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reduce: Add two branch reduction passes (#2507)

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* Fix #2320. `conditional_branch_to_simple_conditional_branch` reduction pass changes conditional branches so both targets point to the same block id (creating a "simple" conditional branch).
* Fix #2501. `simple_conditional_branch_to_branch` reduction pass changes "simple" conditional branches to branches. 
* Fix #2503. `conditional_branch_to_simple_conditional_branch` proper handling of back-edges.
This commit is contained in:
Paul Thomson 2019-04-15 19:54:36 +01:00 committed by GitHub
parent 102e430a88
commit 3335c61147
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GPG Key ID: 4AEE18F83AFDEB23
15 changed files with 1451 additions and 2 deletions
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10
source/reduce/CMakeLists.txt
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@ -35,6 +35,10 @@ set(SPIRV_TOOLS_REDUCE_SOURCES
remove_unreferenced_instruction_reduction_opportunity_finder.h
structured_loop_to_selection_reduction_opportunity.h
structured_loop_to_selection_reduction_opportunity_finder.h
conditional_branch_to_simple_conditional_branch_opportunity_finder.h
conditional_branch_to_simple_conditional_branch_reduction_opportunity.h
simple_conditional_branch_to_branch_opportunity_finder.h
simple_conditional_branch_to_branch_reduction_opportunity.h
change_operand_reduction_opportunity.cpp
change_operand_to_undef_reduction_opportunity.cpp
@ -58,7 +62,11 @@ set(SPIRV_TOOLS_REDUCE_SOURCES
remove_opname_instruction_reduction_opportunity_finder.cpp
structured_loop_to_selection_reduction_opportunity.cpp
structured_loop_to_selection_reduction_opportunity_finder.cpp
)
conditional_branch_to_simple_conditional_branch_opportunity_finder.cpp
conditional_branch_to_simple_conditional_branch_reduction_opportunity.cpp
simple_conditional_branch_to_branch_opportunity_finder.cpp
simple_conditional_branch_to_branch_reduction_opportunity.cpp
)
if(MSVC)
# Enable parallel builds across four cores for this lib

89
source/reduce/conditional_branch_to_simple_conditional_branch_opportunity_finder.cpp Normal file
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@ -0,0 +1,89 @@
// Copyright (c) 2019 Google LLC
//
// 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 "source/reduce/conditional_branch_to_simple_conditional_branch_opportunity_finder.h"
#include "source/reduce/conditional_branch_to_simple_conditional_branch_reduction_opportunity.h"
#include "source/reduce/reduction_util.h"
namespace spvtools {
namespace reduce {
using opt::IRContext;
using opt::Instruction;
std::vector<std::unique_ptr<ReductionOpportunity>>
ConditionalBranchToSimpleConditionalBranchOpportunityFinder::
GetAvailableOpportunities(IRContext* context) const {
std::vector<std::unique_ptr<ReductionOpportunity>> result;
// Find the opportunities for redirecting all false targets before the
// opportunities for redirecting all true targets because the former
// opportunities disable the latter, and vice versa, and the efficiency of the
// reducer is improved by avoiding contiguous opportunities that disable one
// another.
for (bool redirect_to_true : {true, false}) {
// Consider every function.
for (auto& function : *context->module()) {
// Consider every block in the function.
for (auto& block : function) {
// The terminator must be SpvOpBranchConditional.
Instruction* terminator = block.terminator();
if (terminator->opcode() != SpvOpBranchConditional) {
continue;
}
uint32_t true_block_id =
terminator->GetSingleWordInOperand(kTrueBranchOperandIndex);
uint32_t false_block_id =
terminator->GetSingleWordInOperand(kFalseBranchOperandIndex);
// The conditional branch must not already be simplified.
if (true_block_id == false_block_id) {
continue;
}
// The redirected target must not be a back-edge to a structured loop
// header.
uint32_t redirected_block_id =
redirect_to_true ? false_block_id : true_block_id;
uint32_t containing_loop_header =
context->GetStructuredCFGAnalysis()->ContainingLoop(block.id());
// The structured CFG analysis does not include a loop header as part
// of the loop construct, but we want to include it, so handle this
// special case:
if (block.GetLoopMergeInst() != nullptr) {
containing_loop_header = block.id();
}
if (redirected_block_id == containing_loop_header) {
continue;
}
result.push_back(
MakeUnique<
ConditionalBranchToSimpleConditionalBranchReductionOpportunity>(
block.terminator(), redirect_to_true));
}
}
}
return result;
}
std::string
ConditionalBranchToSimpleConditionalBranchOpportunityFinder::GetName() const {
return "ConditionalBranchToSimpleConditionalBranchOpportunityFinder";
}
} // namespace reduce
} // namespace spvtools

