layout/style/nsRuleData.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsRuleData.h"
   7
   8 #include "mozilla/Poison.h"
   9 #include <stdint.h>
  10
  11 inline size_t
  12 nsRuleData::GetPoisonOffset()
  13 {
  14   // Fill in mValueOffsets such that mValueStorage + mValueOffsets[i]
  15   // will yield the frame poison value for all uninitialized value
  16   // offsets.
  17   static_assert(sizeof(uintptr_t) == sizeof(size_t),
  18                 "expect uintptr_t and size_t to be the same size");
  19   static_assert(uintptr_t(-1) > uintptr_t(0),
  20                 "expect uintptr_t to be unsigned");
  21   static_assert(size_t(-1) > size_t(0),
  22                 "expect size_t to be unsigned");
  23   uintptr_t framePoisonValue = mozPoisonValue();
  24   return size_t(framePoisonValue - uintptr_t(mValueStorage)) /
  25          sizeof(nsCSSValue);
  26 }
  27
  28 nsRuleData::nsRuleData(uint32_t aSIDs, nsCSSValue* aValueStorage,
  29                        nsPresContext* aContext, nsStyleContext* aStyleContext)
  30   : mSIDs(aSIDs),
  31     mCanStoreInRuleTree(true),
  32     mPresContext(aContext),
  33     mStyleContext(aStyleContext),
  34     mValueStorage(aValueStorage)
  35 {
  36 #ifndef MOZ_VALGRIND
  37   size_t framePoisonOffset = GetPoisonOffset();
  38   for (size_t i = 0; i < nsStyleStructID_Length; ++i) {
  39     mValueOffsets[i] = framePoisonOffset;
  40   }
  41 #endif
  42 }
  43
  44 #ifdef DEBUG
  45 nsRuleData::~nsRuleData()
  46 {
  47 #ifndef MOZ_VALGRIND
  48   // assert nothing in mSIDs has poison value
  49   size_t framePoisonOffset = GetPoisonOffset();
  50   for (size_t i = 0; i < nsStyleStructID_Length; ++i) {
  51     NS_ABORT_IF_FALSE(!(mSIDs & (1 << i)) ||
  52                       mValueOffsets[i] != framePoisonOffset,
  53                       "value in SIDs was left with poison offset");
  54   }
  55 #endif
  56 }
  57 #endif