SPIRV-Tools/source/fuzz/id_use_descriptor.cpp
Alastair Donaldson 0a07cd1c9a
Add fuzzer pass to replace ids with synonyms (#2857)
If the fuzzer's fact manager knows that ids A and B are synonymous, it
can replace a use of A with a use of B, so long as various conditions
hold (e.g. the definition of B must dominate the use of A, and it is
not legal to replace a use of an OpConstant in a struct's access chain
with a synonym that is not an OpConstant).

This change adds a fuzzer pass to sprinke such synonym replacements
through the module.
2019-09-18 20:47:08 +01:00

111 lines
4.0 KiB
C++

// 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/id_use_descriptor.h"
namespace spvtools {
namespace fuzz {
opt::Instruction* transformation::FindInstruction(
const protobufs::IdUseDescriptor& descriptor,
spvtools::opt::IRContext* context) {
for (auto& function : *context->module()) {
for (auto& block : function) {
bool found_base = block.id() == descriptor.base_instruction_result_id();
uint32_t num_ignored = 0;
for (auto& instruction : block) {
if (instruction.HasResultId() &&
instruction.result_id() ==
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() == descriptor.target_instruction_opcode()) {
if (num_ignored == descriptor.num_opcodes_to_ignore()) {
if (descriptor.in_operand_index() >= instruction.NumInOperands()) {
return nullptr;
}
auto in_operand =
instruction.GetInOperand(descriptor.in_operand_index());
if (in_operand.type != SPV_OPERAND_TYPE_ID) {
return nullptr;
}
if (in_operand.words[0] != descriptor.id_of_interest()) {
return nullptr;
}
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::IdUseDescriptor transformation::MakeIdUseDescriptor(
uint32_t id_of_interest, SpvOp target_instruction_opcode,
uint32_t in_operand_index, uint32_t base_instruction_result_id,
uint32_t num_opcodes_to_ignore) {
protobufs::IdUseDescriptor result;
result.set_id_of_interest(id_of_interest);
result.set_target_instruction_opcode(target_instruction_opcode);
result.set_in_operand_index(in_operand_index);
result.set_base_instruction_result_id(base_instruction_result_id);
result.set_num_opcodes_to_ignore(num_opcodes_to_ignore);
return result;
}
protobufs::IdUseDescriptor transformation::MakeIdUseDescriptorFromUse(
opt::IRContext* context, opt::Instruction* inst,
uint32_t in_operand_index) {
auto in_operand = inst->GetInOperand(in_operand_index);
assert(in_operand.type == SPV_OPERAND_TYPE_ID);
auto id_of_interest = in_operand.words[0];
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 MakeIdUseDescriptor(id_of_interest, inst->opcode(),
in_operand_index, base_instruction_result_id,
num_opcodes_to_ignore);
}
if (inst_in_block.opcode() == inst->opcode()) {
num_opcodes_to_ignore++;
}
}
assert(false && "No matching instruction was found.");
return protobufs::IdUseDescriptor();
}
} // namespace fuzz
} // namespace spvtools