From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Mitchell To: dje@watson.ibm.com Cc: rms@gnu.org, jbuck@synopsys.com, mrs@wrs.com, gcc@gcc.gnu.org Subject: Re: type based aliasing again Date: Sat, 11 Sep 1999 18:20:00 -0000 Message-id: <19990911182424A.mitchell@codesourcery.com> References: <9909120057.AA36240@marc.watson.ibm.com> X-SW-Source: 1999-09/msg00447.html >>>>> "David" == David Edelsohn writes: David> FYI, IBM's AIX compiler does not enable "ANSI David> aliasing" by default when the compiler is invoked with David> "cc". AIX "cc" essentially is "gcc -fno-strict-alias David> -fwriteable-strings"; AIX "xlc" command enables alias David> optimizations and creates read-only constants. Someone reported something similar for the DEC copmiler; `cc' is -fno-strict-aliasing, while some more progressive-sounding compiler name is -fstrict-aliasing. One thing important about these data points, though, is that major vendors must be finding that not too many programs use the invalid constructs in question. Otherwise, they would not have dared to enable these options. (Of course, they could have the kind of behavior Joe and RMS are suggesting, I suppose. And their code-bases may be different than GCC's.) -- Mark Mitchell mark@codesourcery.com CodeSourcery, LLC http://www.codesourcery.com From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Mitchell To: dje@watson.ibm.com Cc: rms@gnu.org, jbuck@synopsys.com, mrs@wrs.com, gcc@gcc.gnu.org Subject: Re: type based aliasing again Date: Thu, 30 Sep 1999 18:02:00 -0000 Message-ID: <19990911182424A.mitchell@codesourcery.com> References: <9909120057.AA36240@marc.watson.ibm.com> X-SW-Source: 1999-09n/msg00447.html Message-ID: <19990930180200.xvZDTr-IWfa1j4880-N4HIXoMexA41q5BmHoavTiU7Q@z> >>>>> "David" == David Edelsohn writes: David> FYI, IBM's AIX compiler does not enable "ANSI David> aliasing" by default when the compiler is invoked with David> "cc". AIX "cc" essentially is "gcc -fno-strict-alias David> -fwriteable-strings"; AIX "xlc" command enables alias David> optimizations and creates read-only constants. Someone reported something similar for the DEC copmiler; `cc' is -fno-strict-aliasing, while some more progressive-sounding compiler name is -fstrict-aliasing. One thing important about these data points, though, is that major vendors must be finding that not too many programs use the invalid constructs in question. Otherwise, they would not have dared to enable these options. (Of course, they could have the kind of behavior Joe and RMS are suggesting, I suppose. And their code-bases may be different than GCC's.) -- Mark Mitchell mark@codesourcery.com CodeSourcery, LLC http://www.codesourcery.com