65 lines
2.6 KiB
C++
65 lines
2.6 KiB
C++
// Copyright 2022 The Tint Authors.
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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 SRC_TINT_TRANSFORM_UNWIND_DISCARD_FUNCTIONS_H_
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#define SRC_TINT_TRANSFORM_UNWIND_DISCARD_FUNCTIONS_H_
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#include "src/tint/transform/transform.h"
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namespace tint::transform {
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/// This transform is responsible for implementing discard semantics as per the
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/// WGSL specification: https://gpuweb.github.io/gpuweb/wgsl/#discard-statement
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///
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/// Not all backend languages implement discard this way (e.g. HLSL), so this
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/// transform does the following:
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///
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/// * Replaces discard statements with setting a module-level boolean
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/// "tint_discard" to true and returning immediately.
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/// * Wherever calls are made to discarding functions (directly or
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/// transitively), it inserts a check afterwards for if "tint_discard" is true,
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/// to return immediately.
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/// * Finally, entry point functions that call discarding functions
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/// emit a call to "tint_discard_func()" that contains the sole discard
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/// statement.
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///
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/// @note Depends on the following transforms to have been run first:
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/// * PromoteSideEffectsToDecl
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class UnwindDiscardFunctions final : public Castable<UnwindDiscardFunctions, Transform> {
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public:
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/// Constructor
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UnwindDiscardFunctions();
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/// Destructor
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~UnwindDiscardFunctions() override;
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protected:
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/// Runs the transform using the CloneContext built for transforming a
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/// program. Run() is responsible for calling Clone() on the CloneContext.
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/// @param ctx the CloneContext primed with the input program and
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/// ProgramBuilder
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/// @param inputs optional extra transform-specific input data
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/// @param outputs optional extra transform-specific output data
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void Run(CloneContext& ctx, const DataMap& inputs, DataMap& outputs) const override;
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/// @param program the program to inspect
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/// @param data optional extra transform-specific input data
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/// @returns true if this transform should be run for the given program
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bool ShouldRun(const Program* program, const DataMap& data = {}) const override;
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};
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} // namespace tint::transform
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#endif // SRC_TINT_TRANSFORM_UNWIND_DISCARD_FUNCTIONS_H_
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