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/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef DFGCorrectableJumpPoint_h
#define DFGCorrectableJumpPoint_h
#if ENABLE(DFG_JIT)
#include "LinkBuffer.h"
#include "MacroAssembler.h"
namespace JSC { namespace DFG {
// This is a type-safe union of MacroAssembler::Jump and CodeLocationJump.
// Furthermore, it supports the notion of branching (possibly conditionally, but
// also possibly jumping unconditionally) to an out-of-line patchable jump.
// Thus it goes through three states:
//
// 1) Label of unpatchable branch or jump (i.e. MacroAssembler::Jump).
// 2) Label of patchable jump (i.e. MacroAssembler::PatchableJump).
// 3) Corrected post-linking label of patchable jump (i.e. CodeLocationJump).
//
// The setting of state (1) corresponds to planting the in-line unpatchable
// branch or jump. The state transition (1)->(2) corresponds to linking the
// in-line branch or jump to the out-of-line patchable jump, and recording
// the latter's label. The state transition (2)->(3) corresponds to recording
// the out-of-line patchable jump's location after branch compaction has
// completed.
//
// You can also go directly from the first state to the third state, if you
// wish to use this class for in-line patchable jumps.
class CorrectableJumpPoint {
public:
CorrectableJumpPoint(MacroAssembler::Jump check)
: m_codeOffset(check.m_label.m_offset)
#ifndef NDEBUG
, m_mode(InitialJump)
#endif
{
#if CPU(ARM_THUMB2)
m_type = check.m_type;
m_condition = check.m_condition;
#endif
}
bool isSet()
{
return m_codeOffset != std::numeric_limits<uint32_t>::max();
}
void switchToLateJump(MacroAssembler::PatchableJump check)
{
#ifndef NDEBUG
ASSERT(m_mode == InitialJump);
m_mode = LateJump;
#endif
// Late jumps should only ever be real jumps.
#if CPU(ARM_THUMB2)
ASSERT(check.m_jump.m_type == ARMv7Assembler::JumpNoConditionFixedSize);
ASSERT(check.m_jump.m_condition == ARMv7Assembler::ConditionInvalid);
m_type = ARMv7Assembler::JumpNoConditionFixedSize;
m_condition = ARMv7Assembler::ConditionInvalid;
#endif
m_codeOffset = check.m_jump.m_label.m_offset;
}
void correctInitialJump(LinkBuffer& linkBuffer)
{
ASSERT(m_mode == InitialJump);
#if CPU(ARM_THUMB2)
ASSERT(m_type == ARMv7Assembler::JumpNoConditionFixedSize);
ASSERT(m_condition == ARMv7Assembler::ConditionInvalid);
#endif
correctJump(linkBuffer);
}
void correctLateJump(LinkBuffer& linkBuffer)
{
ASSERT(m_mode == LateJump);
correctJump(linkBuffer);
}
MacroAssembler::Jump initialJump() const
{
ASSERT(m_mode == InitialJump);
return getJump();
}
MacroAssembler::Jump lateJump() const
{
ASSERT(m_mode == LateJump);
return getJump();
}
CodeLocationJump codeLocationForRepatch(CodeBlock*) const;
private:
void correctJump(LinkBuffer& linkBuffer)
{
#ifndef NDEBUG
m_mode = CorrectedJump;
#endif
MacroAssembler::Label label;
label.m_label.m_offset = m_codeOffset;
m_codeOffset = linkBuffer.offsetOf(label);
}
MacroAssembler::Jump getJump() const
{
MacroAssembler::Jump jump;
jump.m_label.m_offset = m_codeOffset;
#if CPU(ARM_THUMB2)
jump.m_type = m_type;
jump.m_condition = m_condition;
#endif
return jump;
}
unsigned m_codeOffset;
#if CPU(ARM_THUMB2)
ARMv7Assembler::JumpType m_type : 8;
ARMv7Assembler::Condition m_condition : 8;
#endif
#ifndef NDEBUG
enum Mode {
InitialJump,
LateJump,
CorrectedJump
};
Mode m_mode;
#endif
};
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
#endif // DFGCorrectableJumpPoint_h
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