clang/lib/AST/Interp/InterpBlock.cpp

   1 //===--- Block.cpp - Allocated blocks for the interpreter -------*- 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 // Defines the classes describing allocated blocks.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "InterpBlock.h"
  14 #include "Pointer.h"
  15
  16 using namespace clang;
  17 using namespace clang::interp;
  18
  19 void Block::addPointer(Pointer *P) {
  20   assert(P);
  21   if (IsStatic) {
  22     assert(!Pointers);
  23     return;
  24   }
  25
  26 #ifndef NDEBUG
  27   assert(!hasPointer(P));
  28 #endif
  29   if (Pointers)
  30     Pointers->Prev = P;
  31   P->Next = Pointers;
  32   P->Prev = nullptr;
  33   Pointers = P;
  34 }
  35
  36 void Block::removePointer(Pointer *P) {
  37   assert(P);
  38   if (IsStatic) {
  39     assert(!Pointers);
  40     return;
  41   }
  42
  43 #ifndef NDEBUG
  44   assert(hasPointer(P));
  45 #endif
  46
  47   if (Pointers == P)
  48     Pointers = P->Next;
  49
  50   if (P->Prev)
  51     P->Prev->Next = P->Next;
  52   if (P->Next)
  53     P->Next->Prev = P->Prev;
  54 }
  55
  56 void Block::cleanup() {
  57   if (Pointers == nullptr && IsDead)
  58     (reinterpret_cast<DeadBlock *>(this + 1) - 1)->free();
  59 }
  60
  61 void Block::replacePointer(Pointer *Old, Pointer *New) {
  62   assert(Old);
  63   assert(New);
  64   if (IsStatic) {
  65     assert(!Pointers);
  66     return;
  67   }
  68
  69 #ifndef NDEBUG
  70   assert(hasPointer(Old));
  71 #endif
  72
  73   removePointer(Old);
  74   addPointer(New);
  75
  76   Old->Pointee = nullptr;
  77
  78 #ifndef NDEBUG
  79   assert(!hasPointer(Old));
  80   assert(hasPointer(New));
  81 #endif
  82 }
  83
  84 #ifndef NDEBUG
  85 bool Block::hasPointer(const Pointer *P) const {
  86   for (const Pointer *C = Pointers; C; C = C->Next) {
  87     if (C == P)
  88       return true;
  89   }
  90   return false;
  91 }
  92 #endif
  93
  94 DeadBlock::DeadBlock(DeadBlock *&Root, Block *Blk)
  95     : Root(Root), B(Blk->Desc, Blk->IsStatic, Blk->IsExtern, /*isDead=*/true) {
  96   // Add the block to the chain of dead blocks.
  97   if (Root)
  98     Root->Prev = this;
  99
 100   Next = Root;
 101   Prev = nullptr;
 102   Root = this;
 103
 104   // Transfer pointers.
 105   B.Pointers = Blk->Pointers;
 106   for (Pointer *P = Blk->Pointers; P; P = P->Next)
 107     P->Pointee = &B;
 108 }
 109
 110 void DeadBlock::free() {
 111   if (Prev)
 112     Prev->Next = Next;
 113   if (Next)
 114     Next->Prev = Prev;
 115   if (Root == this)
 116     Root = Next;
 117   std::free(this);
 118 }