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Re: [RFH] - Less than optimal code compiling 252.eon -O2 for x86
- From: Andrew Pinski <pinskia at physics dot uc dot edu>
- To: Fariborz Jahanian <fjahanian at apple dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Fri, 24 Jun 2005 18:16:55 -0400
- Subject: Re: [RFH] - Less than optimal code compiling 252.eon -O2 for x86
- References: <B7C12C01-DBA8-4F56-9DF3-4BE0C45D5ADD@apple.com>
On Jun 24, 2005, at 6:07 PM, Fariborz Jahanian wrote:
A source file mrSurfaceList.cc of 252.eon produces less efficient code
initializing instance objects to 0 at -O2 than at -O1. Behavior is
random and it does not happen on all x86 platforms and making the
test smaller makes the problem go away. But here is what I found out
is the cause.
This cannot be simplified by fold_rtx, resulting in less efficient
code.
I wonder why combine can do the simplification though which is why still
produce good code for the simple testcase:
void f1(double *d,float *f2)
{
*f2 = 0.0;
*d = 0.0;
}
Thanks,
Andrew Pinski