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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.
*/
#include "gvn.h"
#include "base/arena_allocator.h"
#include "base/macros.h"
#include "builder.h"
#include "nodes.h"
#include "optimizing_unit_test.h"
#include "side_effects_analysis.h"
namespace art HIDDEN {
class GVNTest : public OptimizingUnitTest {};
TEST_F(GVNTest, LocalFieldElimination) {
HBasicBlock* block = InitEntryMainExitGraphWithReturnVoid();
HInstruction* parameter = MakeParam(DataType::Type::kReference);
MakeIFieldGet(block, parameter, DataType::Type::kReference, MemberOffset(42));
HInstruction* to_remove =
MakeIFieldGet(block, parameter, DataType::Type::kReference, MemberOffset(42));
HInstruction* different_offset =
MakeIFieldGet(block, parameter, DataType::Type::kReference, MemberOffset(43));
// Kill the value.
MakeIFieldSet(block, parameter, parameter, MemberOffset(42));
HInstruction* use_after_kill =
MakeIFieldGet(block, parameter, DataType::Type::kReference, MemberOffset(42));
ASSERT_EQ(to_remove->GetBlock(), block);
ASSERT_EQ(different_offset->GetBlock(), block);
ASSERT_EQ(use_after_kill->GetBlock(), block);
graph_->BuildDominatorTree();
SideEffectsAnalysis side_effects(graph_);
side_effects.Run();
GVNOptimization(graph_, side_effects).Run();
ASSERT_TRUE(to_remove->GetBlock() == nullptr);
ASSERT_EQ(different_offset->GetBlock(), block);
ASSERT_EQ(use_after_kill->GetBlock(), block);
}
TEST_F(GVNTest, GlobalFieldElimination) {
HBasicBlock* join = InitEntryMainExitGraphWithReturnVoid();
auto [block, then, else_] = CreateDiamondPattern(join);
HInstruction* parameter = MakeParam(DataType::Type::kReference);
HInstruction* field_get =
MakeIFieldGet(block, parameter, DataType::Type::kBool, MemberOffset(42));
MakeIf(block, field_get);
MakeIFieldGet(then, parameter, DataType::Type::kBool, MemberOffset(42));
MakeIFieldGet(else_, parameter, DataType::Type::kBool, MemberOffset(42));
MakeIFieldGet(join, parameter, DataType::Type::kBool, MemberOffset(42));
graph_->BuildDominatorTree();
SideEffectsAnalysis side_effects(graph_);
side_effects.Run();
GVNOptimization(graph_, side_effects).Run();
// Check that all field get instructions have been GVN'ed.
ASSERT_TRUE(then->GetFirstInstruction()->IsGoto());
ASSERT_TRUE(else_->GetFirstInstruction()->IsGoto());
ASSERT_TRUE(join->GetFirstInstruction()->IsReturnVoid());
}
TEST_F(GVNTest, LoopFieldElimination) {
HBasicBlock* return_block = InitEntryMainExitGraphWithReturnVoid();
auto [pre_header, loop_header, loop_body] = CreateWhileLoop(return_block);
loop_header->SwapSuccessors(); // Move the loop exit to the "else" successor.
HInstruction* parameter = MakeParam(DataType::Type::kReference);
MakeIFieldGet(pre_header, parameter, DataType::Type::kBool, MemberOffset(42));
HInstruction* field_get_in_loop_header =
MakeIFieldGet(loop_header, parameter, DataType::Type::kBool, MemberOffset(42));
MakeIf(loop_header, field_get_in_loop_header);
// Kill inside the loop body to prevent field gets inside the loop header
// and the body to be GVN'ed.
HInstruction* field_set =
MakeIFieldSet(loop_body, parameter, parameter, DataType::Type::kBool, MemberOffset(42));
HInstruction* field_get_in_loop_body =
MakeIFieldGet(loop_body, parameter, DataType::Type::kBool, MemberOffset(42));
HInstruction* field_get_in_return_block =
MakeIFieldGet(return_block, parameter, DataType::Type::kBool, MemberOffset(42));
ASSERT_EQ(field_get_in_loop_header->GetBlock(), loop_header);
ASSERT_EQ(field_get_in_loop_body->GetBlock(), loop_body);
ASSERT_EQ(field_get_in_return_block->GetBlock(), return_block);
graph_->BuildDominatorTree();
{
SideEffectsAnalysis side_effects(graph_);
side_effects.Run();
GVNOptimization(graph_, side_effects).Run();
}
// Check that all field get instructions are still there.
