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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 "CGCXXABI.h"
#include "CGDebugInfo.h"
#include "CGException.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 "clang/Frontend/CodeGenOptions.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Intrinsics.h"
using namespace clang;
using namespace CodeGen;
static void ResolveAllBranchFixups(CodeGenFunction &CGF,
llvm::SwitchInst *Switch,
llvm::BasicBlock *CleanupEntry);
CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
: BlockFunction(cgm, *this, Builder), CGM(cgm),
Target(CGM.getContext().Target),
Builder(cgm.getModule().getContext()),
NormalCleanupDest(0), EHCleanupDest(0), NextCleanupDestIndex(1),
ExceptionSlot(0), DebugInfo(0), IndirectBranch(0),
SwitchInsn(0), CaseRangeBlock(0),
DidCallStackSave(false), UnreachableBlock(0),
CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0),
ConditionalBranchLevel(0), TerminateLandingPad(0), TerminateHandler(0),
TrapBB(0) {
// Get some frequently used types.
LLVMPointerWidth = Target.getPointerWidth(0);
llvm::LLVMContext &LLVMContext = CGM.getLLVMContext();
IntPtrTy = llvm::IntegerType::get(LLVMContext, LLVMPointerWidth);
Int32Ty = llvm::Type::getInt32Ty(LLVMContext);
Int64Ty = llvm::Type::getInt64Ty(LLVMContext);
Exceptions = getContext().getLangOptions().Exceptions;
CatchUndefined = getContext().getLangOptions().CatchUndefined;
CGM.getCXXABI().getMangleContext().startNewFunction();
}
ASTContext &CodeGenFunction::getContext() const {
return CGM.getContext();
}
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->isObjCObjectType();
}
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.getBlock()->use_empty()) {
ReturnBlock.getBlock()->replaceAllUsesWith(CurBB);
delete ReturnBlock.getBlock();
} else
EmitBlock(ReturnBlock.getBlock());
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.getBlock()->hasOneUse()) {
llvm::BranchInst *BI =
dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin());
if (BI && BI->isUnconditional() &&
BI->getSuccessor(0) == ReturnBlock.getBlock()) {
// Reset insertion point and delete the branch.
Builder.SetInsertPoint(BI->getParent());
BI->eraseFromParent();
delete ReturnBlock.getBlock();
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.getBlock());
}
static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) {
if (!BB) return;
if (!BB->use_empty())
return CGF.CurFn->getBasicBlockList().push_back(BB);
delete BB;
}
void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
assert(BreakContinueStack.empty() &&
"mismatched push/pop in break/continue stack!");
// Emit function epilog (to return).
EmitReturnBlock();
EmitFunctionInstrumentation("__cyg_profile_func_exit");
// Emit debug descriptor for function end.
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(EndLoc);
DI->EmitFunctionEnd(Builder);
}
EmitFunctionEpilog(*CurFnInfo);
EmitEndEHSpec(CurCodeDecl);
assert(EHStack.empty() &&
"did not remove all scopes from cleanup stack!");
// 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();
}
}
EmitIfUsed(*this, RethrowBlock.getBlock());
EmitIfUsed(*this, TerminateLandingPad);
EmitIfUsed(*this, TerminateHandler);
EmitIfUsed(*this, UnreachableBlock);
if (CGM.getCodeGenOpts().EmitDeclMetadata)
EmitDeclMetadata();
}
/// ShouldInstrumentFunction - Return true if the current function should be
/// instrumented with __cyg_profile_func_* calls
bool CodeGenFunction::ShouldInstrumentFunction() {
if (!CGM.getCodeGenOpts().InstrumentFunctions)
return false;
if (CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
return false;
return true;
}
/// EmitFunctionInstrumentation - Emit LLVM code to call the specified
/// instrumentation function with the current function and the call site, if
/// function instrumentation is enabled.
