From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Edelsohn To: Marc Espie Cc: N8TM@aol.com, gcc@gcc.gnu.org Subject: Re: type based aliasing again Date: Thu, 30 Sep 1999 18:02:00 -0000 Message-ID: <9909141656.AA20910@marc.watson.ibm.com> References: <199909141102.NAA18232@quatramaran.ens.fr> X-SW-Source: 1999-09n/msg00543.html Message-ID: <19990930180200.R1wy6Z5lGFT2nnAKwKOQqSbbVE_SH_jOd8MgDRnMql8@z> >>>>> Marc Espie writes: Marc> The only issue here is whether it should be turned on by default for -O#. Marc> Therefore, I don't believe moving -fstrict-aliasing to -O3 or -O4 is a Marc> good idea. It's an issue of whether we consider this optimization as Marc> `safe' or `unsafe'. In the first case, it's a -O2 trigger, probably -Os Marc> as well, as it should decrease the code size. In the second case, I see Marc> no reason to treat it differently from -ffast-math. I think that -ffast-math and the behavior of compilers from other vendors is good precedent that -fstrict-aliasing should be removed from the standard -O# optimization levels and accessed orthogonally. I think that I and the other members of the GCC Steering Committee had good intentions, but were mistaken about the impact of including this optimization in a -O# level. David