Fix bug in 'split blocks', and add tests for fuzzer. (#2658)
There turned out to be a bug in the 'split blocks' transformation due
to blocks being split while they were being iterated over. This
change fixes that issue, and adds tests that were able to expose the
issue by running the fuzzer on some example shaders.
diff --git a/source/fuzz/fuzzer_pass_split_blocks.cpp b/source/fuzz/fuzzer_pass_split_blocks.cpp
index 9d400c8..7c02398 100644
--- a/source/fuzz/fuzzer_pass_split_blocks.cpp
+++ b/source/fuzz/fuzzer_pass_split_blocks.cpp
@@ -31,58 +31,66 @@
FuzzerPassSplitBlocks::~FuzzerPassSplitBlocks() = default;
void FuzzerPassSplitBlocks::Apply() {
- // Consider each block in the module.
+ // Gather up pointers to all the blocks in the module. We are then able to
+ // iterate over these pointers and split the blocks to which they point;
+ // we cannot safely split blocks while we iterate through the module.
+ std::vector<opt::BasicBlock*> blocks;
for (auto& function : *GetIRContext()->module()) {
for (auto& block : function) {
- // Probabilistically decide whether to try to split this block.
- if (GetFuzzerContext()->GetRandomGenerator()->RandomPercentage() >
- GetFuzzerContext()->GetChanceOfSplittingBlock()) {
- continue;
+ blocks.push_back(&block);
+ }
+ }
+
+ // Now go through all the block pointers that were gathered.
+ for (auto& block : blocks) {
+ // Probabilistically decide whether to try to split this block.
+ if (GetFuzzerContext()->GetRandomGenerator()->RandomPercentage() >
+ GetFuzzerContext()->GetChanceOfSplittingBlock()) {
+ continue;
+ }
+ // We are going to try to split this block. We now need to choose where
+ // to split it. We do this by finding a base instruction that has a
+ // result id, and an offset from that base instruction. We would like
+ // offsets to be as small as possible and ideally 0 - we only need offsets
+ // because not all instructions can be identified by a result id (e.g.
+ // OpStore instructions cannot).
+ std::vector<std::pair<uint32_t, uint32_t>> base_offset_pairs;
+ // The initial base instruction is the block label.
+ uint32_t base = block->id();
+ uint32_t offset = 0;
+ // Consider every instruction in the block. The label is excluded: it is
+ // only necessary to consider it as a base in case the first instruction
+ // in the block does not have a result id.
+ for (auto& inst : *block) {
+ if (inst.HasResultId()) {
+ // In the case that the instruction has a result id, we use the
+ // instruction as its own base, with zero offset.
+ base = inst.result_id();
+ offset = 0;
+ } else {
+ // The instruction does not have a result id, so we need to identify
+ // it via the latest instruction that did have a result id (base), and
+ // an incremented offset.
+ offset++;
}
- // We are going to try to split this block. We now need to choose where
- // to split it. We do this by finding a base instruction that has a
- // result id, and an offset from that base instruction. We would like
- // offsets to be as small as possible and ideally 0 - we only need offsets
- // because not all instructions can be identified by a result id (e.g.
- // OpStore instructions cannot).
- std::vector<std::pair<uint32_t, uint32_t>> base_offset_pairs;
- // The initial base instruction is the block label.
- uint32_t base = block.id();
- uint32_t offset = 0;
- // Consider every instruction in the block. The label is excluded: it is
- // only necessary to consider it as a base in case the first instruction
- // in the block does not have a result id.
- for (auto& inst : block) {
- if (inst.HasResultId()) {
- // In the case that the instruction has a result id, we use the
- // instruction as its own base, with zero offset.
- base = inst.result_id();
- offset = 0;
- } else {
- // The instruction does not have a result id, so we need to identify
- // it via the latest instruction that did have a result id (base), and
- // an incremented offset.
- offset++;
- }
- base_offset_pairs.emplace_back(base, offset);
- }
- // Having identified all the places we might be able to split the block,
- // we choose one of them.