void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) {
if (!ShouldInstrumentFunction())
return;
const llvm::PointerType *PointerTy;
const llvm::FunctionType *FunctionTy;
std::vector<const llvm::Type*> ProfileFuncArgs;
// void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site);
PointerTy = llvm::Type::getInt8PtrTy(VMContext);
ProfileFuncArgs.push_back(PointerTy);
ProfileFuncArgs.push_back(PointerTy);
FunctionTy = llvm::FunctionType::get(
llvm::Type::getVoidTy(VMContext),
ProfileFuncArgs, false);
llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn);
llvm::CallInst *CallSite = Builder.CreateCall(
CGM.getIntrinsic(llvm::Intrinsic::returnaddress, 0, 0),
llvm::ConstantInt::get(Int32Ty, 0),
"callsite");
Builder.CreateCall2(F,
llvm::ConstantExpr::getBitCast(CurFn, PointerTy),
CallSite);
}
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(Int32Ty);
AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
if (Builder.isNamePreserving())
AllocaInsertPt->setName("allocapt");
ReturnBlock = getJumpDestInCurrentScope("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);
}
EmitFunctionInstrumentation("__cyg_profile_func_enter");
// 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 (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance())
CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
// 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());
}
/// Tries to mark the given function nounwind based on the
/// non-existence of any throwing calls within it. We believe this is
/// lightweight enough to do at -O0.
static void TryMarkNoThrow(llvm::Function *F) {
// LLVM treats 'nounwind' on a function as part of the type, so we
// can't do this on functions that can be overwritten.
if (F->mayBeOverridden()) return;
for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI)
for (llvm::BasicBlock::iterator
BI = FI->begin(), BE = FI->end(); BI != BE; ++BI)
if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI))
if (!Call->doesNotThrow())
return;
F->setDoesNotThrow(true);
}
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;
QualType ResTy = FD->getResultType();
CurGD = GD;
if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance())
CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args);
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, ResTy, 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());
// If we haven't marked the function nothrow through other means, do
// a quick pass now to see if we can.
if (!CurFn->doesNotThrow())
TryMarkNoThrow(CurFn);
}
/// 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() == BO_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() == BO_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() == UO_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) {
// Ignore empty classes in C++.
if (getContext().getLangOptions().CPlusPlus) {
if (const RecordType *RT = Ty->getAs<RecordType>()) {
if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
return;
}
}
// Cast the dest ptr to the appropriate i8 pointer type.
unsigned DestAS =
cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace();
const llvm::Type *BP =
llvm::Type::getInt8PtrTy(VMContext, DestAS);
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);
uint64_t Size = TypeInfo.first;
unsigned Align = TypeInfo.second;
// Don't bother emitting a zero-byte memset.
if (Size == 0)
return;
llvm::ConstantInt *SizeVal = llvm::ConstantInt::get(IntPtrTy, Size / 8);
llvm::ConstantInt *AlignVal = Builder.getInt32(Align / 8);
// 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().isZeroInitializable(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());
llvm::Value *SrcPtr =
Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy());
// FIXME: variable-size types?
// Get and call the appropriate llvm.memcpy overload.
llvm::Constant *Memcpy =
CGM.getMemCpyFn(DestPtr->getType(), SrcPtr->getType(), IntPtrTy);
Builder.CreateCall5(Memcpy, DestPtr, SrcPtr, SizeVal, AlignVal,
/*volatile*/ Builder.getFalse());
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.
// FIXME: Handle variable sized types.
Builder.CreateCall5(CGM.getMemSetFn(BP, IntPtrTy), DestPtr,
Builder.getInt8(0),
SizeVal, AlignVal, /*volatile*/ Builder.getFalse());
}
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 = getJumpDestForLabel(L).getBlock();
// 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)) {
// unknown size indication requires no size computation.
if (!VAT->getSizeExpr())
return 0;
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 (getContext().getBuiltinVaListType()->isArrayType())
return EmitScalarExpr(E);
return EmitLValue(E).getAddress();
}
/// Pops cleanup blocks until the given savepoint is reached.
void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) {
assert(Old.isValid());
while (EHStack.stable_begin() != Old) {
EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
// As long as Old strictly encloses the scope's enclosing normal
// cleanup, we're going to emit another normal cleanup which
// fallthrough can propagate through.
bool FallThroughIsBranchThrough =
Old.strictlyEncloses(Scope.getEnclosingNormalCleanup());
PopCleanupBlock(FallThroughIsBranchThrough);
}
}
static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
EHCleanupScope &Scope) {
assert(Scope.isNormalCleanup());
llvm::BasicBlock *Entry = Scope.getNormalBlock();
if (!Entry) {
Entry = CGF.createBasicBlock("cleanup");
Scope.setNormalBlock(Entry);
}
return Entry;
}
static llvm::BasicBlock *CreateEHEntry(CodeGenFunction &CGF,
EHCleanupScope &Scope) {
assert(Scope.isEHCleanup());
llvm::BasicBlock *Entry = Scope.getEHBlock();
if (!Entry) {
Entry = CGF.createBasicBlock("eh.cleanup");
Scope.setEHBlock(Entry);
}
return Entry;
}
/// Transitions the terminator of the given exit-block of a cleanup to
/// be a cleanup switch.
