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//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and 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/Basic/Diagnostic.h"
#include "clang/AST/AST.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());
}
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),
SourceLocation()));
CurFuncDecl = FD;
llvm::Constant *CurFnC = CGM.GetAddrOfGlobalDecl(FD);
if (!(CurFn = dyn_cast<llvm::Function>(CurFnC))) {
// If CurFnC is not a constant, it must be a bitcast of another function.
llvm::ConstantExpr *CurFnCE = cast<llvm::ConstantExpr>(CurFnC);
assert(CurFnCE->getOpcode() == llvm::Instruction::BitCast &&
"Unexpected name collision");
llvm::Function *OtherFunc = cast<llvm::Function>(CurFnCE->getOperand(0));
// This happens if there is a prototype for a function (e.g. "int f()") and
// then a definition of a different type (e.g. "int f(int x)"). Start by
// making a new function of the correct type, RAUW, then steal the name.
const llvm::PointerType *PTy = cast<llvm::PointerType>(CurFnC->getType());
const llvm::FunctionType *FTy =
cast<llvm::FunctionType>(PTy->getElementType());
CurFn = new llvm::Function(FTy, llvm::Function::ExternalLinkage, "",
&CGM.getModule());
CurFn->takeName(OtherFunc);
// Replace uses of OtherFunc with the Function we will endow with a body.
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(CurFn, OtherFunc->getType());
OtherFunc->replaceAllUsesWith(NewPtrForOldDecl);
// Make sure the GlobalDecl map for FD is up-to-date.
CGM.ChangeGlobalDeclMap(FD, CurFn);
// FIXME: Update the globaldeclmap for the previous decl of this name. We
// really want a way to walk all of these, but we don't have it yet. This
// is incredibly slow!
CGM.ReplaceMapValuesWith(OtherFunc, NewPtrForOldDecl);
// Ok, delete the old function now, which is dead.
assert(OtherFunc->isDeclaration() && "Shouldn't replace non-declaration");
OtherFunc->eraseFromParent();
}
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->getStorageClass() == FunctionDecl::Static)
CurFn->setLinkage(llvm::Function::InternalLinkage);
else if (FD->isInline())
CurFn->setLinkage(llvm::Function::WeakLinkage);
llvm::BasicBlock *EntryBB = new llvm::BasicBlock("entry", CurFn);
Builder.SetInsertPoint(EntryBB);
// Create a marker to make it easy to insert allocas into the entryblock
// later.
llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::Int32Ty);
AllocaInsertPt = Builder.CreateBitCast(Undef,llvm::Type::Int32Ty, "allocapt");
// 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!");
// 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 RTy) {
assert (isa<RecordType>(RTy)
&& "Unexpected type. RecordType expected here.");
const llvm::Type *Ty = ConvertType(RTy);
assert (Ty && "Unable to find llvm::Type");
return CGT.getCGRecordLayout(Ty);
}
/// WarnUnsupported - Print out a warning that codegen doesn't support the
/// specified stmt yet.
void CodeGenFunction::WarnUnsupported(const Stmt *S, const char *Type) {
unsigned DiagID = CGM.getDiags().getCustomDiagID(Diagnostic::Warning,
"cannot codegen this %0 yet");
SourceRange Range = S->getSourceRange();
std::string Msg = Type;
CGM.getDiags().Report(S->getLocStart(), DiagID, &Msg, 1, &Range, 1);
}
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