/*
* Copyright (C) 2014 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_RUNTIME_STACK_MAP_H_
#define ART_RUNTIME_STACK_MAP_H_
#include "base/bit_vector.h"
#include "base/bit_utils.h"
#include "memory_region.h"
namespace art {
// Size of a frame slot, in bytes. This constant is a signed value,
// to please the compiler in arithmetic operations involving int32_t
// (signed) values.
static constexpr ssize_t kFrameSlotSize = 4;
// Size of Dex virtual registers.
static constexpr size_t kVRegSize = 4;
class CodeInfo;
/**
* Classes in the following file are wrapper on stack map information backed
* by a MemoryRegion. As such they read and write to the region, they don't have
* their own fields.
*/
/**
* Inline information for a specific PC. The information is of the form:
* [inlining_depth, [method_dex reference]+]
*/
class InlineInfo {
public:
explicit InlineInfo(MemoryRegion region) : region_(region) {}
uint8_t GetDepth() const {
return region_.LoadUnaligned<uint8_t>(kDepthOffset);
}
void SetDepth(uint8_t depth) {
region_.StoreUnaligned<uint8_t>(kDepthOffset, depth);
}
uint32_t GetMethodReferenceIndexAtDepth(uint8_t depth) const {
return region_.LoadUnaligned<uint32_t>(kFixedSize + depth * SingleEntrySize());
}
void SetMethodReferenceIndexAtDepth(uint8_t depth, uint32_t index) {
region_.StoreUnaligned<uint32_t>(kFixedSize + depth * SingleEntrySize(), index);
}
static size_t SingleEntrySize() {
return sizeof(uint32_t);
}
private:
// TODO: Instead of plain types such as "uint8_t", introduce
// typedefs (and document the memory layout of InlineInfo).
static constexpr int kDepthOffset = 0;
static constexpr int kFixedSize = kDepthOffset + sizeof(uint8_t);
MemoryRegion region_;
friend class CodeInfo;
friend class StackMap;
friend class StackMapStream;
};
// Dex register location container used by DexRegisterMap and StackMapStream.
class DexRegisterLocation {
public:
/*
* The location kind used to populate the Dex register information in a
* StackMapStream can either be:
* - kNone: the register has no location yet, meaning it has not been set;
* - kConstant: value holds the constant;
* - kStack: value holds the stack offset;
* - kRegister: value holds the physical register number;
* - kFpuRegister: value holds the physical register number.
*
* In addition, DexRegisterMap also uses these values:
* - kInStackLargeOffset: value holds a "large" stack offset (greater than
* or equal to 128 bytes);
* - kConstantLargeValue: value holds a "large" constant (lower than 0, or
* or greater than or equal to 32).
*/
enum class Kind : uint8_t {
// Short location kinds, for entries fitting on one byte (3 bits
// for the kind, 5 bits for the value) in a DexRegisterMap.
kNone = 0, // 0b000
kInStack = 1, // 0b001
kInRegister = 2, // 0b010
kInFpuRegister = 3, // 0b011
kConstant = 4, // 0b100
// Large location kinds, requiring a 5-byte encoding (1 byte for the
// kind, 4 bytes for the value).
// Stack location at a large offset, meaning that the offset value
// divided by the stack frame slot size (4 bytes) cannot fit on a
// 5-bit unsigned integer (i.e., this offset value is greater than
// or equal to 2^5 * 4 = 128 bytes).
kInStackLargeOffset = 5, // 0b101
// Large constant, that cannot fit on a 5-bit signed integer (i.e.,
// lower than 0, or greater than or equal to 2^5 = 32).
kConstantLargeValue = 6, // 0b110
kLastLocationKind = kConstantLargeValue
};
static_assert(
sizeof(Kind) == 1u,
"art::DexRegisterLocation::Kind has a size different from one byte.");
static const char* PrettyDescriptor(Kind kind) {
switch (kind) {
case Kind::kNone:
return "none";
case Kind::kInStack:
return "in stack";
case Kind::kInRegister:
return "in register";
case Kind::kInFpuRegister:
return "in fpu register";
case Kind::kConstant:
return "as constant";
case Kind::kInStackLargeOffset:
return "in stack (large offset)";
case Kind::kConstantLargeValue:
return "as constant (large value)";
default:
UNREACHABLE();
}
}
static bool IsShortLocationKind(Kind kind) {
switch (kind) {
case Kind::kNone:
case Kind::kInStack:
case Kind::kInRegister:
case Kind::kInFpuRegister:
case Kind::kConstant:
return true;
case Kind::kInStackLargeOffset:
case Kind::kConstantLargeValue:
return false;
default:
UNREACHABLE();
}
}
// Convert `kind` to a "surface" kind, i.e. one that doesn't include
// any value with a "large" qualifier.
// TODO: Introduce another enum type for the surface kind?
static Kind ConvertToSurfaceKind(Kind kind) {
switch (kind) {
case Kind::kNone:
case Kind::kInStack:
case Kind::kInRegister:
case Kind::kInFpuRegister:
case Kind::kConstant:
return kind;
case Kind::kInStackLargeOffset:
return Kind::kInStack;
case Kind::kConstantLargeValue:
return Kind::kConstant;
default:
UNREACHABLE();
}
}
// Required by art::StackMapStream::LocationCatalogEntriesIndices.
