1 //===-- CGBlocks.h - state for LLVM CodeGen for blocks ----------*- C++ -*-===//
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 is the internal state used for llvm translation for block literals.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_LIB_CODEGEN_CGBLOCKS_H
15 #define LLVM_CLANG_LIB_CODEGEN_CGBLOCKS_H
16 
17 #include "CGBuilder.h"
18 #include "CGCall.h"
19 #include "CGValue.h"
20 #include "CodeGenFunction.h"
21 #include "CodeGenTypes.h"
22 #include "clang/AST/CharUnits.h"
23 #include "clang/AST/Expr.h"
24 #include "clang/AST/ExprCXX.h"
25 #include "clang/AST/ExprObjC.h"
26 #include "clang/AST/Type.h"
27 #include "clang/Basic/TargetInfo.h"
28 #include "llvm/IR/Module.h"
29 
30 namespace llvm {
31 class Module;
32 class Constant;
33 class Function;
34 class GlobalValue;
35 class DataLayout;
36 class FunctionType;
37 class PointerType;
38 class Value;
39 class LLVMContext;
40 }
41 
42 namespace clang {
43 
44 namespace CodeGen {
45 
46 class CodeGenModule;
47 class CGBlockInfo;
48 
49 // Flags stored in __block variables.
50 enum BlockByrefFlags {
51   BLOCK_BYREF_HAS_COPY_DISPOSE         = (1   << 25), // compiler
52   BLOCK_BYREF_LAYOUT_MASK              = (0xF << 28), // compiler
53   BLOCK_BYREF_LAYOUT_EXTENDED          = (1   << 28),
54   BLOCK_BYREF_LAYOUT_NON_OBJECT        = (2   << 28),
55   BLOCK_BYREF_LAYOUT_STRONG            = (3   << 28),
56   BLOCK_BYREF_LAYOUT_WEAK              = (4   << 28),
57   BLOCK_BYREF_LAYOUT_UNRETAINED        = (5   << 28)
58 };
59 
60 enum BlockLiteralFlags {
61   BLOCK_HAS_COPY_DISPOSE =  (1 << 25),
62   BLOCK_HAS_CXX_OBJ =       (1 << 26),
63   BLOCK_IS_GLOBAL =         (1 << 28),
64   BLOCK_USE_STRET =         (1 << 29),
65   BLOCK_HAS_SIGNATURE  =    (1 << 30),
66   BLOCK_HAS_EXTENDED_LAYOUT = (1 << 31)
67 };
68 class BlockFlags {
69   uint32_t flags;
70 
71 public:
BlockFlags(uint32_t flags)72   BlockFlags(uint32_t flags) : flags(flags) {}
BlockFlags()73   BlockFlags() : flags(0) {}
BlockFlags(BlockLiteralFlags flag)74   BlockFlags(BlockLiteralFlags flag) : flags(flag) {}
BlockFlags(BlockByrefFlags flag)75   BlockFlags(BlockByrefFlags flag) : flags(flag) {}
76 
getBitMask()77   uint32_t getBitMask() const { return flags; }
empty()78   bool empty() const { return flags == 0; }
79 
80   friend BlockFlags operator|(BlockFlags l, BlockFlags r) {
81     return BlockFlags(l.flags | r.flags);
82   }
83   friend BlockFlags &operator|=(BlockFlags &l, BlockFlags r) {
84     l.flags |= r.flags;
85     return l;
86   }
87   friend bool operator&(BlockFlags l, BlockFlags r) {
88     return (l.flags & r.flags);
89   }
90   bool operator==(BlockFlags r) {
91     return (flags == r.flags);
92   }
93 };
94 inline BlockFlags operator|(BlockLiteralFlags l, BlockLiteralFlags r) {
95   return BlockFlags(l) | BlockFlags(r);
96 }
97 
98 enum BlockFieldFlag_t {
99   BLOCK_FIELD_IS_OBJECT   = 0x03,  /* id, NSObject, __attribute__((NSObject)),
100                                     block, ... */
101   BLOCK_FIELD_IS_BLOCK    = 0x07,  /* a block variable */
102 
103   BLOCK_FIELD_IS_BYREF    = 0x08,  /* the on stack structure holding the __block
104                                     variable */
105   BLOCK_FIELD_IS_WEAK     = 0x10,  /* declared __weak, only used in byref copy
106                                     helpers */
107   BLOCK_FIELD_IS_ARC      = 0x40,  /* field has ARC-specific semantics */
108   BLOCK_BYREF_CALLER      = 128,   /* called from __block (byref) copy/dispose
109                                       support routines */
110   BLOCK_BYREF_CURRENT_MAX = 256
111 };
112 
113 class BlockFieldFlags {
114   uint32_t flags;
115 
BlockFieldFlags(uint32_t flags)116   BlockFieldFlags(uint32_t flags) : flags(flags) {}
117 public:
BlockFieldFlags()118   BlockFieldFlags() : flags(0) {}
BlockFieldFlags(BlockFieldFlag_t flag)119   BlockFieldFlags(BlockFieldFlag_t flag) : flags(flag) {}
120 
getBitMask()121   uint32_t getBitMask() const { return flags; }
empty()122   bool empty() const { return flags == 0; }
123 
124   /// Answers whether the flags indicate that this field is an object
125   /// or block pointer that requires _Block_object_assign/dispose.
isSpecialPointer()126   bool isSpecialPointer() const { return flags & BLOCK_FIELD_IS_OBJECT; }
127 
128   friend BlockFieldFlags operator|(BlockFieldFlags l, BlockFieldFlags r) {
129     return BlockFieldFlags(l.flags | r.flags);
130   }
131   friend BlockFieldFlags &operator|=(BlockFieldFlags &l, BlockFieldFlags r) {
132     l.flags |= r.flags;
133     return l;
134   }
135   friend bool operator&(BlockFieldFlags l, BlockFieldFlags r) {
136     return (l.flags & r.flags);
137   }
138 };
139 inline BlockFieldFlags operator|(BlockFieldFlag_t l, BlockFieldFlag_t r) {
140   return BlockFieldFlags(l) | BlockFieldFlags(r);
141 }
142 
143 /// Information about the layout of a __block variable.
