Metal: Use bit fields for state descriptor caching.

src/libANGLE/renderer/metal/mtl_state_cache.h

@@ -28,24 +28,26 @@ class ContextMtl;
 
 namespace mtl
 {
-struct StencilDesc
+struct alignas(1) StencilDesc
 {
     bool operator==(const StencilDesc &rhs) const;
 
     // Set default values
     void reset();
 
-    MTLStencilOperation stencilFailureOperation;
-    MTLStencilOperation depthFailureOperation;
-    MTLStencilOperation depthStencilPassOperation;
+    // Use uint8_t instead of MTLStencilOperation to compact space
+    uint8_t stencilFailureOperation : 3;
+    uint8_t depthFailureOperation : 3;
+    uint8_t depthStencilPassOperation : 3;
 
-    MTLCompareFunction stencilCompareFunction;
+    // Use uint8_t instead of MTLCompareFunction to compact space
+    uint8_t stencilCompareFunction : 3;
 
-    uint32_t readMask;
-    uint32_t writeMask;
+    uint8_t readMask : 8;
+    uint8_t writeMask : 8;
 };
 
-struct DepthStencilDesc
+struct alignas(4) DepthStencilDesc
 {
     DepthStencilDesc();
     DepthStencilDesc(const DepthStencilDesc &src);
@@ -75,11 +77,12 @@ struct DepthStencilDesc
     StencilDesc backFaceStencil;
     StencilDesc frontFaceStencil;
 
-    MTLCompareFunction depthCompareFunction;
-    bool depthWriteEnabled;
+    // Use uint8_t instead of MTLCompareFunction to compact space
+    uint8_t depthCompareFunction : 3;
+    bool depthWriteEnabled : 1;
 };
 
-struct SamplerDesc
+struct alignas(4) SamplerDesc
 {
     SamplerDesc();
     SamplerDesc(const SamplerDesc &src);
@@ -96,15 +99,17 @@ struct SamplerDesc
 
     size_t hash() const;
 
-    MTLSamplerAddressMode rAddressMode;
-    MTLSamplerAddressMode sAddressMode;
-    MTLSamplerAddressMode tAddressMode;
+    // Use uint8_t instead of MTLSamplerAddressMode to compact space
+    uint8_t rAddressMode : 3;
+    uint8_t sAddressMode : 3;
+    uint8_t tAddressMode : 3;
 
-    MTLSamplerMinMagFilter minFilter;
-    MTLSamplerMinMagFilter magFilter;
-    MTLSamplerMipFilter mipFilter;
+    // Use uint8_t instead of MTLSamplerMinMagFilter to compact space
+    uint8_t minFilter : 1;
+    uint8_t magFilter : 1;
+    uint8_t mipFilter : 2;
 
-    uint32_t maxAnisotropy;
+    uint8_t maxAnisotropy : 5;
 };
 
 struct VertexAttributeDesc
@@ -114,9 +119,12 @@ struct VertexAttributeDesc
         return format == rhs.format && offset == rhs.offset && bufferIndex == rhs.bufferIndex;
     }
     inline bool operator!=(const VertexAttributeDesc &rhs) const { return !(*this == rhs); }
-    MTLVertexFormat format;
-    NSUInteger offset;
-    NSUInteger bufferIndex;
+
+    // Use uint8_t instead of MTLVertexFormat to compact space
+    uint8_t format : 6;
+    // Offset is only used for default attributes buffer. So 8 bits are enough.
+    uint8_t offset : 8;
+    uint8_t bufferIndex : 5;
 };
 
 struct VertexBufferLayoutDesc
@@ -127,9 +135,11 @@ struct VertexBufferLayoutDesc
     }
     inline bool operator!=(const VertexBufferLayoutDesc &rhs) const { return !(*this == rhs); }
 
-    MTLVertexStepFunction stepFunction;
-    NSUInteger stepRate;
-    NSUInteger stride;
+    uint32_t stepRate;
+    uint32_t stride;
+
+    // Use uint8_t instead of MTLVertexStepFunction to compact space
+    uint8_t stepFunction;
 };
 
 struct VertexDesc
@@ -155,20 +165,24 @@ struct BlendDesc
     void updateBlendOps(const gl::BlendState &blendState);
     void updateBlendEnabled(const gl::BlendState &blendState);
 
-    MTLColorWriteMask writeMask;
+    // Use uint8_t instead of MTLColorWriteMask to compact space
+    uint8_t writeMask : 4;
 
