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// Copyright (c) 2017 Google Inc.
//
// 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 "id_descriptor.h"
#include <cassert>
#include <iostream>
#include "opcode.h"
#include "operand.h"
namespace libspirv {
namespace {
// Hashes an array of words. Order of words is important.
uint32_t HashU32Array(const std::vector<uint32_t>& words) {
// The hash function is a sum of hashes of each word seeded by word index.
// Knuth's multiplicative hash is used to hash the words.
const uint32_t kKnuthMulHash = 2654435761;
uint32_t val = 0;
for (uint32_t i = 0; i < words.size(); ++i) {
val += (words[i] + i + 123) * kKnuthMulHash;
}
return val;
}
} // namespace
uint32_t IdDescriptorCollection::ProcessInstruction(
const spv_parsed_instruction_t& inst) {
if (!inst.result_id) return 0;
assert(words_.empty());
words_.push_back(inst.words[0]);
for (size_t operand_index = 0; operand_index < inst.num_operands;
++operand_index) {
const auto& operand = inst.operands[operand_index];
if (spvIsIdType(operand.type)) {
const uint32_t id = inst.words[operand.offset];
const auto it = id_to_descriptor_.find(id);
// Forward declared ids are not hashed.
if (it != id_to_descriptor_.end()) {
words_.push_back(it->second);
}
} else {
for (size_t operand_word_index = 0;
operand_word_index < operand.num_words; ++operand_word_index) {
words_.push_back(inst.words[operand.offset + operand_word_index]);
}
}
}
uint32_t descriptor =
custom_hash_func_ ? custom_hash_func_(words_) : HashU32Array(words_);
if (descriptor == 0) descriptor = 1;
assert(descriptor);
words_.clear();
const auto result = id_to_descriptor_.emplace(inst.result_id, descriptor);
assert(result.second);
(void)result;
return descriptor;
}
} // namespace libspirv
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