Re: Massive performance regression from switching to gcc 4.5

no idea what's up yet. -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

Re: Massive performance regression from switching to gcc 4.5

erformance differences between 4.3 and 4.4. FP intensive code could be also affected by: This code isn't using floating-point. -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

Re: Massive performance regression from switching to gcc 4.5

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

Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."

do need is correctness. Actually, all the users of free software need and deserve that correctness. Bottom line: without such a warning, -fwrapv should be the default and should not be turned off by any -O option. Regards -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

Re: GCC optimizes integer overflow: bug or feature?

rs, unless told otherwise (using -ffast-math). Now it is violating another standard (LIA-1) that is not binding, but assumed by many of its users, unless explicitly told to follow that standard (with -fwrapv). That is A Bad Idea. Cheers -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

Re: GCC optimizes integer overflow: bug or feature?

Marcin Dalecki wrote: On 2006-12-20, at 22:48, Richard B. Kreckel wrote: 2) Signed types are not an algebra, they are not even a ring, at least when their elements are interpreted in the canonical way as integer numbers. (Heck, what are they?) You are apparently using a different

Re: GCC optimizes integer overflow: bug or feature?

es the validity of the analogy with IEEE real arithmetic. -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

Re: GCC optimizes integer overflow: bug or feature? (was: avoid integer overflow in mktime.m4)

turning on any optimization that breaks programs which depend on wrapping signed integers. Silently breaking LIA-1 semantics is imprudent. -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

Re: Language Changes in Bug-fix Releases?

way worked since at least GCC 2.7.x) can make your code accidentally fire that ballistic rocket. (If it really can, then you're having a truck load of other problems besides code quality.) Saludos -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

Language Changes in Bug-fix Releases?

be fixed, then forget this email. [0] <http://gcc.gnu.org/develop.html> [1] I don't talk about distros that use the latest version from HEAD. Screw them! -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>