- auto base_offset = base_offset_pairs
- [GetFuzzerContext()->GetRandomGenerator()->RandomUint32(
- static_cast<uint32_t>(base_offset_pairs.size()))];
- auto message = transformation::MakeTransformationSplitBlock(
- base_offset.first, base_offset.second,
- GetFuzzerContext()->GetFreshId());
- // If the position we have chosen turns out to be a valid place to split
- // the block, we apply the split. Otherwise the block just doesn't get
- // split.
- if (transformation::IsApplicable(message, GetIRContext(),
- *GetFactManager())) {
- transformation::Apply(message, GetIRContext(), GetFactManager());
- *GetTransformations()->add_transformation()->mutable_split_block() =
- message;
- }
+ base_offset_pairs.emplace_back(base, offset);
+ }
+ // Having identified all the places we might be able to split the block,
+ // we choose one of them.
+ auto base_offset = base_offset_pairs
+ [GetFuzzerContext()->GetRandomGenerator()->RandomUint32(
+ static_cast<uint32_t>(base_offset_pairs.size()))];
+ auto message = transformation::MakeTransformationSplitBlock(
+ base_offset.first, base_offset.second,
+ GetFuzzerContext()->GetFreshId());
+ // If the position we have chosen turns out to be a valid place to split
+ // the block, we apply the split. Otherwise the block just doesn't get
+ // split.
+ if (transformation::IsApplicable(message, GetIRContext(),
+ *GetFactManager())) {
+ transformation::Apply(message, GetIRContext(), GetFactManager());
+ *GetTransformations()->add_transformation()->mutable_split_block() =
+ message;
}
}
}
diff --git a/test/fuzz/CMakeLists.txt b/test/fuzz/CMakeLists.txt
index ae5cc2f..9578352 100644
--- a/test/fuzz/CMakeLists.txt
+++ b/test/fuzz/CMakeLists.txt
@@ -17,6 +17,7 @@
set(SOURCES
fuzz_test_util.h
+ fuzzer_test.cpp
fuzz_test_util.cpp
transformation_add_constant_boolean_test.cpp
transformation_add_constant_scalar_test.cpp
diff --git a/test/fuzz/fuzzer_test.cpp b/test/fuzz/fuzzer_test.cpp
new file mode 100644
index 0000000..069777f
--- /dev/null
+++ b/test/fuzz/fuzzer_test.cpp
@@ -0,0 +1,464 @@
+// 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/fuzz/fuzzer.h"
+#include "test/fuzz/fuzz_test_util.h"
+
+namespace spvtools {
+namespace fuzz {
+namespace {
+
+// Assembles the given |shader| text, and then runs the fuzzer |num_runs|
+// times, using successive seeds starting from |initial_seed|. Checks that
+// the binary produced after each fuzzer run is valid.
+void RunFuzzer(const std::string& shader, uint32_t initial_seed,
+ uint32_t num_runs) {
+ const auto env = SPV_ENV_UNIVERSAL_1_3;
+
+ std::vector<uint32_t> binary_in;
+ SpirvTools t(env);
+ ASSERT_TRUE(t.Assemble(shader, &binary_in, kFuzzAssembleOption));