static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
llvm::BasicBlock *Block) {
// If it's a branch, turn it into a switch whose default
// destination is its original target.
llvm::TerminatorInst *Term = Block->getTerminator();
assert(Term && "can't transition block without terminator");
if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
assert(Br->isUnconditional());
llvm::LoadInst *Load =
new llvm::LoadInst(CGF.getNormalCleanupDestSlot(), "cleanup.dest", Term);
llvm::SwitchInst *Switch =
llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
Br->eraseFromParent();
return Switch;
} else {
return cast<llvm::SwitchInst>(Term);
}
}
/// Attempts to reduce a cleanup's entry block to a fallthrough. This
/// is basically llvm::MergeBlockIntoPredecessor, except
/// simplified/optimized for the tighter constraints on cleanup blocks.
///
/// Returns the new block, whatever it is.
static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
llvm::BasicBlock *Entry) {
llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
if (!Pred) return Entry;
llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
if (!Br || Br->isConditional()) return Entry;
assert(Br->getSuccessor(0) == Entry);
// If we were previously inserting at the end of the cleanup entry
// block, we'll need to continue inserting at the end of the
// predecessor.
bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
// Kill the branch.
Br->eraseFromParent();
// Merge the blocks.
Pred->getInstList().splice(Pred->end(), Entry->getInstList());
// Kill the entry block.
Entry->eraseFromParent();
if (WasInsertBlock)
CGF.Builder.SetInsertPoint(Pred);
return Pred;
}
static void EmitCleanup(CodeGenFunction &CGF,
EHScopeStack::Cleanup *Fn,
bool ForEH,
llvm::Value *ActiveFlag) {
// EH cleanups always occur within a terminate scope.
if (ForEH) CGF.EHStack.pushTerminate();
// If there's an active flag, load it and skip the cleanup if it's
// false.
llvm::BasicBlock *ContBB = 0;
if (ActiveFlag) {
ContBB = CGF.createBasicBlock("cleanup.done");
llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
llvm::Value *IsActive
= CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
CGF.EmitBlock(CleanupBB);
}
// Ask the cleanup to emit itself.
Fn->Emit(CGF, ForEH);
assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
// Emit the continuation block if there was an active flag.
if (ActiveFlag)
CGF.EmitBlock(ContBB);
// Leave the terminate scope.
if (ForEH) CGF.EHStack.popTerminate();
}
static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
llvm::BasicBlock *From,
llvm::BasicBlock *To) {
// Exit is the exit block of a cleanup, so it always terminates in
// an unconditional branch or a switch.
llvm::TerminatorInst *Term = Exit->getTerminator();
if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
Br->setSuccessor(0, To);
} else {
llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
if (Switch->getSuccessor(I) == From)
Switch->setSuccessor(I, To);
}
}
/// Pops a cleanup block. If the block includes a normal cleanup, the
/// current insertion point is threaded through the cleanup, as are
/// any branch fixups on the cleanup.
void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
assert(!EHStack.empty() && "cleanup stack is empty!");
assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
// Remember activation information.
bool IsActive = Scope.isActive();
llvm::Value *NormalActiveFlag =
Scope.shouldTestFlagInNormalCleanup() ? Scope.getActiveFlag() : 0;
llvm::Value *EHActiveFlag =
Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag() : 0;
// Check whether we need an EH cleanup. This is only true if we've
// generated a lazy EH cleanup block.
bool RequiresEHCleanup = Scope.hasEHBranches();
// Check the three conditions which might require a normal cleanup:
// - whether there are branch fix-ups through this cleanup
unsigned FixupDepth = Scope.getFixupDepth();
bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
// - whether there are branch-throughs or branch-afters
bool HasExistingBranches = Scope.hasBranches();
// - whether there's a fallthrough
llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
bool HasFallthrough = (FallthroughSource != 0 && IsActive);
// Branch-through fall-throughs leave the insertion point set to the
// end of the last cleanup, which points to the current scope. The
// rest of IR gen doesn't need to worry about this; it only happens
// during the execution of PopCleanupBlocks().
bool HasPrebranchedFallthrough =
(FallthroughSource && FallthroughSource->getTerminator());
// If this is a normal cleanup, then having a prebranched
// fallthrough implies that the fallthrough source unconditionally
// jumps here.
assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
(Scope.getNormalBlock() &&
FallthroughSource->getTerminator()->getSuccessor(0)
== Scope.getNormalBlock()));
bool RequiresNormalCleanup = false;
if (Scope.isNormalCleanup() &&
(HasFixups || HasExistingBranches || HasFallthrough)) {
RequiresNormalCleanup = true;
}
// Even if we don't need the normal cleanup, we might still have
// prebranched fallthrough to worry about.
if (Scope.isNormalCleanup() && !RequiresNormalCleanup &&
HasPrebranchedFallthrough) {
assert(!IsActive);
llvm::BasicBlock *NormalEntry = Scope.getNormalBlock();
// If we're branching through this cleanup, just forward the
// prebranched fallthrough to the next cleanup, leaving the insert
// point in the old block.
if (FallthroughIsBranchThrough) {
EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
llvm::BasicBlock *EnclosingEntry =
CreateNormalEntry(*this, cast<EHCleanupScope>(S));
ForwardPrebranchedFallthrough(FallthroughSource,
NormalEntry, EnclosingEntry);
assert(NormalEntry->use_empty() &&
"uses of entry remain after forwarding?");
delete NormalEntry;
// Otherwise, we're branching out; just emit the next block.
} else {
EmitBlock(NormalEntry);
SimplifyCleanupEntry(*this, NormalEntry);
}
}
// If we don't need the cleanup at all, we're done.
if (!RequiresNormalCleanup && !RequiresEHCleanup) {
EHStack.popCleanup(); // safe because there are no fixups
assert(EHStack.getNumBranchFixups() == 0 ||
EHStack.hasNormalCleanups());
return;
}
// Copy the cleanup emission data out. Note that SmallVector
// guarantees maximal alignment for its buffer regardless of its
// type parameter.
llvm::SmallVector<char, 8*sizeof(void*)> CleanupBuffer;
CleanupBuffer.reserve(Scope.getCleanupSize());
memcpy(CleanupBuffer.data(),
Scope.getCleanupBuffer(), Scope.getCleanupSize());
CleanupBuffer.set_size(Scope.getCleanupSize());
EHScopeStack::Cleanup *Fn =
reinterpret_cast<EHScopeStack::Cleanup*>(CleanupBuffer.data());
// We want to emit the EH cleanup after the normal cleanup, but go
// ahead and do the setup for the EH cleanup while the scope is still
// alive.
llvm::BasicBlock *EHEntry = 0;
llvm::SmallVector<llvm::Instruction*, 2> EHInstsToAppend;
if (RequiresEHCleanup) {
EHEntry = CreateEHEntry(*this, Scope);
// Figure out the branch-through dest if necessary.
llvm::BasicBlock *EHBranchThroughDest = 0;
if (Scope.hasEHBranchThroughs()) {
assert(Scope.getEnclosingEHCleanup() != EHStack.stable_end());
EHScope &S = *EHStack.find(Scope.getEnclosingEHCleanup());
EHBranchThroughDest = CreateEHEntry(*this, cast<EHCleanupScope>(S));
}
// If we have exactly one branch-after and no branch-throughs, we
// can dispatch it without a switch.
if (!Scope.hasEHBranchThroughs() &&
Scope.getNumEHBranchAfters() == 1) {
assert(!EHBranchThroughDest);
// TODO: remove the spurious eh.cleanup.dest stores if this edge
// never went through any switches.
llvm::BasicBlock *BranchAfterDest = Scope.getEHBranchAfterBlock(0);
EHInstsToAppend.push_back(llvm::BranchInst::Create(BranchAfterDest));
// Otherwise, if we have any branch-afters, we need a switch.
} else if (Scope.getNumEHBranchAfters()) {
// The default of the switch belongs to the branch-throughs if
// they exist.
llvm::BasicBlock *Default =
(EHBranchThroughDest ? EHBranchThroughDest : getUnreachableBlock());
const unsigned SwitchCapacity = Scope.getNumEHBranchAfters();
llvm::LoadInst *Load =
new llvm::LoadInst(getEHCleanupDestSlot(), "cleanup.dest");
llvm::SwitchInst *Switch =
llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
EHInstsToAppend.push_back(Load);
EHInstsToAppend.push_back(Switch);
for (unsigned I = 0, E = Scope.getNumEHBranchAfters(); I != E; ++I)
Switch->addCase(Scope.getEHBranchAfterIndex(I),
Scope.getEHBranchAfterBlock(I));
// Otherwise, we have only branch-throughs; jump to the next EH
// cleanup.