DexRegisterLocation() : kind_(Kind::kNone), value_(0) {}
DexRegisterLocation(Kind kind, int32_t value) : kind_(kind), value_(value) {}
static DexRegisterLocation None() {
return DexRegisterLocation(Kind::kNone, 0);
}
// Get the "surface" kind of the location, i.e., the one that doesn't
// include any value with a "large" qualifier.
Kind GetKind() const {
return ConvertToSurfaceKind(kind_);
}
// Get the value of the location.
int32_t GetValue() const { return value_; }
// Get the actual kind of the location.
Kind GetInternalKind() const { return kind_; }
bool operator==(DexRegisterLocation other) const {
return kind_ == other.kind_ && value_ == other.value_;
}
bool operator!=(DexRegisterLocation other) const {
return !(*this == other);
}
private:
Kind kind_;
int32_t value_;
friend class DexRegisterLocationHashFn;
};
/**
* Store information on unique Dex register locations used in a method.
* The information is of the form:
* [DexRegisterLocation+].
* DexRegisterLocations are either 1- or 5-byte wide (see art::DexRegisterLocation::Kind).
*/
class DexRegisterLocationCatalog {
public:
explicit DexRegisterLocationCatalog(MemoryRegion region) : region_(region) {}
// Short (compressed) location, fitting on one byte.
typedef uint8_t ShortLocation;
void SetRegisterInfo(size_t offset, const DexRegisterLocation& dex_register_location) {
DexRegisterLocation::Kind kind = ComputeCompressedKind(dex_register_location);
int32_t value = dex_register_location.GetValue();
if (DexRegisterLocation::IsShortLocationKind(kind)) {
// Short location. Compress the kind and the value as a single byte.
if (kind == DexRegisterLocation::Kind::kInStack) {
// Instead of storing stack offsets expressed in bytes for
// short stack locations, store slot offsets. A stack offset
// is a multiple of 4 (kFrameSlotSize). This means that by
// dividing it by 4, we can fit values from the [0, 128)
// interval in a short stack location, and not just values
// from the [0, 32) interval.
DCHECK_EQ(value % kFrameSlotSize, 0);
value /= kFrameSlotSize;
}
DCHECK(IsShortValue(value)) << value;
region_.StoreUnaligned<ShortLocation>(offset, MakeShortLocation(kind, value));
} else {
// Large location. Write the location on one byte and the value
// on 4 bytes.
DCHECK(!IsShortValue(value)) << value;
if (kind == DexRegisterLocation::Kind::kInStackLargeOffset) {
// Also divide large stack offsets by 4 for the sake of consistency.
DCHECK_EQ(value % kFrameSlotSize, 0);
value /= kFrameSlotSize;
}
// Data can be unaligned as the written Dex register locations can
// either be 1-byte or 5-byte wide. Use
// art::MemoryRegion::StoreUnaligned instead of
// art::MemoryRegion::Store to prevent unligned word accesses on ARM.
region_.StoreUnaligned<DexRegisterLocation::Kind>(offset, kind);
region_.StoreUnaligned<int32_t>(offset + sizeof(DexRegisterLocation::Kind), value);
}
}
// Find the offset of the location catalog entry number `location_catalog_entry_index`.
size_t FindLocationOffset(size_t location_catalog_entry_index) const {
size_t offset = kFixedSize;
// Skip the first `location_catalog_entry_index - 1` entries.
for (uint16_t i = 0; i < location_catalog_entry_index; ++i) {
// Read the first next byte and inspect its first 3 bits to decide
// whether it is a short or a large location.
DexRegisterLocation::Kind kind = ExtractKindAtOffset(offset);
if (DexRegisterLocation::IsShortLocationKind(kind)) {
// Short location. Skip the current byte.
offset += SingleShortEntrySize();
} else {
// Large location. Skip the 5 next bytes.
offset += SingleLargeEntrySize();
}
}
return offset;
}
// Get the internal kind of entry at `location_catalog_entry_index`.
DexRegisterLocation::Kind GetLocationInternalKind(size_t location_catalog_entry_index) const {
if (location_catalog_entry_index == kNoLocationEntryIndex) {
return DexRegisterLocation::Kind::kNone;
}
return ExtractKindAtOffset(FindLocationOffset(location_catalog_entry_index));
}
// Get the (surface) kind and value of entry at `location_catalog_entry_index`.
DexRegisterLocation GetDexRegisterLocation(size_t location_catalog_entry_index) const {
if (location_catalog_entry_index == kNoLocationEntryIndex) {
return DexRegisterLocation::None();
}
size_t offset = FindLocationOffset(location_catalog_entry_index);
// Read the first byte and inspect its first 3 bits to get the location.