+ ASSERT_TRUE(t.Validate(binary_in));
+
+ for (uint32_t seed = initial_seed; seed < initial_seed + num_runs; seed++) {
+ protobufs::FactSequence initial_facts;
+ std::vector<uint32_t> binary_out;
+ protobufs::TransformationSequence transformation_sequence_out;
+ spvtools::FuzzerOptions fuzzer_options;
+ spvFuzzerOptionsSetRandomSeed(fuzzer_options, seed);
+
+ Fuzzer fuzzer(env);
+ fuzzer.Run(binary_in, initial_facts, &binary_out,
+ &transformation_sequence_out, fuzzer_options);
+ ASSERT_TRUE(t.Validate(binary_out));
+ }
+}
+
+TEST(FuzzerTest, Miscellaneous1) {
+ // The SPIR-V came from this GLSL:
+ //
+ // #version 310 es
+ //
+ // void foo() {
+ // int x;
+ // x = 2;
+ // for (int i = 0; i < 100; i++) {
+ // x += i;
+ // x = x * 2;
+ // }
+ // return;
+ // }
+ //
+ // void main() {
+ // foo();
+ // for (int i = 0; i < 10; i++) {
+ // int j = 20;
+ // while(j > 0) {
+ // foo();
+ // j--;
+ // }
+ // do {
+ // i++;
+ // } while(i < 4);
+ // }
+ // }
+
+ std::string shader = R"(
+ OpCapability Shader
+ %1 = OpExtInstImport "GLSL.std.450"
+ OpMemoryModel Logical GLSL450
+ OpEntryPoint Fragment %4 "main"
+ OpExecutionMode %4 OriginUpperLeft
+ OpSource ESSL 310
+ OpName %4 "main"
+ OpName %6 "foo("
+ OpName %10 "x"
+ OpName %12 "i"
+ OpName %33 "i"
+ OpName %42 "j"
+ OpDecorate %10 RelaxedPrecision
+ OpDecorate %12 RelaxedPrecision
+ OpDecorate %19 RelaxedPrecision
+ OpDecorate %23 RelaxedPrecision
+ OpDecorate %24 RelaxedPrecision
+ OpDecorate %25 RelaxedPrecision
+ OpDecorate %26 RelaxedPrecision
+ OpDecorate %27 RelaxedPrecision
+ OpDecorate %28 RelaxedPrecision
+ OpDecorate %30 RelaxedPrecision
+ OpDecorate %33 RelaxedPrecision
+ OpDecorate %39 RelaxedPrecision
+ OpDecorate %42 RelaxedPrecision
+ OpDecorate %49 RelaxedPrecision
+ OpDecorate %52 RelaxedPrecision
+ OpDecorate %53 RelaxedPrecision
+ OpDecorate %58 RelaxedPrecision
+ OpDecorate %59 RelaxedPrecision
+ OpDecorate %60 RelaxedPrecision
+ OpDecorate %63 RelaxedPrecision
+ OpDecorate %64 RelaxedPrecision
+ %2 = OpTypeVoid
+ %3 = OpTypeFunction %2
+ %8 = OpTypeInt 32 1
+ %9 = OpTypePointer Function %8
+ %11 = OpConstant %8 2
+ %13 = OpConstant %8 0
+ %20 = OpConstant %8 100
+ %21 = OpTypeBool
+ %29 = OpConstant %8 1
+ %40 = OpConstant %8 10
+ %43 = OpConstant %8 20
+ %61 = OpConstant %8 4
+ %4 = OpFunction %2 None %3
+ %5 = OpLabel
+ %33 = OpVariable %9 Function
+ %42 = OpVariable %9 Function
+ %32 = OpFunctionCall %2 %6
+ OpStore %33 %13
+ OpBranch %34
+ %34 = OpLabel
+ OpLoopMerge %36 %37 None
+ OpBranch %38
+ %38 = OpLabel
+ %39 = OpLoad %8 %33
+ %41 = OpSLessThan %21 %39 %40
+ OpBranchConditional %41 %35 %36
+ %35 = OpLabel
