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clang-1/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;
CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
: CodeGenTypeCache(cgm), CGM(cgm),
Target(CGM.getContext().getTargetInfo()), Builder(cgm.getModule().getContext()),
AutoreleaseResult(false), BlockInfo(0), BlockPointer(0),
NormalCleanupDest(0), NextCleanupDestIndex(1),
EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0),
DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false),
IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0),
CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0),
OutermostConditional(0), TerminateLandingPad(0), TerminateHandler(0),
TrapBB(0) {
CatchUndefined = getContext().getLangOptions().CatchUndefined;
CGM.getCXXABI().getMangleContext().startNewFunction();
}
llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
return CGM.getTypes().ConvertTypeForMem(T);
}
llvm::Type *CodeGenFunction::ConvertType(QualType T) {
return CGM.getTypes().ConvertType(T);
}
bool CodeGenFunction::hasAggregateLLVMType(QualType type) {
switch (type.getCanonicalType()->getTypeClass()) {
#define TYPE(name, parent)
#define ABSTRACT_TYPE(name, parent)
#define NON_CANONICAL_TYPE(name, parent) case Type::name:
#define DEPENDENT_TYPE(name, parent) case Type::name:
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name:
#include "clang/AST/TypeNodes.def"
llvm_unreachable("non-canonical or dependent type in IR-generation");
case Type::Builtin:
case Type::Pointer:
case Type::BlockPointer:
case Type::LValueReference:
case Type::RValueReference:
case Type::MemberPointer:
case Type::Vector:
case Type::ExtVector:
case Type::FunctionProto:
case Type::FunctionNoProto:
case Type::Enum:
case Type::ObjCObjectPointer:
return false;
// Complexes, arrays, records, and Objective-C objects.
case Type::Complex:
case Type::ConstantArray:
case Type::IncompleteArray:
case Type::VariableArray:
case Type::Record:
case Type::ObjCObject:
case Type::ObjCInterface:
return true;
}
llvm_unreachable("unknown type kind!");
}
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, including debug location, and delete the branch.
Builder.SetCurrentDebugLocation(BI->getDebugLoc());
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!");
// Pop any cleanups that might have been associated with the
// parameters. Do this in whatever block we're currently in; it's
// important to do this before we enter the return block or return
// edges will be *really* confused.
if (EHStack.stable_begin() != PrologueCleanupDepth)
PopCleanupBlocks(PrologueCleanupDepth);
// Emit function epilog (to return).
EmitReturnBlock();
if (ShouldInstrumentFunction())
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, EHResumeBlock);
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 || 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) {
// void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site);
llvm::PointerType *PointerTy = Int8PtrTy;
llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy };
llvm::FunctionType *FunctionTy =
llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()),
ProfileFuncArgs, false);
llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn);
llvm::CallInst *CallSite = Builder.CreateCall(
CGM.getIntrinsic(llvm::Intrinsic::returnaddress),
llvm::ConstantInt::get(Int32Ty, 0),
"callsite");
Builder.CreateCall2(F,
llvm::ConstantExpr::getBitCast(CurFn, PointerTy),
CallSite);
}
void CodeGenFunction::EmitMCountInstrumentation() {
llvm::FunctionType *FTy =
llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), false);
llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy,
Target.getMCountName());
Builder.CreateCall(MCountFn);
}
void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
llvm::Function *Fn,
const CGFunctionInfo &FnInfo,
const FunctionArgList &Args,
SourceLocation StartLoc) {
const Decl *D = GD.getDecl();
DidCallStackSave = false;
CurCodeDecl = CurFuncDecl = D;
FnRetTy = RetTy;
CurFn = Fn;
CurFnInfo = &FnInfo;
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;
}
if (getContext().getLangOptions().OpenCL) {
// Add metadata for a kernel function.
if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
if (FD->hasAttr<OpenCLKernelAttr>()) {
llvm::LLVMContext &Context = getLLVMContext();
llvm::NamedMDNode *OpenCLMetadata =
CGM.getModule().getOrInsertNamedMetadata("opencl.kernels");
llvm::Value *Op = Fn;
OpenCLMetadata->addOperand(llvm::MDNode::get(Context, Op));
}
}
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);
// Emit subprogram debug descriptor.
if (CGDebugInfo *DI = getDebugInfo()) {
// FIXME: what is going on here and why does it ignore all these
// interesting type properties?
