src/tint/lang/spirv/writer/discard_test.cc

// Copyright 2023 The Dawn & Tint Authors
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#include "src/tint/lang/spirv/writer/common/helper_test.h"

namespace tint::spirv::writer {
namespace {

using namespace tint::core::fluent_types;     // NOLINT
using namespace tint::core::number_suffixes;  // NOLINT

TEST_F(SpirvWriterTest, Discard) {
    auto* buffer = b.Var("buffer", ty.ptr<storage, i32>());
    buffer->SetBindingPoint(0, 0);
    mod.root_block->Append(buffer);

    auto* front_facing = b.FunctionParam("front_facing", ty.bool_());
    front_facing->SetBuiltin(core::ir::FunctionParam::Builtin::kFrontFacing);
    auto* ep = b.Function("ep", ty.f32(), core::ir::Function::PipelineStage::kFragment);
    ep->SetParams({front_facing});
    ep->SetReturnLocation(0_u, {});

    b.Append(ep->Block(), [&] {
        auto* ifelse = b.If(front_facing);
        b.Append(ifelse->True(), [&] {  //
            b.Discard();
            b.ExitIf(ifelse);
        });
        b.Store(buffer, 42_i);
        b.Return(ep, 0.5_f);
    });

    ASSERT_TRUE(Generate()) << Error() << output_;
    EXPECT_INST(R"(
   %ep_inner = OpFunction %float None %16
%front_facing = OpFunctionParameter %bool
         %17 = OpLabel
               OpSelectionMerge %18 None
               OpBranchConditional %front_facing %19 %18
         %19 = OpLabel
               OpStore %continue_execution %false
               OpBranch %18
         %18 = OpLabel
         %21 = OpAccessChain %_ptr_StorageBuffer_int %1 %uint_0
         %25 = OpLoad %bool %continue_execution
               OpSelectionMerge %26 None
               OpBranchConditional %25 %27 %26
         %27 = OpLabel
               OpStore %21 %int_42
               OpBranch %26
         %26 = OpLabel
         %29 = OpLoad %bool %continue_execution
         %30 = OpLogicalEqual %bool %29 %false
               OpSelectionMerge %31 None
               OpBranchConditional %30 %32 %31
         %32 = OpLabel
               OpKill
         %31 = OpLabel
               OpReturnValue %float_0_5
               OpFunctionEnd
)");
}

TEST_F(SpirvWriterTest, DiscardBeforeAtomic) {
    auto* buffer = b.Var("buffer", ty.ptr(storage, ty.atomic<i32>()));
    buffer->SetBindingPoint(0, 0);
    mod.root_block->Append(buffer);

    auto* front_facing = b.FunctionParam("front_facing", ty.bool_());
    front_facing->SetBuiltin(core::ir::FunctionParam::Builtin::kFrontFacing);
    auto* ep = b.Function("ep", ty.f32(), core::ir::Function::PipelineStage::kFragment);
    ep->SetParams({front_facing});
    ep->SetReturnLocation(0_u, {});

    b.Append(ep->Block(), [&] {
        auto* ifelse = b.If(front_facing);
        b.Append(ifelse->True(), [&] {  //
            b.Discard();
            b.ExitIf(ifelse);
        });
        b.Call(ty.i32(), core::BuiltinFn::kAtomicAdd, buffer, 1_i);
        b.Return(ep, 0.5_f);
    });

    ASSERT_TRUE(Generate()) << Error() << output_;
    EXPECT_INST(R"(
               ; Function ep_inner
   %ep_inner = OpFunction %float None %16
%front_facing = OpFunctionParameter %bool
         %17 = OpLabel
               OpSelectionMerge %18 None
               OpBranchConditional %front_facing %19 %18
         %19 = OpLabel
               OpStore %continue_execution %false
               OpBranch %18
         %18 = OpLabel
         %21 = OpAccessChain %_ptr_StorageBuffer_int %1 %uint_0
         %25 = OpLoad %bool %continue_execution
               OpSelectionMerge %26 None
               OpBranchConditional %25 %27 %28
         %27 = OpLabel
         %29 = OpAtomicIAdd %int %21 %uint_1 %uint_0 %int_1
               OpBranch %26
         %28 = OpLabel
               OpBranch %26
         %26 = OpLabel
         %32 = OpPhi %int %29 %27 %33 %28
         %34 = OpLoad %bool %continue_execution
         %35 = OpLogicalEqual %bool %34 %false
               OpSelectionMerge %36 None
               OpBranchConditional %35 %37 %36
         %37 = OpLabel
               OpKill
         %36 = OpLabel
               OpReturnValue %float_0_5
               OpFunctionEnd
)");
}

}  // namespace
}  // namespace tint::spirv::writer