} else {
assert(EHBranchThroughDest);
EHInstsToAppend.push_back(llvm::BranchInst::Create(EHBranchThroughDest));
}
}
if (!RequiresNormalCleanup) {
EHStack.popCleanup();
} else {
// If we have a fallthrough and no other need for the cleanup,
// emit it directly.
if (HasFallthrough && !HasPrebranchedFallthrough &&
!HasFixups && !HasExistingBranches) {
// Fixups can cause us to optimistically create a normal block,
// only to later have no real uses for it. Just delete it in
// this case.
// TODO: we can potentially simplify all the uses after this.
if (Scope.getNormalBlock()) {
Scope.getNormalBlock()->replaceAllUsesWith(getUnreachableBlock());
delete Scope.getNormalBlock();
}
EHStack.popCleanup();
EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag);
// Otherwise, the best approach is to thread everything through
// the cleanup block and then try to clean up after ourselves.
} else {
// Force the entry block to exist.
llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
// I. Set up the fallthrough edge in.
// If there's a fallthrough, we need to store the cleanup
// destination index. For fall-throughs this is always zero.
if (HasFallthrough) {
if (!HasPrebranchedFallthrough)
Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
// Otherwise, clear the IP if we don't have fallthrough because
// the cleanup is inactive. We don't need to save it because
// it's still just FallthroughSource.
} else if (FallthroughSource) {
assert(!IsActive && "source without fallthrough for active cleanup");
Builder.ClearInsertionPoint();
}
// II. Emit the entry block. This implicitly branches to it if
// we have fallthrough. All the fixups and existing branches
// should already be branched to it.
EmitBlock(NormalEntry);
// III. Figure out where we're going and build the cleanup
// epilogue.
bool HasEnclosingCleanups =
(Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
// Compute the branch-through dest if we need it:
// - if there are branch-throughs threaded through the scope
// - if fall-through is a branch-through
// - if there are fixups that will be optimistically forwarded
// to the enclosing cleanup
llvm::BasicBlock *BranchThroughDest = 0;
if (Scope.hasBranchThroughs() ||
(FallthroughSource && FallthroughIsBranchThrough) ||
(HasFixups && HasEnclosingCleanups)) {
assert(HasEnclosingCleanups);
EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
}
llvm::BasicBlock *FallthroughDest = 0;
llvm::SmallVector<llvm::Instruction*, 2> InstsToAppend;
// If there's exactly one branch-after and no other threads,
// we can route it without a switch.
if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
Scope.getNumBranchAfters() == 1) {
assert(!BranchThroughDest || !IsActive);
// TODO: clean up the possibly dead stores to the cleanup dest slot.
llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
// Build a switch-out if we need it:
// - if there are branch-afters threaded through the scope
// - if fall-through is a branch-after
// - if there are fixups that have nowhere left to go and
// so must be immediately resolved
} else if (Scope.getNumBranchAfters() ||
(HasFallthrough && !FallthroughIsBranchThrough) ||
(HasFixups && !HasEnclosingCleanups)) {
llvm::BasicBlock *Default =
(BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
// TODO: base this on the number of branch-afters and fixups
const unsigned SwitchCapacity = 10;
llvm::LoadInst *Load =
new llvm::LoadInst(getNormalCleanupDestSlot(), "cleanup.dest");
llvm::SwitchInst *Switch =
llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
InstsToAppend.push_back(Load);
InstsToAppend.push_back(Switch);
// Branch-after fallthrough.
if (FallthroughSource && !FallthroughIsBranchThrough) {
FallthroughDest = createBasicBlock("cleanup.cont");
if (HasFallthrough)
Switch->addCase(Builder.getInt32(0), FallthroughDest);
}
for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
Switch->addCase(Scope.getBranchAfterIndex(I),
Scope.getBranchAfterBlock(I));
}
// If there aren't any enclosing cleanups, we can resolve all
// the fixups now.
if (HasFixups && !HasEnclosingCleanups)
ResolveAllBranchFixups(*this, Switch, NormalEntry);
} else {
// We should always have a branch-through destination in this case.
assert(BranchThroughDest);
InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
}
// IV. Pop the cleanup and emit it.
