Metal: Use compute to generate 3D texture's mipmap.

include/platform/FeaturesMtl.h

@@ -59,6 +59,10 @@ struct FeaturesMtl : FeatureSetBase
     Feature allowMultisampleStoreAndResolve = {
         "allow_msaa_store_and_resolve", FeatureCategory::MetalFeatures,
         "The renderer supports MSAA store and resolve in the same pass", &members};
+
+    Feature allowGenMultipleMipsPerPass = {
+        "gen_multiple_mips_per_pass", FeatureCategory::MetalFeatures,
+        "The renderer supports generating multiple mipmaps per pass", &members};
 };
 
 }  // namespace angle

src/libANGLE/renderer/metal/DisplayMtl.mm

@@ -686,6 +686,7 @@ void DisplayMtl::initializeFeatures()
     mFeatures.hasStencilOutput.enabled                  = false;
     mFeatures.hasTextureSwizzle.enabled                 = false;
     mFeatures.allowSeparatedDepthStencilBuffers.enabled = false;
+    mFeatures.allowGenMultipleMipsPerPass.enabled       = true;
 
     ANGLE_FEATURE_CONDITION((&mFeatures), hasDepthTextureFiltering,
                             TARGET_OS_OSX || TARGET_OS_MACCATALYST);

src/libANGLE/renderer/metal/TextureMtl.h

@@ -180,6 +180,7 @@ class TextureMtl : public TextureImpl
     // Ensure all image views at all faces/levels are retained.
     void retainImageDefinitions();
     mtl::TextureRef createImageViewFromNativeTexture(GLuint cubeFaceOrZero, GLuint nativeLevel);
+    angle::Result ensureNativeLevelViewsCreated();
     angle::Result checkForEmulatedChannels(const gl::Context *context,
                                            const mtl::Format &mtlFormat,
                                            const mtl::TextureRef &texture);
@@ -314,6 +315,7 @@ class TextureMtl : public TextureImpl
     // Stored images array defined by glTexImage/glCopy*.
     // Once the images array is complete, they will be transferred to real texture object.
     // NOTE:
+    //  - The second dimension is indexed by configured base level + actual native level
     //  - For Cube map, there will be at most 6 entries in the mTexImageDefs table, one for each
     //  face. This is because the Cube map's image is defined per face & per level.
     //  - For other texture types, there will be only one entry in the map table. All other textures
@@ -324,8 +326,12 @@ class TextureMtl : public TextureImpl
     // - For 2D texture: There will be one key entry in the map.
     // - For Cube map: There will be at most 6 key entries.
     // - For array/3D texture: There will be at most slices/depths number of key entries.
+    // - The second dimension is indexed by configured base level + actual native level
     std::map<int, gl::TexLevelArray<RenderTargetMtl>> mPerLayerRenderTargets;
 
+    // Mipmap views are indexed by native level (ignored base level):
+    gl::TexLevelArray<mtl::TextureRef> mNativeLevelViews;
+
     bool mIsPow2 = false;
 };
 

src/libANGLE/renderer/metal/TextureMtl.mm

@@ -430,6 +430,11 @@ void TextureMtl::releaseTexture(bool releaseImages, bool releaseTextureObjectsOn
         }
     }
 
+    for (mtl::TextureRef &view : mNativeLevelViews)
+    {
+        view.reset();
+    }
+
     if (!releaseTextureObjectsOnly)
     {
         mMetalSamplerState = nil;
@@ -575,6 +580,31 @@ angle::Result TextureMtl::ensureImageCreated(const gl::Context *context,
     return angle::Result::Continue;
 }
 
+angle::Result TextureMtl::ensureNativeLevelViewsCreated()
+{
+    ASSERT(mNativeTexture);
+    const GLuint baseLevel = mState.getEffectiveBaseLevel();
+    for (uint32_t mip = 0; mip < mNativeTexture->mipmapLevels(); ++mip)
+    {
+        if (mNativeLevelViews[mip])
+        {
+            continue;
+        }
+
+        if (mNativeTexture->textureType() != MTLTextureTypeCube &&
+            mTexImageDefs[0][mip + baseLevel].image)
+        {
+            // Reuse texture image view.
+            mNativeLevelViews[mip] = mTexImageDefs[0][mip + baseLevel].image;
+        }
+        else
+        {
+            mNativeLevelViews[mip] = mNativeTexture->createMipView(mip);
+        }
+    }
+    return angle::Result::Continue;
+}
+
 mtl::TextureRef TextureMtl::createImageViewFromNativeTexture(GLuint cubeFaceOrZero,
                                                              GLuint nativeLevel)
 {
@@ -586,8 +616,16 @@ mtl::TextureRef TextureMtl::createImageViewFromNativeTexture(GLuint cubeFaceOrZe
     }
     else
     {
+        if (mNativeLevelViews[nativeLevel])
+        {
+            // Reuse the native level view
+            image = mNativeLevelViews[nativeLevel];
+        }
+        else
+        {
             image = mNativeTexture->createMipView(nativeLevel);
         }
+    }
 
     return image;
 }
@@ -927,7 +965,17 @@ angle::Result TextureMtl::generateMipmap(const gl::Context *context)
 
     const mtl::FormatCaps &caps = mFormat.getCaps();
 
