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[Bug tree-optimization/49715] Could do more efficient unsigned-to-float to conversions based on range information
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 12 Jul 2011 15:22:36 +0000
- Subject: [Bug tree-optimization/49715] Could do more efficient unsigned-to-float to conversions based on range information
- Auto-submitted: auto-generated
- References: <bug-49715-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49715
--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> 2011-07-12 15:21:51 UTC ---
On Tue, 12 Jul 2011, sgunderson at bigfoot dot com wrote:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49715
>
> --- Comment #3 from sgunderson at bigfoot dot com 2011-07-12 15:19:51 UTC ---
> Wow, answer in record time :-)
>
> I don't know anything about GCC internals, so I can't comment much on the
> patch; my only worry here is what would happen if you had a very narrow mask,
> e.g. (x & 0xf) and you try to coerce it into the minimum possible type (a
> char); wouldn't you end up doing some sort of expansion with movzbl again?
That's why I limit it to SImode truncation (that should be
equivalent to an int). Quite lame ;)