CGDecl.cpp revision 77eedd6fcea7b090cb0368d26ec65305a84dbc6c 
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 "CGDebugInfo.h"
15#include "CodeGenFunction.h"
16#include "CodeGenModule.h"
17#include "clang/AST/AST.h"
18#include "clang/Basic/SourceManager.h"
19#include "clang/Basic/TargetInfo.h"
20#include "llvm/GlobalVariable.h"
21#include "llvm/Type.h"
22#include "llvm/Support/Dwarf.h"
23using namespace clang;
24using namespace CodeGen;
25
26
27void CodeGenFunction::EmitDecl(const Decl &D) {
28  switch (D.getKind()) {
29  default: assert(0 && "Unknown decl kind!");
30  case Decl::ParmVar:
31    assert(0 && "Parmdecls should not be in declstmts!");
32  case Decl::Typedef:   // typedef int X;
33  case Decl::Function:  // void X();
34  case Decl::Struct:    // struct X;
35  case Decl::Union:     // union X;
36  case Decl::Class:     // class X;
37  case Decl::Enum:      // enum X;
38    // None of these decls require codegen support.
39    return;
40
41  case Decl::Var:
42    if (cast<VarDecl>(D).isBlockVarDecl())
43      return EmitBlockVarDecl(cast<VarDecl>(D));
44    assert(0 && "Should not see file-scope variables inside a function!");
45
46  case Decl::EnumConstant:
47    return EmitEnumConstantDecl(cast<EnumConstantDecl>(D));
48  }
49}
50
51void CodeGenFunction::EmitEnumConstantDecl(const EnumConstantDecl &D) {
52  assert(0 && "FIXME: Enum constant decls not implemented yet!");
53}
54
55/// EmitBlockVarDecl - This method handles emission of any variable declaration
56/// inside a function, including static vars etc.
57void CodeGenFunction::EmitBlockVarDecl(const VarDecl &D) {
58  switch (D.getStorageClass()) {
59  case VarDecl::Static:
60    return EmitStaticBlockVarDecl(D);
61  case VarDecl::Extern:
62    // Don't emit it now, allow it to be emitted lazily on its first use.
63    return;
64  default:
65    assert((D.getStorageClass() == VarDecl::None ||
66            D.getStorageClass() == VarDecl::Auto ||
67            D.getStorageClass() == VarDecl::Register) &&
68           "Unknown storage class");
69    return EmitLocalBlockVarDecl(D);
70  }
71}
72
73llvm::GlobalValue *
74CodeGenFunction::GenerateStaticBlockVarDecl(const VarDecl &D,
75                                            bool NoInit,
76                                            const char *Separator) {
77  QualType Ty = D.getType();
78  assert(Ty->isConstantSizeType() && "VLAs can't be static");
79
80  const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
81  llvm::Constant *Init = 0;
82  if ((D.getInit() == 0) || NoInit) {
83    Init = llvm::Constant::getNullValue(LTy);
84  } else {
85    Init = CGM.EmitConstantExpr(D.getInit(), this);
86  }
87
88  assert(Init && "Unable to create initialiser for static decl");
89
90  std::string ContextName;
91  if (const FunctionDecl * FD = dyn_cast<FunctionDecl>(CurFuncDecl))
92    ContextName = FD->getName();
93  else
94    assert(0 && "Unknown context for block var decl"); // FIXME Handle objc.
95
96  llvm::GlobalValue *GV =
97    new llvm::GlobalVariable(LTy, false, llvm::GlobalValue::InternalLinkage,
98                             Init, ContextName + Separator + D.getName(),
99                             &CGM.getModule(), 0, Ty.getAddressSpace());
100
101  return GV;
102}
103
104void CodeGenFunction::EmitStaticBlockVarDecl(const VarDecl &D) {
105
106  llvm::Value *&DMEntry = LocalDeclMap[&D];
107  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
108
109  llvm::GlobalValue *GV = GenerateStaticBlockVarDecl(D, false, ".");
110
111  if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
112    SourceManager &SM = CGM.getContext().getSourceManager();
113    llvm::Constant *Ann =
114      CGM.EmitAnnotateAttr(GV, AA, SM.getLogicalLineNumber(D.getLocation()));
115    CGM.AddAnnotation(Ann);
116  }
117
118  DMEntry = GV;
119}
120
121/// EmitLocalBlockVarDecl - Emit code and set up an entry in LocalDeclMap for a
122/// variable declaration with auto, register, or no storage class specifier.
