/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_COMPILER_UTILS_ASSEMBLER_H_
#define ART_COMPILER_UTILS_ASSEMBLER_H_
#include <vector>
#include "base/logging.h"
#include "base/macros.h"
#include "arm/constants_arm.h"
#include "mips/constants_mips.h"
#include "x86/constants_x86.h"
#include "instruction_set.h"
#include "managed_register.h"
#include "memory_region.h"
#include "offsets.h"
namespace art {
class Assembler;
class AssemblerBuffer;
class AssemblerFixup;
namespace arm {
class ArmAssembler;
}
namespace mips {
class MipsAssembler;
}
namespace x86 {
class X86Assembler;
}
class Label {
public:
Label() : position_(0) {}
~Label() {
// Assert if label is being destroyed with unresolved branches pending.
CHECK(!IsLinked());
}
// Returns the position for bound and linked labels. Cannot be used
// for unused labels.
int Position() const {
CHECK(!IsUnused());
return IsBound() ? -position_ - kPointerSize : position_ - kPointerSize;
}
int LinkPosition() const {
CHECK(IsLinked());
return position_ - kWordSize;
}
bool IsBound() const { return position_ < 0; }
bool IsUnused() const { return position_ == 0; }
bool IsLinked() const { return position_ > 0; }
private:
int position_;
void Reinitialize() {
position_ = 0;
}
void BindTo(int position) {
CHECK(!IsBound());
position_ = -position - kPointerSize;
CHECK(IsBound());
}
void LinkTo(int position) {
CHECK(!IsBound());
position_ = position + kPointerSize;
CHECK(IsLinked());
}
friend class arm::ArmAssembler;
friend class mips::MipsAssembler;
friend class x86::X86Assembler;
DISALLOW_COPY_AND_ASSIGN(Label);
};
// Assembler fixups are positions in generated code that require processing
// after the code has been copied to executable memory. This includes building
// relocation information.
class AssemblerFixup {
public:
virtual void Process(const MemoryRegion& region, int position) = 0;
virtual ~AssemblerFixup() {}
private:
AssemblerFixup* previous_;
int position_;
AssemblerFixup* previous() const { return previous_; }
void set_previous(AssemblerFixup* previous) { previous_ = previous; }
int position() const { return position_; }
void set_position(int position) { position_ = position; }
friend class AssemblerBuffer;
};
// Parent of all queued slow paths, emitted during finalization
class SlowPath {
public:
SlowPath() : next_(NULL) {}
virtual ~SlowPath() {}
Label* Continuation() { return &continuation_; }
Label* Entry() { return &entry_; }
// Generate code for slow path
virtual void Emit(Assembler *sp_asm) = 0;
protected:
// Entry branched to by fast path
Label entry_;
// Optional continuation that is branched to at the end of the slow path
Label continuation_;
// Next in linked list of slow paths
SlowPath *next_;
private:
friend class AssemblerBuffer;
DISALLOW_COPY_AND_ASSIGN(SlowPath);
};
class AssemblerBuffer {
public:
AssemblerBuffer();
~AssemblerBuffer();
// Basic support for emitting, loading, and storing.
template<typename T> void Emit(T value) {
CHECK(HasEnsuredCapacity());
*reinterpret_cast<T*>(cursor_) = value;
cursor_ += sizeof(T);
}
template<typename T> T Load(size_t position) {
CHECK_LE(position, Size() - static_cast<int>(sizeof(T)));
return *reinterpret_cast<T*>(contents_ + position);
}
template<typename T> void Store(size_t position, T value) {
CHECK_LE(position, Size() - static_cast<int>(sizeof(T)));
*reinterpret_cast<T*>(contents_ + position) = value;
}
// Emit a fixup at the current location.
void EmitFixup(AssemblerFixup* fixup) {
fixup->set_previous(fixup_);
fixup->set_position(Size());
fixup_ = fixup;
}
void EnqueueSlowPath(SlowPath* slowpath) {
if (slow_path_ == NULL) {
slow_path_ = slowpath;
} else {
SlowPath* cur = slow_path_;
for ( ; cur->next_ != NULL ; cur = cur->next_) {}
cur->next_ = slowpath;
}
}
void EmitSlowPaths(Assembler* sp_asm) {
SlowPath* cur = slow_path_;
SlowPath* next = NULL;
slow_path_ = NULL;
for ( ; cur != NULL ; cur = next) {
cur->Emit(sp_asm);
next = cur->next_;
delete cur;
}
}
// Get the size of the emitted code.
size_t Size() const {
CHECK_GE(cursor_, contents_);
return cursor_ - contents_;
}
byte* contents() const { return contents_; }
// Copy the assembled instructions into the specified memory block
// and apply all fixups.
void FinalizeInstructions(const MemoryRegion& region);
// To emit an instruction to the assembler buffer, the EnsureCapacity helper
// must be used to guarantee that the underlying data area is big enough to
// hold the emitted instruction. Usage:
//
// AssemblerBuffer buffer;
// AssemblerBuffer::EnsureCapacity ensured(&buffer);
// ... emit bytes for single instruction ...
