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llvm-project/clang/lib/CodeGen/CodeGenFunction.cpp

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//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This coordinates the per-function state used while generating code.
//
//===----------------------------------------------------------------------===//
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "CGDebugInfo.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/StmtCXX.h"
#include "llvm/Target/TargetData.h"
using namespace clang;
using namespace CodeGen;
CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
: BlockFunction(cgm, *this, Builder), CGM(cgm),
Target(CGM.getContext().Target),
Builder(cgm.getModule().getContext()),
DebugInfo(0), IndirectBranch(0),
SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0),
CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0),
ConditionalBranchLevel(0), TerminateHandler(0), TrapBB(0),
UniqueAggrDestructorCount(0) {
LLVMIntTy = ConvertType(getContext().IntTy);
LLVMPointerWidth = Target.getPointerWidth(0);
Exceptions = getContext().getLangOptions().Exceptions;
CatchUndefined = getContext().getLangOptions().CatchUndefined;
CGM.getMangleContext().startNewFunction();
}
ASTContext &CodeGenFunction::getContext() const {
return CGM.getContext();
}
llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) {
llvm::BasicBlock *&BB = LabelMap[S];
if (BB) return BB;
// Create, but don't insert, the new block.
return BB = createBasicBlock(S->getName());
}
llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) {
llvm::Value *Res = LocalDeclMap[VD];
assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!");
return Res;
}
llvm::Constant *
CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) {
return cast<llvm::Constant>(GetAddrOfLocalVar(BVD));
}
const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
return CGM.getTypes().ConvertTypeForMem(T);
}
const llvm::Type *CodeGenFunction::ConvertType(QualType T) {
return CGM.getTypes().ConvertType(T);
}
bool CodeGenFunction::hasAggregateLLVMType(QualType T) {
return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() ||
T->isMemberFunctionPointerType();
}
void CodeGenFunction::EmitReturnBlock() {
// For cleanliness, we try to avoid emitting the return block for
// simple cases.
llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
if (CurBB) {
assert(!CurBB->getTerminator() && "Unexpected terminated block.");
// We have a valid insert point, reuse it if it is empty or there are no
// explicit jumps to the return block.
if (CurBB->empty() || ReturnBlock->use_empty()) {
ReturnBlock->replaceAllUsesWith(CurBB);
delete ReturnBlock;
} else
EmitBlock(ReturnBlock);
return;
}
// Otherwise, if the return block is the target of a single direct
// branch then we can just put the code in that block instead. This
// cleans up functions which started with a unified return block.
if (ReturnBlock->hasOneUse()) {
llvm::BranchInst *BI =
dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin());
if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) {
// Reset insertion point and delete the branch.
Builder.SetInsertPoint(BI->getParent());
BI->eraseFromParent();
delete ReturnBlock;
return;
}
}
// FIXME: We are at an unreachable point, there is no reason to emit the block
// unless it has uses. However, we still need a place to put the debug
// region.end for now.
EmitBlock(ReturnBlock);
}
void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
assert(BreakContinueStack.empty() &&
"mismatched push/pop in break/continue stack!");
assert(BlockScopes.empty() &&
"did not remove all blocks from block scope map!");
assert(CleanupEntries.empty() &&
"mismatched push/pop in cleanup stack!");
// Emit function epilog (to return).
EmitReturnBlock();
// Emit debug descriptor for function end.
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(EndLoc);
DI->EmitRegionEnd(CurFn, Builder);
}
EmitFunctionEpilog(*CurFnInfo, ReturnValue);
EmitEndEHSpec(CurCodeDecl);
// If someone did an indirect goto, emit the indirect goto block at the end of
// the function.
if (IndirectBranch) {
EmitBlock(IndirectBranch->getParent());
Builder.ClearInsertionPoint();
}
// Remove the AllocaInsertPt instruction, which is just a convenience for us.
llvm::Instruction *Ptr = AllocaInsertPt;
AllocaInsertPt = 0;
Ptr->eraseFromParent();
// If someone took the address of a label but never did an indirect goto, we
// made a zero entry PHI node, which is illegal, zap it now.
if (IndirectBranch) {
llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
if (PN->getNumIncomingValues() == 0) {
PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
PN->eraseFromParent();
}
}
}
void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
llvm::Function *Fn,
const FunctionArgList &Args,
SourceLocation StartLoc) {
const Decl *D = GD.getDecl();
DidCallStackSave = false;
CurCodeDecl = CurFuncDecl = D;
FnRetTy = RetTy;
CurFn = Fn;
assert(CurFn->isDeclaration() && "Function already has body?");
// Pass inline keyword to optimizer if it appears explicitly on any
// declaration.