+ OpStore %42 %43
+ OpBranch %44
+ %44 = OpLabel
+ OpLoopMerge %46 %47 None
+ OpBranch %48
+ %48 = OpLabel
+ %49 = OpLoad %8 %42
+ %50 = OpSGreaterThan %21 %49 %13
+ OpBranchConditional %50 %45 %46
+ %45 = OpLabel
+ %51 = OpFunctionCall %2 %6
+ %52 = OpLoad %8 %42
+ %53 = OpISub %8 %52 %29
+ OpStore %42 %53
+ OpBranch %47
+ %47 = OpLabel
+ OpBranch %44
+ %46 = OpLabel
+ OpBranch %54
+ %54 = OpLabel
+ OpLoopMerge %56 %57 None
+ OpBranch %55
+ %55 = OpLabel
+ %58 = OpLoad %8 %33
+ %59 = OpIAdd %8 %58 %29
+ OpStore %33 %59
+ OpBranch %57
+ %57 = OpLabel
+ %60 = OpLoad %8 %33
+ %62 = OpSLessThan %21 %60 %61
+ OpBranchConditional %62 %54 %56
+ %56 = OpLabel
+ OpBranch %37
+ %37 = OpLabel
+ %63 = OpLoad %8 %33
+ %64 = OpIAdd %8 %63 %29
+ OpStore %33 %64
+ OpBranch %34
+ %36 = OpLabel
+ OpReturn
+ OpFunctionEnd
+ %6 = OpFunction %2 None %3
+ %7 = OpLabel
+ %10 = OpVariable %9 Function
+ %12 = OpVariable %9 Function
+ OpStore %10 %11
+ OpStore %12 %13
+ OpBranch %14
+ %14 = OpLabel
+ OpLoopMerge %16 %17 None
+ OpBranch %18
+ %18 = OpLabel
+ %19 = OpLoad %8 %12
+ %22 = OpSLessThan %21 %19 %20
+ OpBranchConditional %22 %15 %16
+ %15 = OpLabel
+ %23 = OpLoad %8 %12
+ %24 = OpLoad %8 %10
+ %25 = OpIAdd %8 %24 %23
+ OpStore %10 %25
+ %26 = OpLoad %8 %10
+ %27 = OpIMul %8 %26 %11
+ OpStore %10 %27
+ OpBranch %17
+ %17 = OpLabel
+ %28 = OpLoad %8 %12
+ %30 = OpIAdd %8 %28 %29
+ OpStore %12 %30
+ OpBranch %14
+ %16 = OpLabel
+ OpReturn
+ OpFunctionEnd
+ )";
+
+ // Do 10 fuzzer runs, starting from an initial seed of 0 (seed value chosen
+ // arbitrarily).
+ RunFuzzer(shader, 0, 10);
+}
+
+TEST(FuzzerTest, Miscellaneous2) {
+ // The SPIR-V came from this GLSL, which was then optimized using spirv-opt
+ // with the -O argument:
+ //
+ // #version 310 es
+ //
+ // precision highp float;
+ //
+ // layout(location = 0) out vec4 _GLF_color;
+ //
+ // layout(set = 0, binding = 0) uniform buf0 {
+ // vec2 injectionSwitch;
+ // };
+ // layout(set = 0, binding = 1) uniform buf1 {
+ // vec2 resolution;
+ // };
+ // bool checkSwap(float a, float b)
+ // {
+ // return gl_FragCoord.y < resolution.y / 2.0 ? a > b : a < b;
+ // }
+ // void main()
+ // {
+ // float data[10];
+ // for(int i = 0; i < 10; i++)
+ // {
+ // data[i] = float(10 - i) * injectionSwitch.y;
+ // }
+ // for(int i = 0; i < 9; i++)
+ // {
+ // for(int j = 0; j < 10; j++)
+ // {
+ // if(j < i + 1)
+ // {
+ // continue;
+ // }
+ // bool doSwap = checkSwap(data[i], data[j]);
+ // if(doSwap)
+ // {
+ // float temp = data[i];
+ // data[i] = data[j];
+ // data[j] = temp;
+ // }
+ // }
+ // }
+ // if(gl_FragCoord.x < resolution.x / 2.0)
+ // {
+ // _GLF_color = vec4(data[0] / 10.0, data[5] / 10.0, data[9] / 10.0, 1.0);