#ifndef NDEBUG
class EnsureCapacity {
public:
explicit EnsureCapacity(AssemblerBuffer* buffer) {
if (buffer->cursor() >= buffer->limit()) {
buffer->ExtendCapacity();
}
// In debug mode, we save the assembler buffer along with the gap
// size before we start emitting to the buffer. This allows us to
// check that any single generated instruction doesn't overflow the
// limit implied by the minimum gap size.
buffer_ = buffer;
gap_ = ComputeGap();
// Make sure that extending the capacity leaves a big enough gap
// for any kind of instruction.
CHECK_GE(gap_, kMinimumGap);
// Mark the buffer as having ensured the capacity.
CHECK(!buffer->HasEnsuredCapacity()); // Cannot nest.
buffer->has_ensured_capacity_ = true;
}
~EnsureCapacity() {
// Unmark the buffer, so we cannot emit after this.
buffer_->has_ensured_capacity_ = false;
// Make sure the generated instruction doesn't take up more
// space than the minimum gap.
int delta = gap_ - ComputeGap();
CHECK_LE(delta, kMinimumGap);
}
private:
AssemblerBuffer* buffer_;
int gap_;
int ComputeGap() { return buffer_->Capacity() - buffer_->Size(); }
};
bool has_ensured_capacity_;
bool HasEnsuredCapacity() const { return has_ensured_capacity_; }
#else
class EnsureCapacity {
public:
explicit EnsureCapacity(AssemblerBuffer* buffer) {
if (buffer->cursor() >= buffer->limit()) buffer->ExtendCapacity();
}
};
// When building the C++ tests, assertion code is enabled. To allow
// asserting that the user of the assembler buffer has ensured the
// capacity needed for emitting, we add a dummy method in non-debug mode.
bool HasEnsuredCapacity() const { return true; }
#endif
// Returns the position in the instruction stream.
int GetPosition() { return cursor_ - contents_; }
private:
// The limit is set to kMinimumGap bytes before the end of the data area.
// This leaves enough space for the longest possible instruction and allows
// for a single, fast space check per instruction.
static const int kMinimumGap = 32;
byte* contents_;
byte* cursor_;
byte* limit_;
AssemblerFixup* fixup_;
bool fixups_processed_;
// Head of linked list of slow paths
SlowPath* slow_path_;
byte* cursor() const { return cursor_; }
byte* limit() const { return limit_; }
size_t Capacity() const {
CHECK_GE(limit_, contents_);
return (limit_ - contents_) + kMinimumGap;
}
// Process the fixup chain starting at the given fixup. The offset is
// non-zero for fixups in the body if the preamble is non-empty.
void ProcessFixups(const MemoryRegion& region);
// Compute the limit based on the data area and the capacity. See
// description of kMinimumGap for the reasoning behind the value.
static byte* ComputeLimit(byte* data, size_t capacity) {
return data + capacity - kMinimumGap;
}
void ExtendCapacity();
friend class AssemblerFixup;
};
class Assembler {
public:
static Assembler* Create(InstructionSet instruction_set);
// Emit slow paths queued during assembly
void EmitSlowPaths() { buffer_.EmitSlowPaths(this); }
// Size of generated code
size_t CodeSize() const { return buffer_.Size(); }
// Copy instructions out of assembly buffer into the given region of memory
void FinalizeInstructions(const MemoryRegion& region) {
buffer_.FinalizeInstructions(region);
}
// Emit code that will create an activation on the stack
virtual void BuildFrame(size_t frame_size, ManagedRegister method_reg,
const std::vector<ManagedRegister>& callee_save_regs,
const std::vector<ManagedRegister>& entry_spills) = 0;
// Emit code that will remove an activation from the stack
virtual void RemoveFrame(size_t frame_size,
const std::vector<ManagedRegister>& callee_save_regs) = 0;
virtual void IncreaseFrameSize(size_t adjust) = 0;
virtual void DecreaseFrameSize(size_t adjust) = 0;
// Store routines
virtual void Store(FrameOffset offs, ManagedRegister src, size_t size) = 0;
virtual void StoreRef(FrameOffset dest, ManagedRegister src) = 0;
virtual void StoreRawPtr(FrameOffset dest, ManagedRegister src) = 0;
virtual void StoreImmediateToFrame(FrameOffset dest, uint32_t imm,
ManagedRegister scratch) = 0;