if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(),
RE = FD->redecls_end(); RI != RE; ++RI)
if (RI->isInlineSpecified()) {
Fn->addFnAttr(llvm::Attribute::InlineHint);
break;
}
llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
// Create a marker to make it easy to insert allocas into the entryblock
// later. Don't create this with the builder, because we don't want it
// folded.
llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::getInt32Ty(VMContext));
AllocaInsertPt = new llvm::BitCastInst(Undef,
llvm::Type::getInt32Ty(VMContext), "",
EntryBB);
if (Builder.isNamePreserving())
AllocaInsertPt->setName("allocapt");
ReturnBlock = createBasicBlock("return");
Builder.SetInsertPoint(EntryBB);
QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0,
false, false, 0, 0,
/*FIXME?*/
FunctionType::ExtInfo());
// Emit subprogram debug descriptor.
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(StartLoc);
DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
}
// FIXME: Leaked.
// CC info is ignored, hopefully?
CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args,
FunctionType::ExtInfo());
if (RetTy->isVoidType()) {
// Void type; nothing to return.
ReturnValue = 0;
} else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
hasAggregateLLVMType(CurFnInfo->getReturnType())) {
// Indirect aggregate return; emit returned value directly into sret slot.
// This reduces code size, and affects correctness in C++.
ReturnValue = CurFn->arg_begin();
} else {
ReturnValue = CreateIRTemp(RetTy, "retval");
}
EmitStartEHSpec(CurCodeDecl);
EmitFunctionProlog(*CurFnInfo, CurFn, Args);
if (CXXThisDecl)
CXXThisValue = Builder.CreateLoad(LocalDeclMap[CXXThisDecl], "this");
if (CXXVTTDecl)
CXXVTTValue = Builder.CreateLoad(LocalDeclMap[CXXVTTDecl], "vtt");
// If any of the arguments have a variably modified type, make sure to
// emit the type size.
for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
i != e; ++i) {
QualType Ty = i->second;
if (Ty->isVariablyModifiedType())
EmitVLASize(Ty);
}
}
void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
assert(FD->getBody());
EmitStmt(FD->getBody());
}
void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) {
const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
// Check if we should generate debug info for this function.
if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>())
DebugInfo = CGM.getDebugInfo();
FunctionArgList Args;
CurGD = GD;
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
if (MD->isInstance()) {
// Create the implicit 'this' decl.
// FIXME: I'm not entirely sure I like using a fake decl just for code
// generation. Maybe we can come up with a better way?
CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0,
FD->getLocation(),
&getContext().Idents.get("this"),
MD->getThisType(getContext()));
Args.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType()));
// Check if we need a VTT parameter as well.
if (CodeGenVTables::needsVTTParameter(GD)) {
// FIXME: The comment about using a fake decl above applies here too.
QualType T = getContext().getPointerType(getContext().VoidPtrTy);
CXXVTTDecl =
ImplicitParamDecl::Create(getContext(), 0, FD->getLocation(),
&getContext().Idents.get("vtt"), T);
Args.push_back(std::make_pair(CXXVTTDecl, CXXVTTDecl->getType()));
}
}
}
if (FD->getNumParams()) {
const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>();
assert(FProto && "Function def must have prototype!");
for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
Args.push_back(std::make_pair(FD->getParamDecl(i),
FProto->getArgType(i)));
}
SourceRange BodyRange;
if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
// Emit the standard function prologue.
StartFunction(GD, FD->getResultType(), Fn, Args, BodyRange.getBegin());
// Generate the body of the function.
if (isa<CXXDestructorDecl>(FD))
EmitDestructorBody(Args);
else if (isa<CXXConstructorDecl>(FD))
EmitConstructorBody(Args);
else
EmitFunctionBody(Args);
// Emit the standard function epilogue.
