SPIRV-Tools/test/opt/struct_cfg_analysis_test.cpp
Steven Perron 5f599e700e
Fix infinite loop in dead-branch-elimination (#1891)
* Create structed cfg analysis.

There are lots of optimization that have to traverse the CFG in a
structured order just because it wants to know which constructs a
basic block in contained in.  This adds extra complexity to these
optimizations, for causes too much refactoring of older optimizations.

To help with this problem, I have written an analysis that can give this
information.

* Identify branches breaking from loops.

Dead branch elimination does a search for a conditional branch to the
end of the current selection construct.  This search assumes that the
only way to leave the construct is through the merge node.  But that is
not true.  The code can jump to the merge node of a loop that contains
the construct.

The search needs to take this into consideration.
2018-09-17 13:00:24 -04:00

467 lines
14 KiB
C++

// Copyright (c) 2018 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 <string>
#include "gmock/gmock.h"
#include "source/opt/struct_cfg_analysis.h"
#include "test/opt/assembly_builder.h"
#include "test/opt/pass_fixture.h"
#include "test/opt/pass_utils.h"
namespace spvtools {
namespace opt {
namespace {
using StructCFGAnalysisTest = PassTest<::testing::Test>;
TEST_F(StructCFGAnalysisTest, BBInSelection) {
const std::string text = R"(
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main"
%void = OpTypeVoid
%bool = OpTypeBool
%bool_undef = OpUndef %bool
%uint = OpTypeInt 32 0
%uint_undef = OpUndef %uint
%void_func = OpTypeFunction %void
%main = OpFunction %void None %void_func
%1 = OpLabel
OpSelectionMerge %3 None
OpBranchConditional %undef_bool %2 %3
%2 = OpLabel
OpBranch %3
%3 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_1, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
StructuredCFGAnalysis analysis(context.get());
// The header is not in the construct.
EXPECT_EQ(analysis.ContainingConstruct(1), 0);
EXPECT_EQ(analysis.ContainingLoop(1), 0);
EXPECT_EQ(analysis.MergeBlock(1), 0);
EXPECT_EQ(analysis.LoopMergeBlock(1), 0);
// BB2 is in the construct.
EXPECT_EQ(analysis.ContainingConstruct(2), 1);
EXPECT_EQ(analysis.ContainingLoop(2), 0);
EXPECT_EQ(analysis.MergeBlock(2), 3);
EXPECT_EQ(analysis.LoopMergeBlock(2), 0);
// The merge node is not in the construct.
EXPECT_EQ(analysis.ContainingConstruct(3), 0);
EXPECT_EQ(analysis.ContainingLoop(3), 0);
EXPECT_EQ(analysis.MergeBlock(3), 0);
EXPECT_EQ(analysis.LoopMergeBlock(3), 0);
}
TEST_F(StructCFGAnalysisTest, BBInLoop) {
const std::string text = R"(
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main"
%void = OpTypeVoid
%bool = OpTypeBool
%bool_undef = OpUndef %bool
%uint = OpTypeInt 32 0
%uint_undef = OpUndef %uint
%void_func = OpTypeFunction %void
%main = OpFunction %void None %void_func
%entry_lab = OpLabel
OpBranch %1
%1 = OpLabel
OpLoopMerge %3 %4 None
OpBranchConditional %undef_bool %2 %3
%2 = OpLabel
OpBranch %3
%4 = OpLabel
OpBranch %1
%3 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_1, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
StructuredCFGAnalysis analysis(context.get());
// The header is not in the construct.
EXPECT_EQ(analysis.ContainingConstruct(1), 0);