144 class BlockByrefInfo {
145 public:
146   llvm::StructType *Type;
147   unsigned FieldIndex;
148   CharUnits ByrefAlignment;
149   CharUnits FieldOffset;
150 };
151 
152 /// CGBlockInfo - Information to generate a block literal.
153 class CGBlockInfo {
154 public:
155   /// Name - The name of the block, kindof.
156   StringRef Name;
157 
158   /// The field index of 'this' within the block, if there is one.
159   unsigned CXXThisIndex;
160 
161   class Capture {
162     uintptr_t Data;
163     EHScopeStack::stable_iterator Cleanup;
164     CharUnits::QuantityType Offset;
165 
166   public:
isIndex()167     bool isIndex() const { return (Data & 1) != 0; }
isConstant()168     bool isConstant() const { return !isIndex(); }
169 
getIndex()170     unsigned getIndex() const {
171       assert(isIndex());
172       return Data >> 1;
173     }
getOffset()174     CharUnits getOffset() const {
175       assert(isIndex());
176       return CharUnits::fromQuantity(Offset);
177     }
getCleanup()178     EHScopeStack::stable_iterator getCleanup() const {
179       assert(isIndex());
180       return Cleanup;
181     }
setCleanup(EHScopeStack::stable_iterator cleanup)182     void setCleanup(EHScopeStack::stable_iterator cleanup) {
183       assert(isIndex());
184       Cleanup = cleanup;
185     }
186 
getConstant()187     llvm::Value *getConstant() const {
188       assert(isConstant());
189       return reinterpret_cast<llvm::Value*>(Data);
190     }
191 
makeIndex(unsigned index,CharUnits offset)192     static Capture makeIndex(unsigned index, CharUnits offset) {
193       Capture v;
194       v.Data = (index << 1) | 1;
195       v.Offset = offset.getQuantity();
196       return v;
197     }
198 
makeConstant(llvm::Value * value)199     static Capture makeConstant(llvm::Value *value) {
200       Capture v;
201       v.Data = reinterpret_cast<uintptr_t>(value);
202       return v;
203     }
204   };
205 
206   /// CanBeGlobal - True if the block can be global, i.e. it has
207   /// no non-constant captures.
208   bool CanBeGlobal : 1;
209 
210   /// True if the block needs a custom copy or dispose function.
211   bool NeedsCopyDispose : 1;
212 
213   /// HasCXXObject - True if the block's custom copy/dispose functions
214   /// need to be run even in GC mode.
215   bool HasCXXObject : 1;
216 
217   /// UsesStret : True if the block uses an stret return.  Mutable
218   /// because it gets set later in the block-creation process.
219   mutable bool UsesStret : 1;
220 
221   /// HasCapturedVariableLayout : True if block has captured variables
222   /// and their layout meta-data has been generated.
223   bool HasCapturedVariableLayout : 1;
224 
225   /// The mapping of allocated indexes within the block.
226   llvm::DenseMap<const VarDecl*, Capture> Captures;
227 
228   Address LocalAddress;
229   llvm::StructType *StructureType;
230   const BlockDecl *Block;
231   const BlockExpr *BlockExpression;
232   CharUnits BlockSize;
233   CharUnits BlockAlign;
234   CharUnits CXXThisOffset;
235 
236   // Offset of the gap caused by block header having a smaller
237   // alignment than the alignment of the block descriptor. This
238   // is the gap offset before the first capturued field.
239   CharUnits BlockHeaderForcedGapOffset;
240   // Gap size caused by aligning first field after block header.
241   // This could be zero if no forced alignment is required.
242   CharUnits BlockHeaderForcedGapSize;
243 
244   /// An instruction which dominates the full-expression that the
245   /// block is inside.
246   llvm::Instruction *DominatingIP;
247 
248   /// The next block in the block-info chain.  Invalid if this block
249   /// info is not part of the CGF's block-info chain, which is true
250   /// if it corresponds to a global block or a block whose expression
251   /// has been encountered.
252   CGBlockInfo *NextBlockInfo;
253 
getCapture(const VarDecl * var)254   const Capture &getCapture(const VarDecl *var) const {
255     return const_cast<CGBlockInfo*>(this)->getCapture(var);
256   }
getCapture(const VarDecl * var)257   Capture &getCapture(const VarDecl *var) {
258     llvm::DenseMap<const VarDecl*, Capture>::iterator
259       it = Captures.find(var);
260     assert(it != Captures.end() && "no entry for variable!");
261     return it->second;
262   }
263 
getBlockDecl()264   const BlockDecl *getBlockDecl() const { return Block; }
getBlockExpr()265   const BlockExpr *getBlockExpr() const {
266     assert(BlockExpression);
267     assert(BlockExpression->getBlockDecl() == Block);
268     return BlockExpression;
269   }
270 
271   CGBlockInfo(const BlockDecl *blockDecl, StringRef Name);
272 };
273 
274 }  // end namespace CodeGen
275 }  // end namespace clang
276 
277 #endif
278