1 // Copyright (c) 2018 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_OPT_LICM_PASS_H_ 16 #define SOURCE_OPT_LICM_PASS_H_ 17 18 #include <queue> 19 #include <vector> 20 21 #include "source/opt/basic_block.h" 22 #include "source/opt/instruction.h" 23 #include "source/opt/loop_descriptor.h" 24 #include "source/opt/pass.h" 25 26 namespace spvtools { 27 namespace opt { 28 29 class LICMPass : public Pass { 30 public: 31 LICMPass() {} 32 33 const char* name() const override { return "loop-invariant-code-motion"; } 34 Status Process() override; 35 36 private: 37 // Searches the IRContext for functions and processes each, moving invariants 38 // outside loops within the function where possible. 39 // Returns the status depending on whether or not there was a failure or 40 // change. 41 Pass::Status ProcessIRContext(); 42 43 // Checks the function for loops, calling ProcessLoop on each one found. 44 // Returns the status depending on whether or not there was a failure or 45 // change. 46 Pass::Status ProcessFunction(Function* f); 47 48 // Checks for invariants in the loop and attempts to move them to the loops 49 // preheader. Works from inner loop to outer when nested loops are found. 50 // Returns the status depending on whether or not there was a failure or 51 // change. 52 Pass::Status ProcessLoop(Loop* loop, Function* f); 53 54 // Analyses each instruction in |bb|, hoisting invariants to |pre_header_bb|. 55 // Each child of |bb| wrt to |dom_tree| is pushed to |loop_bbs| 56 // Returns the status depending on whether or not there was a failure or 57 // change. 58 Pass::Status AnalyseAndHoistFromBB(Loop* loop, Function* f, BasicBlock* bb, 59 std::vector<BasicBlock*>* loop_bbs); 60 61 // Returns true if |bb| is immediately contained in |loop| 62 bool IsImmediatelyContainedInLoop(Loop* loop, Function* f, BasicBlock* bb); 63 64 // Move the instruction to the preheader of |loop|. 65 // This method will update the instruction to block mapping for the context 66 bool HoistInstruction(Loop* loop, Instruction* inst); 67 }; 68 69 } // namespace opt 70 } // namespace spvtools 71 72 #endif // SOURCE_OPT_LICM_PASS_H_ 73
