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      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 CLANG_CODEGEN_CGBLOCKS_H
     15 #define CLANG_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:
     72   BlockFlags(uint32_t flags) : flags(flags) {}
     73   BlockFlags() : flags(0) {}
     74   BlockFlags(BlockLiteralFlags flag) : flags(flag) {}
     75   BlockFlags(BlockByrefFlags flag) : flags(flag) {}
     76 
     77   uint32_t getBitMask() const { return flags; }
     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 
    116   BlockFieldFlags(uint32_t flags) : flags(flags) {}
    117 public:
    118   BlockFieldFlags() : flags(0) {}
    119   BlockFieldFlags(BlockFieldFlag_t flag) : flags(flag) {}
    120 
    121   uint32_t getBitMask() const { return flags; }
    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.
    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 /// CGBlockInfo - Information to generate a block literal.
    144 class CGBlockInfo {
    145 public:
    146   /// Name - The name of the block, kindof.
    147   StringRef Name;
    148 
    149   /// The field index of 'this' within the block, if there is one.
    150   unsigned CXXThisIndex;
    151 
    152   class Capture {
    153     uintptr_t Data;
    154     EHScopeStack::stable_iterator Cleanup;
    155 
    156   public:
    157     bool isIndex() const { return (Data & 1) != 0; }
    158     bool isConstant() const { return !isIndex(); }
    159     unsigned getIndex() const { assert(isIndex()); return Data >> 1; }
    160     llvm::Value *getConstant() const {
    161       assert(isConstant());
    162       return reinterpret_cast<llvm::Value*>(Data);
    163     }
    164     EHScopeStack::stable_iterator getCleanup() const {
    165       assert(isIndex());
    166       return Cleanup;
    167     }
    168     void setCleanup(EHScopeStack::stable_iterator cleanup) {
    169       assert(isIndex());
    170       Cleanup = cleanup;
    171     }
    172 
    173     static Capture makeIndex(unsigned index) {
    174       Capture v;
    175       v.Data = (index << 1) | 1;
    176       return v;
    177     }
    178 
    179     static Capture makeConstant(llvm::Value *value) {
    180       Capture v;
    181       v.Data = reinterpret_cast<uintptr_t>(value);
    182       return v;
    183     }
    184   };
    185 
    186   /// CanBeGlobal - True if the block can be global, i.e. it has
    187   /// no non-constant captures.
    188   bool CanBeGlobal : 1;
    189 
    190   /// True if the block needs a custom copy or dispose function.
    191   bool NeedsCopyDispose : 1;
    192 
    193   /// HasCXXObject - True if the block's custom copy/dispose functions
    194   /// need to be run even in GC mode.
    195   bool HasCXXObject : 1;
    196 
    197   /// UsesStret : True if the block uses an stret return.  Mutable
    198   /// because it gets set later in the block-creation process.
    199   mutable bool UsesStret : 1;
    200 
    201   /// HasCapturedVariableLayout : True if block has captured variables
    202   /// and their layout meta-data has been generated.
    203   bool HasCapturedVariableLayout : 1;
    204 
    205   /// The mapping of allocated indexes within the block.
    206   llvm::DenseMap<const VarDecl*, Capture> Captures;
    207 
    208   llvm::AllocaInst *Address;
    209   llvm::StructType *StructureType;
    210   const BlockDecl *Block;
    211   const BlockExpr *BlockExpression;
    212   CharUnits BlockSize;
    213   CharUnits BlockAlign;
    214 
    215   // Offset of the gap caused by block header having a smaller
    216   // alignment than the alignment of the block descriptor. This
    217   // is the gap offset before the first capturued field.
    218   CharUnits BlockHeaderForcedGapOffset;
    219   // Gap size caused by aligning first field after block header.
    220   // This could be zero if no forced alignment is required.
    221   CharUnits BlockHeaderForcedGapSize;
    222 
    223   /// An instruction which dominates the full-expression that the
    224   /// block is inside.
    225   llvm::Instruction *DominatingIP;
    226 
    227   /// The next block in the block-info chain.  Invalid if this block
    228   /// info is not part of the CGF's block-info chain, which is true
    229   /// if it corresponds to a global block or a block whose expression
    230   /// has been encountered.
    231   CGBlockInfo *NextBlockInfo;
    232 
    233   const Capture &getCapture(const VarDecl *var) const {
    234     return const_cast<CGBlockInfo*>(this)->getCapture(var);
    235   }
    236   Capture &getCapture(const VarDecl *var) {
    237     llvm::DenseMap<const VarDecl*, Capture>::iterator
    238       it = Captures.find(var);
    239     assert(it != Captures.end() && "no entry for variable!");
    240     return it->second;
    241   }
    242 
    243   const BlockDecl *getBlockDecl() const { return Block; }
    244   const BlockExpr *getBlockExpr() const {
    245     assert(BlockExpression);
    246     assert(BlockExpression->getBlockDecl() == Block);
    247     return BlockExpression;
    248   }
    249 
    250   CGBlockInfo(const BlockDecl *blockDecl, StringRef Name);
    251 };
    252 
    253 }  // end namespace CodeGen
    254 }  // end namespace clang
    255 
    256 #endif
    257