37
source/reduce/conditional_branch_to_simple_conditional_branch_opportunity_finder.h Normal file
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@ -0,0 +1,37 @@
// Copyright (c) 2019 Google LLC
//
// 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 SOURCE_REDUCE_SIMPLIFY_SELECTION_OPPORTUNITY_FINDER_H_
#define SOURCE_REDUCE_SIMPLIFY_SELECTION_OPPORTUNITY_FINDER_H_
#include "source/reduce/reduction_opportunity_finder.h"
namespace spvtools {
namespace reduce {
// A finder for opportunities to simplify conditional branches into simple
// conditional branches (conditional branches with one target).
class ConditionalBranchToSimpleConditionalBranchOpportunityFinder
: public ReductionOpportunityFinder {
public:
std::vector<std::unique_ptr<ReductionOpportunity>> GetAvailableOpportunities(
opt::IRContext* context) const override;
std::string GetName() const override;
};
} // namespace reduce
} // namespace spvtools
#endif // SOURCE_REDUCE_SIMPLIFY_SELECTION_OPPORTUNITY_FINDER_H_

54
source/reduce/conditional_branch_to_simple_conditional_branch_reduction_opportunity.cpp Normal file
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@ -0,0 +1,54 @@
// Copyright (c) 2019 Google LLC
//
// 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 "source/reduce/conditional_branch_to_simple_conditional_branch_reduction_opportunity.h"
#include "source/reduce/reduction_util.h"
namespace spvtools {
namespace reduce {
using opt::Instruction;
ConditionalBranchToSimpleConditionalBranchReductionOpportunity::
ConditionalBranchToSimpleConditionalBranchReductionOpportunity(
Instruction* conditional_branch_instruction, bool redirect_to_true)
: conditional_branch_instruction_(conditional_branch_instruction),
redirect_to_true_(redirect_to_true) {}
bool ConditionalBranchToSimpleConditionalBranchReductionOpportunity::
PreconditionHolds() {
// Another opportunity may have already simplified this conditional branch,
// which should disable this opportunity.
return conditional_branch_instruction_->GetSingleWordInOperand(
kTrueBranchOperandIndex) !=
conditional_branch_instruction_->GetSingleWordInOperand(
kFalseBranchOperandIndex);
}
void ConditionalBranchToSimpleConditionalBranchReductionOpportunity::Apply() {
uint32_t operand_to_modify =
redirect_to_true_ ? kFalseBranchOperandIndex : kTrueBranchOperandIndex;
uint32_t operand_to_copy =
redirect_to_true_ ? kTrueBranchOperandIndex : kFalseBranchOperandIndex;
// Do the branch redirection.
conditional_branch_instruction_->SetInOperand(
operand_to_modify,
{conditional_branch_instruction_->GetSingleWordInOperand(
operand_to_copy)});
}
} // namespace reduce
} // namespace spvtools

