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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/61010] [4.8/4.9/4.10 Regression] Infinite recursion in fold
Date: Wed, 30 Apr 2014 10:13:00 -0000	[thread overview]
Message-ID: <bug-61010-4-vqQ8p4rEY4@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-61010-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61010

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Indeed we iterate in /* Canonicalize (X & C1) | C2.  */ because we fold

 (unsigned int) (a * 64) & 255

to

 (unsigned int) (a * 64) & 192

in /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero bits from
CST2.  */


The iterating input is

 ((unsigned int) (a * 64) & 192) | 63

where it seems to fail to "Minimize the number of bits set in C1"
because it hits the "unless" case.

One option is to apply the same "unless" case to the "drop known zero bits"
BIT_AND_EXPR folding.


  parent reply	other threads:[~2014-04-30 10:13 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-30  2:02 [Bug tree-optimization/61010] New: ICE in gcc.c ishiura-compiler at ml dot kwansei.ac.jp
2014-04-30  2:28 ` [Bug middle-end/61010] " pinskia at gcc dot gnu.org
2014-04-30  6:00 ` mpolacek at gcc dot gnu.org
2014-04-30  8:21 ` ktkachov at gcc dot gnu.org
2014-04-30  9:06 ` ktkachov at gcc dot gnu.org
2014-04-30  9:29 ` [Bug middle-end/61010] [4.8/4.9/4.10 Regression] Infinite recursion in fold rguenth at gcc dot gnu.org
2014-04-30 10:13 ` rguenth at gcc dot gnu.org [this message]
2014-04-30 10:18 ` rguenth at gcc dot gnu.org
2014-04-30 10:43 ` rguenth at gcc dot gnu.org
2014-04-30 10:43 ` rguenth at gcc dot gnu.org
2014-05-05  9:24 ` [Bug middle-end/61010] [4.8/4.9 " rguenth at gcc dot gnu.org
2014-05-05  9:24 ` rguenth at gcc dot gnu.org
2014-05-22  9:01 ` rguenth at gcc dot gnu.org
2014-05-28 12:47 ` [Bug middle-end/61010] [4.8 " rguenth at gcc dot gnu.org
2014-09-09 13:18 ` rguenth at gcc dot gnu.org
2014-09-09 13:18 ` rguenth at gcc dot gnu.org

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