-    MTLBlendOperation alphaBlendOperation;
-    MTLBlendOperation rgbBlendOperation;
+    // Use uint8_t instead of MTLBlendOperation to compact space
+    uint8_t alphaBlendOperation : 3;
+    uint8_t rgbBlendOperation : 3;
 
-    MTLBlendFactor destinationAlphaBlendFactor;
-    MTLBlendFactor destinationRGBBlendFactor;
-    MTLBlendFactor sourceAlphaBlendFactor;
-    MTLBlendFactor sourceRGBBlendFactor;
+    // Use uint8_t instead of MTLBlendFactor to compact space
+    // NOTE(hqle): enum MTLBlendFactorSource1Color and above are unused.
+    uint8_t destinationAlphaBlendFactor : 4;
+    uint8_t destinationRGBBlendFactor : 4;
+    uint8_t sourceAlphaBlendFactor : 4;
+    uint8_t sourceRGBBlendFactor : 4;
 
-    bool blendingEnabled;
+    bool blendingEnabled : 1;
 };
 
-struct RenderPipelineColorAttachmentDesc : public BlendDesc
+struct alignas(2) RenderPipelineColorAttachmentDesc : public BlendDesc
 {
     bool operator==(const RenderPipelineColorAttachmentDesc &rhs) const;
     inline bool operator!=(const RenderPipelineColorAttachmentDesc &rhs) const
@@ -184,7 +198,8 @@ struct RenderPipelineColorAttachmentDesc : public BlendDesc
 
     void update(const BlendDesc &blendState);
 
-    MTLPixelFormat pixelFormat;
+    // Use uint16_t instead of MTLPixelFormat to compact space
+    uint16_t pixelFormat : 16;
 };
 
 struct RenderPipelineOutputDesc
@@ -192,10 +207,13 @@ struct RenderPipelineOutputDesc
     bool operator==(const RenderPipelineOutputDesc &rhs) const;
 
     RenderPipelineColorAttachmentDesc colorAttachments[kMaxRenderTargets];
-    MTLPixelFormat depthAttachmentPixelFormat;
-    MTLPixelFormat stencilAttachmentPixelFormat;
 
-    uint8_t numColorAttachments;
+    // Use uint16_t instead of MTLPixelFormat to compact space
+    uint16_t depthAttachmentPixelFormat : 16;
+    uint16_t stencilAttachmentPixelFormat : 16;
+
+    static_assert(kMaxRenderTargets <= 4, "kMaxRenderTargets must be <= 4");
+    uint8_t numColorAttachments : 3;
 };
 
 // Some SDK levels don't declare MTLPrimitiveTopologyClass. Needs to do compile time check here:
@@ -212,7 +230,7 @@ constexpr PrimitiveTopologyClass kPrimitiveTopologyClassTriangle =
 constexpr PrimitiveTopologyClass kPrimitiveTopologyClassPoint = MTLPrimitiveTopologyClassPoint;
 #endif
 
-struct RenderPipelineDesc
+struct alignas(4) RenderPipelineDesc
 {
     RenderPipelineDesc();
     RenderPipelineDesc(const RenderPipelineDesc &src);
@@ -228,7 +246,8 @@ struct RenderPipelineDesc
 
     RenderPipelineOutputDesc outputDescriptor;
 
-    PrimitiveTopologyClass inputPrimitiveTopology;
+    // Use uint8_t instead of PrimitiveTopologyClass to compact space.
+    uint8_t inputPrimitiveTopology : 2;
 
     bool rasterizationEnabled;
 };

src/libANGLE/renderer/metal/mtl_state_cache.mm

@@ -18,7 +18,8 @@
 #include "libANGLE/renderer/metal/mtl_resources.h"
 #include "libANGLE/renderer/metal/mtl_utils.h"
 
-#define ANGLE_OBJC_CP_PROPERTY(DST, SRC, PROPERTY) (DST).PROPERTY = ToObjC((SRC).PROPERTY)
+#define ANGLE_OBJC_CP_PROPERTY(DST, SRC, PROPERTY) \
+    (DST).PROPERTY = static_cast<__typeof__((DST).PROPERTY)>(ToObjC((SRC).PROPERTY))
 
 #define ANGLE_PROP_EQ(LHS, RHS, PROP) ((LHS).PROP == (RHS).PROP)