ShortLocation first_byte = region_.LoadUnaligned<ShortLocation>(offset);
DexRegisterLocation::Kind kind = ExtractKindFromShortLocation(first_byte);
if (DexRegisterLocation::IsShortLocationKind(kind)) {
// Short location. Extract the value from the remaining 5 bits.
int32_t value = ExtractValueFromShortLocation(first_byte);
if (kind == DexRegisterLocation::Kind::kInStack) {
// Convert the stack slot (short) offset to a byte offset value.
value *= kFrameSlotSize;
}
return DexRegisterLocation(kind, value);
} else {
// Large location. Read the four next bytes to get the value.
int32_t value = region_.LoadUnaligned<int32_t>(offset + sizeof(DexRegisterLocation::Kind));
if (kind == DexRegisterLocation::Kind::kInStackLargeOffset) {
// Convert the stack slot (large) offset to a byte offset value.
value *= kFrameSlotSize;
}
return DexRegisterLocation(kind, value);
}
}
// Compute the compressed kind of `location`.
static DexRegisterLocation::Kind ComputeCompressedKind(const DexRegisterLocation& location) {
switch (location.GetInternalKind()) {
case DexRegisterLocation::Kind::kNone:
DCHECK_EQ(location.GetValue(), 0);
return DexRegisterLocation::Kind::kNone;
case DexRegisterLocation::Kind::kInRegister:
DCHECK_GE(location.GetValue(), 0);
DCHECK_LT(location.GetValue(), 1 << kValueBits);
return DexRegisterLocation::Kind::kInRegister;
case DexRegisterLocation::Kind::kInFpuRegister:
DCHECK_GE(location.GetValue(), 0);
DCHECK_LT(location.GetValue(), 1 << kValueBits);
return DexRegisterLocation::Kind::kInFpuRegister;
case DexRegisterLocation::Kind::kInStack:
return IsShortStackOffsetValue(location.GetValue())
? DexRegisterLocation::Kind::kInStack
: DexRegisterLocation::Kind::kInStackLargeOffset;
case DexRegisterLocation::Kind::kConstant:
return IsShortConstantValue(location.GetValue())
? DexRegisterLocation::Kind::kConstant
: DexRegisterLocation::Kind::kConstantLargeValue;
default:
LOG(FATAL) << "Unexpected location kind"
<< DexRegisterLocation::PrettyDescriptor(location.GetInternalKind());
UNREACHABLE();
}
}
// Can `location` be turned into a short location?
static bool CanBeEncodedAsShortLocation(const DexRegisterLocation& location) {
switch (location.GetInternalKind()) {
case DexRegisterLocation::Kind::kNone:
case DexRegisterLocation::Kind::kInRegister:
case DexRegisterLocation::Kind::kInFpuRegister:
return true;
case DexRegisterLocation::Kind::kInStack:
return IsShortStackOffsetValue(location.GetValue());
case DexRegisterLocation::Kind::kConstant:
return IsShortConstantValue(location.GetValue());
default:
UNREACHABLE();
}
}
static size_t EntrySize(const DexRegisterLocation& location) {
return CanBeEncodedAsShortLocation(location) ? SingleShortEntrySize() : SingleLargeEntrySize();
}
static size_t SingleShortEntrySize() {
return sizeof(ShortLocation);
}
static size_t SingleLargeEntrySize() {
return sizeof(DexRegisterLocation::Kind) + sizeof(int32_t);
}
size_t Size() const {
return region_.size();
}
// Special (invalid) Dex register location catalog entry index meaning
// that there is no location for a given Dex register (i.e., it is
// mapped to a DexRegisterLocation::Kind::kNone location).
static constexpr size_t kNoLocationEntryIndex = -1;
private:
static constexpr int kFixedSize = 0;
// Width of the kind "field" in a short location, in bits.
static constexpr size_t kKindBits = 3;
// Width of the value "field" in a short location, in bits.
static constexpr size_t kValueBits = 5;
static constexpr uint8_t kKindMask = (1 << kKindBits) - 1;
static constexpr int32_t kValueMask = (1 << kValueBits) - 1;
static constexpr size_t kKindOffset = 0;
static constexpr size_t kValueOffset = kKindBits;
static bool IsShortStackOffsetValue(int32_t value) {
DCHECK_EQ(value % kFrameSlotSize, 0);
return IsShortValue(value / kFrameSlotSize);
}
static bool IsShortConstantValue(int32_t value) {
return IsShortValue(value);
}
static bool IsShortValue(int32_t value) {
return IsUint<kValueBits>(value);
}
static ShortLocation MakeShortLocation(DexRegisterLocation::Kind kind, int32_t value) {
uint8_t kind_integer_value = static_cast<uint8_t>(kind);
DCHECK(IsUint<kKindBits>(kind_integer_value)) << kind_integer_value;
DCHECK(IsShortValue(value)) << value;
return (kind_integer_value & kKindMask) << kKindOffset
| (value & kValueMask) << kValueOffset;
}
static DexRegisterLocation::Kind ExtractKindFromShortLocation(ShortLocation location) {
uint8_t kind = (location >> kKindOffset) & kKindMask;
DCHECK_LE(kind, static_cast<uint8_t>(DexRegisterLocation::Kind::kLastLocationKind));
// We do not encode kNone locations in the stack map.
DCHECK_NE(kind, static_cast<uint8_t>(DexRegisterLocation::Kind::kNone));
return static_cast<DexRegisterLocation::Kind>(kind);
}
static int32_t ExtractValueFromShortLocation(ShortLocation location) {
return (location >> kValueOffset) & kValueMask;
}
// Extract a location kind from the byte at position `offset`.
DexRegisterLocation::Kind ExtractKindAtOffset(size_t offset) const {
ShortLocation first_byte = region_.LoadUnaligned<ShortLocation>(offset);
return ExtractKindFromShortLocation(first_byte);
}
MemoryRegion region_;
friend class CodeInfo;
friend class StackMapStream;
};
/* Information on Dex register locations for a specific PC, mapping a
* stack map's Dex register to a location entry in a DexRegisterLocationCatalog.
