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[Fix] (Xfb): never issue a transform feedback capture-point bind the application did not ask for, and error-check the driver span instead of losing it silently

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swung0x48
2026-08-27 12:28:32 -04:00
parent ea5d52f126
commit 05d627ba2d
6 changed files with 1025 additions and 29 deletions
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MobileGL/MG_Backend/DirectGLES/Managers.cpp
+92
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@@ -1383,10 +1383,24 @@ namespace MobileGL::MG_Backend::DirectGLES {
constexpr SizeT kMaxIndexedBufferBindings = 64;
IndexedBufferBinding g_indexedUBOBindings[kMaxIndexedBufferBindings];
IndexedBufferBinding g_indexedSSBOBindings[kMaxIndexedBufferBindings];
// Transform feedback gets a shadow for a reason the other two do not have: the
// capture points are synced from the application's TOUCHED high-water mark, which
// deqp/glcts permanently raises to GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS by
// clearing every point after each test case. Without a shadow every capture that
// uses fewer points than that (i.e. every INTERLEAVED_ATTRIBS capture) re-issued a
// redundant glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, i, 0) for the unused
// tail immediately before glBeginTransformFeedback - calls a plain GL application
// never makes there, and the only thing MobileGL does differently from one.
//
// Unlike the UBO/SSBO points these are NOT context state: they belong to the bound
// transform feedback OBJECT, so XfbImpl::BindTransformFeedback drops the whole
// shadow to unknown on every object switch (InvalidateTransformFeedbackBindingShadows).
IndexedBufferBinding g_indexedXFBBindings[kMaxIndexedBufferBindings];
IndexedBufferBinding* IndexedBindingShadow(GLenum glTarget, Uint index) {
if (index >= kMaxIndexedBufferBindings) return nullptr; // out of range: never cache
if (glTarget == GL_UNIFORM_BUFFER) return &g_indexedUBOBindings[index];
if (glTarget == GL_SHADER_STORAGE_BUFFER) return &g_indexedSSBOBindings[index];
if (glTarget == GL_TRANSFORM_FEEDBACK_BUFFER) return &g_indexedXFBBindings[index];
return nullptr;
}
@@ -1403,6 +1417,9 @@ namespace MobileGL::MG_Backend::DirectGLES {
for (auto& binding : g_indexedSSBOBindings) {
if (binding.id == id) binding = {};
}
for (auto& binding : g_indexedXFBBindings) {
if (binding.id == id) binding = {};
}
if (g_boundPixelPackBufferKnown && g_boundPixelPackBufferId == id) {
g_boundPixelPackBufferId = 0;
}
@@ -1419,9 +1436,21 @@ namespace MobileGL::MG_Backend::DirectGLES {
for (auto& binding : g_indexedSSBOBindings) {
if (binding.id == id) binding.known = false;
}
for (auto& binding : g_indexedXFBBindings) {
if (binding.id == id) binding.known = false;
}
}
} // namespace
// The capture points belong to the bound transform feedback object, so a bind (or a
// delete, which reverts to the default object) replaces all of them at once with
// state this shadow has never seen. Distrust rather than scrub: the driver's bindings
// are whatever the newly bound object holds, which is NOT necessarily base(0), and
// scrubbing would let a later bind of 0 be false-skipped.
void InvalidateTransformFeedbackBindingShadows() {
for (auto& binding : g_indexedXFBBindings) binding.known = false;
}
void BindBufferBaseCached(GLenum glTarget, Uint index, Uint id) {
auto* s = IndexedBindingShadow(glTarget, index);
if (s && s->known && s->isBase && s->id == id) return;
@@ -1439,6 +1468,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
void InvalidateIndexedBufferBindingCache() {
for (auto& b : g_indexedUBOBindings) b = {};
for (auto& b : g_indexedSSBOBindings) b = {};
for (auto& b : g_indexedXFBBindings) b = {};
}
void TrimBufferPool() {
@@ -5753,6 +5783,10 @@ namespace MobileGL::MG_Backend::DirectGLES {
Uint g_fragColorBroadcastCount = 1;
Uint32 g_unormFallbackClampOutputMask = 0;
Uint g_lastUsedBackendProgramId = 0;
// Every error-queue drain in the program build path is bounded by this: a lost
// context never answers GL_NO_ERROR, and the build runs on the thread that would
// then spin forever.
constexpr Int kMaxDrainedProgramErrors = 32;
StateBackendObjectRegistry<MG_State::GLState::ProgramObject, BackendProgramObjectImpl> g_backendProgramObjects;
BackendProgramObjectImpl::BackendProgramObjectImpl() {
@@ -7523,6 +7557,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
// program before it links. SPIRV-Cross keeps user output names verbatim in
// the transpiled ESSL (`out vec4 result_0;` stays `result_0`), so the
// frontend's requested names carry over unchanged.