+ // }
+ // else
+ // {
+ // _GLF_color = vec4(data[5] / 10.0, data[9] / 10.0, data[0] / 10.0, 1.0);
+ // }
+ // }
+
+ std::string shader = R"(
+ OpCapability Shader
+ %1 = OpExtInstImport "GLSL.std.450"
+ OpMemoryModel Logical GLSL450
+ OpEntryPoint Fragment %4 "main" %16 %139
+ OpExecutionMode %4 OriginUpperLeft
+ OpSource ESSL 310
+ OpName %4 "main"
+ OpName %16 "gl_FragCoord"
+ OpName %23 "buf1"
+ OpMemberName %23 0 "resolution"
+ OpName %25 ""
+ OpName %61 "data"
+ OpName %66 "buf0"
+ OpMemberName %66 0 "injectionSwitch"
+ OpName %68 ""
+ OpName %139 "_GLF_color"
+ OpDecorate %16 BuiltIn FragCoord
+ OpMemberDecorate %23 0 Offset 0
+ OpDecorate %23 Block
+ OpDecorate %25 DescriptorSet 0
+ OpDecorate %25 Binding 1
+ OpDecorate %64 RelaxedPrecision
+ OpMemberDecorate %66 0 Offset 0
+ OpDecorate %66 Block
+ OpDecorate %68 DescriptorSet 0
+ OpDecorate %68 Binding 0
+ OpDecorate %75 RelaxedPrecision
+ OpDecorate %95 RelaxedPrecision
+ OpDecorate %126 RelaxedPrecision
+ OpDecorate %128 RelaxedPrecision
+ OpDecorate %139 Location 0
+ OpDecorate %182 RelaxedPrecision
+ OpDecorate %183 RelaxedPrecision
+ OpDecorate %184 RelaxedPrecision
+ %2 = OpTypeVoid
+ %3 = OpTypeFunction %2
+ %6 = OpTypeFloat 32
+ %7 = OpTypePointer Function %6
+ %8 = OpTypeBool
+ %14 = OpTypeVector %6 4
+ %15 = OpTypePointer Input %14
+ %16 = OpVariable %15 Input
+ %17 = OpTypeInt 32 0
+ %18 = OpConstant %17 1
+ %19 = OpTypePointer Input %6
+ %22 = OpTypeVector %6 2
+ %23 = OpTypeStruct %22
+ %24 = OpTypePointer Uniform %23
+ %25 = OpVariable %24 Uniform
+ %26 = OpTypeInt 32 1
+ %27 = OpConstant %26 0
+ %28 = OpTypePointer Uniform %6
+ %56 = OpConstant %26 10
+ %58 = OpConstant %17 10
+ %59 = OpTypeArray %6 %58
+ %60 = OpTypePointer Function %59
+ %66 = OpTypeStruct %22
+ %67 = OpTypePointer Uniform %66
+ %68 = OpVariable %67 Uniform
+ %74 = OpConstant %26 1
+ %83 = OpConstant %26 9
+ %129 = OpConstant %17 0
+ %138 = OpTypePointer Output %14
+ %139 = OpVariable %138 Output
+ %144 = OpConstant %26 5
+ %151 = OpConstant %6 1
+ %194 = OpConstant %6 0.5
+ %195 = OpConstant %6 0.100000001
+ %4 = OpFunction %2 None %3
+ %5 = OpLabel
+ %61 = OpVariable %60 Function
+ OpBranch %50
+ %50 = OpLabel
+ %182 = OpPhi %26 %27 %5 %75 %51
+ %57 = OpSLessThan %8 %182 %56
+ OpLoopMerge %52 %51 None
+ OpBranchConditional %57 %51 %52
+ %51 = OpLabel
+ %64 = OpISub %26 %56 %182
+ %65 = OpConvertSToF %6 %64
+ %69 = OpAccessChain %28 %68 %27 %18
+ %70 = OpLoad %6 %69
+ %71 = OpFMul %6 %65 %70
+ %72 = OpAccessChain %7 %61 %182
+ OpStore %72 %71
+ %75 = OpIAdd %26 %182 %74
+ OpBranch %50
+ %52 = OpLabel
+ OpBranch %77
+ %77 = OpLabel
