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https://github.com/KhronosGroup/SPIRV-Tools
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c8e1588cfa
This adds two passes to accomplish this: one pass to analyze a shader to determine the input slots that are live. The second pass is run on the preceding shader to eliminate any stores to output slots that are not consumed by the following shader. These passes support vert, tesc, tese, geom, and frag shaders. These passes are currently only available through the API. These passes together with dead code elimination, and elimination of dead input and output components and variables (WIP), will allow users to do dead code elimination across shader boundaries.
100 lines
3.1 KiB
C++
100 lines
3.1 KiB
C++
// Copyright (c) 2022 The Khronos Group Inc.
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// Copyright (c) 2022 LunarG Inc.
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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_LIVENESS_H_
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#define SOURCE_OPT_LIVENESS_H_
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#include <cstdint>
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#include <unordered_set>
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namespace spvtools {
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namespace opt {
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class IRContext;
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class Instruction;
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namespace analysis {
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class Type;
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// This class represents the liveness of the input variables of a module
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class LivenessManager {
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public:
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LivenessManager(IRContext* ctx);
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// Copy liveness info into |live_locs| and |builtin_locs|.
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void GetLiveness(std::unordered_set<uint32_t>* live_locs,
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std::unordered_set<uint32_t>* live_builtins);
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// Return true if builtin |bi| is being analyzed.
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bool IsAnalyzedBuiltin(uint32_t bi);
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// Determine starting loc |offset| and the type |cur_type| of
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// access chain |ac|. Set |no_loc| to true if no loc found.
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// |is_patch| indicates if patch variable. |input| is true
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// if input variable, otherwise output variable.
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void AnalyzeAccessChainLoc(const Instruction* ac,
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const analysis::Type** curr_type, uint32_t* offset,
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bool* no_loc, bool is_patch, bool input = true);
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// Return size of |type_id| in units of locations
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uint32_t GetLocSize(const analysis::Type* type) const;
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private:
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IRContext* context() const { return ctx_; }
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// Initialize analysis
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void InitializeAnalysis();
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// Analyze |id| for builtin var and struct members. Return true if builtins
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// found.
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bool AnalyzeBuiltIn(uint32_t id);
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// Mark all live locations resulting from |user| of |var| at |loc|.
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void MarkRefLive(const Instruction* user, Instruction* var);
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// Mark |count| locations starting at location |start|.
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void MarkLocsLive(uint32_t start, uint32_t count);
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// Return type of component of aggregate type |agg_type| at |index|
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const analysis::Type* GetComponentType(uint32_t index,
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const analysis::Type* agg_type) const;
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// Return offset of |index| into aggregate type |agg_type| in units of
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// input locations
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uint32_t GetLocOffset(uint32_t index, const analysis::Type* agg_type) const;
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// Populate live_locs_ and live_builtins_
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void ComputeLiveness();
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// IR context that owns this liveness manager.
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IRContext* ctx_;
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// True if live_locs_ and live_builtins_ are computed
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bool computed_;
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// Live locations
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std::unordered_set<uint32_t> live_locs_;
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// Live builtins
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std::unordered_set<uint32_t> live_builtins_;
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};
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} // namespace analysis
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} // namespace opt
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} // namespace spvtools
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#endif // SOURCE_OPT_LIVENESS_H_
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