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/*
* 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/scoped_arena_allocator.h"
#include "base/scoped_arena_containers.h"
#include "nodes.h"
#include "optimization.h"
namespace art {
/**
* 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 ValueObject {
public:
SsaBuilder(HGraph* graph,
Handle<mirror::ClassLoader> class_loader,
Handle<mirror::DexCache> dex_cache,
VariableSizedHandleScope* handles,
ScopedArenaAllocator* local_allocator)
: graph_(graph),
class_loader_(class_loader),
dex_cache_(dex_cache),
handles_(handles),
agets_fixed_(false),
local_allocator_(local_allocator),
ambiguous_agets_(local_allocator->Adapter(kArenaAllocGraphBuilder)),
ambiguous_asets_(local_allocator->Adapter(kArenaAllocGraphBuilder)),
uninitialized_strings_(local_allocator->Adapter(kArenaAllocGraphBuilder)),
uninitialized_string_phis_(local_allocator->Adapter(kArenaAllocGraphBuilder)) {
graph_->InitializeInexactObjectRTI(handles);
}
GraphAnalysisResult BuildSsa();
HInstruction* GetFloatOrDoubleEquivalent(HInstruction* instruction, DataType::Type type);
HInstruction* GetReferenceTypeEquivalent(HInstruction* instruction);
void MaybeAddAmbiguousArrayGet(HArrayGet* aget) {
DataType::Type type = aget->GetType();
DCHECK(!DataType::IsFloatingPointType(type));
if (DataType::IsIntOrLongType(type)) {
ambiguous_agets_.push_back(aget);
}
}
void MaybeAddAmbiguousArraySet(HArraySet* aset) {
DataType::Type type = aset->GetValue()->GetType();
if (DataType::IsIntOrLongType(type)) {
ambiguous_asets_.push_back(aset);
}
}
void AddUninitializedString(HNewInstance* string) {
// In some rare cases (b/27847265), the same NewInstance may be seen
// multiple times. We should only consider it once for removal, so we
// ensure it is not added more than once.
// Note that we cannot check whether this really is a NewInstance of String
// before RTP. We DCHECK that in RemoveRedundantUninitializedStrings.
if (!ContainsElement(uninitialized_strings_, string)) {
uninitialized_strings_.push_back(string);
}
}
void AddUninitializedStringPhi(HInvoke* invoke) {
uninitialized_string_phis_.push_back(invoke);
}
private:
void SetLoopHeaderPhiInputs();
void FixEnvironmentPhis();
void FixNullConstantType();
void EquivalentPhisCleanup();
void RunPrimitiveTypePropagation();
// Attempts to resolve types of aget(-wide) instructions and type values passed
// to aput(-wide) instructions from reference type information on the array
// input. Returns false if the type of an array is unknown.
bool FixAmbiguousArrayOps();
bool TypeInputsOfPhi(HPhi* phi, ScopedArenaVector<HPhi*>* worklist);
bool UpdatePrimitiveType(HPhi* phi, ScopedArenaVector<HPhi*>* worklist);
void ProcessPrimitiveTypePropagationWorklist(ScopedArenaVector<HPhi*>* worklist);
HFloatConstant* GetFloatEquivalent(HIntConstant* constant);
HDoubleConstant* GetDoubleEquivalent(HLongConstant* constant);
HPhi* GetFloatDoubleOrReferenceEquivalentOfPhi(HPhi* phi, DataType::Type type);
HArrayGet* GetFloatOrDoubleEquivalentOfArrayGet(HArrayGet* aget);
void RemoveRedundantUninitializedStrings();
bool ReplaceUninitializedStringPhis();
bool HasAliasInEnvironments(HInstruction* instruction);
HGraph* const graph_;
Handle<mirror::ClassLoader> class_loader_;
Handle<mirror::DexCache> dex_cache_;
VariableSizedHandleScope* const handles_;
// True if types of ambiguous ArrayGets have been resolved.
bool agets_fixed_;
ScopedArenaAllocator* const local_allocator_;
ScopedArenaVector<HArrayGet*> ambiguous_agets_;
ScopedArenaVector<HArraySet*> ambiguous_asets_;
ScopedArenaVector<HNewInstance*> uninitialized_strings_;
ScopedArenaVector<HInvoke*> uninitialized_string_phis_;
DISALLOW_COPY_AND_ASSIGN(SsaBuilder);
};
} // namespace art
#endif // ART_COMPILER_OPTIMIZING_SSA_BUILDER_H_