52
source/reduce/conditional_branch_to_simple_conditional_branch_reduction_opportunity.h Normal file
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@ -0,0 +1,52 @@
// Copyright (c) 2019 Google LLC
//
// 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 SOURCE_REDUCE_SIMPLIFY_CONDITIONAL_BRANCH_REDUCTION_OPPORTUNITY_H_
#define SOURCE_REDUCE_SIMPLIFY_CONDITIONAL_BRANCH_REDUCTION_OPPORTUNITY_H_
#include "source/opt/basic_block.h"
#include "source/reduce/reduction_opportunity.h"
namespace spvtools {
namespace reduce {
// An opportunity to simplify a conditional branch to a simple conditional
// branch (a conditional branch with one target).
class ConditionalBranchToSimpleConditionalBranchReductionOpportunity
: public ReductionOpportunity {
public:
// Constructs an opportunity to simplify |conditional_branch_instruction|. If
// |redirect_to_true| is true, the false target will be changed to also point
// to the true target; otherwise, the true target will be changed to also
// point to the false target.
explicit ConditionalBranchToSimpleConditionalBranchReductionOpportunity(
opt::Instruction* conditional_branch_instruction, bool redirect_to_true);
bool PreconditionHolds() override;
protected:
void Apply() override;
private:
opt::Instruction* conditional_branch_instruction_;
// If true, the false target will be changed to point to the true target;
// otherwise, the true target will be changed to point to the false target.
bool redirect_to_true_;
};
} // namespace reduce
} // namespace spvtools
#endif // SOURCE_REDUCE_SIMPLIFY_CONDITIONAL_BRANCH_REDUCTION_OPPORTUNITY_H_

7
source/reduce/reducer.cpp
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@ -17,6 +17,7 @@
#include <cassert>
#include <sstream>
#include "source/reduce/conditional_branch_to_simple_conditional_branch_opportunity_finder.h"
#include "source/reduce/merge_blocks_reduction_opportunity_finder.h"
#include "source/reduce/operand_to_const_reduction_opportunity_finder.h"
#include "source/reduce/operand_to_dominating_id_reduction_opportunity_finder.h"
@ -26,6 +27,7 @@
#include "source/reduce/remove_opname_instruction_reduction_opportunity_finder.h"
#include "source/reduce/remove_selection_reduction_opportunity_finder.h"
#include "source/reduce/remove_unreferenced_instruction_reduction_opportunity_finder.h"
#include "source/reduce/simple_conditional_branch_to_branch_opportunity_finder.h"
#include "source/reduce/structured_loop_to_selection_reduction_opportunity_finder.h"
#include "source/spirv_reducer_options.h"
@ -191,6 +193,11 @@ void Reducer::AddDefaultReductionPasses() {
spvtools::MakeUnique<RemoveBlockReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<RemoveSelectionReductionOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<
ConditionalBranchToSimpleConditionalBranchOpportunityFinder>());
AddReductionPass(
spvtools::MakeUnique<SimpleConditionalBranchToBranchOpportunityFinder>());
}
void Reducer::AddReductionPass(

3
source/reduce/reduction_util.cpp
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@ -22,6 +22,9 @@ namespace reduce {
using opt::IRContext;
using opt::Instruction;
const uint32_t kTrueBranchOperandIndex = 1;
const uint32_t kFalseBranchOperandIndex = 2;
uint32_t FindOrCreateGlobalUndef(IRContext* context, uint32_t type_id) {
for (auto& inst : context->module()->types_values()) {
if (inst.opcode() != SpvOpUndef) {

3
source/reduce/reduction_util.h
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@ -23,6 +23,9 @@
namespace spvtools {
namespace reduce {
extern const uint32_t kTrueBranchOperandIndex;
extern const uint32_t kFalseBranchOperandIndex;
// Returns an OpUndef id from the global value list that is of the given type,
// adding one if it does not exist.
uint32_t FindOrCreateGlobalUndef(opt::IRContext* context, uint32_t type_id);

