Outdoors in Breath of the Wild (the user's Great Plateau save, Mac M4 Pro) a frame had about 386
render passes and loaded and stored about 900 MB of attachments, which an iPhone at 60 fps can
hardly move (about 55 GB/s). 220 of those passes ended only because the game updates the first
64 bytes of a 64 KB vertex uniform block before each draw group (nvnCommandBufferUpdateUniformBuffer
inside the pass) while its shaders read up to 544 bytes of it. A deferred update that covers only
part of what a draw reads used to end the pass.
- Partly covered blocks (nvn_mtl.m ubp_get): the shadow starts from memory and takes every inline
update queued in the submission, newest last, incrementally per range. It is refused, and the
pass ends as before, when something else may have written the range by the time the pass runs:
a copy, fill or feedback write queued in the submission, a storage buffer a shader may write or
a texture->buffer copy over it (sbw, by 4 KB page), or a GPU write or counter report of an
earlier submission still running (gw). A counter report of the same submission does not count:
the host writes reports on the CPU after the whole submission completes (Fire Emblem Engage
writes its reports into a uniform block's page). DM_NVN_UB_PARTIAL=0 turns it off;
DM_NVN_UBP_CHECK=1 lands the updates, waits for the GPU and compares every shadow with memory.
- cb_extent.tsv (new tool dm/gfx/tools/cb_extent.py, c1_guard.py's interval arithmetic over the
translated MSL): per shader, how far into each uniform slot it can read, and the storage slots
it never writes. Like c1_full.tsv, the host loads it only for its chain version; build_ipa.sh
copies it, the NSP script writes it for provisional profiles, and the chain procedure
regenerates it. Without it bindings are copied whole (up to 64 KB). Ten profiles have one.
- Route B's reflection never says whether a storage buffer is written, so every one read as
read-only and its writes went unnoticed: a storage buffer now counts as written unless
SPIRV-Cross typed it const (nvn_refl.m sbuf_rw) or cb_extent.tsv proves the slot unwritten.
- Lazy clears (lc_*): a set of targets that gets only clears before the game sets other targets
no longer opens a pass just to store them; the next pass that attaches the same texture level
and layer through the same view clears it as its load action, and the rest land as before
before anything else could see them. Breath of the Wild's four clear-only passes before the
G-buffer fold into its first pass. Off in TBDR mode; DM_NVN_LAZY_CLEAR=0 turns it off.
- The residency set line counts shadows from memory, refusals by reason, and lazy clears.
On the Mac, old (DM_NVN_UB_PARTIAL=0 DM_NVN_LAZY_CLEAR=0) and new side by side on each game's
route; attachment loads + stores per frame:
- Fire Emblem Engage battles: about 1,850 -> 360 MB, 88 -> 38 passes.
- Tears of the Kingdom: about 1,100 -> 700 MB, 124 -> 116 passes.
- Breath of the Wild outdoors: 386 -> about 158 passes, GPU p50 about 9.3 -> 6.5 ms, submit
5.7 -> 4.2-4.9 ms; where the old host fell to 30 or 20 fps under load, the new held 60.
- Link's Awakening, 13 Sentinels: about 15% less. Super Mario 3D World: 5% less (lazy clears).
- Odyssey, Three Houses: 2-8% less. Mario Wonder, Metroid Dread: unchanged.
No new red lines in any of them. The shadow check found every shadow equal to the GPU's memory
(BotW 346,000, Engage 284,000, TOTK 86,000), and t_nvn passes 68/68. Screenshots differ only by
timing. Tried and dropped: DM_NVN_TBDR=1 (it turns the deferred updates off), DM_NVN_BARRIER=game
(no gain), and same-target continuation outside TBDR mode (BotW's decals end the pass anyway).
What still splits BotW's big passes: the GPU particles' compute dispatches (about 190 MB a frame)
and decals that sample the G-buffer. Mac shader libraries were built for the current chain of
TOTK, Engage, Wonder, Dread, Odyssey, Link's Awakening, Three Houses and 13 Sentinels (c1_full.tsv
headers already matched). The IPA ZeldaBreathOfTheWild-2026-10-21-passes.ipa (an earlier state of
these changes plus the uncommitted frame-step probes) awaits an iPhone test.
seedds
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