-    if (caps.filterable && caps.colorRenderable)
+    if (caps.writable && mState.getType() == gl::TextureType::_3D)
+    {
+        // http://anglebug.com/4921.
+        // Use compute for 3D mipmap generation.
+        ANGLE_TRY(ensureNativeLevelViewsCreated());
+        bool sRGB = mFormat.metalFormat == MTLPixelFormatRGBA8Unorm_sRGB ||
+                    mFormat.metalFormat == MTLPixelFormatBGRA8Unorm_sRGB;
+        ANGLE_TRY(contextMtl->getDisplay()->getUtils().generateMipmapCS(contextMtl, mNativeTexture,
+                                                                        sRGB, &mNativeLevelViews));
+    }
+    else if (caps.filterable && caps.colorRenderable)
     {
         mtl::BlitCommandEncoder *blitEncoder = contextMtl->getBlitCommandEncoder();
         blitEncoder->generateMipmapsForTexture(mNativeTexture);

src/libANGLE/renderer/metal/mtl_render_utils.h

@@ -126,7 +126,7 @@ struct IndexGenerationParams
 };
 
 // Utils class for clear & blitting
-class ClearUtils
+class ClearUtils final : angle::NonCopyable
 {
   public:
     ClearUtils();
@@ -154,7 +154,7 @@ class ClearUtils
     std::array<RenderPipelineCache, kMaxRenderTargets + 1> mClearRenderPipelineCache;
 };
 
-class ColorBlitUtils
+class ColorBlitUtils final : angle::NonCopyable
 {
   public:
     ColorBlitUtils();
@@ -192,7 +192,7 @@ class ColorBlitUtils
     ColorBlitRenderPipelineCacheArray mBlitUnmultiplyAlphaRenderPipelineCache;
 };
 
-class DepthStencilBlitUtils
+class DepthStencilBlitUtils final : angle::NonCopyable
 {
   public:
     void onDestroy();
@@ -242,7 +242,7 @@ class DepthStencilBlitUtils
 };
 
 // util class for generating index buffer
-class IndexGeneratorUtils
+class IndexGeneratorUtils final : angle::NonCopyable
 {
   public:
     void onDestroy();
@@ -310,6 +310,25 @@ class IndexGeneratorUtils
     AutoObjCPtr<id<MTLComputePipelineState>> mTriFanFromArraysGeneratorPipeline;
 };
 
+// Util class for handling mipmap generation
+class MipmapUtils final : angle::NonCopyable
+{
+  public:
+    void onDestroy();
+
+    // Compute based mipmap generation. Only possible for 3D texture for now.
+    angle::Result generateMipmapCS(ContextMtl *contextMtl,
+                                   const TextureRef &srcTexture,
+                                   bool sRGBMipmap,
+                                   gl::TexLevelArray<mtl::TextureRef> *mipmapOutputViews);
+
+  private:
+    void ensure3DMipGeneratorPipelineInitialized(ContextMtl *contextMtl);
+
+    // Mipmaps generating compute pipeline:
+    AutoObjCPtr<id<MTLComputePipelineState>> m3DMipGeneratorPipeline;
+};
+
 // RenderUtils: container class of various util classes above
 class RenderUtils : public Context, angle::NonCopyable
 {
@@ -356,6 +375,12 @@ class RenderUtils : public Context, angle::NonCopyable
     angle::Result generateLineLoopLastSegmentFromElementsArray(ContextMtl *contextMtl,
                                                                const IndexGenerationParams &params);
 
+    // Compute based mipmap generation. Only possible for 3D texture for now.
+    angle::Result generateMipmapCS(ContextMtl *contextMtl,
+                                   const TextureRef &srcTexture,
+                                   bool sRGBMipmap,
+                                   gl::TexLevelArray<mtl::TextureRef> *mipmapOutputViews);
+
   private:
     // override ErrorHandler
     void handleError(GLenum error,
@@ -371,6 +396,7 @@ class RenderUtils : public Context, angle::NonCopyable
     ColorBlitUtils mColorBlitUtils;
     DepthStencilBlitUtils mDepthStencilBlitUtils;
     IndexGeneratorUtils mIndexUtils;
+    MipmapUtils mMipmapUtils;
 };
 
