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