http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57534
ncahill_alt at yahoo dot com changed:
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Attachment #30261|0 |1
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--- Comment #4 from ncahill_alt at yahoo dot com ---
Created attachment 30263
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30263&action=edit
Contained source file demonstrating bug
I have tested GCC 4.8.0 (32 bit of course) and the same slowdown is present.
The slowdown is greater with -mtune=pentium2 for some reason, but the slowdown
with no -mtune specified.
I have attached a single file with all the preprocessed source, including the
timing functions. Reducing it is difficult because it keeps hitting infinite
loops.
The command: gcc -O2 wholesource.c -o cachebench
With -O1, the bug is not present. Uncommenting the commented line so as to try
to remove the timing dependency stops the bug from occurring.
The numbers output by the executable are performance numbers, what used to be
MB/sec of read performance.
Thank you very much.
Neil Cahill.
