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CONTRACT-P7 §3.2's `copy-image-in-place@P7`, retired.
glCopyImageSubData between two subresources of ONE texture is ordinary, defined GL -
4.6 core 18.3.2 spells out that a texture and a view of it are two objects over one
image and may be copied between. The wire arm took the session down for it, and the
reason it gave was true of the code beneath it and of nothing else: the
TRANSFER_SRC/TRANSFER_DST pair cannot describe one image, because both endpoints share
one tracked VkImageLayout and the second transition undoes the first.
VK_IMAGE_LAYOUT_GENERAL can describe it - both sides of vkCmdCopyImage accept it. So a
same-image copy now takes ONE transition of the whole image to GENERAL (the source level
and the destination level are both inside it), GENERAL on both sides of the command, and
ONE restore, with an access mask carrying both directions because that one barrier is
the edge for both. The monolith arm still declines every in-place copy a few lines up,
so the wire arm is the one that performs this - which is what §3.2 asks for rather than
parity. `inPlace` is constexpr false in the pull build so every branch it guards folds:
this function is in the monolith image and G1 pins that image's .text.
The one shape that stays a decline is same image + same level + overlapping slices +
overlapping rectangle, all three at once. GL leaves that undefined, and GENERAL makes
the command legal to RECORD rather than meaningful to execute - vkCmdCopyImage orders
nothing between its own reads and writes inside a region, so a tiler produces whichever
half of each texel it reached first. Level 0 to level 1, disjoint layers, and disjoint
rectangles of one level are all defined, and all performed.
Two split-only cases on the three Magma arms, over one 8x8x2 two-level array texture
whose every touched subresource is a different colour - a flat fill would let "copied to
the wrong level", "copied to the wrong layer" and "did not copy" all read as correct.
CopyImageInPlaceAcrossLevelsAndLayers does level 0 -> level 1 and then layer 0 -> layer 1
and checks the untouched subresources too; CopyImageInPlaceOverlapDeclinesAndLeavesTheLevelAlone
copies (0,0)-(4,4) onto (2,2) and pins every texel unchanged - an executed copy would
turn the texel at (4,4) from yellow to red, so the assertion can tell.
Red once (executed, reverted): with MagmaWireFatal("copy-image-in-place@P7") restored,
both entries die with Fatal{UnmigratedVerb, "Magma:copy-image-in-place@P7"}; without it,
2/2 green.
Gates: integration-magma-split 79 (+2), -spawn 58 (+2), -tcp 60 (+2), 0 red;
ctest -L unit 2410; informational integration-magma-full-split 515, 0 red, 59 skip;
fatal_census green (79 sites / 43 words / 0 unmarked); link_ratchet --assert-monotone
unchanged at 186, p7-magma 101; G1 pull .text 0xa52203 and the defined-symbol name list
identical (30570) - the constexpr-false branches fold as intended.
This tree's integration TCP endpoint moved to 127.0.0.1:40913: a sibling worktree's
libMobileGLServer was already listening on pipe's default 40613 and took the whole tcp
lane down at TcpServer.Start. It is a local configure option, not a lane semantic.