67 lines
2.4 KiB
C++
67 lines
2.4 KiB
C++
// Copyright 2020 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_AST_STRUCT_MEMBER_OFFSET_DECORATION_H_
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#define SRC_AST_STRUCT_MEMBER_OFFSET_DECORATION_H_
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#include <string>
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#include "src/ast/decoration.h"
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namespace tint {
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namespace ast {
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/// A struct member offset decoration
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/// @note The WGSL spec removed the `[[offset(n)]]` decoration for `[[size(n)]]`
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/// and `[[align(n)]]` in https://github.com/gpuweb/gpuweb/pull/1447. However
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/// this decoration is kept because the SPIR-V reader has to deal with absolute
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/// offsets, and transforming these to size / align is complex and can be done
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/// in a number of ways. The Resolver is responsible for consuming the size and
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/// align decorations and transforming these into absolute offsets. It is
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/// trivial for the Resolver to handle `[[offset(n)]]` or `[[size(n)]]` /
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/// `[[align(n)]]` decorations, so this is what we do, keeping all the layout
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/// logic in one place.
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class StructMemberOffsetDecoration
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: public Castable<StructMemberOffsetDecoration, Decoration> {
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public:
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/// constructor
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/// @param program_id the identifier of the program that owns this node
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/// @param source the source of this decoration
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/// @param offset the offset value
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StructMemberOffsetDecoration(ProgramID program_id,
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const Source& source,
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uint32_t offset);
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~StructMemberOffsetDecoration() override;
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/// @returns the offset value
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uint32_t offset() const { return offset_; }
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/// @returns the WGSL name for the decoration
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std::string name() const override;
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/// Clones this node and all transitive child nodes using the `CloneContext`
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/// `ctx`.
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/// @param ctx the clone context
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/// @return the newly cloned node
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StructMemberOffsetDecoration* Clone(CloneContext* ctx) const override;
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private:
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uint32_t const offset_;
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};
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} // namespace ast
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} // namespace tint
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#endif // SRC_AST_STRUCT_MEMBER_OFFSET_DECORATION_H_
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