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Re: Optimization missed
- To: Jason Schonberg <schon at mips dot com>
- Subject: Re: Optimization missed
- From: Alexandre Oliva <oliva at dcc dot unicamp dot br>
- Date: 23 Jun 1999 02:49:51 -0300
- Cc: egcs-bugs at egcs dot cygnus dot com
- References: <199906211751.KAA08094@lightyear.mips.com>
On Jun 21, 1999, Jason Schonberg <schon@mips.com> wrote:
> unsigned A;
> if (A > -5) return 12;
> It's nice to see that the compiler warns about the comparison
> between signed and unsigned. Why does the generated code not
> dispose of the comparison all together?
I can't say for C, but in C++, if either operand of a comparison is
unsigned, the other shall be converted to unsigned, so you'd actually
get:
if (A > (unsigned)-5) return 12;
--
Alexandre Oliva http://www.dcc.unicamp.br/~oliva IC-Unicamp, Bra[sz]il
{oliva,Alexandre.Oliva}@dcc.unicamp.br aoliva@{acm.org,computer.org}
oliva@{gnu.org,kaffe.org,{egcs,sourceware}.cygnus.com,samba.org}
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