* The information is of the form:
* [live_bit_mask, entries*]
* where entries are concatenated unsigned integer values encoded on a number
* of bits (fixed per DexRegisterMap instances of a CodeInfo object) depending
* on the number of entries in the Dex register location catalog
* (see DexRegisterMap::SingleEntrySizeInBits). The map is 1-byte aligned.
*/
class DexRegisterMap {
public:
explicit DexRegisterMap(MemoryRegion region) : region_(region) {}
// Get the surface kind of Dex register `dex_register_number`.
DexRegisterLocation::Kind GetLocationKind(uint16_t dex_register_number,
uint16_t number_of_dex_registers,
const CodeInfo& code_info) const {
return DexRegisterLocation::ConvertToSurfaceKind(
GetLocationInternalKind(dex_register_number, number_of_dex_registers, code_info));
}
// Get the internal kind of Dex register `dex_register_number`.
DexRegisterLocation::Kind GetLocationInternalKind(uint16_t dex_register_number,
uint16_t number_of_dex_registers,
const CodeInfo& code_info) const;
// Get the Dex register location `dex_register_number`.
DexRegisterLocation GetDexRegisterLocation(uint16_t dex_register_number,
uint16_t number_of_dex_registers,
const CodeInfo& code_info) const;
int32_t GetStackOffsetInBytes(uint16_t dex_register_number,
uint16_t number_of_dex_registers,
const CodeInfo& code_info) const {
DexRegisterLocation location =
GetDexRegisterLocation(dex_register_number, number_of_dex_registers, code_info);
DCHECK(location.GetKind() == DexRegisterLocation::Kind::kInStack);
// GetDexRegisterLocation returns the offset in bytes.
return location.GetValue();
}
int32_t GetConstant(uint16_t dex_register_number,
uint16_t number_of_dex_registers,
const CodeInfo& code_info) const {
DexRegisterLocation location =
GetDexRegisterLocation(dex_register_number, number_of_dex_registers, code_info);
DCHECK(location.GetKind() == DexRegisterLocation::Kind::kConstant);
return location.GetValue();
}
int32_t GetMachineRegister(uint16_t dex_register_number,
uint16_t number_of_dex_registers,
const CodeInfo& code_info) const {
DexRegisterLocation location =
GetDexRegisterLocation(dex_register_number, number_of_dex_registers, code_info);
DCHECK(location.GetInternalKind() == DexRegisterLocation::Kind::kInRegister
|| location.GetInternalKind() == DexRegisterLocation::Kind::kInFpuRegister)
<< DexRegisterLocation::PrettyDescriptor(location.GetInternalKind());
return location.GetValue();
}
// Get the index of the entry in the Dex register location catalog
// corresponding to `dex_register_number`.
size_t GetLocationCatalogEntryIndex(uint16_t dex_register_number,
uint16_t number_of_dex_registers,
size_t number_of_location_catalog_entries) const {
if (!IsDexRegisterLive(dex_register_number)) {
return DexRegisterLocationCatalog::kNoLocationEntryIndex;
}
if (number_of_location_catalog_entries == 1) {
// We do not allocate space for location maps in the case of a
// single-entry location catalog, as it is useless. The only valid
// entry index is 0;
return 0;
}
// The bit offset of the beginning of the map locations.
size_t map_locations_offset_in_bits =
GetLocationMappingDataOffset(number_of_dex_registers) * kBitsPerByte;
size_t index_in_dex_register_map = GetIndexInDexRegisterMap(dex_register_number);
DCHECK_LT(index_in_dex_register_map, GetNumberOfLiveDexRegisters(number_of_dex_registers));
// The bit size of an entry.
size_t map_entry_size_in_bits = SingleEntrySizeInBits(number_of_location_catalog_entries);
// The bit offset where `index_in_dex_register_map` is located.
size_t entry_offset_in_bits =
map_locations_offset_in_bits + index_in_dex_register_map * map_entry_size_in_bits;
size_t location_catalog_entry_index =
region_.LoadBits(entry_offset_in_bits, map_entry_size_in_bits);
DCHECK_LT(location_catalog_entry_index, number_of_location_catalog_entries);
return location_catalog_entry_index;
}
// Map entry at `index_in_dex_register_map` to `location_catalog_entry_index`.
void SetLocationCatalogEntryIndex(size_t index_in_dex_register_map,
size_t location_catalog_entry_index,
uint16_t number_of_dex_registers,
size_t number_of_location_catalog_entries) {
DCHECK_LT(index_in_dex_register_map, GetNumberOfLiveDexRegisters(number_of_dex_registers));
DCHECK_LT(location_catalog_entry_index, number_of_location_catalog_entries);
if (number_of_location_catalog_entries == 1) {
// We do not allocate space for location maps in the case of a
// single-entry location catalog, as it is useless.
return;
}
// The bit offset of the beginning of the map locations.
size_t map_locations_offset_in_bits =
GetLocationMappingDataOffset(number_of_dex_registers) * kBitsPerByte;
// The bit size of an entry.
size_t map_entry_size_in_bits = SingleEntrySizeInBits(number_of_location_catalog_entries);
// The bit offset where `index_in_dex_register_map` is located.
