swung0x48/MobileGL
1
0
Fork 0
mirror of https://github.com/MobileGL-Dev/MobileGL synced 2026-09-10 13:18:31 +09:00
Code Issues Packages Projects Releases Wiki Activity

[Fix, Test] (MG_State, BufferObject): land a non-persistent write map's staged bytes into a GPU-resident store at unmap and explicit flush instead of dropping them - SSBO binding and large-store adoption make resident stores reachable through glMapBufferRange, so every per-draw re-initialisation was silently lost

Browse Source
This commit is contained in:
swung0x48
2026-09-05 05:36:48 -04:00
parent 81b17c0b75
commit 1e7ecab4db
3 changed files with 1056 additions and 67 deletions
Download Patch File Download Diff File Expand all files Collapse all files
MobileGL/MG_State/GLState/BufferState/BufferObject.cpp
+140 -64
View File
@@ -67,6 +67,14 @@ namespace MobileGL::MG_State::GLState {
}
void BufferObject::NotifyContentWrite(SizeT offset, SizeT size) {
if (size == 0) {
// An empty write moves the serial and nothing else, exactly as NotifySubData
// and NotifyFlushMappedRange do: it wrote no byte, so it must not promote an
// undefined store to "has content" - that would cost the next orphaning
// respecification a full-size upload of bytes the application never wrote.
++m_changeSerial;
return;
}
m_hasDefinedContent = true;
if (m_resource.IsGpuResident()) {
// The write already landed in coherent GPU memory; the backend has no separate
@@ -111,7 +119,10 @@ namespace MobileGL::MG_State::GLState {
}
void BufferObject::Respecify(SizeT size, const void* data) {
ReleaseMemory();
// The store a live mapping wrote into is about to be replaced, so landing those
// bytes into it would copy a whole mapped range (an adopted arena's map is the
// arena) into storage the next line hands back.
ReleaseMemory(false);
RedefineStorage(size);
if (data && size > 0) {
Memcpy(m_resource.Bytes(), data, size);
@@ -136,7 +147,9 @@ namespace MobileGL::MG_State::GLState {
}
void BufferObject::AllocateImmutableStorage(SizeT size, const void* data, GLbitfield storageFlags) {
ReleaseMemory();
// Same as Respecify: the bytes a live mapping staged have nowhere to land, the
// store they belong to is being replaced.
ReleaseMemory(false);
RedefineStorage(size);
if (data) {
Memcpy(m_resource.Bytes(), data, size);
@@ -190,24 +203,45 @@ namespace MobileGL::MG_State::GLState {
m_usage = usage;
}
void BufferObject::ReleaseMemory() {
void BufferObject::ReleaseMemory(Bool landStagedWrites) {
if (!m_isMapped) return;
if (m_mappingAccess & BufferMappingAccessBit::Write) { // if we wrote to the buffer
// A persistent GPU-resident map wrote straight into coherent GPU memory, so
// there is nothing to copy back and no range to push down on unmap.
if (!m_resource.IsGpuResident() &&
!(m_mappingAccess & BufferMappingAccessBit::FlushExplicit)) { // if we didn't flush explicitly
if (!(m_mappingAccess & BufferMappingAccessBit::Persistent)) {
Memcpy(m_resource.Bytes() + m_mappedRange.start, m_stagingData.data() + m_stagingBias,
m_mappedRange.end - m_mappedRange.start);
if (landStagedWrites &&
(m_mappingAccess & BufferMappingAccessBit::Write)) { // if we wrote to the buffer
if (!(m_mappingAccess & BufferMappingAccessBit::FlushExplicit)) { // if we didn't flush explicitly
const SizeT mappedLength = m_mappedRange.end - m_mappedRange.start;
if (m_resource.IsGpuResident()) {
// A persistent map of an adopted store wrote straight into coherent
// GPU memory: nothing to copy back, no range to push down. A
// NON-persistent write map is a different thing: the application
// wrote a staging copy (glMapBuffer and glMapBufferRange hand one out
// regardless of where the store lives), and GL requires those bytes
// to be visible to every later command the moment glUnmapBuffer
// returns. Residency used to come only from a coherent persistent
// map, which never has a staging copy, so the copy-back was simply
// skipped for a resident store; residency now also comes from a
// shader storage binding (EnsureGpuResidentStorage at draw time) and
// from large-store adoption (TryAdoptLargeStorage), both of which an
// application then re-initialises through an ordinary map/write/unmap.