FinishFunction(BodyRange.getEnd());
// Destroy the 'this' declaration.
if (CXXThisDecl)
CXXThisDecl->Destroy(getContext());
// Destroy the VTT declaration.
if (CXXVTTDecl)
CXXVTTDecl->Destroy(getContext());
}
/// ContainsLabel - Return true if the statement contains a label in it. If
/// this statement is not executed normally, it not containing a label means
/// that we can just remove the code.
bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
// Null statement, not a label!
if (S == 0) return false;
// If this is a label, we have to emit the code, consider something like:
// if (0) { ... foo: bar(); } goto foo;
if (isa<LabelStmt>(S))
return true;
// If this is a case/default statement, and we haven't seen a switch, we have
// to emit the code.
if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
return true;
// If this is a switch statement, we want to ignore cases below it.
if (isa<SwitchStmt>(S))
IgnoreCaseStmts = true;
// Scan subexpressions for verboten labels.
for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
I != E; ++I)
if (ContainsLabel(*I, IgnoreCaseStmts))
return true;
return false;
}
/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to
/// a constant, or if it does but contains a label, return 0. If it constant
/// folds to 'true' and does not contain a label, return 1, if it constant folds
/// to 'false' and does not contain a label, return -1.
int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) {
// FIXME: Rename and handle conversion of other evaluatable things
// to bool.
Expr::EvalResult Result;
if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() ||
Result.HasSideEffects)
return 0; // Not foldable, not integer or not fully evaluatable.
if (CodeGenFunction::ContainsLabel(Cond))
return 0; // Contains a label.
return Result.Val.getInt().getBoolValue() ? 1 : -1;
}
/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
/// statement) to the specified blocks. Based on the condition, this might try
/// to simplify the codegen of the conditional based on the branch.
///
void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
llvm::BasicBlock *TrueBlock,
llvm::BasicBlock *FalseBlock) {
if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond))
return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock);
if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
// Handle X && Y in a condition.
if (CondBOp->getOpcode() == BinaryOperator::LAnd) {
// If we have "1 && X", simplify the code. "0 && X" would have constant
// folded if the case was simple enough.
if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) {
// br(1 && X) -> br(X).
return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
}
// If we have "X && 1", simplify the code to use an uncond branch.
// "X && 0" would have been constant folded to 0.
if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) {
// br(X && 1) -> br(X).
return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
}
// Emit the LHS as a conditional. If the LHS conditional is false, we
// want to jump to the FalseBlock.
llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true");
EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
EmitBlock(LHSTrue);
// Any temporaries created here are conditional.
BeginConditionalBranch();
EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
EndConditionalBranch();
return;
} else if (CondBOp->getOpcode() == BinaryOperator::LOr) {
// If we have "0 || X", simplify the code. "1 || X" would have constant
// folded if the case was simple enough.
if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) {
// br(0 || X) -> br(X).
return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
}
// If we have "X || 0", simplify the code to use an uncond branch.
// "X || 1" would have been constant folded to 1.
if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) {
// br(X || 0) -> br(X).
return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
}
// Emit the LHS as a conditional. If the LHS conditional is true, we
// want to jump to the TrueBlock.
llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false");
EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
EmitBlock(LHSFalse);
// Any temporaries created here are conditional.
BeginConditionalBranch();
EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
EndConditionalBranch();
return;
}
}
if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) {
// br(!x, t, f) -> br(x, f, t)
if (CondUOp->getOpcode() == UnaryOperator::LNot)
return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock);
}
if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) {
// Handle ?: operator.
// Just ignore GNU ?: extension.
if (CondOp->getLHS()) {
// br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f))
llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
EmitBlock(LHSBlock);
EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
EmitBlock(RHSBlock);
EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
return;
}
}
// Emit the code with the fully general case.
llvm::Value *CondV = EvaluateExprAsBool(Cond);
Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
}
/// ErrorUnsupported - Print out an error that codegen doesn't support the
/// specified stmt yet.
void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type,
bool OmitOnError) {
CGM.ErrorUnsupported(S, Type, OmitOnError);
}
void
CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
// If the type contains a pointer to data member we can't memset it to zero.
// Instead, create a null constant and copy it to the destination.
if (CGM.getTypes().ContainsPointerToDataMember(Ty)) {
llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
llvm::GlobalVariable *NullVariable =
new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
/*isConstant=*/true,
llvm::GlobalVariable::PrivateLinkage,
NullConstant, llvm::Twine());
EmitAggregateCopy(DestPtr, NullVariable, Ty, /*isVolatile=*/false);
return;
}
// Ignore empty classes in C++.
if (getContext().getLangOptions().CPlusPlus) {
if (const RecordType *RT = Ty->getAs<RecordType>()) {
if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
return;
}
}
// Otherwise, just memset the whole thing to zero. This is legal
// because in LLVM, all default initializers (other than the ones we just
// handled above) are guaranteed to have a bit pattern of all zeros.
