> There was another interesting question in that mail: is "-O1" flag > something different from just combination of "-fsomething" flags? This really is the question I'm interested in. The problem itself was fixed, I just don't understand why applying the same optimizations (and more) which make up -O1 don't elicit the same behavior. Mike On Mon, Oct 12, 2009 at 3:43 AM, Alexey Salmin <alexey.salmin@xxxxxxxxx> wrote: > > On Mon, Oct 12, 2009 at 2:20 PM, Ian Lance Taylor <iant@xxxxxxxxxx> wrote: > > Mike Sullivan <mbsullivan@xxxxxxxxx> 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 > > -mfpmath=sse. > > > > Ian > > > > There was another interesting question in that mail: is "-O1" flag > something different from just combination of "-fsomething" flags? > > Alexey
