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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sts=4 et sw=4 tw=99:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef jit_x86_shared_Patching_x86_shared_h
#define jit_x86_shared_Patching_x86_shared_h
namespace js {
namespace jit {
namespace X86Encoding {
inline void*
GetPointer(const void* where)
{
void* res;
memcpy(&res, (const char*)where - sizeof(void*), sizeof(void*));
return res;
}
inline void
SetPointer(void* where, const void* value)
{
memcpy((char*)where - sizeof(void*), &value, sizeof(void*));
}
inline int32_t
GetInt32(const void* where)
{
int32_t res;
memcpy(&res, (const char*)where - sizeof(int32_t), sizeof(int32_t));
return res;
}
inline void
SetInt32(void* where, int32_t value)
{
memcpy((char*)where - sizeof(int32_t), &value, sizeof(int32_t));
}
inline void
SetRel32(void* from, void* to)
{
intptr_t offset = reinterpret_cast<intptr_t>(to) - reinterpret_cast<intptr_t>(from);
MOZ_ASSERT(offset == static_cast<int32_t>(offset),
"offset is too great for a 32-bit relocation");
if (offset != static_cast<int32_t>(offset))
MOZ_CRASH("offset is too great for a 32-bit relocation");
SetInt32(from, offset);
}
inline void*
GetRel32Target(void* where)
{
int32_t rel = GetInt32(where);
return (char*)where + rel;
}
class JmpSrc {
public:
JmpSrc()
: offset_(-1)
{
}
explicit JmpSrc(int32_t offset)
: offset_(offset)
{
}
int32_t offset() const {
return offset_;
}
bool isSet() const {
return offset_ != -1;
}
private:
int offset_;
};
class JmpDst {
public:
JmpDst()
: offset_(-1)
, used_(false)
{
}
bool isUsed() const { return used_; }
void used() { used_ = true; }
bool isValid() const { return offset_ != -1; }
explicit JmpDst(int32_t offset)
: offset_(offset)
, used_(false)
{
MOZ_ASSERT(offset_ == offset);
}
int32_t offset() const {
return offset_;
}
private:
int32_t offset_ : 31;
bool used_ : 1;
};
inline bool
CanRelinkJump(void* from, void* to)
{
intptr_t offset = static_cast<char*>(to) - static_cast<char*>(from);
return (offset == static_cast<int32_t>(offset));
}
} // namespace X86Encoding
} // namespace jit
} // namespace js
#endif /* jit_x86_shared_Patching_x86_shared_h */
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