| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Manfred Spraul <manfred(at)colorfullife(dot)com> |
| Cc: | Andrew Dunstan <andrew(at)dunslane(dot)net>, "Patches (PostgreSQL)" <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: fix for strict-alias warnings |
| Date: | 2003-10-14 20:43:05 |
| Message-ID: | 687.1066164185@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-patches |
Manfred Spraul <manfred(at)colorfullife(dot)com> writes:
> After some massaging, I've succeeded in generating bad code using a
> slightly modified MemSetAligned macro (parameters -O2
> -fstrict-aliasing): gcc pipelined the x*x around the memset.
As I already explained, we do not care about the MemSetAligned case.
Is gcc 3.3 smart enough to optimize away the pointer alignment test
in the full macro?
(Hm, if so, maybe that explains Bruce's observation that the warning
only shows up with Node structs that are allocated as local
variables, rather than palloc'd ... that would be the only case where
gcc could possibly optimize away the alignment test ...)
regards, tom lane
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