// Copyright 2017, VIXL authors
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of ARM Limited nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#ifndef VIXL_CODE_BUFFER_H
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#define VIXL_CODE_BUFFER_H
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#include <cstring>
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#include "globals-vixl.h"
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#include "utils-vixl.h"
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namespace vixl {
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class CodeBuffer {
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public:
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static const size_t kDefaultCapacity = 4 * KBytes;
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explicit CodeBuffer(size_t capacity = kDefaultCapacity);
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CodeBuffer(byte* buffer, size_t capacity);
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~CodeBuffer();
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void Reset();
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#ifdef VIXL_CODE_BUFFER_MMAP
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void SetExecutable();
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void SetWritable();
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#else
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// These require page-aligned memory blocks, which we can only guarantee with
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// mmap.
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VIXL_NO_RETURN_IN_DEBUG_MODE void SetExecutable() { VIXL_UNIMPLEMENTED(); }
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VIXL_NO_RETURN_IN_DEBUG_MODE void SetWritable() { VIXL_UNIMPLEMENTED(); }
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#endif
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ptrdiff_t GetOffsetFrom(ptrdiff_t offset) const {
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ptrdiff_t cursor_offset = cursor_ - buffer_;
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VIXL_ASSERT((offset >= 0) && (offset <= cursor_offset));
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return cursor_offset - offset;
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}
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VIXL_DEPRECATED("GetOffsetFrom",
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ptrdiff_t OffsetFrom(ptrdiff_t offset) const) {
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return GetOffsetFrom(offset);
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}
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ptrdiff_t GetCursorOffset() const { return GetOffsetFrom(0); }
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VIXL_DEPRECATED("GetCursorOffset", ptrdiff_t CursorOffset() const) {
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return GetCursorOffset();
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}
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void Rewind(ptrdiff_t offset) {
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byte* rewound_cursor = buffer_ + offset;
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VIXL_ASSERT((buffer_ <= rewound_cursor) && (rewound_cursor <= cursor_));
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cursor_ = rewound_cursor;
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}
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template <typename T>
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T GetOffsetAddress(ptrdiff_t offset) const {
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VIXL_STATIC_ASSERT(sizeof(T) >= sizeof(uintptr_t));
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VIXL_ASSERT((offset >= 0) && (offset <= (cursor_ - buffer_)));
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return reinterpret_cast<T>(buffer_ + offset);
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}
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// Return the address of the start or end of the emitted code.
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template <typename T>
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T GetStartAddress() const {
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VIXL_STATIC_ASSERT(sizeof(T) >= sizeof(uintptr_t));
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return GetOffsetAddress<T>(0);
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}
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template <typename T>
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T GetEndAddress() const {
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VIXL_STATIC_ASSERT(sizeof(T) >= sizeof(uintptr_t));
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return GetOffsetAddress<T>(GetSizeInBytes());
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}
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size_t GetRemainingBytes() const {
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VIXL_ASSERT((cursor_ >= buffer_) && (cursor_ <= (buffer_ + capacity_)));
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return (buffer_ + capacity_) - cursor_;
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}
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VIXL_DEPRECATED("GetRemainingBytes", size_t RemainingBytes() const) {
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return GetRemainingBytes();
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}
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size_t GetSizeInBytes() const {
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VIXL_ASSERT((cursor_ >= buffer_) && (cursor_ <= (buffer_ + capacity_)));
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return cursor_ - buffer_;
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}
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// A code buffer can emit:
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// * 8, 16, 32 or 64-bit data: constant.
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// * 16 or 32-bit data: instruction.
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// * string: debug info.
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void Emit8(uint8_t data) { Emit(data); }
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void Emit16(uint16_t data) { Emit(data); }
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void Emit32(uint32_t data) { Emit(data); }
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void Emit64(uint64_t data) { Emit(data); }
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void EmitString(const char* string);
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void EmitData(const void* data, size_t size);
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template <typename T>
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void Emit(T value) {
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VIXL_ASSERT(HasSpaceFor(sizeof(value)));
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dirty_ = true;
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memcpy(cursor_, &value, sizeof(value));
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cursor_ += sizeof(value);
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}
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void UpdateData(size_t offset, const void* data, size_t size);
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// Align to 32bit.
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void Align();
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// Ensure there is enough space for and emit 'n' zero bytes.
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void EmitZeroedBytes(int n);
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bool Is16bitAligned() const { return IsAligned<2>(cursor_); }
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bool Is32bitAligned() const { return IsAligned<4>(cursor_); }
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size_t GetCapacity() const { return capacity_; }
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VIXL_DEPRECATED("GetCapacity", size_t capacity() const) {
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return GetCapacity();
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}
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bool IsManaged() const { return managed_; }
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void Grow(size_t new_capacity);
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bool IsDirty() const { return dirty_; }
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void SetClean() { dirty_ = false; }
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bool HasSpaceFor(size_t amount) const {
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return GetRemainingBytes() >= amount;
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}
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void EnsureSpaceFor(size_t amount, bool* has_grown) {
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bool is_full = !HasSpaceFor(amount);
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if (is_full) Grow(capacity_ * 2 + amount);
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VIXL_ASSERT(has_grown != NULL);
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*has_grown = is_full;
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}
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void EnsureSpaceFor(size_t amount) {
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bool dummy;
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EnsureSpaceFor(amount, &dummy);
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}
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private:
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// Backing store of the buffer.
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byte* buffer_;
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// If true the backing store is allocated and deallocated by the buffer. The
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// backing store can then grow on demand. If false the backing store is
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// provided by the user and cannot be resized internally.
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bool managed_;
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// Pointer to the next location to be written.
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byte* cursor_;
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// True if there has been any write since the buffer was created or cleaned.
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bool dirty_;
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// Capacity in bytes of the backing store.
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size_t capacity_;
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};
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} // namespace vixl
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#endif // VIXL_CODE_BUFFER_H
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