Reland "Add a Vulkan feature to compress float32 vertex formats."

This reverts commit 8ace36f8c1.

Original change's description:
> Revert "Add a Vulkan feature to compress float32 vertex formats."
>
> Bug: b/167404532
> Bug: b/161716126
> Change-Id: I95157a006d5c1fd2d3c0c2c2be37fa0403c07f93
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2510011
> Reviewed-by: Tim Van Patten <timvp@google.com>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>
> Commit-Queue: Geoff Lang <geofflang@chromium.org>

Bug: b/167404532
Bug: b/161716126
Change-Id: Ic6811fe3a7124e6eb1efe7c72a1a03a120217753
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2815260
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Charlie Lao <cclao@google.com>

include/platform/FeaturesVk.h

@@ -451,6 +451,14 @@ struct FeaturesVk : FeatureSetBase
                                         FeatureCategory::VulkanWorkarounds,
                                         "Force nearest mip filtering when sampling.", &members};
 
+    // Compress float32 vertices in static buffers to float16 at draw time. ANGLE is non-conformant
+    // if this feature is enabled.
+    angle::Feature compressVertexData = {"compress_vertex_data",
+                                         angle::FeatureCategory::VulkanWorkarounds,
+                                         "Compress vertex data to smaller data types when "
+                                         "possible. Using this feature makes ANGLE non-conformant.",
+                                         &members};
+
     // Qualcomm missynchronizes vkCmdClearAttachments in the middle of render pass.
     // https://issuetracker.google.com/166809097
     Feature preferDrawClearOverVkCmdClearAttachments = {

src/libANGLE/renderer/vulkan/RendererVk.cpp

@@ -2396,6 +2396,8 @@ void RendererVk::initFeatures(DisplayVk *displayVk,
     ANGLE_FEATURE_CONDITION(&mFeatures, forceNearestFiltering, false);
     ANGLE_FEATURE_CONDITION(&mFeatures, forceNearestMipFiltering, false);
 
+    ANGLE_FEATURE_CONDITION(&mFeatures, compressVertexData, false);
+
     ANGLE_FEATURE_CONDITION(
         &mFeatures, preferDrawClearOverVkCmdClearAttachments,
         IsPixel2(mPhysicalDeviceProperties.vendorID, mPhysicalDeviceProperties.deviceID));

src/libANGLE/renderer/vulkan/VertexArrayVk.cpp

@@ -601,6 +601,14 @@ angle::Result VertexArrayVk::syncDirtyAttrib(ContextVk *contextVk,
             bool bindingIsAligned               = BindingIsAligned(
                 binding, intendedFormat, intendedFormat.channelCount, attrib.relativeOffset);
 
+            if (renderer->getFeatures().compressVertexData.enabled &&
+                gl::IsStaticBufferUsage(bufferGL->getUsage()) &&
+                vertexFormat.actualCompressedBufferFormatID != angle::FormatID::NONE &&
+                vertexFormat.actualBufferFormatID != vertexFormat.actualCompressedBufferFormatID)
+            {
+                compressed = true;
+            }
+
             if (vertexFormat.getVertexLoadRequiresConversion(compressed) || !bindingIsAligned)
             {
                 ANGLE_TRY(WarnOnVertexFormatConversion(contextVk, vertexFormat, compressed, true));
@@ -610,6 +618,16 @@ angle::Result VertexArrayVk::syncDirtyAttrib(ContextVk *contextVk,
                     binding.getOffset() + attrib.relativeOffset, !bindingIsAligned);
                 if (conversion->dirty)
                 {
+                    if (compressed)
+                    {
+                        INFO() << "Compressing vertex data in buffer " << bufferGL->id().value
+                               << " from "
+                               << static_cast<unsigned int>(vertexFormat.intendedFormatID) << " to "
+                               << static_cast<unsigned int>(
+                                      vertexFormat.actualCompressedBufferFormatID)
+                               << ".";
+                    }
+
                     if (bindingIsAligned)
                     {
                         ANGLE_TRY(convertVertexBufferGPU(contextVk, bufferVk, binding, attribIndex,

src/libANGLE/renderer/vulkan/vk_format_utils.cpp

@@ -178,7 +178,7 @@ void Format::initBufferFallback(RendererVk *renderer,
         vertexLoadRequiresConversion = info[i].vertexLoadRequiresConversion;
     }
 
-    if (compressedStartIndex < numInfo)
+    if (renderer->getFeatures().compressVertexData.enabled && compressedStartIndex < numInfo)
     {
         int i = FindSupportedFormat(renderer, info, compressedStartIndex, numInfo,
                                     HasFullBufferFormatSupport);