::GlobalVariable *NullVariable =
740 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
742 llvm::GlobalVariable::PrivateLinkage,
743 NullConstant, llvm::Twine());
744 llvm::Value *SrcPtr =
745 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy());
747 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal);
749 // Get and call the appropriate llvm.memcpy overload.
750 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false);
754 // Otherwise, just memset the whole thing to zero. This is legal
755 // because in LLVM, all default initializers (other than the ones we just
756 // handled above) are guaranteed to have a bit pattern of all zeros.
757 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal,
758 Align.getQuantity(), false);
761 llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) {
762 // Make sure that there is a block for the indirect goto.
763 if (IndirectBranch == 0)
764 GetIndirectGotoBlock();
766 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock();
768 // Make sure the indirect branch includes all of the address-taken blocks.
769 IndirectBranch->addDestination(BB);
770 return llvm::BlockAddress::get(CurFn, BB);
773 llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() {
774 // If we already made the indirect branch for indirect goto, return its block.
775 if (IndirectBranch) return IndirectBranch->getParent();
777 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto"));
779 // Create the PHI node that indirect gotos will add entries to.
780 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0,
781 "indirect.goto.dest");
783 // Create the indirect branch instruction.
784 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
785 return IndirectBranch->getParent();
788 /// Computes the length of an array in elements, as well as the base
789 /// element type and a properly-typed first element pointer.
790 llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType,
792 llvm::Value *&addr) {
793 const ArrayType *arrayType = origArrayType;
795 // If it's a VLA, we have to load the stored size. Note that
796 // this is the size of the VLA in bytes, not its size in elements.
797 llvm::Value *numVLAElements = 0;
798 if (isa<VariableArrayType>(arrayType)) {
799 numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first;
801 // Walk into all VLAs. This doesn't require changes to addr,
802 // which has type T* where T is the first non-VLA element type.
804 QualType elementType = arrayType->getElementType();
805 arrayType = getContext().getAsArrayType(elementType);
807 // If we only have VLA components, 'addr' requires no adjustment.
809 baseType = elementType;
810 return numVLAElements;
812 } while (isa<VariableArrayType>(arrayType));
814 // We get out here only if we find a constant array type
818 // We have some number of constant-length arrays, so addr should
819 // have LLVM type [M x [N x [...]]]*. Build a GEP that walks
820 // down to the first element of addr.
821 llvm::SmallVector<llvm::Value*, 8> gepIndices;
823 // GEP down to the array type.
824 llvm::ConstantInt *zero = Builder.getInt32(0);
825 gepIndices.push_back(zero);
827 // It's more efficient to calculate the count from the LLVM
828 // constant-length arrays than to re-evaluate the array bounds.
829 uint64_t countFromCLAs = 1;
831 const llvm::ArrayType *llvmArrayType =
832 cast<llvm::ArrayType>(
833 cast<llvm::PointerType>(addr->getType())->getElementType());
835 assert(isa<ConstantArrayType>(arrayType));
836 assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue()
837 == llvmArrayType->getNumElements());
839 gepIndices.push_back(zero);
840 countFromCLAs *= llvmArrayType->getNumElements();
843 dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType());
844 if (!llvmArrayType) break;
846 arrayType = getContext().getAsArrayType(arrayType->getElementType());
847 assert(arrayType && "LLVM and Clang types are out-of-synch");
850 baseType = arrayType->getElementType();
852 // Create the actual GEP.
853 addr = Builder.CreateInBoundsGEP(addr, gepIndices.begin(),
854 gepIndices.end(), "array.begin");
856 llvm::Value *numElements
857 = llvm::ConstantInt::get(SizeTy, countFromCLAs);
859 // If we had any VLA dimensions, factor them in.
861 numElements = Builder.CreateNUWMul(numVLAElements, numElements);
866 std::pair<llvm::Value*, QualType>
867 CodeGenFunction::getVLASize(QualType type) {
868 const VariableArrayType *vla = getContext().getAsVariableArrayType(type);
869 assert(vla && "type was not a variable array type!");
870 return getVLASize(vla);
873 std::pair<llvm::Value*, QualType>
874 CodeGenFunction::getVLASize(const VariableArrayType *type) {
875 // The number of elements so far; always size_t.