// Skipping the copy-back dropped every one of those writes. Land the
// staged bytes through the same route glBufferSubData takes into an
// adopted store - the backend's flush op is for stores it keeps a
// separate copy of and must not run here.
if (!(m_mappingAccess & BufferMappingAccessBit::Persistent)) {
LandBytesIntoResidentStore(m_mappedRange.start,
{m_stagingData.data() + m_stagingBias, mappedLength});
}
} else {
if (!(m_mappingAccess & BufferMappingAccessBit::Persistent)) {
Memcpy(m_resource.Bytes() + m_mappedRange.start, m_stagingData.data() + m_stagingBias,
mappedLength);
}
NotifyFlushMappedRange(m_mappedRange, m_mappingAccess);
}
NotifyFlushMappedRange(m_mappedRange, m_mappingAccess);
}
m_stagingData.clear();
}
m_stagingData.clear();
m_isMapped = false;
m_mappingAccess = BufferMappingAccessBit::Null;
m_mappedRange = {0, 0};
@@ -227,8 +261,21 @@ namespace MobileGL::MG_State::GLState {
MOBILEGL_ASSERT(end <= m_mappedRange.end, "Flush range out of bounds: mappedRange.end (%zu) < end (%zu)",
m_mappedRange.end, end);
// FLUSH_EXPLICIT maps are never GPU-resident (only coherent maps are adopted), so
// the staged bytes must be copied into the shadow before the backend reads them.
// A FLUSH_EXPLICIT map can sit on an adopted store: the map itself never adopts
// (only a coherent persistent one does), but a shader storage binding or
// large-store adoption may have made the buffer resident before the map. The
// flushed bytes then take the same landing as any other CPU write into an
// adopted store - a persistent map already wrote them in place and only has
// to publish the change, a non-persistent map staged them and has to land
// them. The backend's flush op is for stores it keeps a separate copy of.
if (m_resource.IsGpuResident()) {
if (m_mappingAccess & BufferMappingAccessBit::Persistent) {
NotifyContentWrite(start, length);
} else {
LandBytesIntoResidentStore(start, {m_stagingData.data() + m_stagingBias + offset, length});
}
return;
}
if (!(m_mappingAccess & BufferMappingAccessBit::Persistent)) {
Memcpy(m_resource.Bytes() + start, m_stagingData.data() + m_stagingBias + offset, length);
}
@@ -284,35 +331,48 @@ namespace MobileGL::MG_State::GLState {
data.size, m_size);
// An adopted store's Bytes() IS the memory in-flight frames are reading, and
// GL orders a glBufferSubData after those already-submitted reads. A backend
// that can land the bytes on the GPU timeline takes them here, untouched by
// the mapping - the in-place host write below tore the frames still reading
// the old bytes. The bytes are not current in the mapping until the backend's
// ordered copy executes, so reads reconcile through the same gate GPU-written
// buffers use.
if (m_resource.IsGpuResident() && data.size > 0 && g_bufferBackendOps &&
g_bufferBackendOps->ResidentSubData) {
g_bufferBackendOps->ResidentSubData(*this, atOffset, data);
// GL orders a glBufferSubData after those already-submitted reads: the write
// has to take the resident landing, never a plain host write into the mapping.
// Shadow-backed stores need none of this: the Memcpy below touches only the
// shadow, and the backend's SubData op does its own ordering against in-flight
// work.
if (m_resource.IsGpuResident()) {
LandBytesIntoResidentStore(atOffset, data);
return;
}
Memcpy(m_resource.Bytes() + atOffset, data.data, data.size);
NotifyContentWrite(atOffset, data.size);
}
// A backend that can land the bytes on the GPU timeline takes them here, untouched
// by the mapping - an in-place host write into coherent memory tore the frames
// still reading the old bytes (Minecraft patches LIVE chunk sections this way).
// The bytes are then not current in the mapping until the backend's ordered copy
// executes, so reads reconcile through the same gate GPU-written buffers use.
//
// Without that op the write lands in place, after retiring the GPU writes this store
// is known to be waiting on: a backend that defers work (DirectVulkan's frame command
// buffer) may still be holding a recorded-but-unsubmitted dispatch that GL orders this
// write AFTER, and writing the mapping now would land the bytes underneath that
// dispatch - its increments then execute on top of the newer data and invert the call
// order. That gate only knows about work that WROTE the store (MarkGpuWritten); work
// that merely READS it - a draw sourcing an adopted vertex arena - is not tracked here,
// so a backend without the op still owes the ordering against its own recorded reads.
