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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 "CodeGenTypes.h"
     18 #include "clang/AST/Type.h"
     19 #include "llvm/Module.h"
     20 #include "clang/Basic/TargetInfo.h"
     21 #include "clang/AST/CharUnits.h"
     22 #include "clang/AST/Expr.h"
     23 #include "clang/AST/ExprCXX.h"
     24 #include "clang/AST/ExprObjC.h"
     25 
     26 #include "CodeGenFunction.h"
     27 #include "CGBuilder.h"
     28 #include "CGCall.h"
     29 #include "CGValue.h"
     30 
     31 namespace llvm {
     32   class Module;
     33   class Constant;
     34   class Function;
     35   class GlobalValue;
     36   class TargetData;
     37   class FunctionType;
     38   class PointerType;
     39   class Value;
     40   class LLVMContext;
     41 }
     42 
     43 namespace clang {
     44 
     45 namespace CodeGen {
     46 
     47 class CodeGenModule;
     48 class CGBlockInfo;
     49 
     50 enum BlockFlag_t {
     51   BLOCK_HAS_COPY_DISPOSE =  (1 << 25),
     52   BLOCK_HAS_CXX_OBJ =       (1 << 26),
     53   BLOCK_IS_GLOBAL =         (1 << 28),
     54   BLOCK_USE_STRET =         (1 << 29),
     55   BLOCK_HAS_SIGNATURE  =    (1 << 30)
     56 };
     57 class BlockFlags {
     58   uint32_t flags;
     59 
     60   BlockFlags(uint32_t flags) : flags(flags) {}
     61 public:
     62   BlockFlags() : flags(0) {}
     63   BlockFlags(BlockFlag_t flag) : flags(flag) {}
     64 
     65   uint32_t getBitMask() const { return flags; }
     66   bool empty() const { return flags == 0; }
     67 
     68   friend BlockFlags operator|(BlockFlags l, BlockFlags r) {
     69     return BlockFlags(l.flags | r.flags);
     70   }
     71   friend BlockFlags &operator|=(BlockFlags &l, BlockFlags r) {
     72     l.flags |= r.flags;
     73     return l;
     74   }
     75   friend bool operator&(BlockFlags l, BlockFlags r) {
     76     return (l.flags & r.flags);
     77   }
     78 };
     79 inline BlockFlags operator|(BlockFlag_t l, BlockFlag_t r) {
     80   return BlockFlags(l) | BlockFlags(r);
     81 }
     82 
     83 enum BlockFieldFlag_t {
     84   BLOCK_FIELD_IS_OBJECT   = 0x03,  /* id, NSObject, __attribute__((NSObject)),
     85                                     block, ... */
     86   BLOCK_FIELD_IS_BLOCK    = 0x07,  /* a block variable */
     87 
     88   BLOCK_FIELD_IS_BYREF    = 0x08,  /* the on stack structure holding the __block
     89                                     variable */
     90   BLOCK_FIELD_IS_WEAK     = 0x10,  /* declared __weak, only used in byref copy
     91                                     helpers */
     92   BLOCK_FIELD_IS_ARC      = 0x40,  /* field has ARC-specific semantics */
     93   BLOCK_BYREF_CALLER      = 128,   /* called from __block (byref) copy/dispose
     94                                       support routines */
     95   BLOCK_BYREF_CURRENT_MAX = 256
     96 };
     97 
     98 class BlockFieldFlags {
     99   uint32_t flags;
    100 
    101   BlockFieldFlags(uint32_t flags) : flags(flags) {}
    102 public:
    103   BlockFieldFlags() : flags(0) {}
    104   BlockFieldFlags(BlockFieldFlag_t flag) : flags(flag) {}
    105 
    106   uint32_t getBitMask() const { return flags; }
    107   bool empty() const { return flags == 0; }
    108 
    109   /// Answers whether the flags indicate that this field is an object
    110   /// or block pointer that requires _Block_object_assign/dispose.