virtual void StoreImmediateToThread(ThreadOffset dest, uint32_t imm,
ManagedRegister scratch) = 0;
virtual void StoreStackOffsetToThread(ThreadOffset thr_offs,
FrameOffset fr_offs,
ManagedRegister scratch) = 0;
virtual void StoreStackPointerToThread(ThreadOffset thr_offs) = 0;
virtual void StoreSpanning(FrameOffset dest, ManagedRegister src,
FrameOffset in_off, ManagedRegister scratch) = 0;
// Load routines
virtual void Load(ManagedRegister dest, FrameOffset src, size_t size) = 0;
virtual void Load(ManagedRegister dest, ThreadOffset src, size_t size) = 0;
virtual void LoadRef(ManagedRegister dest, FrameOffset src) = 0;
virtual void LoadRef(ManagedRegister dest, ManagedRegister base,
MemberOffset offs) = 0;
virtual void LoadRawPtr(ManagedRegister dest, ManagedRegister base,
Offset offs) = 0;
virtual void LoadRawPtrFromThread(ManagedRegister dest,
ThreadOffset offs) = 0;
// Copying routines
virtual void Move(ManagedRegister dest, ManagedRegister src, size_t size) = 0;
virtual void CopyRawPtrFromThread(FrameOffset fr_offs, ThreadOffset thr_offs,
ManagedRegister scratch) = 0;
virtual void CopyRawPtrToThread(ThreadOffset thr_offs, FrameOffset fr_offs,
ManagedRegister scratch) = 0;
virtual void CopyRef(FrameOffset dest, FrameOffset src,
ManagedRegister scratch) = 0;
virtual void Copy(FrameOffset dest, FrameOffset src, ManagedRegister scratch, size_t size) = 0;
virtual void Copy(FrameOffset dest, ManagedRegister src_base, Offset src_offset,
ManagedRegister scratch, size_t size) = 0;
virtual void Copy(ManagedRegister dest_base, Offset dest_offset, FrameOffset src,
ManagedRegister scratch, size_t size) = 0;
virtual void Copy(FrameOffset dest, FrameOffset src_base, Offset src_offset,
ManagedRegister scratch, size_t size) = 0;
virtual void Copy(ManagedRegister dest, Offset dest_offset,
ManagedRegister src, Offset src_offset,
ManagedRegister scratch, size_t size) = 0;
virtual void Copy(FrameOffset dest, Offset dest_offset, FrameOffset src, Offset src_offset,
ManagedRegister scratch, size_t size) = 0;
virtual void MemoryBarrier(ManagedRegister scratch) = 0;
// Sign extension
virtual void SignExtend(ManagedRegister mreg, size_t size) = 0;
// Zero extension
virtual void ZeroExtend(ManagedRegister mreg, size_t size) = 0;
// Exploit fast access in managed code to Thread::Current()
virtual void GetCurrentThread(ManagedRegister tr) = 0;
virtual void GetCurrentThread(FrameOffset dest_offset,
ManagedRegister scratch) = 0;
// Set up out_reg to hold a Object** into the SIRT, or to be NULL if the
// value is null and null_allowed. in_reg holds a possibly stale reference
// that can be used to avoid loading the SIRT entry to see if the value is
// NULL.
virtual void CreateSirtEntry(ManagedRegister out_reg, FrameOffset sirt_offset,
ManagedRegister in_reg, bool null_allowed) = 0;
// Set up out_off to hold a Object** into the SIRT, or to be NULL if the
// value is null and null_allowed.
virtual void CreateSirtEntry(FrameOffset out_off, FrameOffset sirt_offset,
ManagedRegister scratch, bool null_allowed) = 0;
// src holds a SIRT entry (Object**) load this into dst
virtual void LoadReferenceFromSirt(ManagedRegister dst,
ManagedRegister src) = 0;
// Heap::VerifyObject on src. In some cases (such as a reference to this) we
// know that src may not be null.
virtual void VerifyObject(ManagedRegister src, bool could_be_null) = 0;
virtual void VerifyObject(FrameOffset src, bool could_be_null) = 0;
// Call to address held at [base+offset]
virtual void Call(ManagedRegister base, Offset offset,
ManagedRegister scratch) = 0;
virtual void Call(FrameOffset base, Offset offset,
ManagedRegister scratch) = 0;
virtual void Call(ThreadOffset offset, ManagedRegister scratch) = 0;
// Generate code to check if Thread::Current()->exception_ is non-null
// and branch to a ExceptionSlowPath if it is.
virtual void ExceptionPoll(ManagedRegister scratch, size_t stack_adjust) = 0;
virtual ~Assembler() {}
protected:
Assembler() : buffer_() {}
AssemblerBuffer buffer_;
};
} // namespace art
#endif // ART_COMPILER_UTILS_ASSEMBLER_H_