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Re: -O* Gives Different Results than Individual Optimizations?
On Mon, Oct 12, 2009 at 2:20 PM, Ian Lance Taylor <email@example.com> wrote:
> Mike Sullivan <firstname.lastname@example.org> writes:
>> A co-worker of mine is having some odd floating-point issues that are
>> related to the compilation options passed to GCC v4.3.3.
> There are many instability issues with gcc floating point when using
> the 80387 FP stack on x86. ?This is the classic bug report
> http://gcc.gnu.org/PR323 , which has finally been fixed for the
> upcoming gcc 4.5 by adding a new option -fexcess-precision=standard.
> If your processor is newer than a Pentium 3, then you can avoid the
> problem by using option such as -march=pentium4 -mtune=generic
There was another interesting question in that mail: is "-O1" flag
something different from just combination of "-fsomething" flags?