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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.
// Classes that describe assembly patterns as used by inline caches.
#ifndef RUNTIME_VM_INSTRUCTIONS_X64_H_
#define RUNTIME_VM_INSTRUCTIONS_X64_H_
#ifndef RUNTIME_VM_INSTRUCTIONS_H_
#error "Do not include instructions_x64.h directly; use instructions.h instead."
#endif
#include <limits>
#include "platform/unaligned.h"
#include "vm/allocation.h"
namespace dart {
intptr_t IndexFromPPLoadDisp8(uword start);
intptr_t IndexFromPPLoadDisp32(uword start);
// Template class for all instruction pattern classes.
// P has to specify a static pattern and a pattern length method.
template <class P>
class InstructionPattern : public ValueObject {
public:
explicit InstructionPattern(uword pc) : start_(pc) { ASSERT(pc != 0); }
// Call to check if the instruction pattern at 'pc' match the instruction.
// 'P::pattern()' returns the expected byte pattern in form of an integer
// array with length of 'P::pattern_length_in_bytes()'. A '-1' element means
// 'any byte'.
bool IsValid() const {
return TestBytesWith(P::pattern(), P::pattern_length_in_bytes());
}
protected:
uword start() const { return start_; }
private:
// Returns true if the 'num_bytes' bytes at 'start_' correspond to
// array of integers 'data'. 'data' elements are either a byte or -1, which
// represents any byte.
bool TestBytesWith(const int* data, int num_bytes) const {
ASSERT(data != nullptr);
const uint8_t* byte_array = reinterpret_cast<const uint8_t*>(start_);
for (int i = 0; i < num_bytes; i++) {
// Skip comparison for data[i] < 0.
if ((data[i] >= 0) && (byte_array[i] != (0xFF & data[i]))) {
return false;
}
}
return true;
}
const uword start_;
DISALLOW_COPY_AND_ASSIGN(InstructionPattern);
};
class ReturnPattern : public InstructionPattern<ReturnPattern> {
public:
explicit ReturnPattern(uword pc) : InstructionPattern(pc) {}
static const int* pattern() {
static const int kReturnPattern[kLengthInBytes] = {0xC3};
return kReturnPattern;
}
static int pattern_length_in_bytes() { return kLengthInBytes; }
private:
static constexpr int kLengthInBytes = 1;
};
// push rbp
// mov rbp, rsp
class ProloguePattern : public InstructionPattern<ProloguePattern> {
public:
explicit ProloguePattern(uword pc) : InstructionPattern(pc) {}
static const int* pattern() {
static const int kProloguePattern[kLengthInBytes] = {0x55, 0x48, 0x89,
0xe5};
return kProloguePattern;
}
static int pattern_length_in_bytes() { return kLengthInBytes; }
private:
static constexpr int kLengthInBytes = 4;
};
// mov rbp, rsp
class SetFramePointerPattern
: public InstructionPattern<SetFramePointerPattern> {
public:
explicit SetFramePointerPattern(uword pc) : InstructionPattern(pc) {}
static const int* pattern() {
static const int kFramePointerPattern[kLengthInBytes] = {0x48, 0x89, 0xe5};
return kFramePointerPattern;
}
static int pattern_length_in_bytes() { return kLengthInBytes; }
private:
static constexpr int kLengthInBytes = 3;
};
// callq *[rip+offset]
class PcRelativeCallPattern : public InstructionPattern<PcRelativeCallPattern> {
public:
static constexpr int kLengthInBytes = 5;
// Theoretically we can encode offsets 5 bytes more than INT_MAX since the
// instruction encoding uses the PC after current instruction.
// Though in order to use int32_t as type on all architectures for distances,
// we make the upper limit not have `+ kLengthInBytes`.
static constexpr int32_t kLowerCallingRange =
std::numeric_limits<int32_t>::min() + kLengthInBytes;
static constexpr int32_t kUpperCallingRange =
std::numeric_limits<int32_t>::max();
explicit PcRelativeCallPattern(uword pc) : InstructionPattern(pc) {}
int32_t distance() {
return LoadUnaligned(reinterpret_cast<int32_t*>(start() + 1)) +
kLengthInBytes;
}
void set_distance(int32_t distance) {
// [distance] is relative to the start of the instruction, x64 considers the
// offset relative to next PC.
StoreUnaligned(reinterpret_cast<int32_t*>(start() + 1),
distance - kLengthInBytes);
}
static const int* pattern() {
static const int kPattern[kLengthInBytes] = {0xe8, -1, -1, -1, -1};
return kPattern;
}
static int pattern_length_in_bytes() { return kLengthInBytes; }
};
// Instruction pattern for a tail call to a signed 32-bit PC-relative offset
//
// The AOT compiler can emit PC-relative calls. If the destination of such a
// call is not in range for the "bl.<cond> <offset>" instruction, the AOT
// compiler will emit a trampoline which is in range. That trampoline will
// then tail-call to the final destination (also via PC-relative offset, but it
// supports a full signed 32-bit offset).
//
// The pattern of the trampoline looks like:
//
// jmp $rip + <offset>
//
// (Strictly speaking the pc-relative call distance on X64 is big enough, but
// for making AOT relocation code (i.e. relocation.cc) platform independent and
// allow testing of trampolines on X64 we have it nonetheless)
class PcRelativeTrampolineJumpPattern : public ValueObject {
public:
static constexpr int kLengthInBytes = 5;
explicit PcRelativeTrampolineJumpPattern(uword pattern_start)
: pattern_start_(pattern_start) {}
void Initialize() {
uint8_t* pattern = reinterpret_cast<uint8_t*>(pattern_start_);
pattern[0] = 0xe9;
}
int32_t distance() {
return LoadUnaligned(reinterpret_cast<int32_t*>(pattern_start_ + 1)) +
kLengthInBytes;
}
void set_distance(intptr_t distance) {
// [distance] is relative to the start of the instruction, x64 considers the
// offset relative to next PC.
StoreUnaligned(reinterpret_cast<int32_t*>(pattern_start_ + 1),
static_cast<int32_t>(distance - kLengthInBytes));
}
bool IsValid() const {
uint8_t* pattern = reinterpret_cast<uint8_t*>(pattern_start_);
return pattern[0] == 0xe9;
}
private:
uword pattern_start_;
};
class PcRelativeTailCallPattern : public PcRelativeTrampolineJumpPattern {
public:
static constexpr int32_t kLowerCallingRange =
PcRelativeCallPattern::kLowerCallingRange;
static constexpr int32_t kUpperCallingRange =
PcRelativeCallPattern::kUpperCallingRange;
explicit PcRelativeTailCallPattern(uword pc)
: PcRelativeTrampolineJumpPattern(pc) {}
};
} // namespace dart
#endif // RUNTIME_VM_INSTRUCTIONS_X64_H_