// NotifyContentWrite on a resident store only bumps the serial: the backend has no
// separate copy to sync, so no transfer op runs.
void BufferObject::LandBytesIntoResidentStore(SizeT offset, DataPtr bytes) {
if (bytes.size > 0 && g_bufferBackendOps && g_bufferBackendOps->ResidentSubData) {
g_bufferBackendOps->ResidentSubData(*this, offset, bytes);
m_hasDefinedContent = true;
++m_changeSerial;
m_gpuWritePending = true;
return;
}
// An adopted store's Bytes() IS the memory the GPU reads, and a backend that
// defers work (DirectVulkan's frame command buffer) may still be holding a
// recorded-but-unsubmitted dispatch that GL orders this write AFTER. Writing
// the mapping now would land the bytes underneath that dispatch - its
// increments then execute on top of the newer data and invert the call order.
// Retire the pending GPU writes first, as FillSubData already does. Shadow-
// backed stores need none of this: the Memcpy below touches only the shadow,
// and the backend's SubData op does its own ordering against in-flight work.
if (m_resource.IsGpuResident()) {
SyncGpuWrites();
}
Memcpy(m_resource.Bytes() + atOffset, data.data, data.size);
NotifyContentWrite(atOffset, data.size);
SyncGpuWrites();
Memcpy(m_resource.Bytes() + offset, bytes.data, bytes.size);
NotifyContentWrite(offset, bytes.size);
}
void BufferObject::FillSubData(DataPtr pattern, SizeT atOffset, SizeT size) {
@@ -327,8 +387,13 @@ namespace MobileGL::MG_State::GLState {
"Cannot fill data while buffer is non-persistently mapped.");
if (size == 0) return;
// An adopted store takes the same GPU-timeline landing as UploadSubData: the
// in-place write below would tear in-flight readers of the mapping.
// An adopted store takes the same landing as UploadSubData: the in-place write
// below would tear in-flight readers of the mapping. The pattern is expanded
// first because the landing takes the final bytes, not a repeat rule - which is
// why only a backend that actually takes them comes through here. Without that
// op the landing would memcpy the expansion into the mapping the loop below
// fills in place anyway, so a whole-arena clear would allocate a whole arena
// for nothing.
if (m_resource.IsGpuResident() && g_bufferBackendOps && g_bufferBackendOps->ResidentSubData) {
Vector<Uint8> expanded(size);
if (pattern.size == 1) {
@@ -338,16 +403,13 @@ namespace MobileGL::MG_State::GLState {
Memcpy(expanded.data() + at, pattern.data, pattern.size);
}
}
g_bufferBackendOps->ResidentSubData(*this, atOffset, {expanded.data(), size});
m_hasDefinedContent = true;
++m_changeSerial;
m_gpuWritePending = true;
LandBytesIntoResidentStore(atOffset, {expanded.data(), size});
return;
}
// A clear is ordered after all earlier GPU writes. Partial clears additionally need the
// retained shadow bytes; whole-store clears need the same synchronization before writing
// an adopted persistent mapping that the GPU may still be accessing.
// A clear is ordered after all earlier GPU writes; partial clears additionally need
// the retained shadow bytes, and a resident store the backend cannot take the bytes
// for is written in place, which needs the same synchronization the landing does.
SyncGpuWrites();
Uint8* dst = m_resource.Bytes() + atOffset;
@@ -381,22 +443,13 @@ namespace MobileGL::MG_State::GLState {
size, m_size);
src->SyncGpuWrites();
// An adopted DESTINATION takes the same GPU-timeline landing as UploadSubData;
// the in-place write below would tear in-flight readers of the mapping.
if (m_resource.IsGpuResident() && size > 0 && g_bufferBackendOps &&
g_bufferBackendOps->ResidentSubData) {
g_bufferBackendOps->ResidentSubData(*this, dstOffset,
{src->m_resource.Bytes() + srcOffset, size});
m_hasDefinedContent = true;
++m_changeSerial;
m_gpuWritePending = true;
return;
}
// The DESTINATION needs the same ordering as UploadSubData: an adopted store is
// written in place, so pending recorded GPU writes to it must retire before the
// copy lands or they would execute on top of it.