65
source/reduce/simple_conditional_branch_to_branch_opportunity_finder.cpp Normal file
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@ -0,0 +1,65 @@
// Copyright (c) 2019 Google LLC
//
// 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 "source/reduce/simple_conditional_branch_to_branch_opportunity_finder.h"
#include "source/reduce/reduction_util.h"
#include "source/reduce/simple_conditional_branch_to_branch_reduction_opportunity.h"
namespace spvtools {
namespace reduce {
using opt::IRContext;
using opt::Instruction;
std::vector<std::unique_ptr<ReductionOpportunity>>
SimpleConditionalBranchToBranchOpportunityFinder::GetAvailableOpportunities(
IRContext* context) const {
std::vector<std::unique_ptr<ReductionOpportunity>> result;
// Consider every function.
for (auto& function : *context->module()) {
// Consider every block in the function.
for (auto& block : function) {
// The terminator must be SpvOpBranchConditional.
Instruction* terminator = block.terminator();
if (terminator->opcode() != SpvOpBranchConditional) {
continue;
}
// It must not be a selection header, as these cannot be followed by
// OpBranch.
if (block.GetMergeInst() &&
block.GetMergeInst()->opcode() == SpvOpSelectionMerge) {
continue;
}
// The conditional branch must be simplified.
if (terminator->GetSingleWordInOperand(kTrueBranchOperandIndex) !=
terminator->GetSingleWordInOperand(kFalseBranchOperandIndex)) {
continue;
}
result.push_back(
MakeUnique<SimpleConditionalBranchToBranchReductionOpportunity>(
block.terminator()));
}
}
return result;
}
std::string SimpleConditionalBranchToBranchOpportunityFinder::GetName() const {
return "SimpleConditionalBranchToBranchOpportunityFinder";
}
} // namespace reduce
} // namespace spvtools

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@ -0,0 +1,37 @@
// Copyright (c) 2019 Google LLC
//
// 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 SOURCE_REDUCE_SIMPLE_CONDITIONAL_BRANCH_TO_BRANCH_OPPORTUNITY_FINDER_H_
#define SOURCE_REDUCE_SIMPLE_CONDITIONAL_BRANCH_TO_BRANCH_OPPORTUNITY_FINDER_H_
#include "source/reduce/reduction_opportunity_finder.h"
namespace spvtools {
namespace reduce {
// A finder for opportunities to change simple conditional branches (conditional
// branches with one target) to an OpBranch.
class SimpleConditionalBranchToBranchOpportunityFinder
: public ReductionOpportunityFinder {
public:
std::vector<std::unique_ptr<ReductionOpportunity>> GetAvailableOpportunities(
opt::IRContext* context) const override;
std::string GetName() const override;
};
} // namespace reduce
} // namespace spvtools
#endif // SOURCE_REDUCE_SIMPLE_CONDITIONAL_BRANCH_TO_BRANCH_OPPORTUNITY_FINDER_H_

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source/reduce/simple_conditional_branch_to_branch_reduction_opportunity.cpp Normal file
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@ -0,0 +1,59 @@
// Copyright (c) 2019 Google LLC
//
// 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 "source/reduce/simple_conditional_branch_to_branch_reduction_opportunity.h"
#include "source/reduce/reduction_util.h"
namespace spvtools {
namespace reduce {
using namespace opt;
SimpleConditionalBranchToBranchReductionOpportunity::
SimpleConditionalBranchToBranchReductionOpportunity(
Instruction* conditional_branch_instruction)
: conditional_branch_instruction_(conditional_branch_instruction) {}
bool SimpleConditionalBranchToBranchReductionOpportunity::PreconditionHolds() {
// We find at most one opportunity per conditional branch and simplifying
// another branch cannot disable this opportunity.
return true;
}
void SimpleConditionalBranchToBranchReductionOpportunity::Apply() {
assert(conditional_branch_instruction_->opcode() == SpvOpBranchConditional &&
"SimpleConditionalBranchToBranchReductionOpportunity: branch was not "
"a conditional branch");
assert(conditional_branch_instruction_->GetSingleWordInOperand(
kTrueBranchOperandIndex) ==
conditional_branch_instruction_->GetSingleWordInOperand(
kFalseBranchOperandIndex) &&
"SimpleConditionalBranchToBranchReductionOpportunity: branch was not "
"simple");
// OpBranchConditional %condition %block_id %block_id ...
// ->
// OpBranch %block_id
conditional_branch_instruction_->SetOpcode(SpvOpBranch);
conditional_branch_instruction_->ReplaceOperands(
{{SPV_OPERAND_TYPE_ID,
{conditional_branch_instruction_->GetSingleWordInOperand(
kTrueBranchOperandIndex)}}});
}
} // namespace reduce
} // namespace spvtools

