Metal: Preemptively Start Provoking Vertex CmdBuffer on AMD

There seems to be a bug in older AMD drivers and this appears
to work around it

Bug: angleproject:7635
Change-Id: I1b22e4b7d5d1ce0d405e422d08d33eeeb731050a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3877666
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>

include/platform/FeaturesMtl_autogen.h

@@ -222,6 +222,11 @@ struct FeaturesMtl : FeatureSetBase
         "limitMaxColorTargetBitsForTesting", FeatureCategory::MetalFeatures,
         "Metal iOS has a limit on the number of color target bits per pixel.", &members,
         "http://anglebug.com/7280"};
+
+    FeatureInfo preemptivelyStartProvokingVertexCommandBuffer = {
+        "preemptivelyStartProvokingVertexCommandBuffer", FeatureCategory::MetalFeatures,
+        "AMD Metal Drivers appear to have a bug this works around", &members,
+        "http://anglebug.com/7635"};
 };
 
 inline FeaturesMtl::FeaturesMtl()  = default;

include/platform/mtl_features.json

@@ -227,6 +227,13 @@
                 "Metal iOS has a limit on the number of color target bits per pixel."
             ],
             "issue": "http://anglebug.com/7280"
-        }
-    ]
+        },
+        {
+            "name": "preemptively_start_provoking_vertex_command_buffer",
+            "category": "Features",
+            "description": [
+                "AMD Metal Drivers appear to have a bug this works around"
+            ],
+            "issue": "http://anglebug.com/7635"
+        }    ]
 }

scripts/code_generation_hashes/ANGLE_features.json

@@ -4,7 +4,7 @@
   "include/platform/FeaturesGL_autogen.h":
     "b559f25f72ed9e103c39ef7e130ca58c",
   "include/platform/FeaturesMtl_autogen.h":
-    "6b6d49c35bc9246361f8dac0a5445a02",
+    "2eae56120878fb633700e1cdf56557dd",
   "include/platform/FeaturesVk_autogen.h":
     "c0daa0104f737a5670a00e1183f4e300",
   "include/platform/FrontendFeatures_autogen.h":
@@ -18,11 +18,11 @@
   "include/platform/gl_features.json":
     "3fb9baa3748a8dd383cf189f1bc12d30",
   "include/platform/mtl_features.json":
-    "1fabfe4d5c2eb3683a5b567ab60ad83c",
+    "383be09e93f3d28c79a9f36c186ae2d7",
   "include/platform/vk_features.json":
     "fca1269d2ae63781842f78ef1eaeefea",
   "util/angle_features_autogen.cpp":
-    "a83882020a07f73c06b376a07e0c44a7",
+    "c18ecaee137793f043e35996256ad8e6",
   "util/angle_features_autogen.h":
-    "cb4638d9b5fdddf67659d305f6d387bd"
+    "748e62a5172bb4d469e1a4dd7d1909fc"
 }

src/libANGLE/renderer/metal/ContextMtl.mm

@@ -1881,6 +1881,12 @@ mtl::ComputeCommandEncoder *ContextMtl::getIndexPreprocessingCommandEncoder()
 void ContextMtl::ensureCommandBufferReady()
 {
     flushCommandBufferIfNeeded();
+
+    if (getDisplay()->getFeatures().preemptivelyStartProvokingVertexCommandBuffer.enabled)
+    {
+        mProvokingVertexHelper.ensureCommandBufferReady();
+    }
+
     if (!mCmdBuffer.ready())
     {
         mCmdBuffer.restart();

src/libANGLE/renderer/metal/DisplayMtl.mm

@@ -1141,6 +1141,8 @@ void DisplayMtl::initializeFeatures()
 
     ANGLE_FEATURE_CONDITION((&mFeatures), forceNonCSBaseMipmapGeneration, isIntel());
 
+    ANGLE_FEATURE_CONDITION((&mFeatures), preemptivelyStartProvokingVertexCommandBuffer, isAMD());
+
     bool defaultDirectToMetal = true;
 
     ANGLE_FEATURE_CONDITION((&mFeatures), directMetalGeneration, defaultDirectToMetal);

util/angle_features_autogen.cpp

@@ -182,6 +182,8 @@ constexpr PackedEnumMap<Feature, const char *> kFeatureNames = {{
     {Feature::PersistentlyMappedBuffers, "persistentlyMappedBuffers"},
     {Feature::PreAddTexelFetchOffsets, "preAddTexelFetchOffsets"},
     {Feature::PrecisionSafeDivision, "precisionSafeDivision"},
+    {Feature::PreemptivelyStartProvokingVertexCommandBuffer,
+     "preemptivelyStartProvokingVertexCommandBuffer"},
     {Feature::PreferAggregateBarrierCalls, "preferAggregateBarrierCalls"},
     {Feature::PreferCPUForBufferSubData, "preferCPUForBufferSubData"},
     {Feature::PreferDeviceLocalMemoryHostVisible, "preferDeviceLocalMemoryHostVisible"},

util/angle_features_autogen.h

@@ -173,6 +173,7 @@ enum class Feature
     PersistentlyMappedBuffers,
     PreAddTexelFetchOffsets,
     PrecisionSafeDivision,
+    PreemptivelyStartProvokingVertexCommandBuffer,
     PreferAggregateBarrierCalls,
     PreferCPUForBufferSubData,
     PreferDeviceLocalMemoryHostVisible,