EHStack.popCleanup();
assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag);
// Append the prepared cleanup prologue from above.
llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
NormalExit->getInstList().push_back(InstsToAppend[I]);
// Optimistically hope that any fixups will continue falling through.
for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
I < E; ++I) {
BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
if (!Fixup.Destination) continue;
if (!Fixup.OptimisticBranchBlock) {
new llvm::StoreInst(Builder.getInt32(Fixup.DestinationIndex),
getNormalCleanupDestSlot(),
Fixup.InitialBranch);
Fixup.InitialBranch->setSuccessor(0, NormalEntry);
}
Fixup.OptimisticBranchBlock = NormalExit;
}
// V. Set up the fallthrough edge out.
// Case 1: a fallthrough source exists but shouldn't branch to
// the cleanup because the cleanup is inactive.
if (!HasFallthrough && FallthroughSource) {
assert(!IsActive);
// If we have a prebranched fallthrough, that needs to be
// forwarded to the right block.
if (HasPrebranchedFallthrough) {
llvm::BasicBlock *Next;
if (FallthroughIsBranchThrough) {
Next = BranchThroughDest;
assert(!FallthroughDest);
} else {
Next = FallthroughDest;
}
ForwardPrebranchedFallthrough(FallthroughSource, NormalEntry, Next);
}
Builder.SetInsertPoint(FallthroughSource);
// Case 2: a fallthrough source exists and should branch to the
// cleanup, but we're not supposed to branch through to the next
// cleanup.
} else if (HasFallthrough && FallthroughDest) {
assert(!FallthroughIsBranchThrough);
EmitBlock(FallthroughDest);
// Case 3: a fallthrough source exists and should branch to the
// cleanup and then through to the next.
} else if (HasFallthrough) {
// Everything is already set up for this.
// Case 4: no fallthrough source exists.
} else {
Builder.ClearInsertionPoint();
}
// VI. Assorted cleaning.
// Check whether we can merge NormalEntry into a single predecessor.
// This might invalidate (non-IR) pointers to NormalEntry.
llvm::BasicBlock *NewNormalEntry =
SimplifyCleanupEntry(*this, NormalEntry);
// If it did invalidate those pointers, and NormalEntry was the same
// as NormalExit, go back and patch up the fixups.
if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
I < E; ++I)
CGF.EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
}
}
assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
// Emit the EH cleanup if required.
if (RequiresEHCleanup) {
CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
EmitBlock(EHEntry);
EmitCleanup(*this, Fn, /*ForEH*/ true, EHActiveFlag);
// Append the prepared cleanup prologue from above.
llvm::BasicBlock *EHExit = Builder.GetInsertBlock();
for (unsigned I = 0, E = EHInstsToAppend.size(); I != E; ++I)
EHExit->getInstList().push_back(EHInstsToAppend[I]);
Builder.restoreIP(SavedIP);
SimplifyCleanupEntry(*this, EHEntry);
}
}
/// Terminate the current block by emitting a branch which might leave
/// the current cleanup-protected scope. The target scope may not yet
/// be known, in which case this will require a fixup.
///
/// As a side-effect, this method clears the insertion point.
void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) {
assert(Dest.getScopeDepth().encloses(EHStack.getInnermostNormalCleanup())
&& "stale jump destination");
if (!HaveInsertPoint())
return;
// Create the branch.
llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
// Calculate the innermost active normal cleanup.
EHScopeStack::stable_iterator
TopCleanup = EHStack.getInnermostActiveNormalCleanup();
// If we're not in an active normal cleanup scope, or if the
// destination scope is within the innermost active normal cleanup
// scope, we don't need to worry about fixups.
if (TopCleanup == EHStack.stable_end() ||
TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
Builder.ClearInsertionPoint();
return;
}
// If we can't resolve the destination cleanup scope, just add this
// to the current cleanup scope as a branch fixup.
if (!Dest.getScopeDepth().isValid()) {
BranchFixup &Fixup = EHStack.addBranchFixup();
Fixup.Destination = Dest.getBlock();
Fixup.DestinationIndex = Dest.getDestIndex();
Fixup.InitialBranch = BI;
Fixup.OptimisticBranchBlock = 0;
Builder.ClearInsertionPoint();
return;
}
// Otherwise, thread through all the normal cleanups in scope.
// Store the index at the start.
llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
new llvm::StoreInst(Index, getNormalCleanupDestSlot(), BI);
// Adjust BI to point to the first cleanup block.
{
EHCleanupScope &Scope =
cast<EHCleanupScope>(*EHStack.find(TopCleanup));
BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
}
// Add this destination to all the scopes involved.