SizeT declaredXfbVaryingCount = 0;
if (stateProgramObject->GetTransformFeedbackVaryingCount() > 0 &&
g_GLESFuncs.glTransformFeedbackVaryings != nullptr) {
const auto& xfbVaryings = stateProgramObject->GetTransformFeedbackVaryings();
@@ -7548,9 +7583,31 @@ namespace MobileGL::MG_Backend::DirectGLES {
}
MGLOG_D("Declaring %zu transform feedback varyings on program %u", xfbNames.size(),
m_backendProgramId);
// Bounded: a lost context never answers GL_NO_ERROR, and this runs on the
// thread that would then spin forever.
for (Int i = 0; i < kMaxDrainedProgramErrors && g_GLESFuncs.glGetError() != GL_NO_ERROR; ++i) {
}
g_GLESFuncs.glTransformFeedbackVaryings(m_backendProgramId, static_cast<GLsizei>(xfbNames.size()),
xfbNames.data(),
stateProgramObject->GetTransformFeedbackBufferMode());
// Unchecked before. A rejected capture set leaves the program linking happily
// with NO capture set at all, and then every draw of every span records
// nothing while the application reads its buffer's pre-draw bytes and
// GL_NO_ERROR - the signature four conformance families were stuck on.
if (const GLenum xfbError = g_GLESFuncs.glGetError(); xfbError != GL_NO_ERROR) {
String declared;
for (const auto& xfbName : rewrittenXfbNames) {
if (!declared.empty()) declared += ", ";
declared += xfbName;
}
MGLOG_E("The ES driver REJECTED the transform feedback capture set for backend program %u with "
"%s (mode %s): [%s]. Every capture made with GL program %u will record nothing.",
m_backendProgramId, MG_Util::ConvertGLEnumToString(xfbError).c_str(),
MG_Util::ConvertGLEnumToString(
stateProgramObject->GetTransformFeedbackBufferMode()).c_str(),
declared.c_str(), stateProgramObject->GetExternalIndex());
}
declaredXfbVaryingCount = xfbNames.size();
}
// Link program
@@ -7593,6 +7650,41 @@ namespace MobileGL::MG_Backend::DirectGLES {
}
} else {
MGLOG_D("Program linked successfully. ID: %u", m_backendProgramId);
// A link that SUCCEEDS can still have dropped the capture set: ESSL rejects a
// requested name the transpiled shader does not actually declare by simply not
// capturing it, and a program whose last vertex-processing stage was rewritten
// by a SPIR-V pass (viewport-index lowering, gl_PerVertex handling, the
// synthesized pass-through tessellation control stage) can end up spelling its
// outputs differently from the frontend's request. Asking the driver what it
// ACTUALLY linked is the only way to tell that apart from a driver that just
// captures nothing - which is the whole ambiguity the empty-capture failures
// across geometry_shader / tessellation_shader / gpu_shader5 / DSA sat on.
if (declaredXfbVaryingCount > 0) {
GLint linkedXfbVaryings = 0;
GLint linkedXfbBufferMode = 0;
g_GLESFuncs.glGetProgramiv(m_backendProgramId, GL_TRANSFORM_FEEDBACK_VARYINGS,
&linkedXfbVaryings);
g_GLESFuncs.glGetProgramiv(m_backendProgramId, GL_TRANSFORM_FEEDBACK_BUFFER_MODE,
&linkedXfbBufferMode);
for (Int i = 0; i < kMaxDrainedProgramErrors && g_GLESFuncs.glGetError() != GL_NO_ERROR; ++i) {
}
const GLenum requestedMode = stateProgramObject->GetTransformFeedbackBufferMode();
if (static_cast<SizeT>(std::max(linkedXfbVaryings, 0)) != declaredXfbVaryingCount ||
static_cast<GLenum>(linkedXfbBufferMode) != requestedMode) {
MGLOG_E("Backend program %u (GL program %u) linked with a capture set the driver does not "
"agree with: asked for %zu varying(s) in mode %s, the driver reports %d varying(s) "
"in mode %s. Captures made with it will be empty or wrongly laid out.",
m_backendProgramId, stateProgramObject->GetExternalIndex(), declaredXfbVaryingCount,
MG_Util::ConvertGLEnumToString(requestedMode).c_str(), linkedXfbVaryings,
MG_Util::ConvertGLEnumToString(
static_cast<GLenum>(linkedXfbBufferMode)).c_str());
} else {
MGLOG_D("Backend program %u capture set confirmed by the driver: %d varying(s), mode %s",
m_backendProgramId, linkedXfbVaryings,
MG_Util::ConvertGLEnumToString(
static_cast<GLenum>(linkedXfbBufferMode)).c_str());
}
}
}
// The driver program was relinked IN PLACE, so its GL name no longer identifies
// the executable behind it - and that name is exactly what Use()'s