// An adopted DESTINATION takes the same landing as UploadSubData: the in-place
// write below would tear in-flight readers of the mapping, and pending recorded
// GPU writes to it must retire before the copy lands or they would execute on
// top of it.
if (m_resource.IsGpuResident()) {
SyncGpuWrites();
LandBytesIntoResidentStore(dstOffset, {src->m_resource.Bytes() + srcOffset, size});
return;
}
Memcpy(m_resource.Bytes() + dstOffset, src->m_resource.Bytes() + srcOffset, size);
NotifyContentWrite(dstOffset, size);
@@ -433,6 +486,16 @@ namespace MobileGL::MG_State::GLState {
if (m_resource.IsGpuResident()) {
return true;
}
// Adoption releases the CPU shadow, and a live mapping may BE that shadow: a
// persistent map that did not itself adopt (a FLUSH_EXPLICIT one, or a read map)
// handed the application shadow + offset, and GL keeps that pointer valid while
// the buffer is drawn with - which is exactly when this runs, on the storage
// binding walk. Freeing it under the application is a use-after-free, so a mapped
// buffer keeps the shadow model until it is unmapped; the binding that follows
// adopts then. Same rule as TryAdoptLargeStorage.
if (m_isMapped) {
return false;
}
if (m_size == 0 || g_bufferBackendOps == nullptr || g_bufferBackendOps->AcquirePersistentMap == nullptr) {
return false;
}
@@ -451,7 +514,20 @@ namespace MobileGL::MG_State::GLState {
// The app is about to look at the bytes; a shader may have rewritten them since
// the shadow was last authoritative. Also needed for a write map without an
// invalidate bit, whose staging copy is seeded from the shadow.
SyncGpuWrites();
//
// One map shape looks at nothing: a non-persistent write map that discards the
// range it maps gets a staging copy the seeding below skips, so no reader of the
// store exists between here and the unmap. Reconciling an ADOPTED store would
// still cost the backend's full drain-and-wait (its queued landings are made
// visible to the CPU by finishing the pipeline), once per map, on exactly the
// streaming arena the adoption exists to keep cheap. The outstanding-write flag
// stays set, so the first read that DOES look at the bytes still pays for it.
const Bool discardsWhatItMaps =
(access & BufferMappingAccessBit::Write) && !(access & BufferMappingAccessBit::Persistent) &&
(access & (BufferMappingAccessBit::InvalidateRange | BufferMappingAccessBit::InvalidateBuffer));
if (!(m_resource.IsGpuResident() && discardsWhatItMaps)) {
SyncGpuWrites();
}
m_isMapped = true;
m_mappingAccess = access;
m_mappedRange = range;
MobileGL/MG_State/GLState/BufferState/BufferObject.h
+16 -3
View File
@@ -81,7 +81,9 @@ namespace MobileGL {
// Contents update of [offset, offset + size) from the shadow.
void (*SubData)(BufferObject& bufferObject, SizeT offset, SizeT size) = nullptr;
// Contents update of an ADOPTED (GPU-resident) store. `data` holds the app's
// bytes; the frontend has NOT touched the resident mapping. GL orders a
// bytes, valid for the duration of the call only (a write map's staging
// store is freed the moment the unmap that lands it returns); the frontend
// has NOT touched the resident mapping. GL orders a
// glBufferSubData after already-submitted GPU reads of the store, and an
// in-place host write into the coherent mapping tears the frames still
// reading the old bytes (Minecraft patches LIVE chunk sections this way -
@@ -157,9 +159,14 @@ namespace MobileGL {
// Adopt backend host-visible coherent GPU storage as the source of truth
// (used for GPU-written targets like transform feedback capture, so
// MapBuffer/GetBufferSubData read real GPU results). No-op when already
// resident or when the backend declines.
// resident, while the buffer is mapped (adoption releases the shadow a
// mapping may have handed the application), or when the backend declines.
Bool EnsureGpuResidentStorage();
void ReleaseMemory();
// Unmap. A write map's staged bytes land in the store on the way out, unless
// the caller is about to replace that store (a respecification) and passes
// false - landing them there would copy a whole mapped range into storage
// being handed back on the next line.
void ReleaseMemory(Bool landStagedWrites = true);
void FlushMemoryRange(SizeT offset, SizeT length);
// Pushes the persistently-mapped write range to the backend; called by
@@ -234,6 +241,12 @@ namespace MobileGL {
// so this only bumps the change serial; otherwise it dispatches a backend
// SubData transfer to sync the backend's separate GPU copy.
void NotifyContentWrite(SizeT offset, SizeT size);
// The one route CPU-sourced bytes take into an ADOPTED (GPU-resident) store:
// glBufferSubData, a buffer clear, a buffer copy, and the landing of a
// non-persistent write map at unmap / explicit flush all go through it, so
// the routes cannot drift apart again. Carries no mapping asserts on
// purpose - the unmap landing runs while the buffer is still mapped.
void LandBytesIntoResidentStore(SizeT offset, DataPtr bytes);
static Uint64 AllocateLifetimeId();