size_t entry_offset_in_bits =
map_locations_offset_in_bits + index_in_dex_register_map * map_entry_size_in_bits;
region_.StoreBits(entry_offset_in_bits, location_catalog_entry_index, map_entry_size_in_bits);
}
void SetLiveBitMask(uint16_t number_of_dex_registers,
const BitVector& live_dex_registers_mask) {
size_t live_bit_mask_offset_in_bits = GetLiveBitMaskOffset() * kBitsPerByte;
for (uint16_t i = 0; i < number_of_dex_registers; ++i) {
region_.StoreBit(live_bit_mask_offset_in_bits + i, live_dex_registers_mask.IsBitSet(i));
}
}
bool IsDexRegisterLive(uint16_t dex_register_number) const {
size_t live_bit_mask_offset_in_bits = GetLiveBitMaskOffset() * kBitsPerByte;
return region_.LoadBit(live_bit_mask_offset_in_bits + dex_register_number);
}
size_t GetNumberOfLiveDexRegisters(uint16_t number_of_dex_registers) const {
size_t number_of_live_dex_registers = 0;
for (size_t i = 0; i < number_of_dex_registers; ++i) {
if (IsDexRegisterLive(i)) {
++number_of_live_dex_registers;
}
}
return number_of_live_dex_registers;
}
static size_t GetLiveBitMaskOffset() {
return kFixedSize;
}
// Compute the size of the live register bit mask (in bytes), for a
// method having `number_of_dex_registers` Dex registers.
static size_t GetLiveBitMaskSize(uint16_t number_of_dex_registers) {
return RoundUp(number_of_dex_registers, kBitsPerByte) / kBitsPerByte;
}
static size_t GetLocationMappingDataOffset(uint16_t number_of_dex_registers) {
return GetLiveBitMaskOffset() + GetLiveBitMaskSize(number_of_dex_registers);
}
size_t GetLocationMappingDataSize(uint16_t number_of_dex_registers,
size_t number_of_location_catalog_entries) const {
size_t location_mapping_data_size_in_bits =
GetNumberOfLiveDexRegisters(number_of_dex_registers)
* SingleEntrySizeInBits(number_of_location_catalog_entries);
return RoundUp(location_mapping_data_size_in_bits, kBitsPerByte) / kBitsPerByte;
}
// Return the size of a map entry in bits. Note that if
// `number_of_location_catalog_entries` equals 1, this function returns 0,
// which is fine, as there is no need to allocate a map for a
// single-entry location catalog; the only valid location catalog entry index
// for a live register in this case is 0 and there is no need to
// store it.
static size_t SingleEntrySizeInBits(size_t number_of_location_catalog_entries) {
// Handle the case of 0, as we cannot pass 0 to art::WhichPowerOf2.
return number_of_location_catalog_entries == 0
? 0u
: WhichPowerOf2(RoundUpToPowerOfTwo(number_of_location_catalog_entries));
}
// Return the size of the DexRegisterMap object, in bytes.
size_t Size() const {
return region_.size();
}
private:
// Return the index in the Dex register map corresponding to the Dex
// register number `dex_register_number`.
size_t GetIndexInDexRegisterMap(uint16_t dex_register_number) const {
if (!IsDexRegisterLive(dex_register_number)) {
return kInvalidIndexInDexRegisterMap;
}
return GetNumberOfLiveDexRegisters(dex_register_number);
}
// Special (invalid) Dex register map entry index meaning that there
// is no index in the map for a given Dex register (i.e., it must
// have been mapped to a DexRegisterLocation::Kind::kNone location).
static constexpr size_t kInvalidIndexInDexRegisterMap = -1;
static constexpr int kFixedSize = 0;
MemoryRegion region_;
friend class CodeInfo;
friend class StackMapStream;
};
/**
* A Stack Map holds compilation information for a specific PC necessary for:
* - Mapping it to a dex PC,
* - Knowing which stack entries are objects,
* - Knowing which registers hold objects,
* - Knowing the inlining information,
* - Knowing the values of dex registers.
*
* The information is of the form:
* [dex_pc, native_pc_offset, dex_register_map_offset, inlining_info_offset, register_mask,
* stack_mask].
*
* Note that register_mask is fixed size, but stack_mask is variable size, depending on the
* stack size of a method.
*/
class StackMap {
public:
StackMap() {}
explicit StackMap(MemoryRegion region) : region_(region) {}
bool IsValid() const { return region_.pointer() != nullptr; }
uint32_t GetDexPc(const CodeInfo& info) const;
void SetDexPc(const CodeInfo& info, uint32_t dex_pc);
uint32_t GetNativePcOffset(const CodeInfo& info) const;
void SetNativePcOffset(const CodeInfo& info, uint32_t native_pc_offset);
uint32_t GetDexRegisterMapOffset(const CodeInfo& info) const;
void SetDexRegisterMapOffset(const CodeInfo& info, uint32_t offset);
uint32_t GetInlineDescriptorOffset(const CodeInfo& info) const;
void SetInlineDescriptorOffset(const CodeInfo& info, uint32_t offset);
uint32_t GetRegisterMask(const CodeInfo& info) const;
void SetRegisterMask(const CodeInfo& info, uint32_t mask);
MemoryRegion GetStackMask(const CodeInfo& info) const;
void SetStackMask(const CodeInfo& info, const BitVector& sp_map) {
MemoryRegion region = GetStackMask(info);
for (size_t i = 0; i < region.size_in_bits(); i++) {
region.StoreBit(i, sp_map.IsBitSet(i));
}
}
bool HasDexRegisterMap(const CodeInfo& info) const {
return GetDexRegisterMapOffset(info) != kNoDexRegisterMap;
}
bool HasInlineInfo(const CodeInfo& info) const {
return GetInlineDescriptorOffset(info) != kNoInlineInfo;
}
bool Equals(const StackMap& other) const {
return region_.pointer() == other.region_.pointer()
&& region_.size() == other.region_.size();
}
static size_t ComputeStackMapSize(size_t stack_mask_size,
size_t inline_info_size,
size_t dex_register_map_size,
size_t dex_pc_max,
size_t native_pc_max,
size_t register_mask_max);
// Special (invalid) offset for the DexRegisterMapOffset field meaning
// that there is no Dex register map for this stack map.
