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[Fix] (Espryt): order a dispatch after unbarriered storage-buffer writes so adjacent components survive

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swung0x48
2026-10-12 05:59:28 -04:00
parent c639e17514
commit 363fce247f
2 changed files with 81 additions and 2 deletions
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MobileGL/MG_IntegrationTest/Scenarios/SsboArrayDynamicIndexScenario.cpp
+47
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@@ -186,4 +186,51 @@ void main() {
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, static_cast<GLuint>(i), 0);
}
}
// Four back-to-back dispatches with NO barrier between them, each writing one component of the
// same uvec4 (KHR-GL43.shader_storage_buffer_object.advanced-switchBuffers-cs). GL leaves them
// unordered, but the four components are separate memory locations and all four writes have
// to land; a driver that stores a vector component as a read-modify-write of the whole vector
// loses some unless the backend orders the dispatches (DirectGLES's PrepareForCompute does).
TEST_F(SsboArrayDynamicIndexScenario, BackToBackDispatchesKeepEachOthersComponents) {
if (!Ready() || IsSkipped()) return;
const GLuint program = CompileComputeProgram(R"(#version 430 core
layout(local_size_x = 1) in;
layout(binding = 0, std430) buffer Input { uint cookie[4]; } g_in;
layout(binding = 1, std430) buffer Output { uvec4 digest; };
void main() {
switch (g_in.cookie[0] + g_in.cookie[1] + g_in.cookie[2] + g_in.cookie[3]) {
case 0x000000ffu: digest.x = 0xff000000u; break;
case 0x0000ff00u: digest.y = 0x00ff0000u; break;
case 0x00ff0000u: digest.z = 0x0000ff00u; break;
case 0xff000000u: digest.w = 0x000000ffu; break;
}
}
)");
ASSERT_NE(program, 0u) << m_buildLog;
GLuint inputs[4] = {};
for (int i = 0; i < 4; ++i) {
// Four cookies summing to 0xff << 8i: dispatch i selects case i.
const unsigned int part = 0x11u << (8 * i);
inputs[i] = MakeStorageBuffer({part, part, part * 2, (0xffu << (8 * i)) - part * 4});
}
const GLuint output = MakeStorageBuffer({0u, 0u, 0u, 0u});
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, output);
glUseProgram(program);
for (int i = 0; i < 4; ++i) {
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, inputs[i]);
glDispatchCompute(1, 1, 1);
}
glMemoryBarrier(GL_BUFFER_UPDATE_BARRIER_BIT);
glUseProgram(0);
EXPECT_EQ(FirstGLError(), 0u);
const std::vector<unsigned int> digest = ReadBuffer(output, 4);
EXPECT_EQ(digest[0], 0xff000000u);
EXPECT_EQ(digest[1], 0x00ff0000u);
EXPECT_EQ(digest[2], 0x0000ff00u);
EXPECT_EQ(digest[3], 0x000000ffu);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, 0);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, 0);
glDeleteProgram(program);
}
} // namespace MGITest