From 023f2e776eff285da50bcae18f44cb7216e9cc00 Mon Sep 17 00:00:00 2001
From: Jim Van Verth <jvanverth@google.com>
Date: Fri, 9 Oct 2020 15:38:58 -0400
Subject: [PATCH] Use push constants cap in Metal.

* Sets the cap and uses it for verifying vertex/fragmentBytes size instead
of a magic number.
* Also makes maxPushConstantsSize unsigned to avoid warnings and
unnecessary casting.

Change-Id: I2aaea853604eb3c652ddbae3adb0168a4e41799a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324880
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
---
 src/gpu/GrCaps.h                             | 4 ++--
 src/gpu/mtl/GrMtlCaps.mm                     | 2 ++
 src/gpu/mtl/GrMtlPipelineStateDataManager.mm | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/gpu/GrCaps.h b/src/gpu/GrCaps.h
index 89d729edf8..70be646606 100644
--- a/src/gpu/GrCaps.h
+++ b/src/gpu/GrCaps.h
@@ -204,7 +204,7 @@ public:
         return this->maxWindowRectangles() > 0 && this->onIsWindowRectanglesSupportedForRT(rt);
     }
 
-    int maxPushConstantsSize() const { return fMaxPushConstantsSize; }
+    uint32_t maxPushConstantsSize() const { return fMaxPushConstantsSize; }
 
     virtual bool isFormatSRGB(const GrBackendFormat&) const = 0;
 
@@ -544,7 +544,7 @@ protected:
     int fMaxTileSize;
     int fMaxWindowRectangles;
     int fInternalMultisampleCount;
-    int fMaxPushConstantsSize = 0;
+    uint32_t fMaxPushConstantsSize = 0;
 
     GrDriverBugWorkarounds fDriverBugWorkarounds;
 
diff --git a/src/gpu/mtl/GrMtlCaps.mm b/src/gpu/mtl/GrMtlCaps.mm
index 962f9b9a8d..09fdeb9c72 100644
--- a/src/gpu/mtl/GrMtlCaps.mm
+++ b/src/gpu/mtl/GrMtlCaps.mm
@@ -287,6 +287,8 @@ void GrMtlCaps::initGrCaps(const id<MTLDevice> device) {
     fMaxPreferredRenderTargetSize = fMaxRenderTargetSize;
     fMaxTextureSize = fMaxRenderTargetSize;
 
+    fMaxPushConstantsSize = 4*1024;
+
     // Init sample counts. All devices support 1 (i.e. 0 in skia).
     fSampleCounts.push_back(1);
     if (@available(iOS 9.0, *)) {
diff --git a/src/gpu/mtl/GrMtlPipelineStateDataManager.mm b/src/gpu/mtl/GrMtlPipelineStateDataManager.mm
index 63722e1ef9..b8ed721155 100644
--- a/src/gpu/mtl/GrMtlPipelineStateDataManager.mm
+++ b/src/gpu/mtl/GrMtlPipelineStateDataManager.mm
@@ -332,7 +332,7 @@ void GrMtlPipelineStateDataManager::uploadAndBindUniformBuffers(
         id<MTLRenderCommandEncoder> renderCmdEncoder) const {
     if (fUniformSize && fUniformsDirty) {
         if (@available(macOS 10.11, iOS 8.3, *)) {
-            SkASSERT(fUniformSize <= 4*1024);
+            SkASSERT(fUniformSize <= gpu->caps()->maxPushConstantsSize());
             [renderCmdEncoder setVertexBytes: fUniformData.get()
                                       length: fUniformSize
                                      atIndex: GrMtlUniformHandler::kUniformBinding];