Vulkan: Clean up handleDirtyTexturesImpl.

src/common/bitset_utils.h

@@ -139,6 +139,8 @@ class BitSetT final
 
     constexpr static BitSetT Zero() { return BitSetT(); }
 
+    ParamT first() const;
+
   private:
     // Produces a mask of ones up to the "x"th bit.
     constexpr static BitsT Mask(std::size_t x)
@@ -451,6 +453,13 @@ BitSetT<N, BitsT, ParamT> &BitSetT<N, BitsT, ParamT>::flip(ParamT pos)
 }
 
 template <size_t N, typename BitsT, typename ParamT>
+ParamT BitSetT<N, BitsT, ParamT>::first() const
+{
+    ASSERT(!none());
+    return static_cast<ParamT>(gl::ScanForward(mBits));
+}
+
+template <size_t N, typename BitsT, typename ParamT>
 BitSetT<N, BitsT, ParamT>::Iterator::Iterator(const BitSetT &bits) : mBitsCopy(bits), mCurrentBit(0)
 {
     if (bits.any())

src/common/bitset_utils_unittest.cpp

@@ -82,12 +82,14 @@ TYPED_TEST(BitSetTest, Basic)
     EXPECT_TRUE(mBits.any());
     EXPECT_FALSE(mBits.none());
     EXPECT_EQ(mBits.count(), mBits.size() / 2);
+    EXPECT_EQ(mBits.first(), 1u);
 
     mBits.set();
     EXPECT_TRUE(mBits.all());
     EXPECT_TRUE(mBits.any());
     EXPECT_FALSE(mBits.none());
     EXPECT_EQ(mBits.count(), mBits.size());
+    EXPECT_EQ(mBits.first(), 0u);
 
     mBits.reset();
     EXPECT_FALSE(mBits.all());

src/libANGLE/renderer/vulkan/ContextVk.cpp

@@ -1369,27 +1369,20 @@ ANGLE_INLINE angle::Result ContextVk::handleDirtyTexturesImpl(
         }
         else
         {
-            gl::ShaderBitSet shaderBits =
+            gl::ShaderBitSet remainingShaderBits =
                 executable->getSamplerShaderBitsForTextureUnitIndex(textureUnit);
-            if (shaderBits.any())
+            ASSERT(remainingShaderBits.any());
+            gl::ShaderType firstShader = remainingShaderBits.first();
+            remainingShaderBits.reset(firstShader);
+            // If we have multiple shader accessing it, we barrier against all shader stage read
+            // given that we only support vertex/frag shaders
+            if (remainingShaderBits.any())
             {
-                gl::ShaderType shader =
-                    static_cast<gl::ShaderType>(gl::ScanForward(shaderBits.bits()));
-                shaderBits.reset(shader);
-                // If we have multiple shader accessing it, we barrier against all shader stage read
-                // given that we only support vertex/frag shaders
-                if (shaderBits.any())
-                {
-                    textureLayout = vk::ImageLayout::AllGraphicsShadersReadOnly;
-                }
-                else
-                {
-                    textureLayout = kShaderReadOnlyImageLayouts[shader];
-                }
+                textureLayout = vk::ImageLayout::AllGraphicsShadersReadOnly;
             }
             else
             {
-                textureLayout = vk::ImageLayout::AllGraphicsShadersReadOnly;
+                textureLayout = kShaderReadOnlyImageLayouts[firstShader];
             }
         }
         // Ensure the image is in read-only layout