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[Fix, Test] (DirectGLES, ShaderTranspiler): synthesize the pass-through tessellation control stage ES requires

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swung0x48
2026-08-21 05:23:57 -04:00
parent d9def5c1bb
commit 50da7de737
8 changed files with 443 additions and 1 deletions
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MobileGL/MG_Backend/DirectGLES/Managers.cpp
+157
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@@ -5864,6 +5864,123 @@ namespace MobileGL::MG_Backend::DirectGLES {
return true;
}
// GL 4.6 core 11.2.2 lets a program have a tessellation EVALUATION shader and no CONTROL
// shader: the input patch is passed through unmodified and the levels come from the
// PATCH_DEFAULT_OUTER_LEVEL / PATCH_DEFAULT_INNER_LEVEL state. OpenGL ES 3.2 has no such
// state and no such allowance - it rejects the program at link, and with an EMPTY info
// log, which was verified on an Adreno 830 with no MobileGL in the process (TES-only:
// link=0, log empty; the same shaders plus any TCS: link=1, with or without the SSBO and
// atomic counter the failing conformance case also declares). The frontend's own glslang
// link succeeds, so GL_LINK_STATUS reads TRUE, program 0 is bound in its place, and every
// draw silently renders nothing - a black framebuffer, an atomic counter still at 0 and
// an untouched SSBO, with no error anywhere.
//
// So the missing stage is synthesized and attached here, alongside the program's own.
// DirectVulkan already does exactly this for the same structural reason
// (ProgramFactory::BuildPassthroughTessControlSource), so this completes the pair rather
// than inventing an approach.
//
// Nothing that works today can be harmed by it: it fires ONLY for a program that has an
// evaluation stage and no control stage, and every such program fails to link on ES right
// now. The worst case is that the synthesized stage fails to compile or link, which leaves
// the program exactly as dead as it already was - but with a driver log that says why,
// where today there is an empty one.
void BackendProgramObjectImpl::AttachPassthroughTessControlStage(
const MG_State::GLState::ProgramObject& stateProgramObject, const Int tessEvalShaderIndex,
const Vector<Vector<unsigned int>>& shaderSpirvs, const String& vertexStageEssl,
const String& tessEvalStageEssl) {
// PATCH_VERTICES is dynamic state, and it decides the synthesized stage's output
// patch size - so a program built for one value is stale for another. Recorded here
// and compared on the draw path (SyncCurrentProgram), the same shape as the
// storage-block and image-format signatures next to it.
const Uint patchVertices = MG_State::pGLContext != nullptr
? MG_State::pGLContext->GetPatchVertices()
: 3u;
m_passthroughTessControlPatchVertices = static_cast<Int>(patchVertices);
if (tessEvalShaderIndex < 0 ||
static_cast<SizeT>(tessEvalShaderIndex) >= shaderSpirvs.size()) {
MGLOG_E("Program %u has a tessellation evaluation stage with no control stage, but no "
"SPIR-V for it; the pass-through control stage GL describes cannot be checked, so "
"the program is left to fail its ES link.",
stateProgramObject.GetExternalIndex());
m_backendProgramUsable = false;
return;
}
// The one shape the pass-through cannot stand in for. It forwards gl_Position and
// nothing else, so an evaluation stage that reads a user-defined varying or a
// per-patch input - both of which carry a Location, where every built-in it needs
// does not - would start reading undefined values the moment a control stage sat
// between it and the vertex stage. Declining keeps that from being silent; it is the
// identical rule DirectVulkan applies in ReflectPassthroughTessControlNeed.
if (MG_Util::ShaderTranspiler::ShaderCompiler::ModuleReadsLocatedInput(
shaderSpirvs[static_cast<SizeT>(tessEvalShaderIndex)])) {
MGLOG_E("Program %u has a tessellation evaluation stage with no control stage AND reads a "
"user-defined input through it; a synthesized pass-through control stage cannot "
"forward that, so the program is declined rather than fed an undefined varying.",
stateProgramObject.GetExternalIndex());
m_backendProgramUsable = false;
return;
}
// Mirrored from the neighbours rather than fixed: whether SPIRV-Cross redeclares
// gl_PerVertex, and with which members, depends on what the application's shaders
// touched, and a synthesized stage that redeclares a DIFFERENT shape than the stage
// it feeds is an ES link error against a program with no other problem. gl_in copies
// the vertex stage's OUT block (that is what arrives) and gl_out the evaluation
// stage's IN block (that is what is expected). A neighbour that redeclared nothing
// yields an empty list, which leaves the driver's own built-in declaration in place -
// which is exactly what matching it requires.
const String inMembers =
ExtractPerVertexBlockMembers(vertexStageEssl, /*input=*/false).value_or(String());
const String outMembers =
ExtractPerVertexBlockMembers(tessEvalStageEssl, /*input=*/true).value_or(String());
const String source =
BuildPassthroughTessControlEssl(ResolveBackendEsslVersion(), patchVertices, inMembers, outMembers);
const GLuint backendShaderId = g_GLESFuncs.glCreateShader(GL_TESS_CONTROL_SHADER);
if (backendShaderId == 0) {
MGLOG_E("Failed to create the synthesized pass-through tessellation control shader for "
"program %u.",
stateProgramObject.GetExternalIndex());
m_backendProgramUsable = false;
return;
}
const char* sourceCStr = source.c_str();
MGLOG_D("Synthesized pass-through tessellation control stage for program %u (patch vertices "
"%u):\n%s",
stateProgramObject.GetExternalIndex(), patchVertices, sourceCStr);
g_GLESFuncs.glShaderSource(backendShaderId, 1, &sourceCStr, nullptr);
g_GLESFuncs.glCompileShader(backendShaderId);
// GL_FALSE, not GL_TRUE, for the reason the per-stage loop states: an unwritten
// out-param must read as "compile failed" and never as a silent success.
