SPIRV-Tools/source/opt/const_folding_rules.h
dan sinclair eda2cfbe12
Cleanup includes. (#1795)
This Cl cleans up the include paths to be relative to the top level
directory. Various include-what-you-use fixes have been added.
2018-08-03 15:06:09 -04:00

81 lines
2.8 KiB
C++

// Copyright (c) 2018 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.
#ifndef SOURCE_OPT_CONST_FOLDING_RULES_H_
#define SOURCE_OPT_CONST_FOLDING_RULES_H_
#include <unordered_map>
#include <vector>
#include "source/opt/constants.h"
namespace spvtools {
namespace opt {
// Constant Folding Rules:
//
// The folding mechanism is built around the concept of a |ConstantFoldingRule|.
// A constant folding rule is a function that implements a method of simplifying
// an instruction to a constant.
//
// The inputs to a folding rule are:
// |inst| - the instruction to be simplified.
// |constants| - if an in-operands is an id of a constant, then the
// corresponding value in |constants| contains that
// constant value. Otherwise, the corresponding entry in
// |constants| is |nullptr|.
//
// A constant folding rule returns a pointer to an Constant if |inst| can be
// simplified using this rule. Otherwise, it returns |nullptr|.
//
// See const_folding_rules.cpp for examples on how to write a constant folding
// rule.
//
// Be sure to add new constant folding rules to the table of constant folding
// rules in the constructor for ConstantFoldingRules. The new rule should be
// added to the list for every opcode that it applies to. Note that earlier
// rules in the list are given priority. That is, if an earlier rule is able to
// fold an instruction, the later rules will not be attempted.
using ConstantFoldingRule = std::function<const analysis::Constant*(
IRContext* ctx, Instruction* inst,
const std::vector<const analysis::Constant*>& constants)>;
class ConstantFoldingRules {
public:
ConstantFoldingRules();
// Returns true if there is at least 1 folding rule for |opcode|.
bool HasFoldingRule(SpvOp opcode) const { return rules_.count(opcode); }
// Returns an vector of constant folding rules for |opcode|.
const std::vector<ConstantFoldingRule>& GetRulesForOpcode(
SpvOp opcode) const {
auto it = rules_.find(opcode);
if (it != rules_.end()) {
return it->second;
}
return empty_vector_;
}
private:
std::unordered_map<uint32_t, std::vector<ConstantFoldingRule>> rules_;
std::vector<ConstantFoldingRule> empty_vector_;
};
} // namespace opt
} // namespace spvtools
#endif // SOURCE_OPT_CONST_FOLDING_RULES_H_