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[Bug target/49799] gcc arm generates illegal sbfx instruction
- From: "ramana at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 21 Jul 2011 14:28:58 +0000
- Subject: [Bug target/49799] gcc arm generates illegal sbfx instruction
- Auto-submitted: auto-generated
- References: <bug-49799-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49799
Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2011.07.21 14:27:59
CC| |ramana at gcc dot gnu.org
Ever Confirmed|0 |1
--- Comment #3 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> 2011-07-21 14:27:59 UTC ---
Confirmed - and it appears as though combine is doing this transformation .
Based on a quick debug I couldn't spot any pattern in the backend that
encourages this other than the extv matcher.
One could guard this by making sure that the backend doesn't recognize such
forms but combine really shouldn't be generating such a extv instruction
reading more bits than that are already available.
Ramana