EXPECT_EQ(analysis.ContainingLoop(1), 0);
EXPECT_EQ(analysis.MergeBlock(1), 0);
EXPECT_EQ(analysis.LoopMergeBlock(1), 0);
// BB2 is in the construct.
EXPECT_EQ(analysis.ContainingConstruct(2), 1);
EXPECT_EQ(analysis.ContainingLoop(2), 1);
EXPECT_EQ(analysis.MergeBlock(2), 3);
EXPECT_EQ(analysis.LoopMergeBlock(2), 3);
// The merge node is not in the construct.
EXPECT_EQ(analysis.ContainingConstruct(3), 0);
EXPECT_EQ(analysis.ContainingLoop(3), 0);
EXPECT_EQ(analysis.MergeBlock(3), 0);
EXPECT_EQ(analysis.LoopMergeBlock(3), 0);
// The continue block is in the construct.
EXPECT_EQ(analysis.ContainingConstruct(4), 1);
EXPECT_EQ(analysis.ContainingLoop(4), 1);
EXPECT_EQ(analysis.MergeBlock(4), 3);
EXPECT_EQ(analysis.LoopMergeBlock(4), 3);
}
TEST_F(StructCFGAnalysisTest, SelectionInLoop) {
const std::string text = R"(
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main"
%void = OpTypeVoid
%bool = OpTypeBool
%bool_undef = OpUndef %bool
%uint = OpTypeInt 32 0
%uint_undef = OpUndef %uint
%void_func = OpTypeFunction %void
%main = OpFunction %void None %void_func
%entry_lab = OpLabel
OpBranch %1
%1 = OpLabel
OpLoopMerge %3 %4 None
OpBranchConditional %undef_bool %2 %3
%2 = OpLabel
OpSelectionMerge %6 None
OpBranchConditional %undef_bool %5 %6
%5 = OpLabel
OpBranch %6
%6 = OpLabel
OpBranch %3
%4 = OpLabel
OpBranch %1
%3 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_1, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
StructuredCFGAnalysis analysis(context.get());
// The loop header is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(1), 0);
EXPECT_EQ(analysis.ContainingLoop(1), 0);
EXPECT_EQ(analysis.MergeBlock(1), 0);
EXPECT_EQ(analysis.LoopMergeBlock(1), 0);
// Selection header is in the loop only.
EXPECT_EQ(analysis.ContainingConstruct(2), 1);
EXPECT_EQ(analysis.ContainingLoop(2), 1);
EXPECT_EQ(analysis.MergeBlock(2), 3);
EXPECT_EQ(analysis.LoopMergeBlock(2), 3);
// The loop merge node is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(3), 0);
EXPECT_EQ(analysis.ContainingLoop(3), 0);
EXPECT_EQ(analysis.MergeBlock(3), 0);
EXPECT_EQ(analysis.LoopMergeBlock(3), 0);
// The continue block is in the loop only.
EXPECT_EQ(analysis.ContainingConstruct(4), 1);
EXPECT_EQ(analysis.ContainingLoop(4), 1);
EXPECT_EQ(analysis.MergeBlock(4), 3);
EXPECT_EQ(analysis.LoopMergeBlock(4), 3);
// BB5 is in the selection fist and the loop.
EXPECT_EQ(analysis.ContainingConstruct(5), 2);
EXPECT_EQ(analysis.ContainingLoop(5), 1);
EXPECT_EQ(analysis.MergeBlock(5), 6);
EXPECT_EQ(analysis.LoopMergeBlock(5), 3);
// The selection merge is in the loop only.
EXPECT_EQ(analysis.ContainingConstruct(6), 1);
EXPECT_EQ(analysis.ContainingLoop(6), 1);
EXPECT_EQ(analysis.MergeBlock(6), 3);
EXPECT_EQ(analysis.LoopMergeBlock(6), 3);
}
TEST_F(StructCFGAnalysisTest, LoopInSelection) {
const std::string text = R"(
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main"
%void = OpTypeVoid
%bool = OpTypeBool
%bool_undef = OpUndef %bool
%uint = OpTypeInt 32 0
%uint_undef = OpUndef %uint
%void_func = OpTypeFunction %void
%main = OpFunction %void None %void_func
%entry_lab = OpLabel
OpBranch %1
%1 = OpLabel
OpSelectionMerge %3 None
OpBranchConditional %undef_bool %2 %3
%2 = OpLabel
