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/*
* Copyright (C) 2015 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.
*/
#include "x86_memory_gen.h"
#include "code_generator.h"
#include "driver/compiler_options.h"
namespace art HIDDEN {
namespace x86 {
/**
* Replace instructions with memory operand forms.
*/
class MemoryOperandVisitor final : public HGraphVisitor {
public:
MemoryOperandVisitor(HGraph* graph, bool do_implicit_null_checks)
: HGraphVisitor(graph),
do_implicit_null_checks_(do_implicit_null_checks) {}
private:
void VisitBoundsCheck(HBoundsCheck* check) override {
// Replace the length by the array itself, so that we can do compares to memory.
HArrayLength* array_len = check->InputAt(1)->AsArrayLength();
// We only want to replace an ArrayLength.
if (array_len == nullptr) {
return;
}
HInstruction* array = array_len->InputAt(0);
DCHECK_EQ(array->GetType(), DataType::Type::kReference);
// Don't apply this optimization when the array is nullptr.
if (array->IsConstant() || (array->IsNullCheck() && array->InputAt(0)->IsConstant())) {
return;
}
// Is there a null check that could be an implicit check?
if (array->IsNullCheck() && do_implicit_null_checks_) {
// The ArrayLen may generate the implicit null check. Can the
// bounds check do so as well?
if (array_len->GetNextDisregardingMoves() != check) {
// No, it won't. Leave as is.
return;
}
}
// Can we suppress the ArrayLength and generate at BoundCheck?
if (array_len->HasOnlyOneNonEnvironmentUse()) {
array_len->MarkEmittedAtUseSite();
// We need the ArrayLength just before the BoundsCheck.
array_len->MoveBefore(check);
}
}
bool do_implicit_null_checks_;
};
X86MemoryOperandGeneration::X86MemoryOperandGeneration(HGraph* graph,
CodeGenerator* codegen,
OptimizingCompilerStats* stats)
: HOptimization(graph, kX86MemoryOperandGenerationPassName, stats),
do_implicit_null_checks_(codegen->GetCompilerOptions().GetImplicitNullChecks()) {
}
bool X86MemoryOperandGeneration::Run() {
MemoryOperandVisitor visitor(graph_, do_implicit_null_checks_);
visitor.VisitInsertionOrder();
return true;
}
} // namespace x86
} // namespace art
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