QualType FnType =
getContext().getFunctionType(RetTy, 0, 0,
FunctionProtoType::ExtProtoInfo());
DI->setLocation(StartLoc);
DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
}
if (ShouldInstrumentFunction())
EmitFunctionInstrumentation("__cyg_profile_func_enter");
if (CGM.getCodeGenOpts().InstrumentForProfiling)
EmitMCountInstrumentation();
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");
// Tell the epilog emitter to autorelease the result. We do this
// now so that various specialized functions can suppress it
// during their IR-generation.
if (getLangOptions().ObjCAutoRefCount &&
!CurFnInfo->isReturnsRetained() &&
RetTy->isObjCRetainableType())
AutoreleaseResult = true;
}
EmitStartEHSpec(CurCodeDecl);
PrologueCleanupDepth = EHStack.stable_begin();
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)->getType();
if (Ty->isVariablyModifiedType())
EmitVariablyModifiedType(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 CGFunctionInfo &FnInfo) {
const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
// Check if we should generate debug info for this function.
if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>())
DebugInfo = CGM.getModuleDebugInfo();
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())
for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
Args.push_back(FD->getParamDecl(i));
SourceRange BodyRange;
if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
// Emit the standard function prologue.
StartFunction(GD, ResTy, Fn, FnInfo, 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;
//
// TODO: If anyone cared, we could track __label__'s, since we know that you
// can't jump to one from outside their declared region.
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_range I = S->children(); I; ++I)
if (ContainsLabel(*I, IgnoreCaseStmts))
return true;
return false;
}
/// containsBreak - Return true if the statement contains a break out of it.
/// If the statement (recursively) contains a switch or loop with a break
/// inside of it, this is fine.
bool CodeGenFunction::containsBreak(const Stmt *S) {
// Null statement, not a label!
if (S == 0) return false;
// If this is a switch or loop that defines its own break scope, then we can
// include it and anything inside of it.
if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) ||
isa<ForStmt>(S))
return false;
if (isa<BreakStmt>(S))
return true;
// Scan subexpressions for verboten breaks.
for (Stmt::const_child_range I = S->children(); I; ++I)
if (containsBreak(*I))
return true;
return false;
}
/// ConstantFoldsToSimpleInteger - If the specified expression does not fold
/// to a constant, or if it does but contains a label, return false. If it
/// constant folds return true and set the boolean result in Result.
bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond,
bool &ResultBool) {
llvm::APInt ResultInt;
if (!ConstantFoldsToSimpleInteger(Cond, ResultInt))
return false;
ResultBool = ResultInt.getBoolValue();
return true;
}
/// ConstantFoldsToSimpleInteger - If the specified expression does not fold
/// to a constant, or if it does but contains a label, return false. If it
/// constant folds return true and set the folded value.
bool CodeGenFunction::
ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APInt &ResultInt) {
// 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 false; // Not foldable, not integer or not fully evaluatable.
if (CodeGenFunction::ContainsLabel(Cond))
return false; // Contains a label.
ResultInt = Result.Val.getInt();
return true;
}
/// 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) {
Cond = Cond->IgnoreParens();
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.
bool ConstantBool = false;
if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
ConstantBool) {
// 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(), ConstantBool) &&
ConstantBool) {
// 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");
ConditionalEvaluation eval(*this);
EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
EmitBlock(LHSTrue);
// Any temporaries created here are conditional.
eval.begin(*this);
EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
eval.end(*this);
return;
}
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.
bool ConstantBool = false;
if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
!ConstantBool) {
// 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(), ConstantBool) &&
!ConstantBool) {
// 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");
ConditionalEvaluation eval(*this);
EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
EmitBlock(LHSFalse);
// Any temporaries created here are conditional.
eval.begin(*this);
EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
eval.end(*this);
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");
ConditionalEvaluation cond(*this);
EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
cond.begin(*this);
EmitBlock(LHSBlock);
EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
cond.end(*this);
cond.begin(*this);
EmitBlock(RHSBlock);
EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
cond.end(*this);
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);
}
/// emitNonZeroVLAInit - Emit the "zero" initialization of a
/// variable-length array whose elements have a non-zero bit-pattern.
///
/// \param src - a char* pointing to the bit-pattern for a single
/// base element of the array
/// \param sizeInChars - the total size of the VLA, in chars
/// \param align - the total alignment of the VLA
static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType,
llvm::Value *dest, llvm::Value *src,
llvm::Value *sizeInChars) {
std::pair<CharUnits,CharUnits> baseSizeAndAlign
= CGF.getContext().getTypeInfoInChars(baseType);
CGBuilderTy &Builder = CGF.Builder;
llvm::Value *baseSizeInChars
= llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity());
llvm::Type *i8p = Builder.getInt8PtrTy();
llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin");
llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end");
llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock();
llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop");
llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont");
// Make a loop over the VLA. C99 guarantees that the VLA element
// count must be nonzero.
CGF.EmitBlock(loopBB);
llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur");
cur->addIncoming(begin, originBB);
// memcpy the individual element bit-pattern.
