1 // Copyright (c) 2020 Google LLC 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #ifndef SOURCE_REDUCE_REMOVE_STRUCT_MEMBER_REDUCTION_OPPORTUNITY_H_ 16 #define SOURCE_REDUCE_REMOVE_STRUCT_MEMBER_REDUCTION_OPPORTUNITY_H_ 17 18 #include "source/reduce/reduction_opportunity.h" 19 20 #include "source/opt/instruction.h" 21 22 namespace spvtools { 23 namespace reduce { 24 25 // An opportunity for removing a member from a struct type, adjusting all uses 26 // of the struct accordingly. 27 class RemoveStructMemberReductionOpportunity : public ReductionOpportunity { 28 public: 29 // Constructs a reduction opportunity from the struct type |struct_type|, for 30 // removal of member |member_index|. RemoveStructMemberReductionOpportunity(opt::Instruction * struct_type,uint32_t member_index)31 RemoveStructMemberReductionOpportunity(opt::Instruction* struct_type, 32 uint32_t member_index) 33 : struct_type_(struct_type), 34 member_index_(member_index), 35 original_number_of_members_(struct_type->NumInOperands()) {} 36 37 // Opportunities to remove fields from a common struct type mutually 38 // invalidate each other. We guard against this by requiring that the struct 39 // still has the number of members it had when the opportunity was created. 40 bool PreconditionHolds() override; 41 42 protected: 43 void Apply() override; 44 45 private: 46 // |composite_access_instruction| is an instruction that accesses a composite 47 // id using either a series of literal indices (e.g. in the case of 48 // OpCompositeInsert) or a series of index ids (e.g. in the case of 49 // OpAccessChain). 50 // 51 // This function adjusts the indices that are used by 52 // |composite_access_instruction| to that whenever an index is accessing a 53 // member of |struct_type_|, it is decremented if the member is beyond 54 // |member_index_|, to account for the removal of the |member_index_|-th 55 // member. 56 // 57 // |composite_type_id| is the id of the composite type that the series of 58 // indices is to be applied to. 59 // 60 // |first_index_input_operand| specifies the first input operand that is an 61 // index. 62 // 63 // |literal_indices| specifies whether indices are given as literals (true), 64 // or as ids (false). 65 // 66 // If id-based indexing is used, this function will add a constant for 67 // |member_index_| - 1 to the module if needed. 68 void AdjustAccessedIndices( 69 uint32_t composite_type_id, uint32_t first_index_input_operand, 70 bool literal_indices, opt::IRContext* context, 71 opt::Instruction* composite_access_instruction) const; 72 73 // The struct type from which a member is to be removed. 74 opt::Instruction* struct_type_; 75 76 uint32_t member_index_; 77 78 uint32_t original_number_of_members_; 79 }; 80 81 } // namespace reduce 82 } // namespace spvtools 83 84 #endif // SOURCE_REDUCE_REMOVE_STRUCT_MEMBER_REDUCTION_OPPORTUNITY_H_ 85