Alpha and -funroll-loops

[Oskar Enoksson]

Hi! I was just about to write an email complaining about the efficiency
of egcs code on Alpha CPU's when I discovered that -funroll-loops is the
magic that makes it run fast:

Results from the code on a 433 MHz ev56 with no L3-cache:

Compiler                          MFLOPS
========================================
Dec> f77 -O0                           7
Dec> f77 -O1                          44
Dec> f77 -O2                          79
Dec> f77 -O3                         208
Dec> f77 -O4                         207
Dec> f77 -O5                         113

egcs1.1> g77 -O0                      12
egcs1.1> g77 -O1                      71
egcs1.1> g77 -O2                      83
egcs1.1> g77 -O3                      83
egcs1.1> g77 -O3 -funroll-loops      187

The performance with snapshot 980914 was the same for this program.

In case someone is interested, I've attached some interesting pieces
of assembler output.

BTW, is it still true that -funroll-loops is unreliable for g++?
(The info-pages say so).

Regards.
/Oskar