Built egcs-1.1b on i586-pc-linux-gnulibc1, -fgcse slowdowns

N8TM@aol.com N8TM@aol.com
Mon Sep 21 19:37:00 GMT 1998


In a message dated 9/21/98 2:16:03 PM Pacific Daylight Time, drc@adni.net
writes:

> Should I generally compile things with -fno-gcse, or is it likely to be a
>  quirk with this particular program?
>  
I compile for Intel with -Os -fstrict-aliasing unless I have reason to check
whether -O2 may be faster.  Before I try -O2, I try -funroll-loops.  As you
found, the gcse optimizations often fail to improve performance on Intel,
presumably due to register scarcity.

I have seen big improvements from egcs-1.1 to egcs-19980914 on hppa and mips,
using -O2, but not on Intel.



More information about the Gcc mailing list