+ %183 = OpPhi %26 %27 %52 %128 %88
+ %84 = OpSLessThan %8 %183 %83
+ OpLoopMerge %79 %88 None
+ OpBranchConditional %84 %78 %79
+ %78 = OpLabel
+ OpBranch %86
+ %86 = OpLabel
+ %184 = OpPhi %26 %27 %78 %126 %89
+ %92 = OpSLessThan %8 %184 %56
+ OpLoopMerge %88 %89 None
+ OpBranchConditional %92 %87 %88
+ %87 = OpLabel
+ %95 = OpIAdd %26 %183 %74
+ %96 = OpSLessThan %8 %184 %95
+ OpSelectionMerge %98 None
+ OpBranchConditional %96 %97 %98
+ %97 = OpLabel
+ OpBranch %89
+ %98 = OpLabel
+ %104 = OpAccessChain %7 %61 %183
+ %105 = OpLoad %6 %104
+ %107 = OpAccessChain %7 %61 %184
+ %108 = OpLoad %6 %107
+ %166 = OpAccessChain %19 %16 %18
+ %167 = OpLoad %6 %166
+ %168 = OpAccessChain %28 %25 %27 %18
+ %169 = OpLoad %6 %168
+ %170 = OpFMul %6 %169 %194
+ %171 = OpFOrdLessThan %8 %167 %170
+ OpSelectionMerge %172 None
+ OpBranchConditional %171 %173 %174
+ %173 = OpLabel
+ %177 = OpFOrdGreaterThan %8 %105 %108
+ OpBranch %172
+ %174 = OpLabel
+ %180 = OpFOrdLessThan %8 %105 %108
+ OpBranch %172
+ %172 = OpLabel
+ %186 = OpPhi %8 %177 %173 %180 %174
+ OpSelectionMerge %112 None
+ OpBranchConditional %186 %111 %112
+ %111 = OpLabel
+ %116 = OpLoad %6 %104
+ %120 = OpLoad %6 %107
+ OpStore %104 %120
+ OpStore %107 %116
+ OpBranch %112
+ %112 = OpLabel
+ OpBranch %89
+ %89 = OpLabel
+ %126 = OpIAdd %26 %184 %74
+ OpBranch %86
+ %88 = OpLabel
+ %128 = OpIAdd %26 %183 %74
+ OpBranch %77
+ %79 = OpLabel
+ %130 = OpAccessChain %19 %16 %129
+ %131 = OpLoad %6 %130
+ %132 = OpAccessChain %28 %25 %27 %129
+ %133 = OpLoad %6 %132
+ %134 = OpFMul %6 %133 %194
+ %135 = OpFOrdLessThan %8 %131 %134
+ OpSelectionMerge %137 None
+ OpBranchConditional %135 %136 %153
+ %136 = OpLabel
+ %140 = OpAccessChain %7 %61 %27
+ %141 = OpLoad %6 %140
+ %143 = OpFMul %6 %141 %195
+ %145 = OpAccessChain %7 %61 %144
+ %146 = OpLoad %6 %145
+ %147 = OpFMul %6 %146 %195
+ %148 = OpAccessChain %7 %61 %83
+ %149 = OpLoad %6 %148
+ %150 = OpFMul %6 %149 %195
+ %152 = OpCompositeConstruct %14 %143 %147 %150 %151
+ OpStore %139 %152
+ OpBranch %137
+ %153 = OpLabel
+ %154 = OpAccessChain %7 %61 %144
+ %155 = OpLoad %6 %154
+ %156 = OpFMul %6 %155 %195
+ %157 = OpAccessChain %7 %61 %83
+ %158 = OpLoad %6 %157
+ %159 = OpFMul %6 %158 %195
+ %160 = OpAccessChain %7 %61 %27
+ %161 = OpLoad %6 %160
+ %162 = OpFMul %6 %161 %195
+ %163 = OpCompositeConstruct %14 %156 %159 %162 %151
+ OpStore %139 %163
+ OpBranch %137
+ %137 = OpLabel
+ OpReturn
+ OpFunctionEnd
+ )";
+
+ // Do 10 fuzzer runs, starting from an initial seed of 10 (seed value chosen
+ // arbitrarily).
+ RunFuzzer(shader, 10, 10);
+}
+
+} // namespace
+} // namespace fuzz
+} // namespace spvtools
