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// Copyright (c) 2019 Google LLC
//
// 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.
#include "source/fuzz/instruction_descriptor.h"
namespace spvtools {
namespace fuzz {
opt::Instruction* FindInstruction(
const protobufs::InstructionDescriptor& instruction_descriptor,
spvtools::opt::IRContext* context) {
for (auto& function : *context->module()) {
for (auto& block : function) {
bool found_base =
block.id() == instruction_descriptor.base_instruction_result_id();
uint32_t num_ignored = 0;
for (auto& instruction : block) {
if (instruction.HasResultId() &&
instruction.result_id() ==
instruction_descriptor.base_instruction_result_id()) {
assert(!found_base &&
"It should not be possible to find the base instruction "
"multiple times.");
found_base = true;
assert(num_ignored == 0 &&
"The skipped instruction count should only be incremented "
"after the instruction base has been found.");
}
if (found_base &&
instruction.opcode() ==
instruction_descriptor.target_instruction_opcode()) {
if (num_ignored == instruction_descriptor.num_opcodes_to_ignore()) {
return &instruction;
}
num_ignored++;
}
}
if (found_base) {
// We found the base instruction, but did not find the target
// instruction in the same block.
return nullptr;
}
}
}
return nullptr;
}
protobufs::InstructionDescriptor MakeInstructionDescriptor(
uint32_t base_instruction_result_id, SpvOp target_instruction_opcode,
uint32_t num_opcodes_to_ignore) {
protobufs::InstructionDescriptor result;
result.set_base_instruction_result_id(base_instruction_result_id);
result.set_target_instruction_opcode(target_instruction_opcode);
result.set_num_opcodes_to_ignore(num_opcodes_to_ignore);
return result;
}
protobufs::InstructionDescriptor MakeInstructionDescriptor(
const opt::BasicBlock& block,
const opt::BasicBlock::const_iterator& inst_it) {
const SpvOp opcode =
inst_it->opcode(); // The opcode of the instruction being described.
uint32_t skip_count = 0; // The number of these opcodes we have skipped when
// searching backwards.
// Consider instructions in the block in reverse order, starting from
// |inst_it|.
for (opt::BasicBlock::const_iterator backwards_iterator = inst_it;;
--backwards_iterator) {
if (backwards_iterator->HasResultId()) {
// As soon as we find an instruction with a result id, we can return a
// descriptor for |inst_it|.
return MakeInstructionDescriptor(backwards_iterator->result_id(), opcode,
skip_count);
}
if (backwards_iterator != inst_it &&
backwards_iterator->opcode() == opcode) {
// We are skipping over an instruction with the same opcode as |inst_it|;
// we increase our skip count to reflect this.
skip_count++;
}
if (backwards_iterator == block.begin()) {
// We exit the loop when we reach the start of the block, but only after
// we have processed the first instruction in the block.
break;
}
}
// We did not find an instruction inside the block with a result id, so we use
// the block's label's id.
return MakeInstructionDescriptor(block.id(), opcode, skip_count);
}
protobufs::InstructionDescriptor MakeInstructionDescriptor(
opt::IRContext* context, opt::Instruction* inst) {
auto block = context->get_instr_block(inst);
uint32_t base_instruction_result_id = block->id();
uint32_t num_opcodes_to_ignore = 0;
for (auto& inst_in_block : *block) {
if (inst_in_block.HasResultId()) {
base_instruction_result_id = inst_in_block.result_id();
num_opcodes_to_ignore = 0;
}
if (&inst_in_block == inst) {
return MakeInstructionDescriptor(base_instruction_result_id,
inst->opcode(), num_opcodes_to_ignore);
}
if (inst_in_block.opcode() == inst->opcode()) {
num_opcodes_to_ignore++;
}
}
assert(false && "No matching instruction was found.");
return protobufs::InstructionDescriptor();
}
} // namespace fuzz
} // namespace spvtools
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