/* * Copyright (C) 2014 The Android Open Source Project * * 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 ART_COMPILER_OPTIMIZING_SSA_BUILDER_H_ #define ART_COMPILER_OPTIMIZING_SSA_BUILDER_H_ #include "base/arena_containers.h" #include "nodes.h" #include "optimization.h" namespace art { static constexpr int kDefaultNumberOfLoops = 2; /** * Transforms a graph into SSA form. The liveness guarantees of * this transformation are listed below. A DEX register * being killed means its value at a given position in the code * will not be available to its environment uses. A merge in the * following text is materialized as a `HPhi`. * * (a) Dex registers that do not require merging (that is, they do not * have different values at a join block) are available to all their * environment uses. Note that it does not imply the instruction will * have a physical location after register allocation. See the * SsaLivenessAnalysis phase. * * (b) Dex registers that require merging, and the merging gives * incompatible types, will be killed for environment uses of that merge. * * (c) When the `debuggable` flag is passed to the compiler, Dex registers * that require merging and have a proper type after the merge, are * available to all their environment uses. If the `debuggable` flag * is not set, values of Dex registers only used by environments * are killed. */ class SsaBuilder : public HGraphVisitor { public: explicit SsaBuilder(HGraph* graph) : HGraphVisitor(graph), current_locals_(nullptr), loop_headers_(graph->GetArena()->Adapter(kArenaAllocSsaBuilder)), locals_for_(graph->GetBlocks().size(), ArenaVector(graph->GetArena()->Adapter(kArenaAllocSsaBuilder)), graph->GetArena()->Adapter(kArenaAllocSsaBuilder)) { loop_headers_.reserve(kDefaultNumberOfLoops); } void BuildSsa(); // Returns locals vector for `block`. If it is a catch block, the vector will be // prepopulated with catch phis for vregs which are defined in `current_locals_`. ArenaVector* GetLocalsFor(HBasicBlock* block); HInstruction* ValueOfLocal(HBasicBlock* block, size_t local); void VisitBasicBlock(HBasicBlock* block); void VisitLoadLocal(HLoadLocal* load); void VisitStoreLocal(HStoreLocal* store); void VisitInstruction(HInstruction* instruction); void VisitTemporary(HTemporary* instruction); static HInstruction* GetFloatOrDoubleEquivalent(HInstruction* user, HInstruction* instruction, Primitive::Type type); static HInstruction* GetReferenceTypeEquivalent(HInstruction* instruction); static constexpr const char* kSsaBuilderPassName = "ssa_builder"; private: void SetLoopHeaderPhiInputs(); void FixNullConstantType(); void EquivalentPhisCleanup(); static HFloatConstant* GetFloatEquivalent(HIntConstant* constant); static HDoubleConstant* GetDoubleEquivalent(HLongConstant* constant); static HPhi* GetFloatDoubleOrReferenceEquivalentOfPhi(HPhi* phi, Primitive::Type type); // Locals for the current block being visited. ArenaVector* current_locals_; // Keep track of loop headers found. The last phase of the analysis iterates // over these blocks to set the inputs of their phis. ArenaVector loop_headers_; // HEnvironment for each block. ArenaVector> locals_for_; DISALLOW_COPY_AND_ASSIGN(SsaBuilder); }; } // namespace art #endif // ART_COMPILER_OPTIMIZING_SSA_BUILDER_H_