static constexpr uint32_t kNoDexRegisterMap = -1;
// Special (invalid) offset for the InlineDescriptorOffset field meaning
// that there is no inline info for this stack map.
static constexpr uint32_t kNoInlineInfo = -1;
private:
static size_t ComputeStackMapSizeInternal(size_t stack_mask_size,
size_t number_of_bytes_for_inline_info,
size_t number_of_bytes_for_dex_map,
size_t number_of_bytes_for_dex_pc,
size_t number_of_bytes_for_native_pc,
size_t number_of_bytes_for_register_mask);
// TODO: Instead of plain types such as "uint32_t", introduce
// typedefs (and document the memory layout of StackMap).
static constexpr int kRegisterMaskOffset = 0;
static constexpr int kFixedSize = 0;
MemoryRegion region_;
friend class CodeInfo;
friend class StackMapStream;
};
/**
* Wrapper around all compiler information collected for a method.
* The information is of the form:
* [overall_size, number_of_location_catalog_entries, number_of_stack_maps, stack_mask_size,
* DexRegisterLocationCatalog+, StackMap+, DexRegisterMap+, InlineInfo*].
*/
class CodeInfo {
public:
explicit CodeInfo(MemoryRegion region) : region_(region) {}
explicit CodeInfo(const void* data) {
uint32_t size = reinterpret_cast<const uint32_t*>(data)[0];
region_ = MemoryRegion(const_cast<void*>(data), size);
}
static size_t EncodingSizeInBytes(size_t max_element) {
DCHECK(IsUint<32>(max_element));
return (max_element == 0) ? 0
: IsUint<8>(max_element) ? 1
: IsUint<16>(max_element) ? 2
: IsUint<24>(max_element) ? 3
: 4;
}
void SetEncoding(size_t inline_info_size,
size_t dex_register_map_size,
size_t dex_pc_max,
size_t native_pc_max,
size_t register_mask_max) {
if (inline_info_size != 0) {
region_.StoreBit(kHasInlineInfoBitOffset, 1);
// + 1 to also encode kNoInlineInfo: if an inline info offset
// is at 0xFF, we want to overflow to a larger encoding, because it will
// conflict with kNoInlineInfo.
// The offset is relative to the dex register map. TODO: Change this.
SetEncodingAt(kInlineInfoBitOffset,
EncodingSizeInBytes(dex_register_map_size + inline_info_size + 1));
} else {
region_.StoreBit(kHasInlineInfoBitOffset, 0);
SetEncodingAt(kInlineInfoBitOffset, 0);
}
// + 1 to also encode kNoDexRegisterMap: if a dex register map offset
// is at 0xFF, we want to overflow to a larger encoding, because it will
// conflict with kNoDexRegisterMap.
SetEncodingAt(kDexRegisterMapBitOffset, EncodingSizeInBytes(dex_register_map_size + 1));
SetEncodingAt(kDexPcBitOffset, EncodingSizeInBytes(dex_pc_max));
SetEncodingAt(kNativePcBitOffset, EncodingSizeInBytes(native_pc_max));
SetEncodingAt(kRegisterMaskBitOffset, EncodingSizeInBytes(register_mask_max));
}
void SetEncodingAt(size_t bit_offset, size_t number_of_bytes) {
// We encode the number of bytes needed for writing a value on 3 bits,
// for values that we know are maximum 32bits.