 }  // namespace mtl

src/libANGLE/renderer/metal/mtl_render_utils.mm

@@ -77,6 +77,15 @@ struct IndexConversionUniform
     uint32_t padding[2];
 };
 
+// See libANGLE/renderer/metal/shaders/gen_mipmap.metal
+struct GenerateMipmapUniform
+{
+    uint32_t srcLevel;
+    uint32_t numMipmapsToGenerate;
+    uint8_t sRGB;
+    uint8_t padding[7];
+};
+
 void GetBlitTexCoords(uint32_t srcWidth,
                       uint32_t srcHeight,
                       const gl::Rectangle &srcRect,
@@ -570,6 +579,15 @@ angle::Result RenderUtils::generateLineLoopLastSegmentFromElementsArray(
     return mIndexUtils.generateLineLoopLastSegmentFromElementsArray(contextMtl, params);
 }
 
+// Compute based mipmap generation
+angle::Result RenderUtils::generateMipmapCS(ContextMtl *contextMtl,
+                                            const TextureRef &srcTexture,
+                                            bool sRGBMipmap,
+                                            gl::TexLevelArray<mtl::TextureRef> *mipmapOutputViews)
+{
+    return mMipmapUtils.generateMipmapCS(contextMtl, srcTexture, sRGBMipmap, mipmapOutputViews);
+}
+
 // ClearUtils implementation
 ClearUtils::ClearUtils() = default;
 
@@ -1566,5 +1584,110 @@ angle::Result IndexGeneratorUtils::generateLineLoopLastSegmentFromElementsArrayC
     return generateLineLoopLastSegment(contextMtl, first, last, params.dstBuffer, params.dstOffset);
 }
 
+// MipmapUtils implementation
+void MipmapUtils::onDestroy()
+{
+    m3DMipGeneratorPipeline = nil;
+}
+
+void MipmapUtils::ensure3DMipGeneratorPipelineInitialized(ContextMtl *contextMtl)
+{
+    EnsureComputePipelineInitialized(contextMtl->getDisplay(), @"generate3DMipmaps",
+                                     &m3DMipGeneratorPipeline);
+}
+
+angle::Result MipmapUtils::generateMipmapCS(ContextMtl *contextMtl,
+                                            const TextureRef &srcTexture,
+                                            bool sRGBMipmap,
+                                            gl::TexLevelArray<mtl::TextureRef> *mipmapOutputViews)
+{
+    // Only support 3D texture for now.
+    ASSERT(srcTexture->textureType() == MTLTextureType3D);
+
+    MTLSize threadGroupSize;
+    uint32_t slices                             = 1;
+    id<MTLComputePipelineState> computePipeline = nil;
+
+    ensure3DMipGeneratorPipelineInitialized(contextMtl);
+    computePipeline = m3DMipGeneratorPipeline;
+    threadGroupSize =
+        MTLSizeMake(kGenerateMipThreadGroupSizePerDim, kGenerateMipThreadGroupSizePerDim,
+                    kGenerateMipThreadGroupSizePerDim);
+
+    // The compute shader supports up to 4 mipmaps generated per pass.
+    // See shaders/gen_mipmap.metal
+    uint32_t maxMipsPerBatch = 4;
+
+    if (threadGroupSize.width * threadGroupSize.height * threadGroupSize.depth >
+            computePipeline.maxTotalThreadsPerThreadgroup ||
+        ANGLE_UNLIKELY(
+            !contextMtl->getDisplay()->getFeatures().allowGenMultipleMipsPerPass.enabled))
+    {
+        // Multiple mipmaps generation is not supported due to hardware's thread group size limits.
+        // Fallback to generate one mip per pass and reduce thread group size.
+        if (ANGLE_UNLIKELY(threadGroupSize.width * threadGroupSize.height >
+                           computePipeline.maxTotalThreadsPerThreadgroup))
+        {
+            // Even with reduced thread group size, we cannot proceed.
+            // HACK: use blit command encoder to generate mipmaps if it is not possible
+            // to use compute shader due to hardware limits.
+            BlitCommandEncoder *blitEncoder = contextMtl->getBlitCommandEncoder();
+            blitEncoder->generateMipmapsForTexture(srcTexture);
+            return angle::Result::Continue;
+        }
+
+        threadGroupSize.depth = 1;
+        maxMipsPerBatch       = 1;
+    }
+
+    ComputeCommandEncoder *cmdEncoder = contextMtl->getComputeCommandEncoder();
+    ASSERT(cmdEncoder);
+    cmdEncoder->setComputePipelineState(computePipeline);
+
+    GenerateMipmapUniform options;
+
+    uint32_t remainMips = srcTexture->mipmapLevels() - 1;
+    options.srcLevel    = 0;
+    options.sRGB        = sRGBMipmap;
+
+    cmdEncoder->setTexture(srcTexture, 0);
+    cmdEncoder->markResourceBeingWrittenByGPU(srcTexture);
+    while (remainMips)
+    {
+        const TextureRef &firstMipView = mipmapOutputViews->at(options.srcLevel + 1);
+        gl::Extents size               = firstMipView->size();
+        bool isPow2 = gl::isPow2(size.width) && gl::isPow2(size.height) && gl::isPow2(size.depth);
+
+        // Currently multiple mipmaps generation is only supported for power of two base level.
+        if (isPow2)
+        {
+            options.numMipmapsToGenerate = std::min(remainMips, maxMipsPerBatch);
+        }
+        else
+        {
+            options.numMipmapsToGenerate = 1;
+        }
+
+        cmdEncoder->setData(options, 0);
+
+        for (uint32_t i = 1; i <= options.numMipmapsToGenerate; ++i)
+        {
+            cmdEncoder->setTexture(mipmapOutputViews->at(options.srcLevel + i), i);
+        }
+
+        uint32_t threadsPerZ = std::max(slices, firstMipView->depth());
+
+        DispatchCompute(contextMtl, cmdEncoder,
+                        /** allowNonUniform */ false,
+                        MTLSizeMake(firstMipView->width(), firstMipView->height(), threadsPerZ),
+                        threadGroupSize);
+
+        remainMips -= options.numMipmapsToGenerate;
+        options.srcLevel += options.numMipmapsToGenerate;
+    }
+
+    return angle::Result::Continue;
+}
+
 }  // namespace mtl
 }  // namespace rx

