Vulkan: Limit maxPerStageTextures to 4096

Many devices support a huge number of samplers (millions) and every one
needs a uniform location, either generated by ANGLE or assigned by the
user. Limit the number of samplers per stage to something reasonable,
which in turn also lowers the number of uniform locations.

This isn't expected to have any practical effect on real apps/users, but
is instead to keep tests for these limits (e.g., dEQP, end2end) within
reason in terms of shader program sizes and compilation times.

Test:
KHR-GLES31.core.explicit_uniform_location.uniform-loc-mix-with-implicit-max
Test: angle_end2end_tests
  --gtest_filter=GLSLTest.VerifyMaxVertexUniformVectorsWithSamplers*

Bug: b/434763439
Change-Id: I378483fd869b9f5ebee21760eec4dec2dd793b92
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6798920
Reviewed-by: Charlie Lao <[email protected]>
Commit-Queue: Tim Van Patten <[email protected]>
Reviewed-by: Shahbaz Youssefi <[email protected]>

Author: timvpGoogle

src/libANGLE/renderer/vulkan/vk_caps_utils.cpp

@@ -765,8 +765,18 @@ void Renderer::ensureCapsInitialized() const
 
     // Note that Vulkan currently implements textures as combined image+samplers, so the limit is
     // the minimum of supported samplers and sampled images.
-    const uint32_t maxPerStageTextures = std::min(limitsVk.maxPerStageDescriptorSamplers,
-                                                  limitsVk.maxPerStageDescriptorSampledImages);
+    uint32_t maxPerStageTextures = std::min(limitsVk.maxPerStageDescriptorSamplers,
+                                            limitsVk.maxPerStageDescriptorSampledImages);
+
+    // Many devices support a huge number of samplers (millions) and every one needs a uniform
+    // location, either generated by ANGLE or assigned by the user. Limit the number of samplers per
+    // stage to something reasonable, which in turn also lowers the number of uniform locations.
+    // This isn't expected to have any practical effect on real apps/users, but is instead to keep
+    // tests for these limits (e.g., dEQP, end2end) within reason in terms of shader program sizes
+    // and compilation times.
+    constexpr uint32_t kMaximumSamplersPerStage = 4096;
+    maxPerStageTextures = std::min(kMaximumSamplersPerStage, maxPerStageTextures);
+
     const uint32_t maxCombinedTextures =
         std::min(limitsVk.maxDescriptorSetSamplers, limitsVk.maxDescriptorSetSampledImages);
     for (gl::ShaderType shaderType : gl::AllShaderTypes())