GL: Limit uniform block size to 64KB

This change works around an inefficiency in ANGLE when the uniform block has a large size. That will be fixed in a follow up, but in the meantime this clamping makes ANGLE more uniform on different vendors (most of which expose this limit as 64KB already). This also aligns with the strategy adopted by the Vulkan backend. Bug: angleproject:346561003 Change-Id: Id23a1f1bbbc1c7224c432d5bee1c4989ff2c92b7 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5645627 Reviewed-by: Geoff Lang <[email protected]> Commit-Queue: Shahbaz Youssefi <[email protected]>
google · Jun 21, 2024 · 3be15cb · 3be15cb
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commit 3be15cb
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Showing 2 changed files with 7 additions and 6 deletions.
diff --git a/src/libANGLE/renderer/gl/renderergl_utils.cpp b/src/libANGLE/renderer/gl/renderergl_utils.cpp
@@ -1065,6 +1065,10 @@ void GenerateCaps(const FunctionsGL *functions,
  QuerySingleGLInt64(functions, GL_MAX_COMBINED_VERTEX_UNIFORM_COMPONENTS);
  caps->maxCombinedShaderUniformComponents[gl::ShaderType::Fragment] =
  QuerySingleGLInt64(functions, GL_MAX_COMBINED_FRAGMENT_UNIFORM_COMPONENTS);
+
+ // Clamp the maxUniformBlockSize to 64KB (majority of devices support up to this size
+ // currently), some drivers expose an excessively large value.
+ caps->maxUniformBlockSize = std::min<GLint64>(0x10000, caps->maxUniformBlockSize);
  }
  else
  {

diff --git a/src/tests/gl_tests/UniformBufferTest.cpp b/src/tests/gl_tests/UniformBufferTest.cpp
@@ -3835,7 +3835,7 @@ TEST_P(WebGL2UniformBufferTest, LargeArrayOfStructs)
  constexpr char kVertexShader[] = R"(
  struct InstancingData
  {
- mat4 transformation;
+ vec4 transformation;
  };
 
  layout(std140) uniform InstanceBlock
@@ -3845,7 +3845,7 @@ TEST_P(WebGL2UniformBufferTest, LargeArrayOfStructs)
 
  void main()
  {
- gl_Position = vec4(1.0) * instances[gl_InstanceID].transformation;
+ gl_Position = vec4(1.0) * instances[gl_InstanceID].transformation[0];
  })";
 
  constexpr char kFragmentShader[] = R"(#version 300 es
@@ -3860,12 +3860,9 @@ TEST_P(WebGL2UniformBufferTest, LargeArrayOfStructs)
  glGetIntegerv(GL_MAX_UNIFORM_BLOCK_SIZE, &maxUniformBlockSize);
 
  std::string vs = "#version 300 es\n#define MAX_INSTANCE_COUNT " +
- std::to_string(std::min(800, maxUniformBlockSize / 64)) + kVertexShader;
+ std::to_string(maxUniformBlockSize / 16) + kVertexShader;
 
  ANGLE_GL_PROGRAM(program, vs.c_str(), kFragmentShader);
- // Add a draw call for the sake of the Vulkan backend that currently really builds shaders at
- // draw time.
- drawQuad(program, essl3_shaders::PositionAttrib(), 0.5f);
 }
 
 GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(UniformBufferTest);