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Re: [PATCH] combine: Don't create (set (reg:CC) (compare (reg:CC) (const0)))
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Jeff Law <law at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org, rth at redhat dot com
- Date: Mon, 11 May 2015 16:11:48 -0500
- Subject: Re: [PATCH] combine: Don't create (set (reg:CC) (compare (reg:CC) (const0)))
- Authentication-results: sourceware.org; auth=none
- References: <c6ca02f333bffde49b8ec897b5b4acbd5cc0b475 dot 1431349232 dot git dot segher at kernel dot crashing dot org> <5550E5A3 dot 60305 at redhat dot com>
On Mon, May 11, 2015 at 11:23:47AM -0600, Jeff Law wrote:
> > * combine.c (simplify_set): When generating a CC set, if the
> > source already is in the correct mode, do not wrap it in a
> > compare. Simplify the rest of that code.
> Seems reasonable. Might not hurt to do a little testing on a cc0 target
> though.
I tested on mn10300, cris, and m68k. On m68k it triggers while
building libgcc (for 040). I verified the transform is correct.
I don't have a setup to actually bootstrap or regression check
any cc0 target. A recurring theme :-(
Segher