Builder.CreateMemCpy(cur, src, baseSizeInChars,
baseSizeAndAlign.second.getQuantity(),
/*volatile*/ false);
// Go to the next element.
llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next");
// Leave if that's the end of the VLA.
llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone");
Builder.CreateCondBr(done, contBB, loopBB);
cur->addIncoming(next, loopBB);
CGF.EmitBlock(contBB);
}
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();
llvm::Type *BP = Builder.getInt8PtrTy(DestAS);
if (DestPtr->getType() != BP)
DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
// Get size and alignment info for this aggregate.
std::pair<CharUnits, CharUnits> TypeInfo =
getContext().getTypeInfoInChars(Ty);
CharUnits Size = TypeInfo.first;
CharUnits Align = TypeInfo.second;
llvm::Value *SizeVal;
const VariableArrayType *vla;
// Don't bother emitting a zero-byte memset.
if (Size.isZero()) {
// But note that getTypeInfo returns 0 for a VLA.
if (const VariableArrayType *vlaType =
dyn_cast_or_null<VariableArrayType>(
getContext().getAsArrayType(Ty))) {
QualType eltType;
llvm::Value *numElts;
llvm::tie(numElts, eltType) = getVLASize(vlaType);
SizeVal = numElts;
CharUnits eltSize = getContext().getTypeSizeInChars(eltType);
if (!eltSize.isOne())
SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize));
vla = vlaType;
} else {
return;
}
} else {
SizeVal = CGM.getSize(Size);
vla = 0;
}
// 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.
// TODO: there are other patterns besides zero that we can usefully memset,
// like -1, which happens to be the pattern used by member-pointers.
if (!CGM.getTypes().isZeroInitializable(Ty)) {
// For a VLA, emit a single element, then splat that over the VLA.
if (vla) Ty = getContext().getBaseElementType(vla);
llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
llvm::GlobalVariable *NullVariable =
new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
/*isConstant=*/true,
llvm::GlobalVariable::PrivateLinkage,
NullConstant, Twine());
llvm::Value *SrcPtr =
Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy());
if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal);
// Get and call the appropriate llvm.memcpy overload.
Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false);
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.
Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal,
Align.getQuantity(), false);
}
llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *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"));
// Create the PHI node that indirect gotos will add entries to.
llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0,
"indirect.goto.dest");
// Create the indirect branch instruction.
IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
return IndirectBranch->getParent();
}
/// Computes the length of an array in elements, as well as the base
/// element type and a properly-typed first element pointer.
llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType,
QualType &baseType,
llvm::Value *&addr) {
const ArrayType *arrayType = origArrayType;
// If it's a VLA, we have to load the stored size. Note that
// this is the size of the VLA in bytes, not its size in elements.
llvm::Value *numVLAElements = 0;
if (isa<VariableArrayType>(arrayType)) {
numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first;
// Walk into all VLAs. This doesn't require changes to addr,
// which has type T* where T is the first non-VLA element type.
do {
QualType elementType = arrayType->getElementType();
arrayType = getContext().getAsArrayType(elementType);
// If we only have VLA components, 'addr' requires no adjustment.
if (!arrayType) {
baseType = elementType;
return numVLAElements;
}
} while (isa<VariableArrayType>(arrayType));
// We get out here only if we find a constant array type
// inside the VLA.
}
// We have some number of constant-length arrays, so addr should
// have LLVM type [M x [N x [...]]]*. Build a GEP that walks
// down to the first element of addr.
SmallVector<llvm::Value*, 8> gepIndices;
// GEP down to the array type.
llvm::ConstantInt *zero = Builder.getInt32(0);
gepIndices.push_back(zero);
// It's more efficient to calculate the count from the LLVM
// constant-length arrays than to re-evaluate the array bounds.
uint64_t countFromCLAs = 1;
llvm::ArrayType *llvmArrayType =
cast<llvm::ArrayType>(
cast<llvm::PointerType>(addr->getType())->getElementType());
while (true) {
assert(isa<ConstantArrayType>(arrayType));
assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue()
== llvmArrayType->getNumElements());
gepIndices.push_back(zero);
countFromCLAs *= llvmArrayType->getNumElements();
llvmArrayType =
dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType());
if (!llvmArrayType) break;
arrayType = getContext().getAsArrayType(arrayType->getElementType());
assert(arrayType && "LLVM and Clang types are out-of-synch");
}
baseType = arrayType->getElementType();
// Create the actual GEP.
addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin");
llvm::Value *numElements
= llvm::ConstantInt::get(SizeTy, countFromCLAs);
// If we had any VLA dimensions, factor them in.
