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From: "torvalds@linux-foundation.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/100363] gcc generating wider load/store than
 warranted at -O3
Date: Mon, 03 May 2021 16:18:05 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100363

--- Comment #11 from Linus Torvalds <torvalds@linux-foundation.org> ---
(In reply to Linus Torvalds from comment #10)
>=20
>       This particular code comes
> from some old version of zlib, and I can't test because I don't have the =
ARC
> background to make any sense of the generated code.

Heh. We upgraded to a "recent version" of zlib back in 2006:=20

   "Upgrade the zlib_inflate implementation in the kernel from a patched
    version 1.1.3/4 to a patched 1.2.3"

but it turns out that the "do things a 16-bit word at a time" was a
kernel-local optimization for some very slow old PowerPC microcontroller.

The code in upstream zlib actually looks rather better (which is not saying
much, admittedly), doesn't have any 16-bit accesses, and we probably should
just try to synchronize with that instead.=