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// Copyright 2021 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_MODULE_SCOPE_VAR_TO_ENTRY_POINT_PARAM_H_
#define SRC_TINT_TRANSFORM_MODULE_SCOPE_VAR_TO_ENTRY_POINT_PARAM_H_
#include "src/tint/transform/transform.h"
namespace tint::transform {
/// Move module-scope variables into the entry point as parameters.
///
/// MSL does not allow module-scope variables to have any address space other
/// than `constant`. This transform moves all module-scope declarations into the
/// entry point function (either as parameters or function-scope variables) and
/// then passes them as pointer parameters to any function that references them.
///
/// Since WGSL does not allow entry point parameters or function-scope variables
/// to have these storage classes, we annotate the new variable declarations
/// with an attribute that bypasses that validation rule.
///
/// Before:
/// ```
/// struct S {
/// f : f32;
/// };
/// @binding(0) @group(0)
/// var<storage, read> s : S;
/// var<private> p : f32 = 2.0;
///
/// fn foo() {
/// p = p + f;
/// }
///
/// @stage(compute) @workgroup_size(1)
/// fn main() {
/// foo();
/// }
/// ```
///
/// After:
/// ```
/// fn foo(p : ptr<private, f32>, sptr : ptr<storage, S, read>) {
/// *p = *p + (*sptr).f;
/// }
///
/// @stage(compute) @workgroup_size(1)
/// fn main(sptr : ptr<storage, S, read>) {
/// var<private> p : f32 = 2.0;
/// foo(&p, sptr);
/// }
/// ```
class ModuleScopeVarToEntryPointParam
: public Castable<ModuleScopeVarToEntryPointParam, Transform> {
public:
/// Constructor
ModuleScopeVarToEntryPointParam();
/// Destructor
~ModuleScopeVarToEntryPointParam() 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;
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;
struct State;
};
} // namespace tint::transform
#endif // SRC_TINT_TRANSFORM_MODULE_SCOPE_VAR_TO_ENTRY_POINT_PARAM_H_