    111   bool isSpecialPointer() const { return flags & BLOCK_FIELD_IS_OBJECT; }
    112 
    113   friend BlockFieldFlags operator|(BlockFieldFlags l, BlockFieldFlags r) {
    114     return BlockFieldFlags(l.flags | r.flags);
    115   }
    116   friend BlockFieldFlags &operator|=(BlockFieldFlags &l, BlockFieldFlags r) {
    117     l.flags |= r.flags;
    118     return l;
    119   }
    120   friend bool operator&(BlockFieldFlags l, BlockFieldFlags r) {
    121     return (l.flags & r.flags);
    122   }
    123 };
    124 inline BlockFieldFlags operator|(BlockFieldFlag_t l, BlockFieldFlag_t r) {
    125   return BlockFieldFlags(l) | BlockFieldFlags(r);
    126 }
    127 
    128 /// CGBlockInfo - Information to generate a block literal.
    129 class CGBlockInfo {
    130 public:
    131   /// Name - The name of the block, kindof.
    132   llvm::StringRef Name;
    133 
    134   /// The field index of 'this' within the block, if there is one.
    135   unsigned CXXThisIndex;
    136 
    137   class Capture {
    138     uintptr_t Data;
    139     EHScopeStack::stable_iterator Cleanup;
    140 
    141   public:
    142     bool isIndex() const { return (Data & 1) != 0; }
    143     bool isConstant() const { return !isIndex(); }
    144     unsigned getIndex() const { assert(isIndex()); return Data >> 1; }
    145     llvm::Value *getConstant() const {
    146       assert(isConstant());
    147       return reinterpret_cast<llvm::Value*>(Data);
    148     }
    149     EHScopeStack::stable_iterator getCleanup() const {
    150       assert(isIndex());
    151       return Cleanup;
    152     }
    153     void setCleanup(EHScopeStack::stable_iterator cleanup) {
    154       assert(isIndex());
    155       Cleanup = cleanup;
    156     }
    157 
    158     static Capture makeIndex(unsigned index) {
    159       Capture v;
    160       v.Data = (index << 1) | 1;
    161       return v;
    162     }
    163 
    164     static Capture makeConstant(llvm::Value *value) {
    165       Capture v;
    166       v.Data = reinterpret_cast<uintptr_t>(value);
    167       return v;
    168     }
    169   };
    170 
    171   /// CanBeGlobal - True if the block can be global, i.e. it has
    172   /// no non-constant captures.
    173   bool CanBeGlobal : 1;
    174 
    175   /// True if the block needs a custom copy or dispose function.
    176   bool NeedsCopyDispose : 1;
    177 
    178   /// HasCXXObject - True if the block's custom copy/dispose functions
    179   /// need to be run even in GC mode.
    180   bool HasCXXObject : 1;
    181 
    182   /// UsesStret : True if the block uses an stret return.  Mutable
    183   /// because it gets set later in the block-creation process.
    184   mutable bool UsesStret : 1;
    185 
    186   /// The mapping of allocated indexes within the block.
    187   llvm::DenseMap<const VarDecl*, Capture> Captures;
    188 
    189   llvm::AllocaInst *Address;
    190   llvm::StructType *StructureType;
    191   const BlockDecl *Block;
    192   const BlockExpr *BlockExpression;
    193   CharUnits BlockSize;
    194   CharUnits BlockAlign;
    195 
    196   /// An instruction which dominates the full-expression that the
    197   /// block is inside.
    198   llvm::Instruction *DominatingIP;
    199 
    200   /// The next block in the block-info chain.  Invalid if this block
    201   /// info is not part of the CGF's block-info chain, which is true
    202   /// if it corresponds to a global block or a block whose expression
    203   /// has been encountered.
    204   CGBlockInfo *NextBlockInfo;
    205 
    206   const Capture &getCapture(const VarDecl *var) const {
    207     return const_cast<CGBlockInfo*>(this)->getCapture(var);
    208   }
    209   Capture &getCapture(const VarDecl *var) {
    210     llvm::DenseMap<const VarDecl*, Capture>::iterator
    211       it = Captures.find(var);
    212     assert(it != Captures.end() && "no entry for variable!");
    213     return it->second;
    214   }
    215 
    216   const BlockDecl *getBlockDecl() const { return Block; }
    217   const BlockExpr *getBlockExpr() const {
    218     assert(BlockExpression);
    219     assert(BlockExpression->getBlockDecl() == Block);
    220     return BlockExpression;
    221   }
    222 
    223   CGBlockInfo(const BlockDecl *blockDecl, llvm::StringRef Name);
    224 };
    225 
    226 }  // end namespace CodeGen
    227 }  // end namespace clang
    228 
    229 #endif
    230