Add ComputeLog2 test

BUG=chromium:1046622

Change-Id: Ic554190ed95efbd555472db95cbbd9aed66a950d
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/39961
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Auto-Submit: Ryan Harrison <rharrison@chromium.org>

src/tests/BUILD.gn

@@ -320,6 +320,7 @@ source_set("dawn_end2end_tests_sources") {
     "end2end/SamplerTests.cpp",
     "end2end/ScissorTests.cpp",
     "end2end/ShaderFloat16Tests.cpp",
+    "end2end/ShaderTests.cpp",
     "end2end/StorageTextureTests.cpp",
     "end2end/SubresourceRenderAttachmentTests.cpp",
     "end2end/TextureFormatTests.cpp",

src/tests/end2end/ShaderTests.cpp

@@ -0,0 +1,95 @@
+// Copyright 2021 The Dawn 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 "tests/DawnTest.h"
+
+#include "tests/DawnTest.h"
+#include "utils/WGPUHelpers.h"
+
+#include <vector>
+
+class ShaderTests : public DawnTest {};
+
+// Test that log2 is being properly calculated, base on crbug.com/1046622
+TEST_P(ShaderTests, ComputeLog2) {
+    // TODO(crbug.com/dawn/663): log2(32) is currently being incorrectly calculated.
+    DAWN_SKIP_TEST_IF(IsMacOS() && IsIntel());
+
+    uint32_t const kSteps = 19;
+    std::vector<uint32_t> data(kSteps, 0);
+    std::vector<uint32_t> expected{0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 32};
+    uint64_t bufferSize = static_cast<uint64_t>(data.size() * sizeof(uint32_t));
+    wgpu::Buffer buffer = utils::CreateBufferFromData(
+        device, data.data(), bufferSize, wgpu::BufferUsage::Storage | wgpu::BufferUsage::CopySrc);
+
+    std::string shader = R"(
+[[block]] struct Buf {
+    [[offset(0)]] data : [[stride(4)]] array<u32, 19>;
+};
+
+[[group(0), binding(0)]] var<storage_buffer> buf : [[access(read_write)]] Buf;
+
+[[stage(compute)]] fn main() -> void {
+    buf.data[0] = u32(log2(1.0));
+    buf.data[1] = u32(log2(2.0));
+    buf.data[2] = u32(log2(3.0));
+    buf.data[3] = u32(log2(4.0));
+    buf.data[4] = u32(log2(7.0));
+    buf.data[5] = u32(log2(8.0));
+    buf.data[6] = u32(log2(15.0));
+    buf.data[7] = u32(log2(16.0));
+    buf.data[8] = u32(log2(31.0));
+    buf.data[9] = u32(log2(32.0));
+    buf.data[10] = u32(log2(63.0));
+    buf.data[11] = u32(log2(64.0));
+    buf.data[12] = u32(log2(127.0));
+    buf.data[13] = u32(log2(128.0));
+    buf.data[14] = u32(log2(255.0));
+    buf.data[15] = u32(log2(256.0));
+    buf.data[16] = u32(log2(511.0));
+    buf.data[17] = u32(log2(512.0));
+    buf.data[18] = u32(log2(4294967295.0));
+})";
+
+    wgpu::ComputePipelineDescriptor csDesc;
+    csDesc.computeStage.module = utils::CreateShaderModuleFromWGSL(device, shader.c_str());
+    csDesc.computeStage.entryPoint = "main";
+    wgpu::ComputePipeline pipeline = device.CreateComputePipeline(&csDesc);
+
+    wgpu::BindGroup bindGroup =
+        utils::MakeBindGroup(device, pipeline.GetBindGroupLayout(0), {{0, buffer}});
+
+    wgpu::CommandBuffer commands;
+    {
+        wgpu::CommandEncoder encoder = device.CreateCommandEncoder();
+        wgpu::ComputePassEncoder pass = encoder.BeginComputePass();
+        pass.SetPipeline(pipeline);
+        pass.SetBindGroup(0, bindGroup);
+        pass.Dispatch(1);
+        pass.EndPass();
+
+        commands = encoder.Finish();
+    }
+
+    queue.Submit(1, &commands);
+
+    EXPECT_BUFFER_U32_RANGE_EQ(expected.data(), buffer, 0, kSteps);
+}
+
+DAWN_INSTANTIATE_TEST(ShaderTests,
+                      D3D12Backend(),
+                      MetalBackend(),
+                      OpenGLBackend(),
+                      OpenGLESBackend(),
+                      VulkanBackend());