OpLoopMerge %4 %5 None
OpBranchConditional %undef_bool %4 %6
%5 = OpLabel
OpBranch %2
%6 = OpLabel
OpBranch %4
%4 = OpLabel
OpBranch %3
%3 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_1, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
StructuredCFGAnalysis analysis(context.get());
// The selection header is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(1), 0);
EXPECT_EQ(analysis.ContainingLoop(1), 0);
EXPECT_EQ(analysis.MergeBlock(1), 0);
EXPECT_EQ(analysis.LoopMergeBlock(1), 0);
// Loop header is in the selection only.
EXPECT_EQ(analysis.ContainingConstruct(2), 1);
EXPECT_EQ(analysis.ContainingLoop(2), 0);
EXPECT_EQ(analysis.MergeBlock(2), 3);
EXPECT_EQ(analysis.LoopMergeBlock(2), 0);
// The selection merge node is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(3), 0);
EXPECT_EQ(analysis.ContainingLoop(3), 0);
EXPECT_EQ(analysis.MergeBlock(3), 0);
EXPECT_EQ(analysis.LoopMergeBlock(3), 0);
// The loop merge is in the selection only.
EXPECT_EQ(analysis.ContainingConstruct(4), 1);
EXPECT_EQ(analysis.ContainingLoop(4), 0);
EXPECT_EQ(analysis.MergeBlock(4), 3);
EXPECT_EQ(analysis.LoopMergeBlock(4), 0);
// The loop continue target is in the loop.
EXPECT_EQ(analysis.ContainingConstruct(5), 2);
EXPECT_EQ(analysis.ContainingLoop(5), 2);
EXPECT_EQ(analysis.MergeBlock(5), 4);
EXPECT_EQ(analysis.LoopMergeBlock(5), 4);
// BB6 is in the loop.
EXPECT_EQ(analysis.ContainingConstruct(6), 2);
EXPECT_EQ(analysis.ContainingLoop(6), 2);
EXPECT_EQ(analysis.MergeBlock(6), 4);
EXPECT_EQ(analysis.LoopMergeBlock(6), 4);
}
TEST_F(StructCFGAnalysisTest, SelectionInSelection) {
const std::string text = R"(
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main"
%void = OpTypeVoid
%bool = OpTypeBool
%bool_undef = OpUndef %bool
%uint = OpTypeInt 32 0
%uint_undef = OpUndef %uint
%void_func = OpTypeFunction %void
%main = OpFunction %void None %void_func
%entry_lab = OpLabel
OpBranch %1
%1 = OpLabel
OpSelectionMerge %3 None
OpBranchConditional %undef_bool %2 %3
%2 = OpLabel
OpSelectionMerge %4 None
OpBranchConditional %undef_bool %4 %5
%5 = OpLabel
OpBranch %4
%4 = OpLabel
OpBranch %3
%3 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_1, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
StructuredCFGAnalysis analysis(context.get());
// The outer selection header is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(1), 0);
EXPECT_EQ(analysis.ContainingLoop(1), 0);
EXPECT_EQ(analysis.MergeBlock(1), 0);
EXPECT_EQ(analysis.LoopMergeBlock(1), 0);
// The inner header is in the outer selection.
EXPECT_EQ(analysis.ContainingConstruct(2), 1);
EXPECT_EQ(analysis.ContainingLoop(2), 0);
EXPECT_EQ(analysis.MergeBlock(2), 3);
EXPECT_EQ(analysis.LoopMergeBlock(2), 0);
// The outer merge node is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(3), 0);
EXPECT_EQ(analysis.ContainingLoop(3), 0);
EXPECT_EQ(analysis.MergeBlock(3), 0);
EXPECT_EQ(analysis.LoopMergeBlock(3), 0);
// The inner merge is in the outer selection.
EXPECT_EQ(analysis.ContainingConstruct(4), 1);
EXPECT_EQ(analysis.ContainingLoop(4), 0);
EXPECT_EQ(analysis.MergeBlock(4), 3);
EXPECT_EQ(analysis.LoopMergeBlock(4), 0);
// BB5 is in the inner selection.
EXPECT_EQ(analysis.ContainingConstruct(5), 2);
EXPECT_EQ(analysis.ContainingLoop(5), 0);