EHScopeStack::stable_iterator I = TopCleanup;
EHScopeStack::stable_iterator E = Dest.getScopeDepth();
if (E.strictlyEncloses(I)) {
while (true) {
EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
assert(Scope.isNormalCleanup());
I = Scope.getEnclosingNormalCleanup();
// If this is the last cleanup we're propagating through, tell it
// that there's a resolved jump moving through it.
if (!E.strictlyEncloses(I)) {
Scope.addBranchAfter(Index, Dest.getBlock());
break;
}
// Otherwise, tell the scope that there's a jump propoagating
// through it. If this isn't new information, all the rest of
// the work has been done before.
if (!Scope.addBranchThrough(Dest.getBlock()))
break;
}
}
Builder.ClearInsertionPoint();
}
void CodeGenFunction::EmitBranchThroughEHCleanup(UnwindDest Dest) {
// We should never get invalid scope depths for an UnwindDest; that
// implies that the destination wasn't set up correctly.
assert(Dest.getScopeDepth().isValid() && "invalid scope depth on EH dest?");
if (!HaveInsertPoint())
return;
// Create the branch.
llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
// Calculate the innermost active cleanup.
EHScopeStack::stable_iterator
InnermostCleanup = EHStack.getInnermostActiveEHCleanup();
// If the destination is in the same EH cleanup scope as us, we
// don't need to thread through anything.
if (InnermostCleanup.encloses(Dest.getScopeDepth())) {
Builder.ClearInsertionPoint();
return;
}
assert(InnermostCleanup != EHStack.stable_end());
// Store the index at the start.
llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
new llvm::StoreInst(Index, getEHCleanupDestSlot(), BI);
// Adjust BI to point to the first cleanup block.
{
EHCleanupScope &Scope =
cast<EHCleanupScope>(*EHStack.find(InnermostCleanup));
BI->setSuccessor(0, CreateEHEntry(*this, Scope));
}
// Add this destination to all the scopes involved.
for (EHScopeStack::stable_iterator
I = InnermostCleanup, E = Dest.getScopeDepth(); ; ) {
assert(E.strictlyEncloses(I));
EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
assert(Scope.isEHCleanup());
I = Scope.getEnclosingEHCleanup();
// If this is the last cleanup we're propagating through, add this
// as a branch-after.
if (I == E) {
Scope.addEHBranchAfter(Index, Dest.getBlock());
break;
}
// Otherwise, add it as a branch-through. If this isn't new
// information, all the rest of the work has been done before.
if (!Scope.addEHBranchThrough(Dest.getBlock()))
break;
}
Builder.ClearInsertionPoint();
}
/// All the branch fixups on the EH stack have propagated out past the
/// outermost normal cleanup; resolve them all by adding cases to the
/// given switch instruction.
static void ResolveAllBranchFixups(CodeGenFunction &CGF,
llvm::SwitchInst *Switch,
llvm::BasicBlock *CleanupEntry) {
llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
// Skip this fixup if its destination isn't set.
BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
if (Fixup.Destination == 0) continue;
// If there isn't an OptimisticBranchBlock, then InitialBranch is
// still pointing directly to its destination; forward it to the
// appropriate cleanup entry. This is required in the specific
// case of
// { std::string s; goto lbl; }
// lbl:
// i.e. where there's an unresolved fixup inside a single cleanup
// entry which we're currently popping.
if (Fixup.OptimisticBranchBlock == 0) {
new llvm::StoreInst(CGF.Builder.getInt32(Fixup.DestinationIndex),
CGF.getNormalCleanupDestSlot(),
Fixup.InitialBranch);
Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
}
// Don't add this case to the switch statement twice.
if (!CasesAdded.insert(Fixup.Destination)) continue;
Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
Fixup.Destination);
}
CGF.EHStack.clearFixups();
}
void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
assert(Block && "resolving a null target block");
if (!EHStack.getNumBranchFixups()) return;
assert(EHStack.hasNormalCleanups() &&
"branch fixups exist with no normal cleanups on stack");
llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
bool ResolvedAny = false;
for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
// Skip this fixup if its destination doesn't match.
BranchFixup &Fixup = EHStack.getBranchFixup(I);
if (Fixup.Destination != Block) continue;
Fixup.Destination = 0;
ResolvedAny = true;
// If it doesn't have an optimistic branch block, LatestBranch is
// already pointing to the right place.
llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
if (!BranchBB)
continue;
// Don't process the same optimistic branch block twice.
if (!ModifiedOptimisticBlocks.insert(BranchBB))
continue;
llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
// Add a case to the switch.
Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
}
if (ResolvedAny)
EHStack.popNullFixups();
}
static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack,
EHScopeStack::stable_iterator C) {
// If we needed a normal block for any reason, that counts.
if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
return true;
// Check whether any enclosed cleanups were needed.
for (EHScopeStack::stable_iterator
I = EHStack.getInnermostNormalCleanup();
I != C; ) {
assert(C.strictlyEncloses(I));
EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
if (S.getNormalBlock()) return true;
I = S.getEnclosingNormalCleanup();
}
return false;
}
static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
EHScopeStack::stable_iterator C) {
// If we needed an EH block for any reason, that counts.
if (cast<EHCleanupScope>(*EHStack.find(C)).getEHBlock())
return true;
// Check whether any enclosed cleanups were needed.
for (EHScopeStack::stable_iterator
I = EHStack.getInnermostEHCleanup(); I != C; ) {
assert(C.strictlyEncloses(I));
EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
if (S.getEHBlock()) return true;
I = S.getEnclosingEHCleanup();
}
return false;
}
enum ForActivation_t {
ForActivation,
ForDeactivation
};
/// The given cleanup block is changing activation state. Configure a
/// cleanup variable if necessary.
///
/// It would be good if we had some way of determining if there were
/// extra uses *after* the change-over point.
static void SetupCleanupBlockActivation(CodeGenFunction &CGF,
EHScopeStack::stable_iterator C,
ForActivation_t Kind) {
EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
// We always need the flag if we're activating the cleanup, because
// we have to assume that the current location doesn't necessarily
// dominate all future uses of the cleanup.
bool NeedFlag = (Kind == ForActivation);
// Calculate whether the cleanup was used:
// - as a normal cleanup
if (Scope.isNormalCleanup() && IsUsedAsNormalCleanup(CGF.EHStack, C)) {
Scope.setTestFlagInNormalCleanup();
NeedFlag = true;
}
// - as an EH cleanup
if (Scope.isEHCleanup() && IsUsedAsEHCleanup(CGF.EHStack, C)) {
Scope.setTestFlagInEHCleanup();
NeedFlag = true;
}
// If it hasn't yet been used as either, we're done.
if (!NeedFlag) return;
llvm::AllocaInst *Var = Scope.getActiveFlag();
if (!Var) {
Var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "cleanup.isactive");
Scope.setActiveFlag(Var);
// Initialize to true or false depending on whether it was
// active up to this point.
CGF.InitTempAlloca(Var, CGF.Builder.getInt1(Kind == ForDeactivation));
}
CGF.Builder.CreateStore(CGF.Builder.getInt1(Kind == ForActivation), Var);
}
/// Activate a cleanup that was created in an inactivated state.
void CodeGenFunction::ActivateCleanupBlock(EHScopeStack::stable_iterator C) {
assert(C != EHStack.stable_end() && "activating bottom of stack?");
EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
assert(!Scope.isActive() && "double activation");
SetupCleanupBlockActivation(*this, C, ForActivation);
Scope.setActive(true);
}
/// Deactive a cleanup that was created in an active state.
void CodeGenFunction::DeactivateCleanupBlock(EHScopeStack::stable_iterator C) {
assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
assert(Scope.isActive() && "double deactivation");
// If it's the top of the stack, just pop it.
if (C == EHStack.stable_begin()) {
// If it's a normal cleanup, we need to pretend that the
// fallthrough is unreachable.
CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
PopCleanupBlock();
Builder.restoreIP(SavedIP);
return;
}
// Otherwise, follow the general case.
SetupCleanupBlockActivation(*this, C, ForDeactivation);
Scope.setActive(false);
}
llvm::Value *CodeGenFunction::getNormalCleanupDestSlot() {
if (!NormalCleanupDest)
NormalCleanupDest =
CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
return NormalCleanupDest;
}
llvm::Value *CodeGenFunction::getEHCleanupDestSlot() {
if (!EHCleanupDest)
EHCleanupDest =
CreateTempAlloca(Builder.getInt32Ty(), "eh.cleanup.dest.slot");
return EHCleanupDest;
}
void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E,
llvm::Constant *Init) {
assert (Init && "Invalid DeclRefExpr initializer!");
if (CGDebugInfo *Dbg = getDebugInfo())
Dbg->EmitGlobalVariable(E->getDecl(), Init);
}
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