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https://github.com/KhronosGroup/SPIRV-Tools
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15fc19d091
* Refactor instruction folders We want to refactor the instruction folder to allow different sets of rules to be added to the instruction folder. We might want different sets of rules in different circumstances. We also need a way to add rules for extended instructions. Changes are made to the FoldingRules class and ConstFoldingRules class to enable that. We added tests to check that we can fold extended instructions using the new framework. At the same time, I noticed that there were two tests that did not tests what they were suppose to. They could not be easily salvaged. #2813 was opened to track adding the new tests.
119 lines
3.7 KiB
C++
119 lines
3.7 KiB
C++
// Copyright (c) 2018 Google LLC
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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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#ifndef SOURCE_OPT_FOLDING_RULES_H_
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#define SOURCE_OPT_FOLDING_RULES_H_
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#include <cstdint>
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#include <unordered_map>
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#include <vector>
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#include "source/opt/constants.h"
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namespace spvtools {
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namespace opt {
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// Folding Rules:
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//
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// The folding mechanism is built around the concept of a |FoldingRule|. A
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// folding rule is a function that implements a method of simplifying an
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// instruction.
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//
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// The inputs to a folding rule are:
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// |inst| - the instruction to be simplified.
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// |constants| - if an in-operands is an id of a constant, then the
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// corresponding value in |constants| contains that
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// constant value. Otherwise, the corresponding entry in
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// |constants| is |nullptr|.
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//
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// A folding rule returns true if |inst| can be simplified using this rule. If
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// the instruction can be simplified, then |inst| is changed to the simplified
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// instruction. Otherwise, |inst| remains the same.
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//
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// See folding_rules.cpp for examples on how to write a folding rule. It is
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// important to note that if |inst| can be folded to the result of an
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// instruction that feed it, then |inst| should be changed to an OpCopyObject
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// that copies that id.
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//
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// Be sure to add new folding rules to the table of folding rules in the
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// constructor for FoldingRules. The new rule should be added to the list for
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// every opcode that it applies to. Note that earlier rules in the list are
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// given priority. That is, if an earlier rule is able to fold an instruction,
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// the later rules will not be attempted.
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using FoldingRule = std::function<bool(
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IRContext* context, Instruction* inst,
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const std::vector<const analysis::Constant*>& constants)>;
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class FoldingRules {
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public:
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using FoldingRuleSet = std::vector<FoldingRule>;
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explicit FoldingRules(IRContext* ctx) : context_(ctx) {}
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virtual ~FoldingRules() = default;
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const FoldingRuleSet& GetRulesForInstruction(Instruction* inst) const {
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if (inst->opcode() != SpvOpExtInst) {
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auto it = rules_.find(inst->opcode());
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if (it != rules_.end()) {
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return it->second;
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}
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} else {
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uint32_t ext_inst_id = inst->GetSingleWordInOperand(0);
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uint32_t ext_opcode = inst->GetSingleWordInOperand(1);
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auto it = ext_rules_.find({ext_inst_id, ext_opcode});
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if (it != ext_rules_.end()) {
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return it->second;
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}
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}
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return empty_vector_;
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}
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IRContext* context() { return context_; }
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// Adds the folding rules for the object.
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virtual void AddFoldingRules();
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protected:
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// The folding rules for core instructions.
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std::unordered_map<uint32_t, FoldingRuleSet> rules_;
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// The folding rules for extended instructions.
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struct Key {
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uint32_t instruction_set;
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uint32_t opcode;
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};
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friend bool operator<(const Key& a, const Key& b) {
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if (a.instruction_set < b.instruction_set) {
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return true;
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}
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if (a.instruction_set > b.instruction_set) {
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return false;
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}
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return a.opcode < b.opcode;
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}
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std::map<Key, FoldingRuleSet> ext_rules_;
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private:
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IRContext* context_;
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FoldingRuleSet empty_vector_;
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};
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} // namespace opt
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} // namespace spvtools
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#endif // SOURCE_OPT_FOLDING_RULES_H_
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