Skip noop draws in the frontend

src/libANGLE/Context.cpp

@@ -14,6 +14,7 @@
 #include <sstream>
 #include <vector>
 
+#include "common/PackedEnums.h"
 #include "common/matrix_utils.h"
 #include "common/platform.h"
 #include "common/utilities.h"
@@ -254,6 +255,46 @@ void LimitCap(CapT *cap, MaxT maximum)
     *cap = std::min(*cap, static_cast<CapT>(maximum));
 }
 
+constexpr angle::PackedEnumMap<gl::PrimitiveMode, GLsizei> kMinimumPrimitiveCounts = {{
+    /* Points */ 1,
+    /* Lines */ 2,
+    /* LineLoop */ 2,
+    /* LineStrip */ 2,
+    /* Triangles */ 3,
+    /* TriangleStrip */ 3,
+    /* TriangleFan */ 3,
+    /* LinesAdjacency */ 2,
+    /* LineStripAdjacency */ 2,
+    /* TrianglesAdjacency */ 3,
+    /* TriangleStripAdjacency */ 3,
+}};
+// Indices above are code-gen'd so make sure they don't change
+//  if any of these static asserts are hit, must update kMinimumPrimitiveCounts abouve
+static_assert(static_cast<gl::PrimitiveMode>(0) == gl::PrimitiveMode::Points,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(1) == gl::PrimitiveMode::Lines,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(2) == gl::PrimitiveMode::LineLoop,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(3) == gl::PrimitiveMode::LineStrip,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(4) == gl::PrimitiveMode::Triangles,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(5) == gl::PrimitiveMode::TriangleStrip,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(6) == gl::PrimitiveMode::TriangleFan,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(7) == gl::PrimitiveMode::LinesAdjacency,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(8) == gl::PrimitiveMode::LineStripAdjacency,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(9) == gl::PrimitiveMode::TrianglesAdjacency,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(10) == gl::PrimitiveMode::TriangleStripAdjacency,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+static_assert(static_cast<gl::PrimitiveMode>(11) == gl::PrimitiveMode::EnumCount,
+              "gl::PrimitiveMode enum values have changed, update kMinimumPrimitiveCounts.");
+
 }  // anonymous namespace
 
 namespace gl
@@ -2090,8 +2131,8 @@ void Context::texParameterIuivRobust(TextureType target,
 
 void Context::drawArrays(PrimitiveMode mode, GLint first, GLsizei count)
 {
-    // No-op if zero count
-    if (count == 0)
+    // No-op if count draws no primitives for given mode
+    if (noopDraw(mode, count))
     {
         return;
     }
@@ -2106,8 +2147,8 @@ void Context::drawArraysInstanced(PrimitiveMode mode,
                                   GLsizei count,
                                   GLsizei instanceCount)
 {
-    // No-op if zero count
-    if (count == 0 || instanceCount == 0)
+    // No-op if count draws no primitives for given mode
+    if (noopDrawInstanced(mode, count, instanceCount))
     {
         return;
     }
@@ -2121,8 +2162,8 @@ void Context::drawArraysInstanced(PrimitiveMode mode,
 
 void Context::drawElements(PrimitiveMode mode, GLsizei count, GLenum type, const void *indices)
 {
-    // No-op if zero count
-    if (count == 0)
+    // No-op if count draws no primitives for given mode
+    if (noopDraw(mode, count))
     {
         return;
     }
@@ -2137,8 +2178,8 @@ void Context::drawElementsInstanced(PrimitiveMode mode,
                                     const void *indices,
                                     GLsizei instances)
 {
-    // No-op if zero count
-    if (count == 0 || instances == 0)
+    // No-op if count draws no primitives for given mode
+    if (noopDrawInstanced(mode, count, instances))
     {
         return;
     }
@@ -2155,8 +2196,8 @@ void Context::drawRangeElements(PrimitiveMode mode,
                                 GLenum type,
                                 const void *indices)
 {
-    // No-op if zero count
-    if (count == 0)
+    // No-op if count draws no primitives for given mode
+    if (noopDraw(mode, count))
     {
         return;
     }
@@ -3331,6 +3372,19 @@ void Context::initWorkarounds()
     mWorkarounds.loseContextOnOutOfMemory = (mResetStrategy == GL_LOSE_CONTEXT_ON_RESET_EXT);
 }
 