const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
if (DestPtr->getType() != BP)
DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
// Get size and alignment info for this aggregate.
std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
// Don't bother emitting a zero-byte memset.
if (TypeInfo.first == 0)
return;
// FIXME: Handle variable sized types.
const llvm::Type *IntPtr = llvm::IntegerType::get(VMContext,
LLVMPointerWidth);
Builder.CreateCall5(CGM.getMemSetFn(BP, IntPtr), DestPtr,
llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext)),
// TypeInfo.first describes size in bits.
llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
TypeInfo.second/8),
llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext),
0));
}
llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelStmt *L) {
// Make sure that there is a block for the indirect goto.
if (IndirectBranch == 0)
GetIndirectGotoBlock();
llvm::BasicBlock *BB = getBasicBlockForLabel(L);
// Make sure the indirect branch includes all of the address-taken blocks.
IndirectBranch->addDestination(BB);
return llvm::BlockAddress::get(CurFn, BB);
}
llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() {
// If we already made the indirect branch for indirect goto, return its block.
if (IndirectBranch) return IndirectBranch->getParent();
CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto"));
const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
// Create the PHI node that indirect gotos will add entries to.
llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest");
// Create the indirect branch instruction.
IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
return IndirectBranch->getParent();
}
llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) {
llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()];
assert(SizeEntry && "Did not emit size for type");
return SizeEntry;
}
llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) {
assert(Ty->isVariablyModifiedType() &&
"Must pass variably modified type to EmitVLASizes!");
EnsureInsertPoint();
if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) {
llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()];
if (!SizeEntry) {
const llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
// Get the element size;
QualType ElemTy = VAT->getElementType();
llvm::Value *ElemSize;
if (ElemTy->isVariableArrayType())
ElemSize = EmitVLASize(ElemTy);
else
ElemSize = llvm::ConstantInt::get(SizeTy,
getContext().getTypeSizeInChars(ElemTy).getQuantity());
llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr());
NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp");
SizeEntry = Builder.CreateMul(ElemSize, NumElements);
}
return SizeEntry;
}
if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
EmitVLASize(AT->getElementType());
return 0;
}
const PointerType *PT = Ty->getAs<PointerType>();
assert(PT && "unknown VM type!");
EmitVLASize(PT->getPointeeType());
return 0;
}
llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
if (CGM.getContext().getBuiltinVaListType()->isArrayType()) {
return EmitScalarExpr(E);
}
return EmitLValue(E).getAddress();
}
void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupEntryBlock,
llvm::BasicBlock *CleanupExitBlock,
llvm::BasicBlock *PreviousInvokeDest,
bool EHOnly) {
CleanupEntries.push_back(CleanupEntry(CleanupEntryBlock, CleanupExitBlock,
PreviousInvokeDest, EHOnly));
}
void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) {
assert(CleanupEntries.size() >= OldCleanupStackSize &&
"Cleanup stack mismatch!");
while (CleanupEntries.size() > OldCleanupStackSize)
EmitCleanupBlock();
}
CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() {
CleanupEntry &CE = CleanupEntries.back();
llvm::BasicBlock *CleanupEntryBlock = CE.CleanupEntryBlock;
std::vector<llvm::BasicBlock *> Blocks;
std::swap(Blocks, CE.Blocks);
std::vector<llvm::BranchInst *> BranchFixups;
std::swap(BranchFixups, CE.BranchFixups);
bool EHOnly = CE.EHOnly;
setInvokeDest(CE.PreviousInvokeDest);
CleanupEntries.pop_back();
// Check if any branch fixups pointed to the scope we just popped. If so,
// we can remove them.
for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) {
llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0);
BlockScopeMap::iterator I = BlockScopes.find(Dest);
if (I == BlockScopes.end())
continue;
assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!");
if (I->second == CleanupEntries.size()) {
// We don't need to do this branch fixup.
BranchFixups[i] = BranchFixups.back();
BranchFixups.pop_back();
i--;
e--;
continue;
}
}
llvm::BasicBlock *SwitchBlock = CE.CleanupExitBlock;
llvm::BasicBlock *EndBlock = 0;
if (!BranchFixups.empty()) {
if (!SwitchBlock)
SwitchBlock = createBasicBlock("cleanup.switch");
EndBlock = createBasicBlock("cleanup.end");
llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
Builder.SetInsertPoint(SwitchBlock);
llvm::Value *DestCodePtr
= CreateTempAlloca(llvm::Type::getInt32Ty(VMContext),
"cleanup.dst");
llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp");
// Create a switch instruction to determine where to jump next.
llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock,
BranchFixups.size());
// Restore the current basic block (if any)
if (CurBB) {
Builder.SetInsertPoint(CurBB);
// If we had a current basic block, we also need to emit an instruction
// to initialize the cleanup destination.
