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// Copyright (c) 2013, 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_ARM.
#if defined(TARGET_ARCH_ARM)
#include "vm/constants_arm.h"
#include "vm/cpu.h"
#include "vm/instructions.h"
#include "vm/object.h"
namespace dart {
CallPattern::CallPattern(uword pc, const Code& code)
: end_(reinterpret_cast<uword*>(pc)),
target_address_pool_index_(-1),
args_desc_load_end_(-1),
args_desc_(Array::Handle()),
ic_data_load_end_(-1),
ic_data_(ICData::Handle()),
object_pool_(Array::Handle(code.ObjectPool())) {
ASSERT(code.ContainsInstructionAt(pc));
ASSERT(Back(1) == 0xe12fff3e); // Last instruction: blx lr
Register reg;
ic_data_load_end_ =
DecodeLoadWordFromPool(1, &reg, &target_address_pool_index_);
ASSERT(reg == LR);
}
uword CallPattern::Back(int n) const {
ASSERT(n > 0);
return *(end_ - n);
}
// Decodes a load sequence ending at end. Returns the register being loaded and
// the loaded object.
// Returns the location of the load sequence, counting the number of
// instructions back from the end of the call pattern.
int CallPattern::DecodeLoadObject(int end, Register* reg, Object* obj) {
ASSERT(end > 0);
uword instr = Back(end + 1);
if ((instr & 0xfff00000) == 0xe5900000) { // ldr reg, [reg, #+offset]
int index = 0;
end = DecodeLoadWordFromPool(end, reg, &index);
*obj = object_pool_.At(index);
} else {
int value = 0;
end = DecodeLoadWordImmediate(end, reg, &value);
*obj = reinterpret_cast<RawObject*>(value);
}
return end;
}
// Decodes a load sequence ending at end. Returns the register being loaded and
// the loaded immediate value.
// Returns the location of the load sequence, counting the number of
// instructions back from the end of the call pattern.
int CallPattern::DecodeLoadWordImmediate(int end, Register* reg, int* value) {
ASSERT(end > 0);
uword instr = Back(++end);
int imm = 0;
if ((instr & 0xfff00000) == 0xe3400000) { // movt reg, #imm_hi
imm |= (instr & 0xf0000) << 12;
imm |= (instr & 0xfff) << 16;
instr = Back(++end);
}
ASSERT((instr & 0xfff00000) == 0xe3000000); // movw reg, #imm_lo
imm |= (instr & 0xf0000) >> 4;
imm |= instr & 0xfff;
*reg = static_cast<Register>((instr & 0xf000) >> 12);
*value = imm;
return end;
}
// Decodes a load sequence ending at end. Returns the register being loaded and
// the index in the pool being read from.
// Returns the location of the load sequence, counting the number of
// instructions back from the end of the call pattern.
int CallPattern::DecodeLoadWordFromPool(int end, Register* reg, int* index) {
ASSERT(end > 0);
uword instr = Back(++end);
int offset = 0;
if ((instr & 0xffff0000) == 0xe59a0000) { // ldr reg, [pp, #+offset]
offset = instr & 0xfff;
*reg = static_cast<Register>((instr & 0xf000) >> 12);
} else {
ASSERT((instr & 0xfff00000) == 0xe5900000); // ldr reg, [reg, #+offset]
offset = instr & 0xfff;
instr = Back(++end);
if ((instr & 0xffff0000) == 0xe28a0000) { // add reg, pp, shifter_op
const int rot = (instr & 0xf00) * 2;
const int imm8 = instr & 0xff;
offset |= (imm8 >> rot) | (imm8 << (32 - rot));
*reg = static_cast<Register>((instr & 0xf000) >> 12);
} else {
ASSERT((instr & 0xffff0000) == 0xe08a0000); // add reg, pp, reg
end = DecodeLoadWordImmediate(end, reg, &offset);
}
}
offset += kHeapObjectTag;
ASSERT(Utils::IsAligned(offset, 4));
*index = (offset - Array::data_offset())/4;
return end;
}
RawICData* CallPattern::IcData() {
if (ic_data_.IsNull()) {
Register reg;
args_desc_load_end_ = DecodeLoadObject(ic_data_load_end_, &reg, &ic_data_);
ASSERT(reg == R5);
}
return ic_data_.raw();
}
RawArray* CallPattern::ArgumentsDescriptor() {
if (args_desc_.IsNull()) {
IcData(); // Loading of the ic_data must be decoded first, if not already.
Register reg;
DecodeLoadObject(args_desc_load_end_, &reg, &args_desc_);
ASSERT(reg == R4);
}
return args_desc_.raw();
}
uword CallPattern::TargetAddress() const {
ASSERT(target_address_pool_index_ >= 0);
const Object& target_address =
Object::Handle(object_pool_.At(target_address_pool_index_));
ASSERT(target_address.IsSmi());
// The address is stored in the object array as a RawSmi.
return reinterpret_cast<uword>(target_address.raw());
}
void CallPattern::SetTargetAddress(uword target_address) const {
ASSERT(Utils::IsAligned(target_address, 4));
// The address is stored in the object array as a RawSmi.
const Smi& smi = Smi::Handle(reinterpret_cast<RawSmi*>(target_address));
object_pool_.SetAt(target_address_pool_index_, smi);
// No need to flush the instruction cache, since the code is not modified.
}
JumpPattern::JumpPattern(uword pc) : pc_(pc) { }
bool JumpPattern::IsValid() const {
Instr* movw = Instr::At(pc_ + (0 * Instr::kInstrSize)); // movw ip, target_lo
Instr* movt = Instr::At(pc_ + (1 * Instr::kInstrSize)); // movw ip, target_lo
Instr* bxip = Instr::At(pc_ + (2 * Instr::kInstrSize)); // bx ip
return (movw->InstructionBits() & 0xfff0f000) == 0xe300c000 &&
(movt->InstructionBits() & 0xfff0f000) == 0xe340c000 &&
(bxip->InstructionBits() & 0xffffffff) == 0xe12fff1c;
}
uword JumpPattern::TargetAddress() const {
Instr* movw = Instr::At(pc_ + (0 * Instr::kInstrSize)); // movw ip, target_lo
Instr* movt = Instr::At(pc_ + (1 * Instr::kInstrSize)); // movw ip, target_lo
uint16_t target_lo = movw->MovwField();
uint16_t target_hi = movt->MovwField();
return (target_hi << 16) | target_lo;
}
void JumpPattern::SetTargetAddress(uword target_address) const {
uint16_t target_lo = target_address & 0xffff;
uint16_t target_hi = target_address >> 16;
uword movw = 0xe300c000 | ((target_lo >> 12) << 16) | (target_lo & 0xfff);
uword movt = 0xe340c000 | ((target_hi >> 12) << 16) | (target_hi & 0xfff);
*reinterpret_cast<uword*>(pc_ + (0 * Instr::kInstrSize)) = movw;
*reinterpret_cast<uword*>(pc_ + (1 * Instr::kInstrSize)) = movt;
CPU::FlushICache(pc_, 2 * Instr::kInstrSize);
}
} // namespace dart
#endif // defined TARGET_ARCH_ARM