From: Paul Floyd <paulf@free.fr>
To: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
Subject: Re: Safe transposition of logical and operands
Date: Mon, 18 Sep 2023 22:15:26 +0200 [thread overview]
Message-ID: <1dbda88a-60dd-bb00-1217-244d111598fb@free.fr> (raw)
In-Reply-To: <2cabfda8e4ef48627a681fdb1619f2937cc4bd97.camel@gwdg.de>
On 18-09-23 21:09, Martin Uecker wrote:
> I do not understand why memcheck cares about the potential trap when
> deciding to do the backwards transformation that combines the two
> comparisons? Can't you just remove this condition? I assume it
> is meant as a filter to only transform cases which really come
> from an '&&' condition in the source, but as this example show, this
> is too strict. Or am I missing something?
My understanding is that this is a generic transformation of
if (a && b) [which might have been transposed from if (b && a)]
into
if (a & b) [with appropriate extension to the right size].
That means both get evaluated and we can't take that risk that one of
them traps.
A+
Paul
next prev parent reply other threads:[~2023-09-18 20:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-17 19:33 Paul Floyd
2023-09-17 20:51 ` Jonathan Wakely
2023-09-18 7:03 ` Paul Floyd
2023-09-18 7:23 ` Jonathan Wakely
2023-09-18 8:00 ` Richard Biener
2023-09-18 14:46 ` Floyd, Paul
2023-09-18 14:55 ` Richard Biener
2023-09-18 17:56 ` Paul Floyd
2023-09-18 19:09 ` Martin Uecker
2023-09-18 20:15 ` Paul Floyd [this message]
2023-09-18 20:52 ` Martin Uecker
2023-09-19 5:03 ` Paul Floyd
2023-09-18 9:36 ` Jonathan Wakely
2023-09-18 10:30 ` Andreas Schwab
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