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[Fix] (DirectVulkan): key the program cache on the transform feedback capture layout

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The program cache is content-hash-shared across GL program names, so its key has
to cover everything that changes the modules it stores. The capture layout did
not: XfbCaptureDecoratePass bakes XfbBuffer/XfbStride/Offset into the SPIR-V from
the frontend's layout, none of which is in the SPIR-V being hashed.

Two programs with identical shaders and different glTransformFeedbackVaryings
therefore shared one entry, and the first one linked decided how both captured.
That is precisely what changing the buffer mode does -- the same varyings
recorded with GL_SEPARATE_ATTRIBS instead of GL_INTERLEAVED_ATTRIBS -- so the
separate-attribs pass of transform_feedback.draw_xfb_test replayed a capture that
was still interleaved into buffer 0.

Hash the captured varyings' names, buffer indices and offsets plus the per-buffer
strides, and only for a capturing compile, so no other program changes key.
This commit is contained in:
BZLZHH
2026-08-04 19:47:39 -04:00
parent 90ae0f048c
commit fbed4485b7
1 changed files with 19 additions and 0 deletions
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MobileGL/MG_Backend/DirectVulkan/Renderer/ProgramFactory.cpp
+19
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@@ -1761,6 +1761,25 @@ namespace MobileGL::MG_Backend::DirectVulkan {
XXHASH_VERIFY(XXH64_update(m_hashState, &binding, sizeof(binding)));
}
// The transform feedback capture layout is baked into the modules by
// XfbCaptureDecoratePass rather than coming from the SPIR-V, so it has to be part of
// the key: two programs can share every shader and still capture differently, which
// is exactly what changing the buffer mode does (glTransformFeedbackVaryings with the
// same varyings but GL_SEPARATE_ATTRIBS instead of GL_INTERLEAVED_ATTRIBS). Only
// hashed for a capturing compile, so nothing else changes key.
if (flags & CompileOptionBit::XfbCapture) {
for (const auto& varying : program.GetTransformFeedbackVaryings()) {
XXHASH_VERIFY(XXH64_update(m_hashState, varying.name.data(), varying.name.size()));
XXHASH_VERIFY(XXH64_update(m_hashState, &varying.bufferIndex, sizeof(varying.bufferIndex)));
XXHASH_VERIFY(XXH64_update(m_hashState, &varying.offsetBytes, sizeof(varying.offsetBytes)));
}
const SizeT bufferCount = program.GetTransformFeedbackBufferCount();
for (SizeT i = 0; i < bufferCount; ++i) {
const Uint32 stride = program.GetTransformFeedbackStride(static_cast<Uint32>(i));
XXHASH_VERIFY(XXH64_update(m_hashState, &stride, sizeof(stride)));
}
}
HashType hash = XXH64_digest(m_hashState);
return hash;
}