45
source/reduce/simple_conditional_branch_to_branch_reduction_opportunity.h Normal file
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@ -0,0 +1,45 @@
// Copyright (c) 2019 Google LLC
//
// 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 SOURCE_REDUCE_SIMPLE_CONDITIONAL_BRANCH_TO_BRANCH_REDUCTION_OPPORTUNITY_H_
#define SOURCE_REDUCE_SIMPLE_CONDITIONAL_BRANCH_TO_BRANCH_REDUCTION_OPPORTUNITY_H_
#include "source/opt/instruction.h"
#include "source/reduce/reduction_opportunity.h"
namespace spvtools {
namespace reduce {
// An opportunity to change simple conditional branches (conditional branches
// with one target) to an OpBranch.
class SimpleConditionalBranchToBranchReductionOpportunity
: public ReductionOpportunity {
public:
// Constructs an opportunity to simplify |conditional_branch_instruction|.
explicit SimpleConditionalBranchToBranchReductionOpportunity(
opt::Instruction* conditional_branch_instruction);
bool PreconditionHolds() override;
protected:
void Apply() override;
private:
opt::Instruction* conditional_branch_instruction_;
};
} // namespace reduce
} // namespace spvtools
#endif // SOURCE_REDUCE_SIMPLE_CONDITIONAL_BRANCH_TO_BRANCH_REDUCTION_OPPORTUNITY_H_

5
test/reduce/CMakeLists.txt
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@ -13,7 +13,8 @@
# limitations under the License.
add_spvtools_unittest(TARGET reduce
SRCS merge_blocks_test.cpp
SRCS
merge_blocks_test.cpp
operand_to_constant_test.cpp
operand_to_undef_test.cpp
operand_to_dominating_id_test.cpp
@ -27,6 +28,8 @@ add_spvtools_unittest(TARGET reduce
remove_unreferenced_instruction_test.cpp
structured_loop_to_selection_test.cpp
validation_during_reduction_test.cpp
conditional_branch_to_simple_conditional_branch_test.cpp
simple_conditional_branch_to_branch_test.cpp
LIBS SPIRV-Tools-reduce
)

