From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Earnshaw To: Mark Mitchell Cc: richard.earnshaw@arm.com Subject: Re: type based aliasing again Date: Mon, 13 Sep 1999 04:05:00 -0000 Message-id: <199909131102.MAA25960@sun52.NIS.cambridge> References: <19990911152505P.mitchell@codesourcery.com> X-SW-Source: 1999-09/msg00483.html mark@codesourcery.com said: > I think that making -fno-strict-aliasing the default is sensible > proposal, and worth debating. It is the default at -O1 or less. I would be inclined to argue that this should be adequate for "legacy" code and that the higher levels of optimization should be allowed to fully exploit the provisions of the C standard (this is not to suggest that a warning shouldn't be generated if possible). We are somewhat constrained by our relatively limited number of optimization levels (0, 1, 2, 3, s); I guess extending the range is hard, mainly because of a user-education issue. But it would be useful if we could have a level above which we say that we assume that code fully conforms to the C (or other relevant) standard. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Earnshaw To: Mark Mitchell Cc: richard.earnshaw@arm.com Subject: Re: type based aliasing again Date: Thu, 30 Sep 1999 18:02:00 -0000 Message-ID: <199909131102.MAA25960@sun52.NIS.cambridge> References: <19990911152505P.mitchell@codesourcery.com> X-SW-Source: 1999-09n/msg00483.html Message-ID: <19990930180200.1VGTMDa_i0aLPfzgdwSbBC7GRI5tCzcqG5eVx7z5mVg@z> mark@codesourcery.com said: > I think that making -fno-strict-aliasing the default is sensible > proposal, and worth debating. It is the default at -O1 or less. I would be inclined to argue that this should be adequate for "legacy" code and that the higher levels of optimization should be allowed to fully exploit the provisions of the C standard (this is not to suggest that a warning shouldn't be generated if possible). We are somewhat constrained by our relatively limited number of optimization levels (0, 1, 2, 3, s); I guess extending the range is hard, mainly because of a user-education issue. But it would be useful if we could have a level above which we say that we assume that code fully conforms to the C (or other relevant) standard.