Builder.CreateStore(llvm::Constant::getNullValue(llvm::Type::getInt32Ty(VMContext)),
DestCodePtr);
} else
Builder.ClearInsertionPoint();
for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) {
llvm::BranchInst *BI = BranchFixups[i];
llvm::BasicBlock *Dest = BI->getSuccessor(0);
// Fixup the branch instruction to point to the cleanup block.
BI->setSuccessor(0, CleanupEntryBlock);
if (CleanupEntries.empty()) {
llvm::ConstantInt *ID;
// Check if we already have a destination for this block.
if (Dest == SI->getDefaultDest())
ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 0);
else {
ID = SI->findCaseDest(Dest);
if (!ID) {
// No code found, get a new unique one by using the number of
// switch successors.
ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
SI->getNumSuccessors());
SI->addCase(ID, Dest);
}
}
// Store the jump destination before the branch instruction.
new llvm::StoreInst(ID, DestCodePtr, BI);
} else {
// We need to jump through another cleanup block. Create a pad block
// with a branch instruction that jumps to the final destination and add
// it as a branch fixup to the current cleanup scope.
// Create the pad block.
llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn);
// Create a unique case ID.
llvm::ConstantInt *ID
= llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
SI->getNumSuccessors());
// Store the jump destination before the branch instruction.
new llvm::StoreInst(ID, DestCodePtr, BI);
// Add it as the destination.
SI->addCase(ID, CleanupPad);
// Create the branch to the final destination.
llvm::BranchInst *BI = llvm::BranchInst::Create(Dest);
CleanupPad->getInstList().push_back(BI);
// And add it as a branch fixup.
CleanupEntries.back().BranchFixups.push_back(BI);
}
}
}
// Remove all blocks from the block scope map.
for (size_t i = 0, e = Blocks.size(); i != e; ++i) {
assert(BlockScopes.count(Blocks[i]) &&
"Did not find block in scope map!");
BlockScopes.erase(Blocks[i]);
}
return CleanupBlockInfo(CleanupEntryBlock, SwitchBlock, EndBlock, EHOnly);
}
void CodeGenFunction::EmitCleanupBlock() {
CleanupBlockInfo Info = PopCleanupBlock();
if (Info.EHOnly) {
// FIXME: Add this to the exceptional edge
if (Info.CleanupBlock->getNumUses() == 0)
delete Info.CleanupBlock;
return;
}
// Scrub debug location info.
for (llvm::BasicBlock::iterator LBI = Info.CleanupBlock->begin(),
LBE = Info.CleanupBlock->end(); LBI != LBE; ++LBI)
Builder.SetInstDebugLocation(LBI);
llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
if (CurBB && !CurBB->getTerminator() &&
Info.CleanupBlock->getNumUses() == 0) {
CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList());
delete Info.CleanupBlock;
} else
EmitBlock(Info.CleanupBlock);
if (Info.SwitchBlock)
EmitBlock(Info.SwitchBlock);
if (Info.EndBlock)
EmitBlock(Info.EndBlock);
}
void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) {
assert(!CleanupEntries.empty() &&
"Trying to add branch fixup without cleanup block!");
// FIXME: We could be more clever here and check if there's already a branch
// fixup for this destination and recycle it.
CleanupEntries.back().BranchFixups.push_back(BI);
}
void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) {
if (!HaveInsertPoint())
return;
llvm::BranchInst* BI = Builder.CreateBr(Dest);
Builder.ClearInsertionPoint();
// The stack is empty, no need to do any cleanup.
if (CleanupEntries.empty())
return;
if (!Dest->getParent()) {
// We are trying to branch to a block that hasn't been inserted yet.
AddBranchFixup(BI);
return;
}
BlockScopeMap::iterator I = BlockScopes.find(Dest);
if (I == BlockScopes.end()) {
// We are trying to jump to a block that is outside of any cleanup scope.
AddBranchFixup(BI);
return;
}
assert(I->second < CleanupEntries.size() &&
"Trying to branch into cleanup region");
if (I->second == CleanupEntries.size() - 1) {
// We have a branch to a block in the same scope.
return;
}
AddBranchFixup(BI);
}
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