On 20 Apr 2007, at 08:30, Ian Lance Taylor wrote:
13) Michael Meissner raised the idea of compiling functions
differently for different processors, choosing the version based
on a runtime decision. This led to some discussion of how this
could be done effectively. In particular if there is an
architectural difference, such as Altivec, you may get prologue
instructions which save and restore registers which are not
present on all architectures.
Related to this: have you guys ever considered to making the -On
flags dependent on the architecture?
Now, the decision which flags are activated for the -On flags is
independent of the architecture I believe (except for flags which
need to be disabled to ensure correct code generation, such as -
fschedule-insns for x86). I must say I haven't looked into this in
great detail, but atleast for the passes controlled by flags on x86,
this seems to be the case.
I think choosing the flags in function of the architecture you are
compiling for, might be highly beneficial (see http://gcc.gnu.org/
bugzilla/show_bug.cgi?id=31528 for example).
greetings,
Kenneth
--
Statistics are like a bikini. What they reveal is suggestive, but
what they conceal is vital (Aaron Levenstein)
Kenneth Hoste
ELIS - Ghent University
[EMAIL PROTECTED]
http://www.elis.ugent.be/~kehoste
