[Python-Dev] Accessing globals without dict lookup (original) (raw)

Skip Montanaro skip@pobox.com
Tue, 12 Feb 2002 21:54:01 -0600 

Tim> Maybe more interesting: One of the folks at Zope Corp reported
Tim> getting significant speedups by using some gcc option that can feed
Tim> real-life branch histories back into the compiler.  Less work and
Tim> less error-prone than guessing annotations.

That would be -fprofile-args and -fbranch-probabilities:

-fprofile-arcs also makes it possible to estimate branch probabilities,
and to calculate basic block execution counts.  In general, basic block
execution counts do not give enough information to estimate all branch
probabilities.  When the compiled program exits, it saves the arc
execution counts to a file called sourcename.da.  Use the compiler
option -fbranch-probabilities when recompiling, to optimize using
estimated branch probabilities.

I fiddled with a bunch of gcc options a few months ago. I finally settled on

-O3 -minline-all-stringops -fomit-frame-pointer

Skip