+// Return true if the draw is a no-op, else return false.
+//  A no-op draw occurs if the count of vertices is less than the minimum required to
+//  have a valid primitive for this mode (0 for points, 0-1 for lines, 0-2 for tris).
+bool Context::noopDraw(PrimitiveMode mode, GLsizei count)
+{
+    return count < kMinimumPrimitiveCounts[mode];
+}
+
+bool Context::noopDrawInstanced(PrimitiveMode mode, GLsizei count, GLsizei instanceCount)
+{
+    return (instanceCount == 0) || noopDraw(mode, count);
+}
+
 Error Context::prepareForDraw(PrimitiveMode mode)
 {
     if (mGLES1Renderer)

src/libANGLE/Context.h

@@ -1475,6 +1475,9 @@ class Context final : public egl::LabeledObject, angle::NonCopyable
   private:
     void initialize();
 
+    bool noopDraw(PrimitiveMode mode, GLsizei count);
+    bool noopDrawInstanced(PrimitiveMode mode, GLsizei count, GLsizei instanceCount);
+
     Error prepareForDraw(PrimitiveMode mode);
     Error prepareForClear(GLbitfield mask);
     Error prepareForClearBuffer(GLenum buffer, GLint drawbuffer);

src/libANGLE/renderer/d3d/d3d11/Renderer11.cpp

@@ -1458,7 +1458,7 @@ gl::Error Renderer11::drawWithGeometryShaderAndTransformFeedback(const gl::Conte
 
 gl::Error Renderer11::drawArrays(const gl::Context *context, const gl::DrawCallParams &params)
 {
-    if (params.vertexCount() < static_cast<size_t>(mStateManager.getCurrentMinimumDrawCount()))
+    if (mStateManager.getCullEverything())
     {
         return gl::NoError();
     }
@@ -1541,7 +1541,7 @@ gl::Error Renderer11::drawArrays(const gl::Context *context, const gl::DrawCallP
 
 gl::Error Renderer11::drawElements(const gl::Context *context, const gl::DrawCallParams &params)
 {
-    if (params.indexCount() < mStateManager.getCurrentMinimumDrawCount())
+    if (mStateManager.getCullEverything())
     {
         return gl::NoError();
     }
@@ -1624,7 +1624,7 @@ gl::Error Renderer11::drawElements(const gl::Context *context, const gl::DrawCal
 gl::Error Renderer11::drawArraysIndirect(const gl::Context *context,
                                          const gl::DrawCallParams &params)
 {
-    if (std::numeric_limits<GLsizei>::max() == mStateManager.getCurrentMinimumDrawCount())
+    if (mStateManager.getCullEverything())
     {
         return gl::NoError();
     }
@@ -1647,7 +1647,7 @@ gl::Error Renderer11::drawArraysIndirect(const gl::Context *context,
 gl::Error Renderer11::drawElementsIndirect(const gl::Context *context,
                                            const gl::DrawCallParams &params)
 {
-    if (std::numeric_limits<GLsizei>::max() == mStateManager.getCurrentMinimumDrawCount())
+    if (mStateManager.getCullEverything())
     {
         return gl::NoError();
     }

