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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/103121] [12 Regression] Warnings in
 cp/optimize.c causing build failure
Date: Fri, 21 Jan 2022 16:16:52 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103121

--- Comment #29 from Martin Sebor <msebor at gcc dot gnu.org> ---
>>From memory: At use1 the cache is empty so go and find its definition and
record the offset at that point, with the pointer addition as the context. =
 And
at use2 we look up the same offset.  So use1 won't reflect the constant off=
set.
 That could be both good (if the code is unreachable) and bad (if it is and=
 the
use is invalid.

If it did work the way you're concerned I'd expect to see a lot of mysterio=
us
false positives.  The cache has been in use since GCC 11 and I don't recall
coming across any puzzling problems.  But we have seen an uptick in false
positives in GCC 12 after we switched over to Ranger so let me double check=
 it
really does work the way I say it does.=