1//===-- CGBlocks.h - state for LLVM CodeGen for blocks ----------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This is the internal state used for llvm translation for block literals.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_LIB_CODEGEN_CGBLOCKS_H
14#define LLVM_CLANG_LIB_CODEGEN_CGBLOCKS_H
15
16#include "CGBuilder.h"
17#include "CGCall.h"
18#include "CGValue.h"
19#include "CodeGenFunction.h"
20#include "CodeGenTypes.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#include "clang/AST/Type.h"
26#include "clang/Basic/TargetInfo.h"
27
28namespace llvm {
29class Constant;
30class Function;
31class GlobalValue;
32class DataLayout;
33class FunctionType;
34class PointerType;
35class Value;
36class LLVMContext;
37}
38
39namespace clang {
40namespace CodeGen {
41
42class CGBlockInfo;
43
44// Flags stored in __block variables.
45enum BlockByrefFlags {
46  BLOCK_BYREF_HAS_COPY_DISPOSE         = (1   << 25), // compiler
47  BLOCK_BYREF_LAYOUT_MASK              = (0xF << 28), // compiler
48  BLOCK_BYREF_LAYOUT_EXTENDED          = (1   << 28),
49  BLOCK_BYREF_LAYOUT_NON_OBJECT        = (2   << 28),
50  BLOCK_BYREF_LAYOUT_STRONG            = (3   << 28),
51  BLOCK_BYREF_LAYOUT_WEAK              = (4   << 28),
52  BLOCK_BYREF_LAYOUT_UNRETAINED        = (5   << 28)
53};
54
55enum BlockLiteralFlags {
56  BLOCK_IS_NOESCAPE      =  (1 << 23),
57  BLOCK_HAS_COPY_DISPOSE =  (1 << 25),
58  BLOCK_HAS_CXX_OBJ =       (1 << 26),
59  BLOCK_IS_GLOBAL =         (1 << 28),
60  BLOCK_USE_STRET =         (1 << 29),
61  BLOCK_HAS_SIGNATURE  =    (1 << 30),
62  BLOCK_HAS_EXTENDED_LAYOUT = (1u << 31)
63};
64class BlockFlags {
65  uint32_t flags;
66
67public:
68  BlockFlags(uint32_t flags) : flags(flags) {}
69  BlockFlags() : flags(0) {}
70  BlockFlags(BlockLiteralFlags flag) : flags(flag) {}
71  BlockFlags(BlockByrefFlags flag) : flags(flag) {}
72
73  uint32_t getBitMask() const { return flags; }
74  bool empty() const { return flags == 0; }
75
76  friend BlockFlags operator|(BlockFlags l, BlockFlags r) {
77    return BlockFlags(l.flags | r.flags);
78  }
79  friend BlockFlags &operator|=(BlockFlags &l, BlockFlags r) {
80    l.flags |= r.flags;
81    return l;
82  }
83  friend bool operator&(BlockFlags l, BlockFlags r) {
84    return (l.flags & r.flags);
85  }
86  bool operator==(BlockFlags r) {
87    return (flags == r.flags);
88  }
89};
90inline BlockFlags operator|(BlockLiteralFlags l, BlockLiteralFlags r) {
91  return BlockFlags(l) | BlockFlags(r);
92}
93
94enum BlockFieldFlag_t {
95  BLOCK_FIELD_IS_OBJECT   = 0x03,  /* id, NSObject, __attribute__((NSObject)),
96                                    block, ... */
97  BLOCK_FIELD_IS_BLOCK    = 0x07,  /* a block variable */
98
99  BLOCK_FIELD_IS_BYREF    = 0x08,  /* the on stack structure holding the __block
100                                    variable */
101  BLOCK_FIELD_IS_WEAK     = 0x10,  /* declared __weak, only used in byref copy
102                                    helpers */
103  BLOCK_FIELD_IS_ARC      = 0x40,  /* field has ARC-specific semantics */
104  BLOCK_BYREF_CALLER      = 128,   /* called from __block (byref) copy/dispose
105                                      support routines */
106  BLOCK_BYREF_CURRENT_MAX = 256
107};
108
109class BlockFieldFlags {
110  uint32_t flags;
111
112  BlockFieldFlags(uint32_t flags) : flags(flags) {}
113public:
114  BlockFieldFlags() : flags(0) {}
115  BlockFieldFlags(BlockFieldFlag_t flag) : flags(flag) {}
116
117  uint32_t getBitMask() const { return flags; }
118  bool empty() const { return flags == 0; }
119
120  /// Answers whether the flags indicate that this field is an object
121  /// or block pointer that requires _Block_object_assign/dispose.
122  bool isSpecialPointer() const { return flags & BLOCK_FIELD_IS_OBJECT; }
123
124  friend BlockFieldFlags operator|(BlockFieldFlags l, BlockFieldFlags r) {
125    return BlockFieldFlags(l.flags | r.flags);
126  }
127  friend BlockFieldFlags &operator|=(BlockFieldFlags &l, BlockFieldFlags r) {
128    l.flags |= r.flags;
129    return l;
130  }
131  friend bool operator&(BlockFieldFlags l, BlockFieldFlags r) {
132    return (l.flags & r.flags);
133  }
134  bool operator==(BlockFieldFlags Other) const {
135    return flags == Other.flags;
136  }
137};
138inline BlockFieldFlags operator|(BlockFieldFlag_t l, BlockFieldFlag_t r) {
139  return BlockFieldFlags(l) | BlockFieldFlags(r);
140}
141
142/// Information about the layout of a __block variable.
