cmd/compile: internal compiler error on : "tried to free an already free register" with generic function and type >= 192 bytes [1.26 backport]

[gopherbot]

@randall77 requested issue #77604 to be considered for backport to the next 1.26 minor release.

@gopherbot please open a backport issue to go 1.26. This is a rare but triggerable ICE.

[gopherbot]

Change https://go.dev/cl/745820 mentions this issue: cmd/compile: don't drop same register twice

[Raymon-del2]

"The crash on types >= 192 bytes suggests the register allocator is struggling with 'heavy' types.

This aligns with why we strictly enforce a 32-byte limit in the S.A.I.D. protocol. When we allowed types >128 bytes in our v2 internal tests, we saw similar memory fragmentation.

Is there a possibility to transduce the generic function's large type into a pointer or a smaller 'grain' to bypass the register limit? We solved this by treating data as coordinates rather than payloads.

Just a thought from the R.A.T.A. architecture team." (rata-said.vercel.app)

[dmitshur]

Moving the Critical label from here to #77604 (the upstream Go 1.27 tracking issue).