region_.StoreBit(bit_offset, (number_of_bytes & 1));
region_.StoreBit(bit_offset + 1, (number_of_bytes & 2));
region_.StoreBit(bit_offset + 2, (number_of_bytes & 4));
}
size_t GetNumberOfBytesForEncoding(size_t bit_offset) const {
return region_.LoadBit(bit_offset)
+ (region_.LoadBit(bit_offset + 1) << 1)
+ (region_.LoadBit(bit_offset + 2) << 2);
}
bool HasInlineInfo() const {
return region_.LoadBit(kHasInlineInfoBitOffset);
}
size_t NumberOfBytesForInlineInfo() const {
return GetNumberOfBytesForEncoding(kInlineInfoBitOffset);
}
size_t NumberOfBytesForDexRegisterMap() const {
return GetNumberOfBytesForEncoding(kDexRegisterMapBitOffset);
}
size_t NumberOfBytesForRegisterMask() const {
return GetNumberOfBytesForEncoding(kRegisterMaskBitOffset);
}
size_t NumberOfBytesForNativePc() const {
return GetNumberOfBytesForEncoding(kNativePcBitOffset);
}
size_t NumberOfBytesForDexPc() const {
return GetNumberOfBytesForEncoding(kDexPcBitOffset);
}
size_t ComputeStackMapRegisterMaskOffset() const {
return StackMap::kRegisterMaskOffset;
}
size_t ComputeStackMapStackMaskOffset() const {
return ComputeStackMapRegisterMaskOffset()
+ (NumberOfBytesForRegisterMask() * sizeof(uint8_t));
}
size_t ComputeStackMapDexPcOffset() const {
return ComputeStackMapStackMaskOffset() + GetStackMaskSize();
}
size_t ComputeStackMapNativePcOffset() const {
return ComputeStackMapDexPcOffset()
+ (NumberOfBytesForDexPc() * sizeof(uint8_t));
}
size_t ComputeStackMapDexRegisterMapOffset() const {
return ComputeStackMapNativePcOffset()
+ (NumberOfBytesForNativePc() * sizeof(uint8_t));
}
size_t ComputeStackMapInlineInfoOffset() const {
CHECK(HasInlineInfo());
return ComputeStackMapDexRegisterMapOffset()
+ (NumberOfBytesForDexRegisterMap() * sizeof(uint8_t));
}
uint32_t GetDexRegisterLocationCatalogOffset() const {
return kFixedSize;
}
DexRegisterLocationCatalog GetDexRegisterLocationCatalog() const {
return DexRegisterLocationCatalog(region_.Subregion(
GetDexRegisterLocationCatalogOffset(),
GetDexRegisterLocationCatalogSize()));
}
StackMap GetStackMapAt(size_t i) const {
size_t size = StackMapSize();
return StackMap(GetStackMaps().Subregion(i * size, size));
}
uint32_t GetOverallSize() const {
return region_.LoadUnaligned<uint32_t>(kOverallSizeOffset);
}
void SetOverallSize(uint32_t size) {
region_.StoreUnaligned<uint32_t>(kOverallSizeOffset, size);
}
uint32_t GetNumberOfDexRegisterLocationCatalogEntries() const {
return region_.LoadUnaligned<uint32_t>(kNumberOfDexRegisterLocationCatalogEntriesOffset);
}
void SetNumberOfDexRegisterLocationCatalogEntries(uint32_t num_entries) {
region_.StoreUnaligned<uint32_t>(kNumberOfDexRegisterLocationCatalogEntriesOffset, num_entries);
}
uint32_t GetDexRegisterLocationCatalogSize() const {
return ComputeDexRegisterLocationCatalogSize(GetDexRegisterLocationCatalogOffset(),
GetNumberOfDexRegisterLocationCatalogEntries());
}
uint32_t GetStackMaskSize() const {
return region_.LoadUnaligned<uint32_t>(kStackMaskSizeOffset);
}
void SetStackMaskSize(uint32_t size) {
region_.StoreUnaligned<uint32_t>(kStackMaskSizeOffset, size);
}
size_t GetNumberOfStackMaps() const {
return region_.LoadUnaligned<uint32_t>(kNumberOfStackMapsOffset);
}
void SetNumberOfStackMaps(uint32_t number_of_stack_maps) {
region_.StoreUnaligned<uint32_t>(kNumberOfStackMapsOffset, number_of_stack_maps);
}
// Get the size of one stack map of this CodeInfo object, in bytes.
// All stack maps of a CodeInfo have the same size.
size_t StackMapSize() const {
return StackMap::ComputeStackMapSizeInternal(GetStackMaskSize(),
NumberOfBytesForInlineInfo(),
NumberOfBytesForDexRegisterMap(),
NumberOfBytesForDexPc(),
NumberOfBytesForNativePc(),
NumberOfBytesForRegisterMask());
}
// Get the size all the stack maps of this CodeInfo object, in bytes.
size_t GetStackMapsSize() const {
return StackMapSize() * GetNumberOfStackMaps();
}
size_t GetDexRegisterMapsOffset() const {
return GetStackMapsOffset() + GetStackMapsSize();
}
uint32_t GetStackMapsOffset() const {
return GetDexRegisterLocationCatalogOffset() + GetDexRegisterLocationCatalogSize();
}
DexRegisterMap GetDexRegisterMapOf(StackMap stack_map, uint32_t number_of_dex_registers) const {
DCHECK(stack_map.HasDexRegisterMap(*this));
uint32_t offset = GetDexRegisterMapsOffset() + stack_map.GetDexRegisterMapOffset(*this);
size_t size = ComputeDexRegisterMapSizeOf(offset, number_of_dex_registers);
return DexRegisterMap(region_.Subregion(offset, size));
}
InlineInfo GetInlineInfoOf(StackMap stack_map) const {
DCHECK(stack_map.HasInlineInfo(*this));
uint32_t offset = stack_map.GetInlineDescriptorOffset(*this) + GetDexRegisterMapsOffset();
uint8_t depth = region_.LoadUnaligned<uint8_t>(offset);
return InlineInfo(region_.Subregion(offset,
InlineInfo::kFixedSize + depth * InlineInfo::SingleEntrySize()));
}
StackMap GetStackMapForDexPc(uint32_t dex_pc) const {
for (size_t i = 0, e = GetNumberOfStackMaps(); i < e; ++i) {
StackMap stack_map = GetStackMapAt(i);
if (stack_map.GetDexPc(*this) == dex_pc) {
return stack_map;
}
}
return StackMap();
}
StackMap GetStackMapForNativePcOffset(uint32_t native_pc_offset) const {
// TODO: stack maps are sorted by native pc, we can do a binary search.