876 llvm::Value *numElements = 0;
878 QualType elementType;
880 elementType = type->getElementType();
881 llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()];
882 assert(vlaSize && "no size for VLA!");
883 assert(vlaSize->getType() == SizeTy);
886 numElements = vlaSize;
888 // It's undefined behavior if this wraps around, so mark it that way.
889 numElements = Builder.CreateNUWMul(numElements, vlaSize);
891 } while ((type = getContext().getAsVariableArrayType(elementType)));
893 return std::pair<llvm::Value*,QualType>(numElements, elementType);
896 void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
897 assert(type->isVariablyModifiedType() &&
898 "Must pass variably modified type to EmitVLASizes!");
902 // We're going to walk down into the type and look for VLA
904 type = type.getCanonicalType();
906 assert(type->isVariablyModifiedType());
908 const Type *ty = type.getTypePtr();
909 switch (ty->getTypeClass()) {
910 #define TYPE(Class, Base)
911 #define ABSTRACT_TYPE(Class, Base)
912 #define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
913 #define DEPENDENT_TYPE(Class, Base) case Type::Class:
914 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
915 #include "clang/AST/TypeNodes.def"
916 llvm_unreachable("unexpected dependent or non-canonical type!");
918 // These types are never variably-modified.
922 case Type::ExtVector:
925 case Type::ObjCObject:
926 case Type::ObjCInterface:
927 case Type::ObjCObjectPointer:
928 llvm_unreachable("type class is never variably-modified!");
931 type = cast<PointerType>(ty)->getPointeeType();
934 case Type::BlockPointer:
935 type = cast<BlockPointerType>(ty)->getPointeeType();
938 case Type::LValueReference:
939 case Type::RValueReference:
940 type = cast<ReferenceType>(ty)->getPointeeType();
943 case Type::MemberPointer:
944 type = cast<MemberPointerType>(ty)->getPointeeType();
947 case Type::ConstantArray:
948 case Type::IncompleteArray:
949 // Losing element qualification here is fine.
950 type = cast<ArrayType>(ty)->getElementType();
953 case Type::VariableArray: {
954 // Losing element qualification here is fine.
955 const VariableArrayType *vat = cast<VariableArrayType>(ty);
957 // Unknown size indication requires no size computation.
958 // Otherwise, evaluate and record it.
959 if (const Expr *size = vat->getSizeExpr()) {
960 // It's possible that we might have emitted this already,
961 // e.g. with a typedef and a pointer to it.
962 llvm::Value *&entry = VLASizeMap[size];
964 // Always zexting here would be wrong if it weren't
965 // undefined behavior to have a negative bound.
966 entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy,
970 type = vat->getElementType();
974 case Type::FunctionProto:
975 case Type::FunctionNoProto:
976 type = cast<FunctionType>(ty)->getResultType();
979 } while (type->isVariablyModifiedType());
982 llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
983 if (getContext().getBuiltinVaListType()->isArrayType())
984 return EmitScalarExpr(E);
985 return EmitLValue(E).getAddress();
988 void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E,
989 llvm::Constant *Init) {
990 assert (Init && "Invalid DeclRefExpr initializer!");
991 if (CGDebugInfo *Dbg = getDebugInfo())
992 Dbg->EmitGlobalVariable(E->getDecl(), Init);
995 CodeGenFunction::PeepholeProtection
996 CodeGenFunction::protectFromPeepholes(RValue rvalue) {
997 // At the moment, the only aggressive peephole we do in IR gen
998 // is trunc(zext) folding, but if we add more, we can easily
999 // extend this protection.
1001 if (!rvalue.isScalar()) return PeepholeProtection();
1002 llvm::Value *value = rvalue.getScalarVal();
1003 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection();
1005 // Just make an extra bitcast.
1006 assert(HaveInsertPoint());
1007 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "",
1008 Builder.GetInsertBlock());
1010 PeepholeProtection protection;
1011 protection.Inst = inst;
1015 void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) {
1016 if (!protection.Inst) return;
1018 // In theory, we could try to duplicate the peepholes now, but whatever.
1019 protection.Inst->eraseFromParent();