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[Fix] (DirectVulkan, ShaderTranspiler, MG_IntegrationTest, SelfTest, TraceReplay): use native subgroups and patch iterationRP's under-declared scratch

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iterationRP's Program 203 declares shared vec2 prefixSumCache[32] for a
512-invocation workgroup indexed by gl_SubgroupID; any device narrower
than 16 lanes partitions into more than 32 subgroups and the pack writes
shared memory out of bounds (heap corruption on lavapipe's CPU
rasterizer, ssim 0.028 on the CI retrace). Fix it where the fault lies -
in the fixture - and keep the GL contract sound everywhere else:

- FixIterationRPSubgroupScratchPass: fingerprint-gated SPIR-V pass that
  grows exactly that array to ceil(invocations/width) entries on sub-16-lane devices; every other module passes through byte-identical.
- DeriveNumSubgroupsPass stays default-on for the Adreno topology bug
  and is made spec-sound: pipelines request REQUIRE_FULL_SUBGROUPS
  whenever the workgroup shape makes the flag legal (computeFullSubgroups
  enabled, local_size_x a multiple of the native width, subgroup count
  within maxComputeWorkgroupSubgroups).
- EmulateSubgroupsPass: 32-lane virtual-subgroup lowering kept in-tree
  as a last resort, enabled only by MOBILEGL_MAGMA_EMULATE_SUBGROUP=1 on
  devices with no native subgroup support; fails closed on extended
  subgroup instructions and on modules whose added scratch would exceed
  maxComputeSharedMemorySize.
- IterationRPFirstReductionScenario skips gracefully outside the pack's
  16..256-lane source domain; the new IterationRPScratchFixScenario runs
  the fixture-shaped reduction on any width and asserts the exact
  width-independent total. DriverPost keeps reporting FAIL on
  out-of-domain devices.
- Program203 -> IterationRP rename throughout; the per-trace
  num_subgroups_quirk plumbing is removed from the trace replayer, JNI
  chain, and CI workflows.
This commit is contained in:
swung0x48
2026-08-19 09:48:11 -04:00
parent 2b6c2b561c
commit d8576a2ed3
38 changed files with 3354 additions and 396 deletions
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MobileGL/MG_Backend/DirectVulkan/Renderer/ProgramFactory.cpp
+96 -14
View File
@@ -8,7 +8,6 @@
#include "ProgramFactory.h"
#include "Config.h"
#include "MG_Backend/DirectVulkan/DirectVulkanResourceState.h"
#include "MG_Util/ShaderTranspiler/ShaderCompiler.h"
#include "MG_Util/ShaderTranspiler/SpvcSession.h"
@@ -34,6 +33,32 @@ namespace MobileGL::MG_Backend::DirectVulkan {
using SpvcSession = MG_Util::ShaderTranspiler::SpvcSession;
using SessionUsageBit = MG_Util::ShaderTranspiler::SessionUsageBit;
// Local size of a compute module, read from OpExecutionMode LocalSize; all-zero
// when absent. The compile chain pins SPIR-V 1.3, where a literal local size
// always reaches the module as this execution mode (LocalSizeId does not exist
// yet).
struct ComputeLocalSize {
Uint32 x = 0;
Uint32 y = 0;
Uint32 z = 0;
Uint64 Total() const { return static_cast<Uint64>(x) * y * z; }
};
ComputeLocalSize TryGetComputeLocalSize(const Vector<Uint>& spirv) {
constexpr SizeT kHeaderWords = 5;
constexpr Uint32 kOpExecutionMode = 16;
constexpr Uint32 kModeLocalSize = 17;
for (SizeT offset = kHeaderWords; offset < spirv.size();) {
const Uint32 wordCount = spirv[offset] >> 16u;
const Uint32 opcode = spirv[offset] & 0xffffu;
if (wordCount == 0 || offset + wordCount > spirv.size()) break;
if (opcode == kOpExecutionMode && wordCount >= 6 && spirv[offset + 2] == kModeLocalSize) {
return {spirv[offset + 3], spirv[offset + 4], spirv[offset + 5]};
}
offset += wordCount;
}
return {};
}
struct DescriptorKey {
ProgramFactory::DescriptorBindingKind kind = ProgramFactory::DescriptorBindingKind::None;
String name;
@@ -3164,20 +3189,56 @@ namespace MobileGL::MG_Backend::DirectVulkan {
}
}
// NumSubgroups is defined by the local workgroup dimensions and SubgroupSize. Derive
// it in SPIR-V instead of trusting a driver builtin that can disagree with the
// SubgroupId topology produced by the same compute dispatch (Adreno reports 1 while
// emitting IDs 0..7 for a 512-invocation, 64-wide workgroup).
if (MG_Config::Features.NumSubgroupsQuirk && shaders[i] &&
shaders[i]->GetShaderStage() == ShaderStage::Compute) {
Vector<Uint> derivedNumSubgroupsSpirv;
if (MG_Util::ShaderTranspiler::ShaderCompiler::DeriveNumSubgroupsForVulkan(
moduleSpirvs[i], derivedNumSubgroupsSpirv, enableSpirvValidation)) {
moduleSpirvs[i] = std::move(derivedNumSubgroupsSpirv);
// GL_KHR_shader_subgroup handling (SubgroupSupportPolicy.h). Native subgroup
// operations execute natively; two module repairs keep the GL contract intact
// around them. The opt-in emulation path replaces them only on devices with no
// subgroup support at all (MOBILEGL_MAGMA_EMULATE_SUBGROUP).
