CodeGenFunction.cpp revision 5f016e2cb5d11daeb237544de1c5d59f20fe1a6e 
1//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by Chris Lattner and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This coordinates the per-function state used while generating code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CodeGenModule.h"
16#include "clang/Basic/TargetInfo.h"
17#include "clang/AST/AST.h"
18#include "llvm/Constants.h"
19#include "llvm/DerivedTypes.h"
20#include "llvm/Function.h"
21#include "llvm/Analysis/Verifier.h"
22using namespace clang;
23using namespace CodeGen;
24
25CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
26  : CGM(cgm), Target(CGM.getContext().Target) {}
27
28ASTContext &CodeGenFunction::getContext() const {
29  return CGM.getContext();
30}
31
32
33llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) {
34  llvm::BasicBlock *&BB = LabelMap[S];
35  if (BB) return BB;
36
37  // Create, but don't insert, the new block.
38  return BB = new llvm::BasicBlock(S->getName());
39}
40
41
42const llvm::Type *CodeGenFunction::ConvertType(QualType T) {
43  return CGM.getTypes().ConvertType(T);
44}
45
46bool CodeGenFunction::hasAggregateLLVMType(QualType T) {
47  return !T->isRealType() && !T->isPointerType() && !T->isVoidType() &&
48         !T->isVectorType();
49}
50
51
52void CodeGenFunction::GenerateCode(const FunctionDecl *FD) {
53  LLVMIntTy = ConvertType(getContext().IntTy);
54  LLVMPointerWidth = Target.getPointerWidth(SourceLocation());
55
56  CurFn = cast<llvm::Function>(CGM.GetAddrOfGlobalDecl(FD));
57  CurFuncDecl = FD;
58
59  // TODO: Set up linkage and many other things.
60  assert(CurFn->isDeclaration() && "Function already has body?");
61
62  llvm::BasicBlock *EntryBB = new llvm::BasicBlock("entry", CurFn);
63
64  Builder.SetInsertPoint(EntryBB);
65
66  // Create a marker to make it easy to insert allocas into the entryblock
67  // later.
68  llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::Int32Ty);
69  AllocaInsertPt = Builder.CreateBitCast(Undef,llvm::Type::Int32Ty, "allocapt");
70
71  // Emit allocs for param decls.  Give the LLVM Argument nodes names.
72  llvm::Function::arg_iterator AI = CurFn->arg_begin();
73
74  // Name the struct return argument.
75  if (hasAggregateLLVMType(FD->getResultType())) {
76    AI->setName("agg.result");
77    ++AI;
78  }
79
80  for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i, ++AI) {
81    assert(AI != CurFn->arg_end() && "Argument mismatch!");
82    EmitParmDecl(*FD->getParamDecl(i), AI);
83  }
84
85  // Emit the function body.
86  EmitStmt(FD->getBody());
87
88  // Emit a return for code that falls off the end.
89  // FIXME: if this is C++ main, this should return 0.
90  if (CurFn->getReturnType() == llvm::Type::VoidTy)
91    Builder.CreateRetVoid();
92  else
93    Builder.CreateRet(llvm::UndefValue::get(CurFn->getReturnType()));
94
95  // Verify that the function is well formed.
96  assert(!verifyFunction(*CurFn));
97}
98
99