EXPECT_EQ(analysis.MergeBlock(5), 4);
EXPECT_EQ(analysis.LoopMergeBlock(5), 0);
}
TEST_F(StructCFGAnalysisTest, LoopInLoop) {
const std::string text = R"(
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main"
%void = OpTypeVoid
%bool = OpTypeBool
%bool_undef = OpUndef %bool
%uint = OpTypeInt 32 0
%uint_undef = OpUndef %uint
%void_func = OpTypeFunction %void
%main = OpFunction %void None %void_func
%entry_lab = OpLabel
OpBranch %1
%1 = OpLabel
OpLoopMerge %3 %7 None
OpBranchConditional %undef_bool %2 %3
%2 = OpLabel
OpLoopMerge %4 %5 None
OpBranchConditional %undef_bool %4 %6
%5 = OpLabel
OpBranch %2
%6 = OpLabel
OpBranch %4
%4 = OpLabel
OpBranch %3
%7 = OpLabel
OpBranch %1
%3 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_1, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
StructuredCFGAnalysis analysis(context.get());
// The outer loop header is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(1), 0);
EXPECT_EQ(analysis.ContainingLoop(1), 0);
EXPECT_EQ(analysis.MergeBlock(1), 0);
EXPECT_EQ(analysis.LoopMergeBlock(1), 0);
// The inner loop header is in the outer loop.
EXPECT_EQ(analysis.ContainingConstruct(2), 1);
EXPECT_EQ(analysis.ContainingLoop(2), 1);
EXPECT_EQ(analysis.MergeBlock(2), 3);
EXPECT_EQ(analysis.LoopMergeBlock(2), 3);
// The outer merge node is not in either construct.
EXPECT_EQ(analysis.ContainingConstruct(3), 0);
EXPECT_EQ(analysis.ContainingLoop(3), 0);
EXPECT_EQ(analysis.MergeBlock(3), 0);
EXPECT_EQ(analysis.LoopMergeBlock(3), 0);
// The inner merge is in the outer loop.
EXPECT_EQ(analysis.ContainingConstruct(4), 1);
EXPECT_EQ(analysis.ContainingLoop(4), 1);
EXPECT_EQ(analysis.MergeBlock(4), 3);
EXPECT_EQ(analysis.LoopMergeBlock(4), 3);
// The inner continue target is in the inner loop.
EXPECT_EQ(analysis.ContainingConstruct(5), 2);
EXPECT_EQ(analysis.ContainingLoop(5), 2);
EXPECT_EQ(analysis.MergeBlock(5), 4);
EXPECT_EQ(analysis.LoopMergeBlock(5), 4);
// BB6 is in the loop.
EXPECT_EQ(analysis.ContainingConstruct(6), 2);
EXPECT_EQ(analysis.ContainingLoop(6), 2);
EXPECT_EQ(analysis.MergeBlock(6), 4);
EXPECT_EQ(analysis.LoopMergeBlock(6), 4);
// The outer continue target is in the outer loop.
EXPECT_EQ(analysis.ContainingConstruct(7), 1);
EXPECT_EQ(analysis.ContainingLoop(7), 1);
EXPECT_EQ(analysis.MergeBlock(7), 3);
EXPECT_EQ(analysis.LoopMergeBlock(7), 3);
}
TEST_F(StructCFGAnalysisTest, KernelTest) {
const std::string text = R"(
OpCapability Kernel
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %main "main"
%void = OpTypeVoid
%bool = OpTypeBool
%bool_undef = OpUndef %bool
%void_func = OpTypeFunction %void
%main = OpFunction %void None %void_func
%1 = OpLabel
OpBranchConditional %undef_bool %2 %3
%2 = OpLabel
OpBranch %3
%3 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_1, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
StructuredCFGAnalysis analysis(context.get());
// No structured control flow, so none of the basic block are in any
// construct.
for (uint32_t i = 1; i <= 3; i++) {
EXPECT_EQ(analysis.ContainingConstruct(i), 0);
EXPECT_EQ(analysis.ContainingLoop(i), 0);
EXPECT_EQ(analysis.MergeBlock(i), 0);
EXPECT_EQ(analysis.LoopMergeBlock(i), 0);
}
}
} // namespace
} // namespace opt
} // namespace spvtools