ASSERT_EQ(field_get_in_loop_header->GetBlock(), loop_header);
ASSERT_EQ(field_get_in_loop_body->GetBlock(), loop_body);
// The `return_block` is dominated by the `loop_header`, whose field get
// does not get killed by the loop flags.
ASSERT_TRUE(field_get_in_return_block->GetBlock() == nullptr);
// Now remove the field set, and check that all field get instructions have been GVN'ed.
loop_body->RemoveInstruction(field_set);
{
SideEffectsAnalysis side_effects(graph_);
side_effects.Run();
GVNOptimization(graph_, side_effects).Run();
}
ASSERT_TRUE(field_get_in_loop_header->GetBlock() == nullptr);
ASSERT_TRUE(field_get_in_loop_body->GetBlock() == nullptr);
ASSERT_TRUE(field_get_in_return_block->GetBlock() == nullptr);
}
// Test that inner loops affect the side effects of the outer loop.
TEST_F(GVNTest, LoopSideEffects) {
static const SideEffects kCanTriggerGC = SideEffects::CanTriggerGC();
HBasicBlock* outer_loop_exit = InitEntryMainExitGraphWithReturnVoid();
auto [outer_preheader, outer_loop_header, inner_loop_exit] = CreateWhileLoop(outer_loop_exit);
outer_loop_header->SwapSuccessors(); // Move the loop exit to the "else" successor.
auto [outer_loop_body, inner_loop_header, inner_loop_body] = CreateWhileLoop(inner_loop_exit);
inner_loop_header->SwapSuccessors(); // Move the loop exit to the "else" successor.
HInstruction* parameter = MakeParam(DataType::Type::kBool);
MakeSuspendCheck(outer_loop_header);
MakeIf(outer_loop_header, parameter);
MakeSuspendCheck(inner_loop_header);
MakeIf(inner_loop_header, parameter);
graph_->BuildDominatorTree();
ASSERT_TRUE(inner_loop_header->GetLoopInformation()->IsIn(
*outer_loop_header->GetLoopInformation()));
// Check that the only side effect of loops is to potentially trigger GC.
{
// Make one block with a side effect.
MakeIFieldSet(entry_block_, parameter, parameter, DataType::Type::kReference, MemberOffset(42));
SideEffectsAnalysis side_effects(graph_);
side_effects.Run();
ASSERT_TRUE(side_effects.GetBlockEffects(entry_block_).DoesAnyWrite());
ASSERT_FALSE(side_effects.GetBlockEffects(outer_loop_body).DoesAnyWrite());
ASSERT_FALSE(side_effects.GetLoopEffects(outer_loop_header).DoesAnyWrite());
ASSERT_FALSE(side_effects.GetLoopEffects(inner_loop_header).DoesAnyWrite());
ASSERT_TRUE(side_effects.GetLoopEffects(outer_loop_header).Equals(kCanTriggerGC));
ASSERT_TRUE(side_effects.GetLoopEffects(inner_loop_header).Equals(kCanTriggerGC));
}
// Check that the side effects of the outer loop does not affect the inner loop.
{
MakeIFieldSet(
outer_loop_body, parameter, parameter, DataType::Type::kReference, MemberOffset(42));
SideEffectsAnalysis side_effects(graph_);
side_effects.Run();
ASSERT_TRUE(side_effects.GetBlockEffects(entry_block_).DoesAnyWrite());
ASSERT_TRUE(side_effects.GetBlockEffects(outer_loop_body).DoesAnyWrite());
ASSERT_TRUE(side_effects.GetLoopEffects(outer_loop_header).DoesAnyWrite());
ASSERT_FALSE(side_effects.GetLoopEffects(inner_loop_header).DoesAnyWrite());
ASSERT_TRUE(side_effects.GetLoopEffects(inner_loop_header).Equals(kCanTriggerGC));
}
// Check that the side effects of the inner loop affects the outer loop.
{
outer_loop_body->RemoveInstruction(outer_loop_body->GetFirstInstruction());
MakeIFieldSet(
inner_loop_body, parameter, parameter, DataType::Type::kReference, MemberOffset(42));
SideEffectsAnalysis side_effects(graph_);
side_effects.Run();
ASSERT_TRUE(side_effects.GetBlockEffects(entry_block_).DoesAnyWrite());
ASSERT_FALSE(side_effects.GetBlockEffects(outer_loop_body).DoesAnyWrite());
ASSERT_TRUE(side_effects.GetLoopEffects(outer_loop_header).DoesAnyWrite());
ASSERT_TRUE(side_effects.GetLoopEffects(inner_loop_header).DoesAnyWrite());
}
}
} // namespace art
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