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Re: Fix for df problems, and and an ifcvt improvement
- From: Bernd Schmidt <bernds at codesourcery dot com>
- To: Paolo Bonzini <bonzini at gnu dot org>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 22 Apr 2010 12:30:44 +0200
- Subject: Re: Fix for df problems, and and an ifcvt improvement
- References: <4BD01EEE.3010108@codesourcery.com> <4BD02405.7010600@gnu.org>
On 04/22/2010 12:25 PM, Paolo Bonzini wrote:
> I fixed it to at least make sense, but I didn't recognize the
> possibility to ignore clobbers (note that for
> df_simulate_one_insn_forwards it won't usually matter to ignore partial
> and conditional sets, because those should already be live).
This isn't always true. While working on regrename a while ago I was
reminded that there are sequences like
(set (zero_extract of upper 16 bits) (something))
(set (zero_extract of lower 16 bits) (something else))
The same happens (more frequently actually) with cond_exec:
(cond_exec (condition A) (set (reg X) (Y)))
(cond_exec (reverse-condition A) (set (reg X) (Z)))
> Patch is okay, thanks.
Thanks!
Bernd