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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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <cstdio>
#include <memory>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include "source/opt/function.h"
#include "source/opt/pass.h"
#include "source/opt/type_manager.h"
namespace spvtools {
namespace opt {
// Documented in optimizer.hpp
class DescriptorScalarReplacement : public Pass {
DescriptorScalarReplacement() {}
const char* name() const override { return "descriptor-scalar-replacement"; }
Status Process() override;
IRContext::Analysis GetPreservedAnalyses() override {
return IRContext::kAnalysisDefUse |
IRContext::kAnalysisInstrToBlockMapping |
IRContext::kAnalysisCombinators | IRContext::kAnalysisCFG |
IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;
// Returns true if |var| is an OpVariable instruction that represents a
// descriptor array. These are the variables that we want to replace.
bool IsCandidate(Instruction* var);
// Replaces all references to |var| by new variables, one for each element of
// the array |var|. The binding for the new variables corresponding to
// element i will be the binding of |var| plus i. Returns true if successful.
bool ReplaceCandidate(Instruction* var);
// Replaces the base address |var| in the OpAccessChain or
// OpInBoundsAccessChain instruction |use| by the variable that the access
// chain accesses. The first index in |use| must be an |OpConstant|. Returns
// |true| if successful.
bool ReplaceAccessChain(Instruction* var, Instruction* use);
// Replaces the given compososite variable |var| loaded by OpLoad |value| with
// replacement variables, one for each component that's accessed in the
// shader. Assumes that |value| is only used by OpCompositeExtract
// instructions, one index at a time. Returns true on success, and false
// otherwise.
bool ReplaceLoadedValue(Instruction* var, Instruction* value);
// Replaces the given OpCompositeExtract |extract| and all of its references
// with an OpLoad of a replacement variable. |var| is the variable with
// composite type whose value is being used by |extract|. Assumes that
// |extract| is extracting one index only. Returns true on success, and false
// otherwise.
bool ReplaceCompositeExtract(Instruction* var, Instruction* extract);
// Returns the id of the variable that will be used to replace the |idx|th
// element of |var|. The variable is created if it has not already been
// created.
uint32_t GetReplacementVariable(Instruction* var, uint32_t idx);
// Returns the id of a new variable that can be used to replace the |idx|th
// element of |var|.
uint32_t CreateReplacementVariable(Instruction* var, uint32_t idx);
// Returns the number of bindings used by the given |type_id|.
// All types are considered to use 1 binding slot, except:
// 1- A pointer type consumes as many binding numbers as its pointee.
// 2- An array of size N consumes N*M binding numbers, where M is the number
// of bindings used by each array element.
// 3- The number of bindings consumed by a structure is the sum of the
// bindings used by its members.
uint32_t GetNumBindingsUsedByType(uint32_t type_id);
// Returns true if |type| is a type that could be used for a structured buffer
// as opposed to a type that would be used for a structure of resource
// descriptors.
bool IsTypeOfStructuredBuffer(const Instruction* type) const;
// A map from an OpVariable instruction to the set of variables that will be
// used to replace it. The entry |replacement_variables_[var][i]| is the id of
// a variable that will be used in the place of the the ith element of the
// array |var|. If the entry is |0|, then the variable has not been
// created yet.
std::map<Instruction*, std::vector<uint32_t>> replacement_variables_;
} // namespace opt
} // namespace spvtools