// Copyright 2020 The Tint Authors.
//
// 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 <vector>

#include "gmock/gmock.h"
#include "src/reader/spirv/function.h"
#include "src/reader/spirv/parser_impl.h"
#include "src/reader/spirv/parser_impl_test_helper.h"
#include "src/reader/spirv/spirv_tools_helpers_test.h"

namespace tint {
namespace reader {
namespace spirv {
namespace {

using ::testing::ElementsAre;

std::string CommonTypes() {
  return R"(
    %void = OpTypeVoid
    %voidfn = OpTypeFunction %void

    %bool = OpTypeBool
    %cond = OpUndef %bool

    %uint = OpTypeInt 32 0
    %selector = OpUndef %uint
  )";
}

TEST_F(SpvParserTest, ComputeBlockOrder_OneBlock) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %42 = OpLabel
     OpReturn

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(42));
}

TEST_F(SpvParserTest, ComputeBlockOrder_IgnoreStaticalyUnreachable) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpBranch %20

     %15 = OpLabel ; statically dead
     OpReturn

     %20 = OpLabel
     OpReturn

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 20));
}

TEST_F(SpvParserTest, ComputeBlockOrder_ReorderSequence) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpBranch %20

     %30 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %30 ; backtrack

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 20, 30));
}

TEST_F(SpvParserTest, ComputeBlockOrder_RespectConditionalBranchOrder) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpBranchConditional %cond %20 %30

     %99 = OpLabel
     OpReturn

     %30 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 20, 30, 99));
}

TEST_F(SpvParserTest, ComputeBlockOrder_TrueOnlyBranch) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpBranchConditional %cond %20 %99

     %99 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 20, 99));
}

TEST_F(SpvParserTest, ComputeBlockOrder_FalseOnlyBranch) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpBranchConditional %cond %99 %20

     %99 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 20, 99));
}

TEST_F(SpvParserTest, ComputeBlockOrder_SwitchOrderNaturallyReversed) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpSwitch %selector %99 20 %20 30 %30

     %99 = OpLabel
     OpReturn

     %30 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 30, 20, 99));
}

TEST_F(SpvParserTest,
       ComputeBlockOrder_SwitchWithDefaultOrderNaturallyReversed) {
  auto* p = parser(test::Assemble(CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpSwitch %selector %80 20 %20 30 %30

     %80 = OpLabel ; the default case
     OpBranch %99

     %99 = OpLabel
     OpReturn

     %30 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )"));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 30, 20, 80, 99));
}

TEST_F(SpvParserTest, ComputeBlockOrder_RespectSwitchCaseFallthrough) {
  auto assembly = CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpSwitch %selector %99 20 %20 30 %30 40 %40 50 %50

     %50 = OpLabel
     OpBranch %99

     %99 = OpLabel
     OpReturn

     %40 = OpLabel
     OpBranch %99

     %30 = OpLabel
     OpBranch %50 ; fallthrough

     %20 = OpLabel
     OpBranch %40 ; fallthrough

     OpFunctionEnd
  )";
  auto* p = parser(test::Assemble(assembly));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 30, 50, 20, 40, 99)) << assembly;
}

TEST_F(SpvParserTest,
       ComputeBlockOrder_RespectSwitchCaseFallthrough_FromDefault) {
  auto assembly = CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpSwitch %selector %80 20 %20 30 %30 40 %40

     %80 = OpLabel ; the default case
     OpBranch %30 ; fallthrough to another case

     %99 = OpLabel
     OpReturn

     %40 = OpLabel
     OpBranch %99

     %30 = OpLabel
     OpBranch %40

     %20 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )";
  auto* p = parser(test::Assemble(assembly));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 20, 80, 30, 40, 99)) << assembly;
}

TEST_F(SpvParserTest,
       ComputeBlockOrder_RespectSwitchCaseFallthrough_FromCaseToDefaultToCase) {
  auto assembly = CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpSwitch %selector %80 20 %20 30 %30

     %99 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %80 ; fallthrough to default

     %80 = OpLabel ; the default case
     OpBranch %30 ; fallthrough to 30

     %30 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )";
  auto* p = parser(test::Assemble(assembly));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 20, 80, 30, 99)) << assembly;
}

TEST_F(SpvParserTest,
       ComputeBlockOrder_SwitchCasesFallthrough_OppositeDirections) {
  auto assembly = CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpSwitch %selector %99 20 %20 30 %30 40 %40 50 %50

     %99 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %30 ; forward

     %40 = OpLabel
     OpBranch %99

     %30 = OpLabel
     OpBranch %99

     ; SPIR-V doesn't actually allow a fall-through that goes backward in the
     ; module. But the block ordering algorithm tolerates it.
     %50 = OpLabel
     OpBranch %40 ; backward

     OpFunctionEnd
  )";
  auto* p = parser(test::Assemble(assembly));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 50, 40, 20, 30, 99)) << assembly;
}

TEST_F(SpvParserTest,
       ComputeBlockOrder_RespectSwitchCaseFallthrough_Interleaved) {
  auto assembly = CommonTypes() + R"(
     %100 = OpFunction %void None %voidfn

     %10 = OpLabel
     OpSelectionMerge %99 None
     OpSwitch %selector %99 20 %20 30 %30 40 %40 50 %50

     %99 = OpLabel
     OpReturn

     %20 = OpLabel
     OpBranch %40

     %30 = OpLabel
     OpBranch %50

     %40 = OpLabel
     OpBranch %60

     %50 = OpLabel
     OpBranch %70

     %60 = OpLabel
     OpBranch %99

     %70 = OpLabel
     OpBranch %99

     OpFunctionEnd
  )";
  auto* p = parser(test::Assemble(assembly));
  ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
  FunctionEmitter fe(p, *spirv_function(100));
  fe.ComputeBlockOrderAndPositions();

  EXPECT_THAT(fe.rspo(), ElementsAre(10, 30, 50, 70, 20, 40, 60, 99))
      << assembly;
}

// TODO(dneto): test nesting
// TODO(dneto): test loops

}  // namespace
}  // namespace spirv
}  // namespace reader
}  // namespace tint