CGObjC.cpp revision 7ded7f4983dc4a20561db7a8d02c6b2435030961 
1//===---- CGBuiltin.cpp - Emit LLVM Code for builtins ---------------------===//
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 Objective-C code as LLVM code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CGObjCRuntime.h"
15#include "CodeGenFunction.h"
16#include "CodeGenModule.h"
17#include "clang/AST/DeclObjC.h"
18
19using namespace clang;
20using namespace CodeGen;
21
22/// Emits an instance of NSConstantString representing the object.
23llvm::Value *CodeGenFunction::EmitObjCStringLiteral(const ObjCStringLiteral *E) {
24  std::string String(E->getString()->getStrData(), E->getString()->getByteLength());
25  llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(String);
26  return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
27}
28
29/// Emit a selector.
30llvm::Value *CodeGenFunction::EmitObjCSelectorExpr(const ObjCSelectorExpr *E) {
31  // Untyped selector.
32  // Note that this implementation allows for non-constant strings to be passed
33  // as arguments to @selector().  Currently, the only thing preventing this
34  // behaviour is the type checking in the front end.
35  return CGM.getObjCRuntime().GetSelector(Builder, E->getSelector());
36}
37
38
39
40llvm::Value *CodeGenFunction::EmitObjCMessageExpr(const ObjCMessageExpr *E) {
41  // Only the lookup mechanism and first two arguments of the method
42  // implementation vary between runtimes.  We can get the receiver and
43  // arguments in generic code.
44
45  CGObjCRuntime &Runtime = CGM.getObjCRuntime();
46  const Expr *ReceiverExpr = E->getReceiver();
47  bool isSuperMessage = false;
48  // Find the receiver
49  llvm::Value *Receiver;
50  if (!ReceiverExpr) {
51    const char * classname = E->getClassName()->getName();
52    if (!strcmp(classname, "super")) {
53      classname = E->getMethodDecl()->getClassInterface()->getName();
54    }
55    llvm::Value *ClassName = CGM.GetAddrOfConstantCString(classname);
56    ClassName = Builder.CreateStructGEP(ClassName, 0);
57    Receiver = Runtime.LookupClass(Builder, ClassName);
58  } else if (const PredefinedExpr *PDE =
59               dyn_cast<PredefinedExpr>(E->getReceiver())) {
60    assert(PDE->getIdentType() == PredefinedExpr::ObjCSuper);
61    isSuperMessage = true;
62    Receiver = LoadObjCSelf();
63  } else {
64    Receiver = EmitScalarExpr(E->getReceiver());
65  }
66
67  // Process the arguments
68  unsigned ArgC = E->getNumArgs();
69  llvm::SmallVector<llvm::Value*, 16> Args;
70  for (unsigned i = 0; i != ArgC; ++i) {
71    const Expr *ArgExpr = E->getArg(i);
72    QualType ArgTy = ArgExpr->getType();
73    if (!hasAggregateLLVMType(ArgTy)) {
74      // Scalar argument is passed by-value.
75      Args.push_back(EmitScalarExpr(ArgExpr));
76    } else if (ArgTy->isAnyComplexType()) {
77      // Make a temporary alloca to pass the argument.
78      llvm::Value *DestMem = CreateTempAlloca(ConvertType(ArgTy));
79      EmitComplexExprIntoAddr(ArgExpr, DestMem, false);
80      Args.push_back(DestMem);
81    } else {
82      llvm::Value *DestMem = CreateTempAlloca(ConvertType(ArgTy));
83      EmitAggExpr(ArgExpr, DestMem, false);
84      Args.push_back(DestMem);
85    }
86  }
87
88  if (isSuperMessage) {
89    // super is only valid in an Objective-C method
90    const ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(CurFuncDecl);
91    const char *SuperClass =
92      OMD->getClassInterface()->getSuperClass()->getName();
93    return Runtime.GenerateMessageSendSuper(Builder, ConvertType(E->getType()),
94                                             SuperClass,
95                                             Receiver, E->getSelector(),
96                                             &Args[0], Args.size());
97  }
98  return Runtime.GenerateMessageSend(Builder, ConvertType(E->getType()),
99                                      Receiver, E->getSelector(),
100                                      &Args[0], Args.size());
101}
102
103/// Generate an Objective-C method.  An Objective-C method is a C function with
104/// its pointer, name, and types registered in the class struture.
105void CodeGenFunction::GenerateObjCMethod(const ObjCMethodDecl *OMD) {
106  CurFn = CGM.getObjCRuntime().GenerateMethod(OMD);
107  llvm::BasicBlock *EntryBB = llvm::BasicBlock::Create("entry", CurFn);
108
109  // Create a marker to make it easy to insert allocas into the entryblock
110  // later.  Don't create this with the builder, because we don't want it
111  // folded.
112  llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::Int32Ty);
113  AllocaInsertPt = new llvm::BitCastInst(Undef, llvm::Type::Int32Ty, "allocapt",
114                                         EntryBB);
115
116  FnRetTy = OMD->getResultType();
117  CurFuncDecl = OMD;
118
119  Builder.SetInsertPoint(EntryBB);
120
121  // Emit allocs for param decls.  Give the LLVM Argument nodes names.
122  llvm::Function::arg_iterator AI = CurFn->arg_begin();
123
124  if (hasAggregateLLVMType(OMD->getResultType())) {
125    ++AI;
126  }
127  // Add implicit parameters to the decl map.
128  // TODO: Add something to AST to let the runtime specify the names and types
129  // of these.
130
131  llvm::Value *&SelfEntry = LocalDeclMap[OMD->getSelfDecl()];
132  const llvm::Type *IPTy = AI->getType();
133  llvm::Value *DeclPtr = new llvm::AllocaInst(IPTy, 0, AI->getName() +
134      ".addr", AllocaInsertPt);
135  // Store the initial value into the alloca.
136  Builder.CreateStore(AI, DeclPtr);
137  SelfEntry = DeclPtr;
138  ++AI;
139  llvm::Value *&CmdEntry = LocalDeclMap[OMD->getCmdDecl()];
140  IPTy = AI->getType();
141  DeclPtr = new llvm::AllocaInst(IPTy, 0, AI->getName() +
142      ".addr", AllocaInsertPt);
143  // Store the initial value into the alloca.
144  Builder.CreateStore(AI, DeclPtr);
145  CmdEntry = DeclPtr;
146
147  for (unsigned i = 0, e = OMD->getNumParams(); i != e; ++i, ++AI) {
148    assert(AI != CurFn->arg_end() && "Argument mismatch!");
149    EmitParmDecl(*OMD->getParamDecl(i), AI);
150  }
151
152  GenerateFunction(OMD->getBody());
153}
154
155llvm::Value *CodeGenFunction::LoadObjCSelf(void)
156{
157  if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(CurFuncDecl)) {
158    ValueDecl *Decl = OMD->getSelfDecl();
159    llvm::Value *SelfPtr = LocalDeclMap[&(*(Decl))];
160    return Builder.CreateLoad(SelfPtr, "self");
161  }
162  return NULL;
163}
164
165CGObjCRuntime::~CGObjCRuntime() {}
166