Date: Sun, 14 Mar 1999 00:37:04 +0100 (CET) From: Remy Nonnenmacher <remy@synx.com> To: dennis@etinc.com Cc: hackers@FreeBSD.ORG Subject: Re: 'C' language question Message-ID: <199903132345.AAA29762@rt2.synx.com> In-Reply-To: <199903132232.RAA19255@etinc.com>
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On 13 Mar, Dennis wrote:
> *reg |= 0x80000000;
>
> generates a byte OR (ORB instruction) which trashes the register with
> gcc 2.9.2....a stupid "optimization" that happens to be wrong in this
> case.
Just for fun: i couldn't resist to expose you all a real 'optimization'
madness of the C compiler of a big (really big) company :
(after macros expension)
Original :
if (A == 0) {...}
if ((A == 0 ? *ptr++ : func()) == 7) {...}
assembler code generated :
if (A == 0) {..}
else if (*++ptr == 7) {..}
^^^^^
just to say that 'stupid' seems a little hard in the original
message case.
RN.
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