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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/59387] [4.9 Regression] wrong code (hangs) at -Os on x86_64-linux-gnu Date: Thu, 19 Dec 2013 11:31:00 -0000 [thread overview] Message-ID: <bug-59387-4-yWFueXmRF0@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-59387-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59387 --- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Note already the chrec is {c_lsm.11_15, +, -1}_2 with char type everywhere (but the 2 which is int, but that is irrelevant), so the information that the decrement was performed carefully in non-wrapping type is lost at that point. Dunno if we want and whether it would be possible to generate a chrec with unsigned char type in that case instead (i.e. (char) {(unsigned char)c_lsm.11_15, +, 255}_2 instead), or some special bit on the chrec to tell us that it is wrapping.
next prev parent reply other threads:[~2013-12-19 11:31 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2013-12-04 18:41 [Bug tree-optimization/59387] New: " su at cs dot ucdavis.edu 2013-12-05 10:57 ` [Bug tree-optimization/59387] " rguenth at gcc dot gnu.org 2013-12-19 11:01 ` [Bug tree-optimization/59387] [4.9 Regression] " jakub at gcc dot gnu.org 2013-12-19 11:22 ` jakub at gcc dot gnu.org 2013-12-19 11:31 ` jakub at gcc dot gnu.org [this message] 2014-01-08 16:38 ` jakub at gcc dot gnu.org 2014-01-08 22:48 ` jakub at gcc dot gnu.org 2014-01-09 9:34 ` rguenth at gcc dot gnu.org 2014-01-10 14:56 ` jakub at gcc dot gnu.org 2014-01-13 19:14 ` jakub at gcc dot gnu.org 2014-01-15 21:43 ` law at redhat dot com 2014-01-16 19:15 ` jakub at gcc dot gnu.org
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