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Re: Compiler Analysis: 3.3, 3.4, or tree-ssa?
Matt Fago wrote:
The -O1, -O2, and -O3 options are general-purpose choices for
producing good code in general circumstances.
Are they? How is this determined?
I'll amend my statement...
"The -O1, -O2, and -O3 options *SHOULD BE* general-purpose choices for
producing good code in general circumstances."
I think Acovea might allow the flags implied by these options to be
chosen in a more quantitative way. Obviously Acovia should give better
results when used with a specific code of interest.
I note that on some experiments, -O2 and -O3 produce *slower* code than
does -O1; and in several cases, Acovea finds options sets that produce
code which runs in 40% less time than it does when compiled with any of
the predefined optimization sets.
We could define variations on the -O?? theme... -Ofp, for example, that
optimizes for floating-point applications.
--
Scott Robert Ladd
Coyote Gulch Productions (http://www.coyotegulch.com)
Software Invention for High-Performance Computing