501
test/reduce/conditional_branch_to_simple_conditional_branch_test.cpp Normal file
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@ -0,0 +1,501 @@
// Copyright (c) 2019 Google LLC
//
// 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 "source/reduce/conditional_branch_to_simple_conditional_branch_opportunity_finder.h"
#include "source/opt/build_module.h"
#include "source/reduce/reduction_opportunity.h"
#include "source/reduce/reduction_pass.h"
#include "test/reduce/reduce_test_util.h"
namespace spvtools {
namespace reduce {
namespace {
const spv_target_env kEnv = SPV_ENV_UNIVERSAL_1_3;
TEST(ConditionalBranchToSimpleConditionalBranchTest, Diamond) {
// A test with the following structure.
//
// selection header
// OpBranchConditional
// | |
// b b
// | |
// selection merge
//
// There should be two opportunities for redirecting the OpBranchConditional
// targets: redirecting the true to false, and vice-versa. E.g. false to true:
//
// selection header
// OpBranchConditional
// ||
// b b
// | |
// selection merge
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpSelectionMerge %11 None
OpBranchConditional %8 %12 %13
%12 = OpLabel
OpBranch %11
%13 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
auto context = BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(2, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ASSERT_TRUE(ops[1]->PreconditionHolds());
ops[0]->TryToApply();
// The other opportunity should now be disabled.
ASSERT_FALSE(ops[1]->PreconditionHolds());
CheckValid(kEnv, context.get());
{
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpSelectionMerge %11 None
OpBranchConditional %8 %12 %12
%12 = OpLabel
OpBranch %11
%13 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
}
ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
// Start again, and apply the other op.
context = BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(2, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ASSERT_TRUE(ops[1]->PreconditionHolds());
ops[1]->TryToApply();
// The other opportunity should now be disabled.
ASSERT_FALSE(ops[0]->PreconditionHolds());
CheckValid(kEnv, context.get());
{
std::string after2 = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpSelectionMerge %11 None
OpBranchConditional %8 %13 %13
%12 = OpLabel
OpBranch %11
%13 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after2, context.get());
}
}
TEST(ConditionalBranchToSimpleConditionalBranchTest, AlreadySimplified) {
// A test with the following structure.
//
// selection header
// OpBranchConditional
// ||
// b b
// | |
// selection merge
//
// There should be no opportunities for redirecting the OpBranchConditional
// as it is already simplified.
//
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpSelectionMerge %11 None
OpBranchConditional %8 %12 %12
%12 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
auto context = BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(ConditionalBranchToSimpleConditionalBranchTest, DontRemoveBackEdge) {
// A test with the following structure. The loop has a continue construct that
// ends with OpBranchConditional. The OpBranchConditional can be simplified,
// but only to point to the loop header, otherwise we have removed the
// back-edge. Thus, there should be one opportunity instead of two.
//
// loop header
// |
// loop continue target and back-edge block
// OpBranchConditional
// | |
// loop merge (to loop header^)
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %12
%12 = OpLabel
OpBranchConditional %8 %11 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
const auto context =
BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(1, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ops[0]->TryToApply();
CheckValid(kEnv, context.get());
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %12
%12 = OpLabel
OpBranchConditional %8 %10 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(ConditionalBranchToSimpleConditionalBranchTest,
DontRemoveBackEdgeCombinedHeaderContinue) {
// A test with the following structure.
//
// loop header and continue target and back-edge block
// OpBranchConditional
// | |
// loop merge (to loop header^)
//
// The OpBranchConditional-to-header edge must not be removed, so there should
// only be one opportunity. It should change both targets to be to the loop
// header.
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %10 None
OpBranchConditional %8 %11 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
const auto context =
BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(1, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ops[0]->TryToApply();
CheckValid(kEnv, context.get());
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %10 None
OpBranchConditional %8 %10 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(ConditionalBranchToSimpleConditionalBranchTest, BackEdgeUnreachable) {
// A test with the following structure. I.e. a loop with an unreachable
// continue construct that ends with OpBranchConditional.
//
// loop header
// |
// | loop continue target (unreachable)
// | |
// | back-edge block (unreachable)
// | OpBranchConditional
// | | |
// loop merge (to loop header^)
//
// The branch to the loop header must not be removed, even though the continue
// construct is unreachable. So there should only be one opportunity to make
// the true and false targets of the OpBranchConditional to point to the loop
// header.
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %11
%12 = OpLabel
OpBranch %13
%13 = OpLabel
OpBranchConditional %8 %11 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
const auto context =
BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(1, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ops[0]->TryToApply();
CheckValid(kEnv, context.get());
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %11
%12 = OpLabel
OpBranch %13
%13 = OpLabel
OpBranchConditional %8 %10 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
ops = ConditionalBranchToSimpleConditionalBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
} // namespace
} // namespace reduce
} // namespace spvtools

