Optimization: Conclusions from Evolutionary Analysis

[Dan Nicolaescu]

Scott Robert Ladd <coyote@coyotegulch.com> writes:

[snip]
  > Processor-specific options do not appear to be a major factor in
  > performance on these benchmarks. I don't know if this is due to
  > the nature of the processor, or if GCC can't take advantage of
  > processor-specific instructions. I have double-checked my results;
  > adding -mfpmath=sse (or any of its variants, or -msse) to a
  > compile of almabench does not make the code run any faster. The
  > only ia32-specific option that showed consistent value was
  > -momit-leaf-frame-pointer.

You state on your web page that -O1 implies -fomit-frame-pointer. 
The default GCC configuration on a P4 does not do that!
Did you change this when compiling GCC?

If -fomit-frame-pointer were to be enabled by default,  
-momit-leaf-frame-pointer should not have any effect. 
This is rather strange....