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// Copyright (c) 2021 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/opt/dataflow.h"
#include <map>
#include <set>
#include "gtest/gtest.h"
#include "opt/function_utils.h"
#include "source/opt/build_module.h"
namespace spvtools {
namespace opt {
namespace {
using DataFlowTest = ::testing::Test;
// Simple analyses for testing:
// Stores the result IDs of visited instructions in visit order.
struct VisitOrder : public ForwardDataFlowAnalysis {
std::vector<uint32_t> visited_result_ids;
VisitOrder(IRContext& context, LabelPosition label_position)
: ForwardDataFlowAnalysis(context, label_position) {}
VisitResult Visit(Instruction* inst) override {
if (inst->HasResultId()) {
visited_result_ids.push_back(inst->result_id());
}
return DataFlowAnalysis::VisitResult::kResultFixed;
}
};
// For each block, stores the set of blocks it can be preceded by.
// For example, with the following CFG:
// V-----------.
// -> 11 -> 12 -> 13 -> 15
// \-> 14 ---^
//
// The answer is:
// 11: 11, 12, 13
// 12: 11, 12, 13
// 13: 11, 12, 13
// 14: 11, 12, 13
// 15: 11, 12, 13, 14
struct BackwardReachability : public ForwardDataFlowAnalysis {
std::map<uint32_t, std::set<uint32_t>> reachable_from;
BackwardReachability(IRContext& context)
: ForwardDataFlowAnalysis(
context, ForwardDataFlowAnalysis::LabelPosition::kLabelsOnly) {}
VisitResult Visit(Instruction* inst) override {
// Conditional branches can be enqueued from labels, so skip them.
if (inst->opcode() != spv::Op::OpLabel)
return DataFlowAnalysis::VisitResult::kResultFixed;
uint32_t id = inst->result_id();
VisitResult ret = DataFlowAnalysis::VisitResult::kResultFixed;
std::set<uint32_t>& precedents = reachable_from[id];
for (uint32_t pred : context().cfg()->preds(id)) {
bool pred_inserted = precedents.insert(pred).second;
if (pred_inserted) {
ret = DataFlowAnalysis::VisitResult::kResultChanged;
}
for (uint32_t block : reachable_from[pred]) {
bool inserted = precedents.insert(block).second;
if (inserted) {
ret = DataFlowAnalysis::VisitResult::kResultChanged;
}
}
}
return ret;
}
void InitializeWorklist(Function* function,
bool is_first_iteration) override {
// Since successor function is exact, only need one pass.
if (is_first_iteration) {
ForwardDataFlowAnalysis::InitializeWorklist(function, true);
}
}
};
TEST_F(DataFlowTest, ReversePostOrder) {
// Note: labels and IDs are intentionally out of order.
//
// CFG: (order of branches is from bottom to top)
// V-----------.
// -> 50 -> 40 -> 20 -> 60 -> 70
// \-> 30 ---^
// DFS tree with RPO numbering:
// -> 50[0] -> 40[1] -> 20[2] 60[4] -> 70[5]
// \-> 30[3] ---^
const std::string text = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource GLSL 430
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%6 = OpTypeBool
%5 = OpConstantTrue %6
%2 = OpFunction %3 None %4
%50 = OpLabel
%51 = OpUndef %6
%52 = OpUndef %6
OpBranch %40
%70 = OpLabel
%69 = OpUndef %6
OpReturn
%60 = OpLabel
%61 = OpUndef %6
OpBranchConditional %5 %70 %40
%30 = OpLabel
%29 = OpUndef %6
OpBranch %60
%20 = OpLabel
%21 = OpUndef %6
OpBranch %60
%40 = OpLabel
%39 = OpUndef %6
OpBranchConditional %5 %30 %20
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_2, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
ASSERT_NE(context, nullptr);
Function* function = spvtest::GetFunction(context->module(), 2);
std::map<ForwardDataFlowAnalysis::LabelPosition, std::vector<uint32_t>>
expected_order;
expected_order[ForwardDataFlowAnalysis::LabelPosition::kLabelsOnly] = {
50, 40, 20, 30, 60, 70,
};
expected_order[ForwardDataFlowAnalysis::LabelPosition::kLabelsAtBeginning] = {
50, 51, 52, 40, 39, 20, 21, 30, 29, 60, 61, 70, 69,
};
expected_order[ForwardDataFlowAnalysis::LabelPosition::kLabelsAtEnd] = {
51, 52, 50, 39, 40, 21, 20, 29, 30, 61, 60, 69, 70,
};
expected_order[ForwardDataFlowAnalysis::LabelPosition::kNoLabels] = {
51, 52, 39, 21, 29, 61, 69,
};
for (const auto& test_case : expected_order) {
VisitOrder analysis(*context, test_case.first);
analysis.Run(function);
EXPECT_EQ(test_case.second, analysis.visited_result_ids);
}
}
TEST_F(DataFlowTest, BackwardReachability) {
// CFG:
// V-----------.
// -> 11 -> 12 -> 13 -> 15
// \-> 14 ---^
const std::string text = R"(
OpCapability Shader
%1 = OpExtInstImport "GLSL.std.450"
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %2 "main"
OpExecutionMode %2 OriginUpperLeft
OpSource GLSL 430
%3 = OpTypeVoid
%4 = OpTypeFunction %3
%6 = OpTypeBool
%5 = OpConstantTrue %6
%2 = OpFunction %3 None %4
%11 = OpLabel
OpBranch %12
%12 = OpLabel
OpBranchConditional %5 %14 %13
%13 = OpLabel
OpBranchConditional %5 %15 %11
%14 = OpLabel
OpBranch %15
%15 = OpLabel
OpReturn
OpFunctionEnd
)";
std::unique_ptr<IRContext> context =
BuildModule(SPV_ENV_UNIVERSAL_1_2, nullptr, text,
SPV_TEXT_TO_BINARY_OPTION_PRESERVE_NUMERIC_IDS);
ASSERT_NE(context, nullptr);
Function* function = spvtest::GetFunction(context->module(), 2);
BackwardReachability analysis(*context);
analysis.Run(function);
std::map<uint32_t, std::set<uint32_t>> expected_result;
expected_result[11] = {11, 12, 13};
expected_result[12] = {11, 12, 13};
expected_result[13] = {11, 12, 13};
expected_result[14] = {11, 12, 13};
expected_result[15] = {11, 12, 13, 14};
EXPECT_EQ(expected_result, analysis.reachable_from);
}
} // namespace
} // namespace opt
} // namespace spvtools
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