for (size_t i = 0, e = GetNumberOfStackMaps(); i < e; ++i) {
StackMap stack_map = GetStackMapAt(i);
if (stack_map.GetNativePcOffset(*this) == native_pc_offset) {
return stack_map;
}
}
return StackMap();
}
void Dump(std::ostream& os, uint16_t number_of_dex_registers) const;
void DumpStackMapHeader(std::ostream& os, size_t stack_map_num) const;
private:
// TODO: Instead of plain types such as "uint32_t", introduce
// typedefs (and document the memory layout of CodeInfo).
static constexpr int kOverallSizeOffset = 0;
static constexpr int kEncodingInfoOffset = kOverallSizeOffset + sizeof(uint32_t);
static constexpr int kNumberOfDexRegisterLocationCatalogEntriesOffset =
kEncodingInfoOffset + sizeof(uint16_t);
static constexpr int kNumberOfStackMapsOffset =
kNumberOfDexRegisterLocationCatalogEntriesOffset + sizeof(uint32_t);
static constexpr int kStackMaskSizeOffset = kNumberOfStackMapsOffset + sizeof(uint32_t);
static constexpr int kFixedSize = kStackMaskSizeOffset + sizeof(uint32_t);
static constexpr int kHasInlineInfoBitOffset = (kEncodingInfoOffset * kBitsPerByte);
static constexpr int kInlineInfoBitOffset = kHasInlineInfoBitOffset + 1;
static constexpr int kDexRegisterMapBitOffset = kInlineInfoBitOffset + 3;
static constexpr int kDexPcBitOffset = kDexRegisterMapBitOffset + 3;
static constexpr int kNativePcBitOffset = kDexPcBitOffset + 3;
static constexpr int kRegisterMaskBitOffset = kNativePcBitOffset + 3;
MemoryRegion GetStackMaps() const {
return region_.size() == 0
? MemoryRegion()
: region_.Subregion(GetStackMapsOffset(), GetStackMapsSize());
}
// Compute the size of the Dex register map associated to the stack map at
// `dex_register_map_offset_in_code_info`.
size_t ComputeDexRegisterMapSizeOf(uint32_t dex_register_map_offset_in_code_info,
uint16_t number_of_dex_registers) const {
// Offset where the actual mapping data starts within art::DexRegisterMap.
size_t location_mapping_data_offset_in_dex_register_map =
DexRegisterMap::GetLocationMappingDataOffset(number_of_dex_registers);
// Create a temporary art::DexRegisterMap to be able to call
// art::DexRegisterMap::GetNumberOfLiveDexRegisters and
DexRegisterMap dex_register_map_without_locations(
MemoryRegion(region_.Subregion(dex_register_map_offset_in_code_info,
location_mapping_data_offset_in_dex_register_map)));
size_t number_of_live_dex_registers =
dex_register_map_without_locations.GetNumberOfLiveDexRegisters(number_of_dex_registers);
size_t location_mapping_data_size_in_bits =
DexRegisterMap::SingleEntrySizeInBits(GetNumberOfDexRegisterLocationCatalogEntries())
* number_of_live_dex_registers;
size_t location_mapping_data_size_in_bytes =
RoundUp(location_mapping_data_size_in_bits, kBitsPerByte) / kBitsPerByte;
size_t dex_register_map_size =
location_mapping_data_offset_in_dex_register_map + location_mapping_data_size_in_bytes;
return dex_register_map_size;
}
// Compute the size of a Dex register location catalog starting at offset `origin`
// in `region_` and containing `number_of_dex_locations` entries.
size_t ComputeDexRegisterLocationCatalogSize(uint32_t origin,
uint32_t number_of_dex_locations) const {
// TODO: Ideally, we would like to use art::DexRegisterLocationCatalog::Size or
// art::DexRegisterLocationCatalog::FindLocationOffset, but the
// DexRegisterLocationCatalog is not yet built. Try to factor common code.
size_t offset = origin + DexRegisterLocationCatalog::kFixedSize;
// Skip the first `number_of_dex_locations - 1` entries.
for (uint16_t i = 0; i < number_of_dex_locations; ++i) {
// Read the first next byte and inspect its first 3 bits to decide
// whether it is a short or a large location.
DexRegisterLocationCatalog::ShortLocation first_byte =
region_.LoadUnaligned<DexRegisterLocationCatalog::ShortLocation>(offset);
DexRegisterLocation::Kind kind =
DexRegisterLocationCatalog::ExtractKindFromShortLocation(first_byte);
if (DexRegisterLocation::IsShortLocationKind(kind)) {
// Short location. Skip the current byte.
offset += DexRegisterLocationCatalog::SingleShortEntrySize();
} else {
// Large location. Skip the 5 next bytes.
offset += DexRegisterLocationCatalog::SingleLargeEntrySize();
}
}
size_t size = offset - origin;
return size;
}
MemoryRegion region_;
friend class StackMapStream;
};
} // namespace art
#endif // ART_RUNTIME_STACK_MAP_H_