if (shaders[i] && shaders[i]->GetShaderStage() == ShaderStage::Compute) {
if (m_subgroupPolicy.emulateSubgroups) {
Vector<Uint> emulatedSpirv;
if (MG_Util::ShaderTranspiler::ShaderCompiler::EmulateSubgroupsForVulkan(
moduleSpirvs[i], emulatedSpirv,
m_subgroupPolicy.maxComputeSharedMemoryBytes, enableSpirvValidation)) {
moduleSpirvs[i] = std::move(emulatedSpirv);
} else {
MGLOG_E("ProgramFactory: subgroup emulation failed for program %u; the "
"module keeps subgroup operations the device cannot execute",
program.GetExternalIndex());
}
} else {
MGLOG_E("ProgramFactory: failed to derive gl_NumSubgroups for program %u; "
"compute shaders may observe a driver-inconsistent subgroup count",
program.GetExternalIndex());
// iterationRP under-declares its cross-subgroup scratch
// (prefixSumCache[32] for 512 invocations); on a sub-16-lane device
// grow that one fingerprinted array to what the topology needs.
if (m_subgroupPolicy.fixIterationRPSubgroupScratch) {
Vector<Uint> patchedSpirv;
if (MG_Util::ShaderTranspiler::ShaderCompiler::FixIterationRPSubgroupScratchForVulkan(
moduleSpirvs[i], patchedSpirv, m_subgroupPolicy.nativeSubgroupSize,
enableSpirvValidation)) {
moduleSpirvs[i] = std::move(patchedSpirv);
} else {
MGLOG_E("ProgramFactory: iterationRP subgroup scratch patch failed for "
"program %u; the pack's declared array sizes stay in effect",
program.GetExternalIndex());
}
}
// gl_NumSubgroups must agree with the gl_SubgroupID range GL promises;
// derive it from the workgroup dimensions and gl_SubgroupSize instead of
// trusting a driver builtin that can disagree with the topology the same
// dispatch emits (Adreno reports 1 while emitting IDs 0..7 for a
// 512-invocation, 64-wide workgroup). The ceil() partition this derives
// is pinned by REQUIRE_FULL_SUBGROUPS at pipeline creation whenever the
// workgroup shape makes that flag legal (see the stage setup below).
if (m_subgroupPolicy.deriveNumSubgroups) {
Vector<Uint> derivedNumSubgroupsSpirv;
if (MG_Util::ShaderTranspiler::ShaderCompiler::DeriveNumSubgroupsForVulkan(
moduleSpirvs[i], derivedNumSubgroupsSpirv, enableSpirvValidation)) {
moduleSpirvs[i] = std::move(derivedNumSubgroupsSpirv);
} else {
MGLOG_E("ProgramFactory: failed to derive gl_NumSubgroups for program %u; "
"compute shaders may observe a driver-inconsistent subgroup count",
program.GetExternalIndex());
}
}
}
}
@@ -3326,6 +3387,27 @@ namespace MobileGL::MG_Backend::DirectVulkan {
stage.stage = ToVkStage(shaderStage);
stage.module = module;
stage.pName = "main";
// Pin the full-subgroup launch the derived gl_NumSubgroups assumes. Legal
// exactly when the computeFullSubgroups feature is enabled and local_size_x is
// a multiple of the subgroup size (VUID-VkPipelineShaderStageCreateInfo-
// flags-02759/-02785), and only worth requesting while the resulting subgroup
// count fits the device's maxComputeWorkgroupSubgroups (lavapipe caps it at
// 32, below a 512-invocation dispatch's 64). With the bit set, "Full
// Subgroups" guarantees every subgroup launches with all invocations active,
// making the subgroup count exactly invocations / size. Shapes the flag
// cannot cover (e.g. 32x16 on a 64-wide device) fall back to the driver's
// own - spec-encouraged - tight partitioning, which the DriverPost witness
// verifies per device.
if (shaderStage == ShaderStage::Compute && m_subgroupPolicy.requireFullSubgroups &&
!m_subgroupPolicy.emulateSubgroups && m_subgroupPolicy.nativeSubgroupSize != 0) {
const ComputeLocalSize localSize = TryGetComputeLocalSize(moduleSpv);
const Uint64 fullSubgroupCount =
localSize.Total() / m_subgroupPolicy.nativeSubgroupSize;
if (localSize.x != 0 && localSize.x % m_subgroupPolicy.nativeSubgroupSize == 0 &&
fullSubgroupCount <= m_subgroupPolicy.maxComputeWorkgroupSubgroups) {
stage.flags |= VK_PIPELINE_SHADER_STAGE_CREATE_REQUIRE_FULL_SUBGROUPS_BIT;
}
}
entry.modules.push_back(module);
entry.stages.push_back(stage);