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Re: Massive performance regression from switching to gcc 4.5


> Jan Hubicka wrote:
>>> On Fri, 25 Jun 2010, it was written:
>>> There sure is something in 4.5. I've seen a 1-10% slowdown at the GiNaC
>>> (a computer algebra library) benchmark suite after switching from 4.4 to
>>> 4.5 on x86_64 when compiling with -O2. And there hasn't been a measurable
>>> performance differences between 4.3 and 4.4.
>>
>> FP intensive code could be also affected by:
>
> This code isn't using floating-point.

Hmm, building ginac with current 4.5 branch I get:
/bin/sh ../libtool --tag=CXX   --mode=compile /abuild/jh/gcc-4.5-nopatch/bin/g++ -DHAVE_CONFIG_H -I. -I../../ginac -I../config   -I/usr/local/include    -g -O2 -MT function.lo -MD -MP -MF .deps/function.Tpo -c -o function.lo ../../ginac/function.cpp
libtool: compile:  /abuild/jh/gcc-4.5-nopatch/bin/g++ -DHAVE_CONFIG_H -I. -I../../ginac -I../config -I/usr/local/include -g -O2 -MT function.lo -MD -MP -MF .deps/function.Tpo -c ../../ginac/function.cpp  -fPIC -DPIC -o .libs/function.o
../../ginac/function.cpp: In member function â??GiNaC::ex GiNaC::function::power(const GiNaC::ex&) constâ??:
../../ginac/function.cpp:1800:15: error: expected type-specifier
../../ginac/function.cpp:1800:15: error: expected â??)â??
../../ginac/function.cpp:1801:72: error: conversion from â??int*â?? to â??GiNaC::exâ?? is ambiguous
../../ginac/ex.h:279:1: note: candidates are: GiNaC::ex::ex(long unsigned int) <near match>
../../ginac/ex.h:273:1: note:                 GiNaC::ex::ex(long int) <near match>
../../ginac/ex.h:267:1: note:                 GiNaC::ex::ex(unsigned int) <near match>
../../ginac/ex.h:261:1: note:                 GiNaC::ex::ex(int) <near match>

Honza
>
>   -richy.
> -- 
> Richard B. Kreckel
> <http://www.ginac.de/~kreckel/>


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