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122 lines
3.5 KiB
122 lines
3.5 KiB
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_LIBELFFILE_DWARF_EXPRESSION_H_
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#define ART_LIBELFFILE_DWARF_EXPRESSION_H_
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#include <cstddef>
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#include <cstdint>
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#include "dwarf/dwarf_constants.h"
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#include "dwarf/writer.h"
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namespace art {
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namespace dwarf {
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// Writer for DWARF expressions which are used in .debug_info and .debug_loc sections.
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// See the DWARF specification for the precise meaning of the opcodes.
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// If multiple equivalent encodings are possible, it will choose the most compact one.
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// The writer is not exhaustive - it only implements opcodes we have needed so far.
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class Expression : private Writer<> {
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public:
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using Writer<>::data;
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using Writer<>::size;
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// Push signed integer on the stack.
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void WriteOpConsts(int32_t value) {
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if (0 <= value && value < 32) {
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PushUint8(DW_OP_lit0 + value);
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} else {
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PushUint8(DW_OP_consts);
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PushSleb128(value);
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}
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}
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// Push unsigned integer on the stack.
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void WriteOpConstu(uint32_t value) {
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if (value < 32) {
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PushUint8(DW_OP_lit0 + value);
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} else {
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PushUint8(DW_OP_constu);
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PushUleb128(value);
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}
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}
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// Variable is stored in given register.
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void WriteOpReg(uint32_t dwarf_reg_num) {
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if (dwarf_reg_num < 32) {
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PushUint8(DW_OP_reg0 + dwarf_reg_num);
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} else {
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PushUint8(DW_OP_regx);
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PushUleb128(dwarf_reg_num);
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}
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}
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// Variable is stored on stack. Also see DW_AT_frame_base.
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void WriteOpFbreg(int32_t stack_offset) {
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PushUint8(DW_OP_fbreg);
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PushSleb128(stack_offset);
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}
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// The variable is stored in multiple locations (pieces).
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void WriteOpPiece(uint32_t num_bytes) {
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PushUint8(DW_OP_piece);
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PushUleb128(num_bytes);
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}
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// Loads 32-bit or 64-bit value depending on architecture.
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void WriteOpDeref() { PushUint8(DW_OP_deref); }
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// Loads value of given byte size.
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void WriteOpDerefSize(uint8_t num_bytes) {
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PushUint8(DW_OP_deref_size);
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PushUint8(num_bytes);
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}
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// Pop two values and push their sum.
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void WriteOpPlus() { PushUint8(DW_OP_plus); }
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// Add constant value to value on top of stack.
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void WriteOpPlusUconst(uint32_t offset) {
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PushUint8(DW_OP_plus_uconst);
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PushUleb128(offset);
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}
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// Negate top of stack.
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void WriteOpNeg() { PushUint8(DW_OP_neg); }
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// Pop two values and push their bitwise-AND.
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void WriteOpAnd() { PushUint8(DW_OP_and); }
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// Push stack base pointer as determined from .debug_frame.
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void WriteOpCallFrameCfa() { PushUint8(DW_OP_call_frame_cfa); }
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// Push address of the variable we are working with.
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void WriteOpPushObjectAddress() { PushUint8(DW_OP_push_object_address); }
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// Return the top stack as the value of the variable.
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// Otherwise, the top of stack is the variable's location.
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void WriteOpStackValue() { PushUint8(DW_OP_stack_value); }
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explicit Expression(std::vector<uint8_t>* buffer) : Writer<>(buffer) {
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buffer->clear();
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}
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};
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} // namespace dwarf
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} // namespace art
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#endif // ART_LIBELFFILE_DWARF_EXPRESSION_H_
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