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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 "clang/Basic/TargetInfo.h"
#include "clang/AST/AST.h"
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Support/CFG.h"
using namespace clang;
using namespace CodeGen;
CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
: CGM(cgm), Target(CGM.getContext().Target), SwitchInsn(NULL),
CaseRangeBlock(NULL) {}
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 = new llvm::BasicBlock(S->getName());
}
llvm::Constant *
CodeGenFunction::GetAddrOfStaticLocalVar(const BlockVarDecl *BVD) {
return cast<llvm::Constant>(LocalDeclMap[BVD]);
}
const llvm::Type *CodeGenFunction::ConvertType(QualType T) {
return CGM.getTypes().ConvertType(T);
}
bool CodeGenFunction::hasAggregateLLVMType(QualType T) {
return !T->isRealType() && !T->isPointerType() && !T->isReferenceType() &&
!T->isVoidType() && !T->isVectorType() && !T->isFunctionType();
}
void CodeGenFunction::GenerateCode(const FunctionDecl *FD) {
LLVMIntTy = ConvertType(getContext().IntTy);
LLVMPointerWidth = static_cast<unsigned>(
getContext().getTypeSize(getContext().getPointerType(getContext().VoidTy)));
CurFuncDecl = FD;
CurFn = cast<llvm::Function>(CGM.GetAddrOfFunctionDecl(FD, true));
assert(CurFn->isDeclaration() && "Function already has body?");
// TODO: Set up linkage and many other things. Note, this is a simple
// approximation of what we really want.
if (FD->getAttr<DLLImportAttr>())
CurFn->setLinkage(llvm::Function::DLLImportLinkage);
else if (FD->getAttr<DLLExportAttr>())
CurFn->setLinkage(llvm::Function::DLLExportLinkage);
else if (FD->getAttr<WeakAttr>() || FD->isInline())
CurFn->setLinkage(llvm::Function::WeakLinkage);
else if (FD->getStorageClass() == FunctionDecl::Static)
CurFn->setLinkage(llvm::Function::InternalLinkage);
if (FD->getAttr<FastCallAttr>())
CurFn->setCallingConv(llvm::CallingConv::Fast);
if (const VisibilityAttr *attr = FD->getAttr<VisibilityAttr>())
CurFn->setVisibility(attr->getVisibility());
// FIXME: else handle -fvisibility
unsigned FuncAttrs = 0;
if (FD->getAttr<NoThrowAttr>())
FuncAttrs |= llvm::ParamAttr::NoUnwind;
if (FD->getAttr<NoReturnAttr>())
FuncAttrs |= llvm::ParamAttr::NoReturn;
if (FuncAttrs) {
llvm::ParamAttrsWithIndex PAWI =
llvm::ParamAttrsWithIndex::get(0, FuncAttrs);
CurFn->setParamAttrs(llvm::PAListPtr::get(&PAWI, 1));
}
llvm::BasicBlock *EntryBB = new llvm::BasicBlock("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::Int32Ty);
AllocaInsertPt = new llvm::BitCastInst(Undef, llvm::Type::Int32Ty, "allocapt",
EntryBB);
Builder.SetInsertPoint(EntryBB);
// Emit allocs for param decls. Give the LLVM Argument nodes names.
llvm::Function::arg_iterator AI = CurFn->arg_begin();
// Name the struct return argument.
if (hasAggregateLLVMType(FD->getResultType())) {
AI->setName("agg.result");
++AI;
}
for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i, ++AI) {
assert(AI != CurFn->arg_end() && "Argument mismatch!");
EmitParmDecl(*FD->getParamDecl(i), AI);
}
// Emit the function body.
EmitStmt(FD->getBody());
// Emit a return for code that falls off the end. If insert point
// is a dummy block with no predecessors then remove the block itself.
llvm::BasicBlock *BB = Builder.GetInsertBlock();
if (isDummyBlock(BB))
BB->eraseFromParent();
else {
// FIXME: if this is C++ main, this should return 0.
if (CurFn->getReturnType() == llvm::Type::VoidTy)
Builder.CreateRetVoid();
else
Builder.CreateRet(llvm::UndefValue::get(CurFn->getReturnType()));
}
assert(BreakContinueStack.empty() &&
"mismatched push/pop in break/continue stack!");
// Remove the AllocaInsertPt instruction, which is just a convenience for us.
AllocaInsertPt->eraseFromParent();
AllocaInsertPt = 0;
// Verify that the function is well formed.
assert(!verifyFunction(*CurFn));
}
/// isDummyBlock - Return true if BB is an empty basic block
/// with no predecessors.
bool CodeGenFunction::isDummyBlock(const llvm::BasicBlock *BB) {
if (BB->empty() && pred_begin(BB) == pred_end(BB))
return true;
return false;
}
/// StartBlock - Start new block named N. If insert block is a dummy block
/// then reuse it.
void CodeGenFunction::StartBlock(const char *N) {
llvm::BasicBlock *BB = Builder.GetInsertBlock();
if (!isDummyBlock(BB))
EmitBlock(new llvm::BasicBlock(N));
else
BB->setName(N);
}
/// getCGRecordLayout - Return record layout info.
const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT,
QualType Ty) {
const RecordType *RTy = Ty->getAsRecordType();
assert (RTy && "Unexpected type. RecordType expected here.");
return CGT.getCGRecordLayout(RTy->getDecl());
}
/// WarnUnsupported - Print out a warning that codegen doesn't support the
/// specified stmt yet.
void CodeGenFunction::WarnUnsupported(const Stmt *S, const char *Type) {
CGM.WarnUnsupported(S, Type);
}
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