GLint compileStatus = GL_FALSE;
g_GLESFuncs.glGetShaderiv(backendShaderId, GL_COMPILE_STATUS, &compileStatus);
if (compileStatus == GL_FALSE) {
GLint logLength = 0;
g_GLESFuncs.glGetShaderiv(backendShaderId, GL_INFO_LOG_LENGTH, &logLength);
if (logLength < 0) logLength = 0;
Vector<GLchar> log(static_cast<SizeT>(logLength) + 1, '\0');
g_GLESFuncs.glGetShaderInfoLog(backendShaderId, logLength, nullptr, log.data());
log.back() = '\0';
MGLOG_E("The synthesized pass-through tessellation control stage failed to compile for "
"program %u. Driver log: %s\nSource:\n%s",
stateProgramObject.GetExternalIndex(), log.data(), sourceCStr);
m_backendProgramUsable = false;
g_GLESFuncs.glDeleteShader(backendShaderId);
return;
}
g_GLESFuncs.glAttachShader(m_backendProgramId, backendShaderId);
// Same ownership handover as every other stage: glDeleteShader only FLAGS, so this is
// what makes the program own it and what keeps a relink from leaking it.
g_GLESFuncs.glDeleteShader(backendShaderId);
}
void BackendProgramObjectImpl::SyncToBackend(
const SharedPtr<MG_State::GLState::ProgramObject>& stateProgramObject) {
#ifdef TRACY_ENABLE
@@ -5909,6 +6026,10 @@ namespace MobileGL::MG_Backend::DirectGLES {
// reading it afterwards - resolves the same slot for the same GL binding.
m_atomicCounterGlBindings.clear();
m_atomicCounterEsslBindingTop = AtomicCounterEsslBindingTop();
// Re-established by AttachPassthroughTessControlStage below when this program needs
// one; cleared first so a program that stops needing one (a relink that now attaches
// a real control stage) does not keep comparing against a stale patch size.
m_passthroughTessControlPatchVertices = -1;
// The same shape again for image FORMATS: what a format-less image declaration
// compiles to depends on live glBindImageTexture state, so the pairs it was built
// against are recorded here and compared per draw (ImageUnitFormatsStillMatch).
@@ -6047,6 +6168,27 @@ namespace MobileGL::MG_Backend::DirectGLES {
return candidate;
};
// Desktop GL makes the tessellation CONTROL stage optional; OpenGL ES 3.2 rejects a
// program that has an evaluation stage without one, with an empty info log. When that
// is this program's shape, one is synthesized below - and it has to be spelled to
// MATCH the two stages it sits between, so their emitted ESSL is kept here as it is
// produced. Empty for every program that has a control stage of its own, which is
// all but a handful.
Bool hasTessEvalStage = false;
Bool hasTessControlStage = false;
Int tessEvalShaderIndex = -1;
String vertexStageEssl;
String tessEvalStageEssl;
for (int index = 0; index < attachedShaders.size(); ++index) {
const auto stage = attachedShaders[index]->GetShaderStage();
if (stage == ShaderStage::TessControl) hasTessControlStage = true;
if (stage == ShaderStage::TessEval) {
hasTessEvalStage = true;
tessEvalShaderIndex = index;
}
}
const Bool needsPassthroughTessControl = hasTessEvalStage && !hasTessControlStage;
for (int index = 0; index < attachedShaders.size(); ++index) {
auto& shader = attachedShaders[index];
GLenum glShaderType = MG_Util::ConvertShaderStageToGLEnum(shader->GetShaderStage());
@@ -6374,9 +6516,24 @@ namespace MobileGL::MG_Backend::DirectGLES {
// MobileGL creates without an owning wrapper to destroy it.
g_GLESFuncs.glDeleteShader(backendShaderId);
// Kept AFTER every text-level pass, so what the synthesized control stage mirrors
// is the text the driver actually sees, not an intermediate form.
if (needsPassthroughTessControl) {
if (glShaderType == GL_VERTEX_SHADER) {
vertexStageEssl = source;
} else if (glShaderType == GL_TESS_EVALUATION_SHADER) {
tessEvalStageEssl = source;
}
}
MGLOG_D("Processed shader source length: %zu", source.length());
}
if (needsPassthroughTessControl) {
AttachPassthroughTessControlStage(*stateProgramObject, tessEvalShaderIndex, shaderSpirvs,
vertexStageEssl, tessEvalStageEssl);
}
// A counter buffer declared by several stages was recorded once per stage; the draw
// path binds per GL binding point, so collapse the duplicates here rather than
// re-issuing the same glBindBufferBase two or three times every draw.