143class BlockByrefInfo {
144public:
145  llvm::StructType *Type;
146  unsigned FieldIndex;
147  CharUnits ByrefAlignment;
148  CharUnits FieldOffset;
149};
150
151/// CGBlockInfo - Information to generate a block literal.
152class CGBlockInfo {
153public:
154  /// Name - The name of the block, kindof.
155  StringRef Name;
156
157  /// The field index of 'this' within the block, if there is one.
158  unsigned CXXThisIndex;
159
160  class Capture {
161    uintptr_t Data;
162    EHScopeStack::stable_iterator Cleanup;
163    CharUnits::QuantityType Offset;
164
165    /// Type of the capture field. Normally, this is identical to the type of
166    /// the capture's VarDecl, but can be different if there is an enclosing
167    /// lambda.
168    QualType FieldType;
169
170  public:
171    bool isIndex() const { return (Data & 1) != 0; }
172    bool isConstant() const { return !isIndex(); }
173
174    unsigned getIndex() const {
175      assert(isIndex());
176      return Data >> 1;
177    }
178    CharUnits getOffset() const {
179      assert(isIndex());
180      return CharUnits::fromQuantity(Offset);
181    }
182    EHScopeStack::stable_iterator getCleanup() const {
183      assert(isIndex());
184      return Cleanup;
185    }
186    void setCleanup(EHScopeStack::stable_iterator cleanup) {
187      assert(isIndex());
188      Cleanup = cleanup;
189    }
190
191    llvm::Value *getConstant() const {
192      assert(isConstant());
193      return reinterpret_cast<llvm::Value*>(Data);
194    }
195
196    QualType fieldType() const {
197      return FieldType;
198    }
199
200    static Capture makeIndex(unsigned index, CharUnits offset,
201                             QualType FieldType) {
202      Capture v;
203      v.Data = (index << 1) | 1;
204      v.Offset = offset.getQuantity();
205      v.FieldType = FieldType;
206      return v;
207    }
208
209    static Capture makeConstant(llvm::Value *value) {
210      Capture v;
211      v.Data = reinterpret_cast<uintptr_t>(value);
212      return v;
213    }
214  };
215
216  /// CanBeGlobal - True if the block can be global, i.e. it has
217  /// no non-constant captures.
218  bool CanBeGlobal : 1;
219
220  /// True if the block has captures that would necessitate custom copy or
221  /// dispose helper functions if the block were escaping.
222  bool NeedsCopyDispose : 1;
223
224  /// HasCXXObject - True if the block's custom copy/dispose functions
225  /// need to be run even in GC mode.
226  bool HasCXXObject : 1;
227
228  /// UsesStret : True if the block uses an stret return.  Mutable
229  /// because it gets set later in the block-creation process.
230  mutable bool UsesStret : 1;
231
232  /// HasCapturedVariableLayout : True if block has captured variables
233  /// and their layout meta-data has been generated.
234  bool HasCapturedVariableLayout : 1;
235
236  /// Indicates whether an object of a non-external C++ class is captured. This
237  /// bit is used to determine the linkage of the block copy/destroy helper
238  /// functions.
239  bool CapturesNonExternalType : 1;
240
241  /// The mapping of allocated indexes within the block.
242  llvm::DenseMap<const VarDecl*, Capture> Captures;
243
244  Address LocalAddress;
245  llvm::StructType *StructureType;
246  const BlockDecl *Block;
247  const BlockExpr *BlockExpression;
248  CharUnits BlockSize;
249  CharUnits BlockAlign;
250  CharUnits CXXThisOffset;
251
252  // Offset of the gap caused by block header having a smaller
253  // alignment than the alignment of the block descriptor. This
254  // is the gap offset before the first capturued field.
255  CharUnits BlockHeaderForcedGapOffset;
256  // Gap size caused by aligning first field after block header.
257  // This could be zero if no forced alignment is required.
258  CharUnits BlockHeaderForcedGapSize;
259
260  /// An instruction which dominates the full-expression that the
261  /// block is inside.
262  llvm::Instruction *DominatingIP;
263
264  /// The next block in the block-info chain.  Invalid if this block
265  /// info is not part of the CGF's block-info chain, which is true
266  /// if it corresponds to a global block or a block whose expression
267  /// has been encountered.
268  CGBlockInfo *NextBlockInfo;
269
270  const Capture &getCapture(const VarDecl *var) const {
271    return const_cast<CGBlockInfo*>(this)->getCapture(var);
272  }
273  Capture &getCapture(const VarDecl *var) {
274    llvm::DenseMap<const VarDecl*, Capture>::iterator
275      it = Captures.find(var);
276    assert(it != Captures.end() && "no entry for variable!");
277    return it->second;
278  }
279
280  const BlockDecl *getBlockDecl() const { return Block; }
281  const BlockExpr *getBlockExpr() const {
282    assert(BlockExpression);
283    assert(BlockExpression->getBlockDecl() == Block);
284    return BlockExpression;
285  }
286
287  CGBlockInfo(const BlockDecl *blockDecl, StringRef Name);
288
289  // Indicates whether the block needs a custom copy or dispose function.
290  bool needsCopyDisposeHelpers() const {
291    return NeedsCopyDispose && !Block->doesNotEscape();
292  }
293};
294
295}  // end namespace CodeGen
296}  // end namespace clang
297
298#endif
299