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test/reduce/simple_conditional_branch_to_branch_test.cpp Normal file
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@ -0,0 +1,486 @@
// Copyright (c) 2019 Google LLC
//
// 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 "source/reduce/simple_conditional_branch_to_branch_opportunity_finder.h"
#include "source/opt/build_module.h"
#include "source/reduce/reduction_opportunity.h"
#include "source/reduce/reduction_pass.h"
#include "test/reduce/reduce_test_util.h"
namespace spvtools {
namespace reduce {
namespace {
const spv_target_env kEnv = SPV_ENV_UNIVERSAL_1_3;
TEST(SimpleConditionalBranchToBranchTest, Diamond) {
// A test with the following structure.
//
// selection header
// OpBranchConditional
// ||
// b b
// | |
// selection merge
//
// The conditional branch cannot be simplified because selection headers
// cannot end with OpBranch.
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpSelectionMerge %11 None
OpBranchConditional %8 %12 %12
%12 = OpLabel
OpBranch %11
%13 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
auto context = BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(SimpleConditionalBranchToBranchTest, DiamondNoSelection) {
// A test with the following structure.
//
// OpBranchConditional
// ||
// b b
// | /
// b
//
// The conditional branch can be simplified.
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpBranchConditional %8 %12 %12
%12 = OpLabel
OpBranch %11
%13 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
auto context = BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(1, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ops[0]->TryToApply();
CheckValid(kEnv, context.get());
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpBranch %12
%12 = OpLabel
OpBranch %11
%13 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(SimpleConditionalBranchToBranchTest, ConditionalBranchesButNotSimple) {
// A test with the following structure.
//
// selection header
// OpBranchConditional
// | |
// b OpBranchConditional
// | | |
// | b |
// | | |
// selection merge
//
// None of the conditional branches can be simplified; the first is not simple
// AND part of a selection header; the second is just not simple (where
// "simple" means it only has one target).
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpSelectionMerge %11 None
OpBranchConditional %8 %12 %13
%12 = OpLabel
OpBranch %11
%13 = OpLabel
OpBranchConditional %8 %14 %11
%14 = OpLabel
OpBranch %11
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
auto context = BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(SimpleConditionalBranchToBranchTest, SimplifyBackEdge) {
// A test with the following structure. The loop has a continue construct that
// ends with OpBranchConditional. The OpBranchConditional can be simplified.
//
// loop header
// |
// loop continue target and back-edge block
// OpBranchConditional
// ||
// loop merge (to loop header^)
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %12
%12 = OpLabel
OpBranchConditional %8 %10 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
const auto context =
BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(1, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ops[0]->TryToApply();
CheckValid(kEnv, context.get());
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %12
%12 = OpLabel
OpBranch %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(SimpleConditionalBranchToBranchTest,
DontRemoveBackEdgeCombinedHeaderContinue) {
// A test with the following structure.
//
// loop header and continue target and back-edge block
// OpBranchConditional
// ||
// loop merge (to loop header^)
//
// The conditional branch can be simplified.
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %10 None
OpBranchConditional %8 %10 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
const auto context =
BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(1, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ops[0]->TryToApply();
CheckValid(kEnv, context.get());
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %10 None
OpBranch %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
TEST(SimpleConditionalBranchToBranchTest, BackEdgeUnreachable) {
// A test with the following structure. I.e. a loop with an unreachable
// continue construct that ends with OpBranchConditional.
//
// loop header
// |
// | loop continue target (unreachable)
// | |
// | back-edge block (unreachable)
// | OpBranchConditional
// | ||
// loop merge (to loop header^)
//
// The conditional branch can be simplified.
std::string shader = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %11
%12 = OpLabel
OpBranch %13
%13 = OpLabel
OpBranchConditional %8 %10 %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
const auto context =
BuildModule(kEnv, nullptr, shader, kReduceAssembleOption);
CheckValid(kEnv, context.get());
auto ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(1, ops.size());
ASSERT_TRUE(ops[0]->PreconditionHolds());
ops[0]->TryToApply();
CheckValid(kEnv, context.get());
std::string after = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource ESSL 310
OpName %2 "main"
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%5 = OpTypeInt 32 1
%6 = OpTypePointer Function %5
%7 = OpTypeBool
%8 = OpConstantTrue %7
%2 = OpFunction %3 None %4
%9 = OpLabel
OpBranch %10
%10 = OpLabel
OpLoopMerge %11 %12 None
OpBranch %11
%12 = OpLabel
OpBranch %13
%13 = OpLabel
OpBranch %10
%11 = OpLabel
OpReturn
OpFunctionEnd
)";
CheckEqual(kEnv, after, context.get());
ops = SimpleConditionalBranchToBranchOpportunityFinder()
.GetAvailableOpportunities(context.get());
ASSERT_EQ(0, ops.size());
}
} // namespace
} // namespace reduce
} // namespace spvtools