src/libANGLE/renderer/d3d/d3d11/StateManager11.cpp

@@ -549,7 +549,7 @@ StateManager11::StateManager11(Renderer11 *renderer)
       mDirtyVertexBufferRange(gl::MAX_VERTEX_ATTRIBS, 0),
       mCurrentPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_UNDEFINED),
       mLastAppliedDrawMode(gl::PrimitiveMode::InvalidEnum),
-      mCurrentMinimumDrawCount(0),
+      mCullEverything(false),
       mDirtySwizzles(false),
       mAppliedIB(nullptr),
       mAppliedIBFormat(DXGI_FORMAT_UNKNOWN),
@@ -3400,6 +3400,8 @@ void StateManager11::syncPrimitiveTopology(const gl::State &glState,
                                            gl::PrimitiveMode currentDrawMode)
 {
     D3D11_PRIMITIVE_TOPOLOGY primitiveTopology = D3D11_PRIMITIVE_TOPOLOGY_UNDEFINED;
+    // Don't cull everything by default, this also resets if we were previously culling
+    mCullEverything = false;
 
     switch (currentDrawMode)
     {
@@ -3414,7 +3416,7 @@ void StateManager11::syncPrimitiveTopology(const gl::State &glState,
             {
                 // Notify developers of risking undefined behavior.
                 WARN() << "Point rendering without writing to gl_PointSize.";
-                mCurrentMinimumDrawCount = std::numeric_limits<GLsizei>::max();
+                mCullEverything = true;
                 return;
             }
 
@@ -3428,36 +3430,29 @@ void StateManager11::syncPrimitiveTopology(const gl::State &glState,
             {
                 primitiveTopology = D3D11_PRIMITIVE_TOPOLOGY_POINTLIST;
             }
-            mCurrentMinimumDrawCount = 1;
             break;
         }
         case gl::PrimitiveMode::Lines:
             primitiveTopology        = D3D_PRIMITIVE_TOPOLOGY_LINELIST;
-            mCurrentMinimumDrawCount = 2;
             break;
         case gl::PrimitiveMode::LineLoop:
             primitiveTopology        = D3D_PRIMITIVE_TOPOLOGY_LINESTRIP;
-            mCurrentMinimumDrawCount = 2;
             break;
         case gl::PrimitiveMode::LineStrip:
             primitiveTopology        = D3D_PRIMITIVE_TOPOLOGY_LINESTRIP;
-            mCurrentMinimumDrawCount = 2;
             break;
         case gl::PrimitiveMode::Triangles:
             primitiveTopology = D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST;
-            mCurrentMinimumDrawCount =
-                CullsEverything(glState) ? std::numeric_limits<GLsizei>::max() : 3;
+            mCullEverything   = CullsEverything(glState);
             break;
         case gl::PrimitiveMode::TriangleStrip:
             primitiveTopology = D3D_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP;
-            mCurrentMinimumDrawCount =
-                CullsEverything(glState) ? std::numeric_limits<GLsizei>::max() : 3;
+            mCullEverything   = CullsEverything(glState);
             break;
         // emulate fans via rewriting index buffer
         case gl::PrimitiveMode::TriangleFan:
             primitiveTopology = D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST;
-            mCurrentMinimumDrawCount =
-                CullsEverything(glState) ? std::numeric_limits<GLsizei>::max() : 3;
+            mCullEverything   = CullsEverything(glState);
             break;
         default:
             UNREACHABLE();

src/libANGLE/renderer/d3d/d3d11/StateManager11.h

@@ -243,7 +243,7 @@ class StateManager11 final : angle::NonCopyable
     // Only used in testing.
     InputLayoutCache *getInputLayoutCache() { return &mInputLayoutCache; }
 
-    GLsizei getCurrentMinimumDrawCount() const { return mCurrentMinimumDrawCount; }
+    bool getCullEverything() const { return mCullEverything; }
     VertexDataManager *getVertexDataManager() { return &mVertexDataManager; }
 
     ProgramD3D *getProgramD3D() const { return mProgramD3D; }
@@ -487,7 +487,7 @@ class StateManager11 final : angle::NonCopyable
     // Currently applied primitive topology
     D3D11_PRIMITIVE_TOPOLOGY mCurrentPrimitiveTopology;
     gl::PrimitiveMode mLastAppliedDrawMode;
-    GLsizei mCurrentMinimumDrawCount;
+    bool mCullEverything;
 
     // Currently applied shaders
     gl::ShaderMap<ResourceSerial> mAppliedShaders;