CGDecl.cpp revision 2621fd1d6d3c5eadcae246859f62738645df7540 
1//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This contains code to emit Decl nodes as LLVM code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CodeGenModule.h"
16#include "clang/AST/AST.h"
17#include "clang/Basic/SourceManager.h"
18#include "clang/Basic/TargetInfo.h"
19#include "llvm/GlobalVariable.h"
20#include "llvm/Type.h"
21using namespace clang;
22using namespace CodeGen;
23
24
25void CodeGenFunction::EmitDecl(const Decl &D) {
26  switch (D.getKind()) {
27  default: assert(0 && "Unknown decl kind!");
28  case Decl::ParmVar:
29    assert(0 && "Parmdecls should not be in declstmts!");
30  case Decl::Typedef:   // typedef int X;
31  case Decl::Function:  // void X();
32  case Decl::Struct:    // struct X;
33  case Decl::Union:     // union X;
34  case Decl::Class:     // class X;
35  case Decl::Enum:      // enum X;
36    // None of these decls require codegen support.
37    return;
38
39  case Decl::Var:
40    if (cast<VarDecl>(D).isBlockVarDecl())
41      return EmitBlockVarDecl(cast<VarDecl>(D));
42    assert(0 && "Should not see file-scope variables inside a function!");
43
44  case Decl::EnumConstant:
45    return EmitEnumConstantDecl(cast<EnumConstantDecl>(D));
46  }
47}
48
49void CodeGenFunction::EmitEnumConstantDecl(const EnumConstantDecl &D) {
50  assert(0 && "FIXME: Enum constant decls not implemented yet!");
51}
52
53/// EmitBlockVarDecl - This method handles emission of any variable declaration
54/// inside a function, including static vars etc.
55void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) {
56  switch (D.getStorageClass()) {
57  case VarDecl::Static:
58    return EmitStaticBlockVarDecl(D);
59  case VarDecl::Extern:
60    // Don't emit it now, allow it to be emitted lazily on its first use.
61    return;
62  default:
63    assert((D.getStorageClass() == VarDecl::None ||
64            D.getStorageClass() == VarDecl::Auto ||
65            D.getStorageClass() == VarDecl::Register) &&
66           "Unknown storage class");
67    return EmitLocalBlockVarDecl(D);
68  }
69}
70
71llvm::GlobalValue *
72CodeGenFunction::GenerateStaticBlockVarDecl(const VarDecl &D,
73                                            bool NoInit,
74                                            const char *Separator) {
75  QualType Ty = D.getType();
76  assert(Ty->isConstantSizeType() && "VLAs can't be static");
77
78  const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
79  llvm::Constant *Init = 0;
80  if ((D.getInit() == 0) || NoInit) {
81    Init = llvm::Constant::getNullValue(LTy);
82  } else {
83    Init = CGM.EmitConstantExpr(D.getInit(), this);
84  }
85
86  assert(Init && "Unable to create initialiser for static decl");
87
88  std::string ContextName;
89  if (const FunctionDecl * FD = dyn_cast<FunctionDecl>(CurFuncDecl))
90    ContextName = FD->getName();
91  else
92    assert(0 && "Unknown context for block var decl"); // FIXME Handle objc.
93
94  llvm::GlobalValue *GV =
95    new llvm::GlobalVariable(LTy, false, llvm::GlobalValue::InternalLinkage,
96                             Init, ContextName + Separator + D.getName(),
97                             &CGM.getModule(), 0, Ty.getAddressSpace());
98
99  return GV;
100}
101
102void CodeGenFunction::EmitStaticBlockVarDecl(const VarDecl &D) {
103
104  llvm::Value *&DMEntry = LocalDeclMap[&D];
105  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
106
107  llvm::GlobalValue *GV = GenerateStaticBlockVarDecl(D, false, ".");
108
109  if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
110    SourceManager &SM = CGM.getContext().getSourceManager();
111    llvm::Constant *Ann =
112      CGM.EmitAnnotateAttr(GV, AA, SM.getLogicalLineNumber(D.getLocation()));
113    CGM.AddAnnotation(Ann);
114  }
115
116  DMEntry = GV;
117}
118
119/// EmitLocalBlockVarDecl - Emit code and set up an entry in LocalDeclMap for a
120/// variable declaration with auto, register, or no storage class specifier.
121/// These turn into simple stack objects, or GlobalValues depending on target.
122void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) {
123  QualType Ty = D.getType();
124
125  llvm::Value *DeclPtr;
126  if (Ty->isConstantSizeType()) {
127    if (!Target.useGlobalsForAutomaticVariables()) {
128      // A normal fixed sized variable becomes an alloca in the entry block.
129      const llvm::Type *LTy = ConvertType(Ty);
130      // TODO: Alignment
131      DeclPtr = CreateTempAlloca(LTy, D.getName());
132    } else {
133      // Targets that don't support recursion emit locals as globals.
134      const char *Class =
135        D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto.";
136      DeclPtr = GenerateStaticBlockVarDecl(D, true, Class);
137    }
138  } else {
139    // TODO: Create a dynamic alloca.
140    assert(0 && "FIXME: Local VLAs not implemented yet");
141  }
142
143  llvm::Value *&DMEntry = LocalDeclMap[&D];
144  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
145  DMEntry = DeclPtr;
146
147  // If this local has an initializer, emit it now.
148  if (const Expr *Init = D.getInit()) {
149    if (!hasAggregateLLVMType(Init->getType())) {
150      llvm::Value *V = EmitScalarExpr(Init);
151      Builder.CreateStore(V, DeclPtr, D.getType().isVolatileQualified());
152    } else if (Init->getType()->isAnyComplexType()) {
153      EmitComplexExprIntoAddr(Init, DeclPtr, D.getType().isVolatileQualified());
154    } else {
155      EmitAggExpr(Init, DeclPtr, D.getType().isVolatileQualified());
156    }
157  }
158}
159
160/// Emit an alloca (or GlobalValue depending on target)
161/// for the specified parameter and set up LocalDeclMap.
162void CodeGenFunction::EmitParmDecl(const ParmVarDecl &D, llvm::Value *Arg) {
163  QualType Ty = D.getType();
164
165  llvm::Value *DeclPtr;
166  if (!Ty->isConstantSizeType()) {
167    // Variable sized values always are passed by-reference.
168    DeclPtr = Arg;
169  } else if (Target.useGlobalsForAutomaticVariables()) {
170    DeclPtr = GenerateStaticBlockVarDecl(D, true, ".arg.");
171  } else {
172    // A fixed sized first class variable becomes an alloca in the entry block.
173    const llvm::Type *LTy = ConvertType(Ty);
174    if (LTy->isFirstClassType()) {
175      // TODO: Alignment
176      DeclPtr = new llvm::AllocaInst(LTy, 0, std::string(D.getName())+".addr",
177                                     AllocaInsertPt);
178
179      // Store the initial value into the alloca.
180      Builder.CreateStore(Arg, DeclPtr);
181    } else {
182      // Otherwise, if this is an aggregate, just use the input pointer.
183      DeclPtr = Arg;
184    }
185    Arg->setName(D.getName());
186  }
187
188  llvm::Value *&DMEntry = LocalDeclMap[&D];
189  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
190  DMEntry = DeclPtr;
191}
192
193