src/libANGLE/renderer/metal/mtl_resources.mm

@@ -250,6 +250,10 @@ Texture::Texture(ContextMtl *context,
         if (!renderTargetOnly)
         {
             desc.usage = desc.usage | MTLTextureUsageShaderRead;
+            if (context->getNativeFormatCaps(desc.pixelFormat).writable)
+            {
+                desc.usage = desc.usage | MTLTextureUsageShaderWrite;
+            }
         }
 
         if (allowFormatView)

src/tests/test_utils/angle_test_configs.cpp

@@ -214,6 +214,11 @@ std::ostream &operator<<(std::ostream &stream, const PlatformParameters &pp)
         stream << "_NoStencilOutput";
     }
 
+    if (pp.eglParameters.genMultipleMipsPerPassFeature == EGL_FALSE)
+    {
+        stream << "_NoGenMultipleMipsPerPass";
+    }
+
     return stream;
 }
 

src/tests/test_utils/angle_test_configs.h

@@ -234,6 +234,13 @@ inline PlatformParameters WithNoShaderStencilOutput(const PlatformParameters &pa
     return re;
 }
 
+inline PlatformParameters WithNoGenMultipleMipsPerPass(const PlatformParameters &params)
+{
+    PlatformParameters re                          = params;
+    re.eglParameters.genMultipleMipsPerPassFeature = EGL_FALSE;
+    return re;
+}
+
 inline PlatformParameters WithRobustness(const PlatformParameters &params)
 {
     PlatformParameters withRobustness       = params;

util/EGLPlatformParameters.h

@@ -61,7 +61,8 @@ struct EGLPlatformParameters
         return std::tie(renderer, majorVersion, minorVersion, deviceType, presentPath,
                         debugLayersEnabled, contextVirtualization, transformFeedbackFeature,
                         allocateNonZeroMemoryFeature, emulateCopyTexImage2DFromRenderbuffers,
-                        shaderStencilOutputFeature, platformMethods, robustness);
+                        shaderStencilOutputFeature, genMultipleMipsPerPassFeature, platformMethods,
+                        robustness);
     }
 
     EGLint renderer                               = EGL_PLATFORM_ANGLE_TYPE_DEFAULT_ANGLE;
@@ -76,6 +77,7 @@ struct EGLPlatformParameters
     EGLint allocateNonZeroMemoryFeature           = EGL_DONT_CARE;
     EGLint emulateCopyTexImage2DFromRenderbuffers = EGL_DONT_CARE;
     EGLint shaderStencilOutputFeature             = EGL_DONT_CARE;
+    EGLint genMultipleMipsPerPassFeature          = EGL_DONT_CARE;
     angle::PlatformMethods *platformMethods       = nullptr;
 };
 

util/EGLWindow.cpp

@@ -201,6 +201,11 @@ bool EGLWindow::initializeDisplay(OSWindow *osWindow,
         disabledFeatureOverrides.push_back("has_shader_stencil_output");
     }
 
+    if (params.genMultipleMipsPerPassFeature == EGL_FALSE)
+    {
+        disabledFeatureOverrides.push_back("gen_multiple_mips_per_pass");
+    }
+
     if (!disabledFeatureOverrides.empty())
     {
         if (strstr(extensionString, "EGL_ANGLE_feature_control") == nullptr)