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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/67328] range test rather than single bit test for code testing enum values Date: Tue, 25 Aug 2015 08:38:00 -0000 [thread overview] Message-ID: <bug-67328-4-oygfMB2OFO@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-67328-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67328 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |WAITING Last reconfirmed| |2015-08-25 Ever confirmed|0 |1 --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- Note this is already fold-const.c:optimize_bit_field_compare at work. With -DALT (non-working code) we get ;; Function test_pic (null) ;; enabled by -tree-original { if ((BIT_FIELD_REF <*info, 8, 0> & 3) + 254 <= 1) and ;; Function test_exe (null) ;; enabled by -tree-original { if ((SAVE_EXPR <BIT_FIELD_REF <*info, 8, 0> & 3>) == 0 || (SAVE_EXPR <BIT_FIELD_REF <*info, 8, 0> & 3>) == 2) from it. Without -DALT ;; Function test_pic (null) ;; enabled by -tree-original { if ((SAVE_EXPR <BIT_FIELD_REF <*info, 8, 0> & 3>) == 3 || (SAVE_EXPR <BIT_FIELD_REF <*info, 8, 0> & 3>) == 1) ;; Function test_exe (null) ;; enabled by -tree-original { if ((BIT_FIELD_REF <*info, 8, 0> & 3) <= 1) I see more that a single bit test for both cases btw, mostly because we need to mask the padding. Not sure what optimal code you expect here.
next prev parent reply other threads:[~2015-08-25 8:38 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-08-23 13:41 [Bug tree-optimization/67328] New: " amodra at gmail dot com 2015-08-23 13:45 ` [Bug tree-optimization/67328] " amodra at gmail dot com 2015-08-25 8:38 ` rguenth at gcc dot gnu.org [this message] 2015-08-25 13:09 ` amodra at gmail dot com
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