| // Copyright 2020 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_AST_STRUCT_MEMBER_OFFSET_ATTRIBUTE_H_ |
| #define SRC_TINT_AST_STRUCT_MEMBER_OFFSET_ATTRIBUTE_H_ |
| |
| #include <string> |
| |
| #include "src/tint/ast/attribute.h" |
| #include "src/tint/ast/expression.h" |
| |
| namespace tint::ast { |
| |
| /// A struct member offset attribute |
| /// @note The WGSL spec removed the `@offset(n)` attribute for `@size(n)` |
| /// and `@align(n)` in https://github.com/gpuweb/gpuweb/pull/1447. However |
| /// this attribute is kept because the SPIR-V reader has to deal with absolute |
| /// offsets, and transforming these to size / align is complex and can be done |
| /// in a number of ways. The Resolver is responsible for consuming the size and |
| /// align attributes and transforming these into absolute offsets. It is |
| /// trivial for the Resolver to handle `@offset(n)` or `@size(n)` / |
| /// `@align(n)` attributes, so this is what we do, keeping all the layout |
| /// logic in one place. |
| class StructMemberOffsetAttribute final |
| : public utils::Castable<StructMemberOffsetAttribute, Attribute> { |
| public: |
| /// constructor |
| /// @param pid the identifier of the program that owns this node |
| /// @param nid the unique node identifier |
| /// @param src the source of this node |
| /// @param expr the offset expression |
| StructMemberOffsetAttribute(ProgramID pid, |
| NodeID nid, |
| const Source& src, |
| const Expression* expr); |
| ~StructMemberOffsetAttribute() override; |
| |
| /// @returns the WGSL name for the attribute |
| std::string Name() const override; |
| |
| /// Clones this node and all transitive child nodes using the `CloneContext` |
| /// `ctx`. |
| /// @param ctx the clone context |
| /// @return the newly cloned node |
| const StructMemberOffsetAttribute* Clone(CloneContext* ctx) const override; |
| |
| /// The offset expression |
| const Expression* const expr; |
| }; |
| |
| } // namespace tint::ast |
| |
| #endif // SRC_TINT_AST_STRUCT_MEMBER_OFFSET_ATTRIBUTE_H_ |