kAsyncShaderCompileDefault flips to true, which also advertises
GL_KHR_parallel_shader_compile by default on both backends. Unset
MOBILEGL_ASYNC_SHADER_COMPILE now resolves to ON; =0 remains the complete kill
switch (reverts the threading and withdraws the extension together).
The gate behind the flip (headless Mesa - llvmpipe for Espryt, lavapipe for
Magma - at c6299f75): GL30/31/32/33/40 mustpass plus the
KHR-GL46.parallel_shader_compile group, both backends, async=1 with the
extension advertised. 58,344 case-runs, 8 failures - and every one of the 8
also fails standalone at async=0, in the full async=0 suite arms with an
identical per-case failure set, and under the pre-P1-stage-6 library. Zero
async-attributable deltas; the 8 are Mesa-upgrade drift (4 unique signatures:
Espryt GL40 transform_feedback.draw_xfb{,_feedbackk}_test, Magma
texture_size_promotion.functional + packed_pixels rgb9_e5_format_red on
GL32/33/40), recorded for separate follow-up.
Validation under the flipped default (no env var): 553/553 unit at the default
AND with the kill switch; parallel_shader_compile 3/3 on both backends proving
the default advertises; 44+44 integration scenarios; 71/72 CI trace-replay
fixtures (the one failure is the pre-existing create-indirect lavapipe crash,
identical under the pre-fix library). The lifecycle test's contract updates
with the default: AsyncIsOnByDefaultAndTheOverrideDecidesEitherWay.
Not covered by this gate and deliberately left open: SSO/DSA suites (GL41+,
separate follow-up per review), and real-driver confirmation on NVIDIA/Mali -
the Mali-G77 on-device sweep runs separately as a report-only pass.
GL_COMPLETION_STATUS_KHR in both object getters, reading the non-joining
node-direct state - the one query that must never block is asserted never
to reach a join gate. glMaxShaderCompilerThreadsKHR/ARB share one
implementation: a zero count suspends async FIRST and then joins every
outstanding compile and link this context owns (suspend-before-join is the
only order whose post-condition is 'nothing in flight'), a nonzero count
restores; the suspension is a process latch the extension controls, kept
distinct from the configuration flag that gates the ADVERTISEMENT - an app
that turned threading off has not made the extension disappear.
GL_MAX_SHADER_COMPILER_THREADS_KHR reports the thread count. DriverPost
gains the MobileGL-side async row (PASS/INFO naming the env knob) and an
informational host-driver row backed by a new GLES capability probe.
The extension string itself lands per backend in the two follow-up
commits, keeping this one green stand-alone.
glLinkProgram with the flag on snapshots its inputs in a GL-thread prologue
(stage-sorted shaders with their compile nodes taken without joining, env,
explicit locations/fragdata/xfb, draw-buffer count), then runs the whole
link body - glslang link/mapIO, SPIR-V, reflection, routing tables - as a
ProgramLinkTask that auto-posts when its last compile dependency settles
(+1-guarded countdown; no worker ever waits on another job). The publish is
one move of the LinkArtifacts block at the join, with the second version
bump so nothing memoized during the pending window survives.
The consume-once TShader claim moved onto the shared compile node as a CAS:
two link jobs racing for one shader resolve to winner-takes-the-parse,
loser re-parses the preprocessed source against the node's own env -
identical SPIR-V pinned by test for 2 and for 12 sharing programs.
Two deliberate corrections to the design's cancel matrix, both test-proven:
attach/detach do NOT cancel a pending link (the snapshot isolates it, and
glCreateShaderProgramv's link-then-detach would otherwise discard its own
result before anyone read it); and a compile node a pending link depends on
is pinned against the orphan-name sweep - the ordinary LWJGL teardown
compile/attach/link/detach/delete used to cancel the dependency and turn a
must-pass link into GL_FALSE.