123/// These turn into simple stack objects, or GlobalValues depending on target.
124void CodeGenFunction::EmitLocalBlockVarDecl(const VarDecl &D) {
125  QualType Ty = D.getType();
126
127  llvm::Value *DeclPtr;
128  if (Ty->isConstantSizeType()) {
129    if (!Target.useGlobalsForAutomaticVariables()) {
130      // A normal fixed sized variable becomes an alloca in the entry block.
131      const llvm::Type *LTy = ConvertType(Ty);
132      llvm::AllocaInst * Alloc = CreateTempAlloca(LTy, D.getName());
133      unsigned align = getContext().getTypeAlign(Ty);
134      if (const AlignedAttr* AA = D.getAttr<AlignedAttr>())
135        align = std::max(align, AA->getAlignment());
136      Alloc->setAlignment(align >> 3);
137      DeclPtr = Alloc;
138    } else {
139      // Targets that don't support recursion emit locals as globals.
140      const char *Class =
141        D.getStorageClass() == VarDecl::Register ? ".reg." : ".auto.";
142      DeclPtr = GenerateStaticBlockVarDecl(D, true, Class);
143    }
144  } else {
145    // TODO: Create a dynamic alloca.
146    assert(0 && "FIXME: Local VLAs not implemented yet");
147  }
148
149  llvm::Value *&DMEntry = LocalDeclMap[&D];
150  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
151  DMEntry = DeclPtr;
152
153  // Emit debug info for local var declaration.
154  CGDebugInfo *DI = CGM.getDebugInfo();
155  if(DI) {
156    if(D.getLocation().isValid())
157      DI->setLocation(D.getLocation());
158    DI->EmitDeclare(&D, llvm::dwarf::DW_TAG_auto_variable,
159                    DeclPtr, Builder);
160  }
161
162  // If this local has an initializer, emit it now.
163  if (const Expr *Init = D.getInit()) {
164    if (!hasAggregateLLVMType(Init->getType())) {
165      llvm::Value *V = EmitScalarExpr(Init);
166      Builder.CreateStore(V, DeclPtr, D.getType().isVolatileQualified());
167    } else if (Init->getType()->isAnyComplexType()) {
168      EmitComplexExprIntoAddr(Init, DeclPtr, D.getType().isVolatileQualified());
169    } else {
170      EmitAggExpr(Init, DeclPtr, D.getType().isVolatileQualified());
171    }
172  }
173}
174
175/// Emit an alloca (or GlobalValue depending on target)
176/// for the specified parameter and set up LocalDeclMap.
177void CodeGenFunction::EmitParmDecl(const ParmVarDecl &D, llvm::Value *Arg) {
178  QualType Ty = D.getType();
179
180  llvm::Value *DeclPtr;
181  if (!Ty->isConstantSizeType()) {
182    // Variable sized values always are passed by-reference.
183    DeclPtr = Arg;
184  } else if (Target.useGlobalsForAutomaticVariables()) {
185    DeclPtr = GenerateStaticBlockVarDecl(D, true, ".arg.");
186  } else {
187    // A fixed sized single-value variable becomes an alloca in the entry block.
188    const llvm::Type *LTy = ConvertType(Ty);
189    if (LTy->isSingleValueType()) {
190      // TODO: Alignment
191      DeclPtr = new llvm::AllocaInst(LTy, 0, std::string(D.getName())+".addr",
192                                     AllocaInsertPt);
193
194      // Store the initial value into the alloca.
195      Builder.CreateStore(Arg, DeclPtr);
196    } else {
197      // Otherwise, if this is an aggregate, just use the input pointer.
198      DeclPtr = Arg;
199    }
200    Arg->setName(D.getName());
201  }
202
203  llvm::Value *&DMEntry = LocalDeclMap[&D];
204  assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
205  DMEntry = DeclPtr;
206
207  // Emit debug info for param declaration.
208  CGDebugInfo *DI = CGM.getDebugInfo();
209  if(DI) {
210    if(D.getLocation().isValid())
211      DI->setLocation(D.getLocation());
212    DI->EmitDeclare(&D, llvm::dwarf::DW_TAG_arg_variable,
213                    DeclPtr, Builder);
214  }
215
216}
217
218