if (numVLAElements)
numElements = Builder.CreateNUWMul(numVLAElements, numElements);
return numElements;
}
std::pair<llvm::Value*, QualType>
CodeGenFunction::getVLASize(QualType type) {
const VariableArrayType *vla = getContext().getAsVariableArrayType(type);
assert(vla && "type was not a variable array type!");
return getVLASize(vla);
}
std::pair<llvm::Value*, QualType>
CodeGenFunction::getVLASize(const VariableArrayType *type) {
// The number of elements so far; always size_t.
llvm::Value *numElements = 0;
QualType elementType;
do {
elementType = type->getElementType();
llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()];
assert(vlaSize && "no size for VLA!");
assert(vlaSize->getType() == SizeTy);
if (!numElements) {
numElements = vlaSize;
} else {
// It's undefined behavior if this wraps around, so mark it that way.
numElements = Builder.CreateNUWMul(numElements, vlaSize);
}
} while ((type = getContext().getAsVariableArrayType(elementType)));
return std::pair<llvm::Value*,QualType>(numElements, elementType);
}
void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
assert(type->isVariablyModifiedType() &&
"Must pass variably modified type to EmitVLASizes!");
EnsureInsertPoint();
// We're going to walk down into the type and look for VLA
// expressions.
type = type.getCanonicalType();
do {
assert(type->isVariablyModifiedType());
const Type *ty = type.getTypePtr();
switch (ty->getTypeClass()) {
#define TYPE(Class, Base)
#define ABSTRACT_TYPE(Class, Base)
#define NON_CANONICAL_TYPE(Class, Base) case Type::Class:
#define DEPENDENT_TYPE(Class, Base) case Type::Class:
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base) case Type::Class:
#include "clang/AST/TypeNodes.def"
llvm_unreachable("unexpected dependent or non-canonical type!");
// These types are never variably-modified.
case Type::Builtin:
case Type::Complex:
case Type::Vector:
case Type::ExtVector:
case Type::Record:
case Type::Enum:
case Type::ObjCObject:
case Type::ObjCInterface:
case Type::ObjCObjectPointer:
llvm_unreachable("type class is never variably-modified!");
case Type::Pointer:
type = cast<PointerType>(ty)->getPointeeType();
break;
case Type::BlockPointer:
type = cast<BlockPointerType>(ty)->getPointeeType();
break;
case Type::LValueReference:
case Type::RValueReference:
type = cast<ReferenceType>(ty)->getPointeeType();
break;
case Type::MemberPointer:
type = cast<MemberPointerType>(ty)->getPointeeType();
break;
case Type::ConstantArray:
case Type::IncompleteArray:
// Losing element qualification here is fine.
type = cast<ArrayType>(ty)->getElementType();
break;
case Type::VariableArray: {
// Losing element qualification here is fine.
const VariableArrayType *vat = cast<VariableArrayType>(ty);
// Unknown size indication requires no size computation.
// Otherwise, evaluate and record it.
if (const Expr *size = vat->getSizeExpr()) {
// It's possible that we might have emitted this already,
// e.g. with a typedef and a pointer to it.
llvm::Value *&entry = VLASizeMap[size];
if (!entry) {
// Always zexting here would be wrong if it weren't
// undefined behavior to have a negative bound.
entry = Builder.CreateIntCast(EmitScalarExpr(size), SizeTy,
/*signed*/ false);
}
}
type = vat->getElementType();
break;
}
case Type::FunctionProto:
case Type::FunctionNoProto:
type = cast<FunctionType>(ty)->getResultType();
break;
}
} while (type->isVariablyModifiedType());
}
llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
if (getContext().getBuiltinVaListType()->isArrayType())
return EmitScalarExpr(E);
return EmitLValue(E).getAddress();
}
void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E,
llvm::Constant *Init) {
assert (Init && "Invalid DeclRefExpr initializer!");
if (CGDebugInfo *Dbg = getDebugInfo())
Dbg->EmitGlobalVariable(E->getDecl(), Init);
}
CodeGenFunction::PeepholeProtection
CodeGenFunction::protectFromPeepholes(RValue rvalue) {
// At the moment, the only aggressive peephole we do in IR gen
// is trunc(zext) folding, but if we add more, we can easily
// extend this protection.
if (!rvalue.isScalar()) return PeepholeProtection();
llvm::Value *value = rvalue.getScalarVal();
if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection();
// Just make an extra bitcast.
assert(HaveInsertPoint());
llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "",
Builder.GetInsertBlock());
PeepholeProtection protection;
protection.Inst = inst;
return protection;
}
void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) {
if (!protection.Inst) return;
// In theory, we could try to duplicate the peepholes now, but whatever.
protection.Inst->eraseFromParent();
}
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