Continuations are now throw-contained per-item (a stage-3 leftover made
load-bearing by the first real continuation), and the review's deadlock
find is fixed: the dispatch loop no longer cancels a node while holding the
pool mutex, since that cancel can run OnDepSettled -> Post -> same mutex.
Explicit joins: the draw path (GetProgramForDraw, both the pipeline stage
loop and the plain-UseProgram half) and the composite-link site; destroy
paths cancel-not-join; COMPLETION_STATUS readers stay non-joining.
Gates: 506/506 unit both flag states; AsyncCompile/AsyncLink/AsyncTeardown
suites x10 repeats clean both states (teardown with 128 jobs in flight,
then re-Initialize); full NVIDIA DirectGLES retrace flag on twice - result
sets identical to flag off, zero new deltas. Compile-phase prefix-diff,
flag on vs off: complementary-reimagined 5.21s -> 2.16s, BSL 1.72s ->
0.90s - past the design's final acceptance targets before the KHR
extension is even advertised. Default remains OFF until stage 5+7.
glCompileShader with MOBILEGL_ASYNC_SHADER_COMPILE=1 snapshots its inputs on
the GL thread (source SharedPtr, CompileEnv, cache handle) and runs the whole
pure pipeline - preprocess, validators, extractors, glslang parse - as a
ShaderCompileTask on the worker pool, returning immediately. Every read of
compile-produced state joins through the single Compiled() gate; links stay
synchronous this stage and join their attached shaders at the top of the
body. Flag off, the path is the same code run inline.
Mechanics: the job node owns all its inputs (no back-pointer, no lifetime
tie to the shader object), so re-sourcing or deleting a pending shader is
cancel-and-drop, never a wait; glslang worker hygiene is a TLS-allocator
scope guard plus GL-thread builtin prewarm (gated on the flag, latch reset
on Destroy so re-initialization re-warms); worker-side diagnostics defer
through the job and replay on the GL thread at the join, enforced by
IsPoolThread asserts in RecordError and an empty-deferred-errors tripwire.
A body that throws publishes a COMPLETE failed compile (status false, real
info log) rather than an abandoned node, and never memoizes away the retry;
a failed enqueue (OOM) cancels the node instead of stranding the joiner -
including inside the dispatch loop, where the in-flight slot is repaid.
The pool StopAndDrains from an atexit sentinel too: workers still inside
glslang parse while exit() ran static destructors was a real 2-in-5 SIGSEGV,
reproduced and fixed (15/15 clean after).
Backend-internal shader objects (default FS, DirectVulkan blit/mipmap) are
cache-less and always compile inline - compile-and-read-in-one-breath needs
no round trip.
Gates: unit suite 488/488 with the flag off AND on (x5); AsyncCompileTest
(12 e2e cases: pending re-source/delete/recompile, byte-identical failure
logs across modes, 48-compile cache stress) x10 repeats clean both modes;
full NVIDIA DirectGLES retrace identical result sets flag off/on (zero new
deltas); compile-phase timing flat as designed (links still serial - the
parallel win arrives with stage 4's async link + stage 5's
KHR_parallel_shader_compile).
Standalone Asio (submodule, asio-1-38-2 @ 8806a680, ASIO_STANDALONE +
ASIO_NO_DEPRECATED, header-only - no linked artifact) and the job machinery
the async shader pipeline will run on: JobNode (state machine with deferred
errors, continuations firing exactly once, dependency counters, cancel
semantics split into request vs outcome) and ShaderCompilePool
(asio::thread_pool behind a pimpl so no header leaks asio; big-core count
via cpufreq at >=85% of peak clamped to [1,4]; lazily constructed, so with
the flag off no worker thread ever exists; StopAndDrain leads DestroyImpl).
MOBILEGL_ASYNC_SHADER_COMPILE / _THREADS config knobs, default OFF. Nothing
in the GL pipeline references the pool yet - grep-verified; the full
DirectGLES retrace and compile benches are byte- and time-identical. 25
threaded unit tests, clean across 20x gtest_repeat.
swung0x48
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