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Re: [RFC] Add a new argument to SELECT_CC_MODE
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Eric Botcazou <ebotcazou at adacore dot com>, Jie Zhang <jie at codesourcery dot com>
- Cc: gcc-patches at gcc dot gnu dot org, Sandra Loosemore <sandra at codesourcery dot com>
- Date: Thu, 24 Mar 2011 13:31:53 +0000
- Subject: Re: [RFC] Add a new argument to SELECT_CC_MODE
- References: <4D4D94D1.4040606@codesourcery.com> <201102091140.37550.ebotcazou@adacore.com> <201102091245.57413.ebotcazou@adacore.com> <201103222100.59014.ebotcazou@adacore.com>
On Tue, 2011-03-22 at 21:00 +0100, Eric Botcazou wrote:
> > Like in the attached patch.
>
> Sandra expressed an interest for it so I've installed it on the mainline after
> bootstrapping and regtesting on x86_64-suse-linux.
>
>
> 2011-03-22 Eric Botcazou <ebotcazou@adacore.com>
>
> * combine.c (simplify_set): Try harder to find the best CC mode when
> simplifying a nested COMPARE on the RHS.
>
>
So I've always suspected that the way the ARM port handles this is
broken. I think this now confirms that suspicion.
Taking a look at the x86 backend the code there looks far more sensible
and more in-line with what I think ARM should be doing. For a floating
point operation the code is:
TARGET_IEEE_FP ? CCFPUmode : CCFPmode;
That is, if generating IEEE compliant code, then use non-excepting
comparisions, otherwise use exception raising ones.
R.