commit be7f44fb57412071a76cd9995ba8e4c21bb09c7b
author jchen10 <jie.a.chen@intel.com> Mon May 21 14:35:32 2018 +0800
committer Commit Bot <commit-bot@chromium.org> Wed May 23 05:15:32 2018 +0000
tree 6bea9df7a513739bf49505b4f472334fe6874179
parent b1e913801502c7380d68d0101e4399f4550f4dc3

Vulkan: Use push constant for masked clear color

Storing the color in an uniform buffer, and updating it by
vkCmdUpdateBuffer can hit a driver bug. Using vkCmdPushConstants
instead can workaround this bug. Besides, push constant is expected
to outperform memory-backed resource update according to the vkspec
(section 13.2.6).

Bug: angleproject:2547

Change-Id: I319cd8e07e0a1d0cb56005b78a46466d9fca436e
Reviewed-on: https://chromium-review.googlesource.com/1067247
Commit-Queue: Jie A Chen <jie.a.chen@intel.com>
Reviewed-by: Luc Ferron <lucferron@chromium.org>

src/libANGLE/renderer/vulkan/RendererVk.cpp

diff --git a/src/libANGLE/renderer/vulkan/RendererVk.cpp b/src/libANGLE/renderer/vulkan/RendererVk.cpp
index 37a0ad1..175ce65 100644
--- a/src/libANGLE/renderer/vulkan/RendererVk.cpp
+++ b/src/libANGLE/renderer/vulkan/RendererVk.cpp
@@ -220,7 +220,7 @@
     }
 
     mGraphicsPipelineLayout.destroy(mDevice);
-    mInternalUniformPipelineLayout.destroy(mDevice);
+    mInternalPushConstantPipelineLayout.destroy(mDevice);
 
     mRenderPassCache.destroy(mDevice);
     mPipelineCache.destroy(mDevice);
@@ -952,30 +952,30 @@
     return vk::NoError();
 }
 
-const vk::DescriptorSetLayout &RendererVk::getInternalUniformDescriptorSetLayout() const
+vk::Error RendererVk::getInternalPushConstantPipelineLayout(
+    const vk::PipelineLayout **pipelineLayoutOut)
 {
-    return mGraphicsDescriptorSetLayouts[0];
-}
-
-vk::Error RendererVk::getInternalUniformPipelineLayout(const vk::PipelineLayout **pipelineLayoutOut)
-{
-    *pipelineLayoutOut = &mInternalUniformPipelineLayout;
-    if (mInternalUniformPipelineLayout.valid())
+    *pipelineLayoutOut = &mInternalPushConstantPipelineLayout;
+    if (mInternalPushConstantPipelineLayout.valid())
     {
         return vk::NoError();
     }
 
-    // Here we use the knowledge that the "graphics" descriptor set has uniform blocks at offset 0.
+    VkPushConstantRange pushConstantRange;
+    pushConstantRange.stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;
+    pushConstantRange.offset     = 0;
+    pushConstantRange.size       = sizeof(VkClearColorValue);
+
     VkPipelineLayoutCreateInfo createInfo;
     createInfo.sType                  = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
     createInfo.pNext                  = nullptr;
     createInfo.flags                  = 0;
-    createInfo.setLayoutCount         = 1;
-    createInfo.pSetLayouts            = mGraphicsDescriptorSetLayouts[0].ptr();
-    createInfo.pushConstantRangeCount = 0;
-    createInfo.pPushConstantRanges    = nullptr;
+    createInfo.setLayoutCount         = 0;
+    createInfo.pSetLayouts            = nullptr;
+    createInfo.pushConstantRangeCount = 1;
+    createInfo.pPushConstantRanges    = &pushConstantRange;
 
-    ANGLE_TRY(mInternalUniformPipelineLayout.init(mDevice, createInfo));
+    ANGLE_TRY(mInternalPushConstantPipelineLayout.init(mDevice, createInfo));
 
     return vk::NoError();
 }