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// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/globals.h" // Needed here to get TARGET_ARCH_X64.
#if defined(TARGET_ARCH_X64)
#include "platform/unaligned.h"
#include "vm/code_patcher.h"
#include "vm/instructions.h"
#include "vm/instructions_x64.h"
#include "vm/constants.h"
#include "vm/cpu.h"
#include "vm/object.h"
namespace dart {
// [start] is the address of a displacement inside a load instruction
intptr_t IndexFromPPLoadDisp8(uword start) {
int8_t offset = *reinterpret_cast<int8_t*>(start);
return ObjectPool::IndexFromOffset(offset);
}
intptr_t IndexFromPPLoadDisp32(uword start) {
int32_t offset = LoadUnaligned(reinterpret_cast<int32_t*>(start));
return ObjectPool::IndexFromOffset(offset);
}
bool DecodeLoadObjectFromPoolOrThread(uword pc, const Code& code, Object* obj) {
ASSERT(code.ContainsInstructionAt(pc));
uint8_t* bytes = reinterpret_cast<uint8_t*>(pc);
COMPILE_ASSERT(THR == R14);
if ((bytes[0] == 0x49) || (bytes[0] == 0x4d)) {
if ((bytes[1] == 0x8b) || (bytes[1] == 0x3b)) { // movq, cmpq
if ((bytes[2] & 0xc7) == (0x80 | (THR & 7))) { // [r14+disp32]
int32_t offset = LoadUnaligned(reinterpret_cast<int32_t*>(pc + 3));
return Thread::ObjectAtOffset(offset, obj);
}
if ((bytes[2] & 0xc7) == (0x40 | (THR & 7))) { // [r14+disp8]
uint8_t offset = *reinterpret_cast<uint8_t*>(pc + 3);
return Thread::ObjectAtOffset(offset, obj);
}
}
}
if (((bytes[0] == 0x41) && (bytes[1] == 0xff) && (bytes[2] == 0x76))) {
// push [r14+disp8]
uint8_t offset = *reinterpret_cast<uint8_t*>(pc + 3);
return Thread::ObjectAtOffset(offset, obj);
}
// A code object may have an object pool attached in bare instructions mode
// if the v8 snapshot profile writer is active, but this pool cannot be used
// for object loading.
if (FLAG_use_bare_instructions) return false;
COMPILE_ASSERT(PP == R15);
if ((bytes[0] == 0x49) || (bytes[0] == 0x4d)) {
if ((bytes[1] == 0x8b) || (bytes[1] == 0x3b)) { // movq, cmpq
if ((bytes[2] & 0xc7) == (0x80 | (PP & 7))) { // [r15+disp32]
intptr_t index = IndexFromPPLoadDisp32(pc + 3);
const ObjectPool& pool = ObjectPool::Handle(code.object_pool());
if (!pool.IsNull()) {
if (pool.TypeAt(index) == ObjectPool::EntryType::kTaggedObject) {
*obj = pool.ObjectAt(index);
return true;
}
}
}
if ((bytes[2] & 0xc7) == (0x40 | (PP & 7))) { // [r15+disp8]
intptr_t index = IndexFromPPLoadDisp8(pc + 3);
const ObjectPool& pool = ObjectPool::Handle(code.object_pool());
if (!pool.IsNull()) {
if (pool.TypeAt(index) == ObjectPool::EntryType::kTaggedObject) {
*obj = pool.ObjectAt(index);
return true;
}
}
}
}
}
return false;
}
intptr_t TypeTestingStubCallPattern::GetSubtypeTestCachePoolIndex() {
static int16_t indirect_call_pattern[] = {
0xff, -1 /* 0x53 or 0x56 */, 0x07, // callq [RBX/RSI + 0x7]
};
static int16_t direct_call_pattern[] = {
0xe8, -1, -1, -1, -1, // callq [PC + <offset>]
};
static int16_t pattern_disp8[] = {
0x4d, 0x8b, 0x4f, -1, // movq R9, [PP + offset]
};
static int16_t pattern_disp32[] = {
0x4d, 0x8b, 0x8f, -1, -1, -1, -1, // movq R9, [PP + offset]
};
uword pc = pc_;
if (MatchesPattern(pc, direct_call_pattern,
ARRAY_SIZE(direct_call_pattern))) {
pc -= ARRAY_SIZE(direct_call_pattern);
} else if (MatchesPattern(pc, indirect_call_pattern,
ARRAY_SIZE(indirect_call_pattern))) {
pc -= ARRAY_SIZE(indirect_call_pattern);
} else {
FATAL1("Failed to decode at %" Px, pc_);
}
if (MatchesPattern(pc, pattern_disp8, ARRAY_SIZE(pattern_disp8))) {
return IndexFromPPLoadDisp8(pc - 1);
} else if (MatchesPattern(pc, pattern_disp32, ARRAY_SIZE(pattern_disp32))) {
return IndexFromPPLoadDisp32(pc - 4);
} else {
FATAL1("Failed to decode at %" Px, pc);
}
}
} // namespace dart
#endif // defined TARGET_ARCH_X64