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From: "fkastrati at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/66520] New: bad code generated code for branches with single & Date: Fri, 12 Jun 2015 11:52:00 -0000 [thread overview] Message-ID: <bug-66520-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66520 Bug ID: 66520 Summary: bad code generated code for branches with single & Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: fkastrati at gmail dot com Target Milestone: --- consider the following code snippet (c++): void ampamp(int x, int y) { if (x < 3 && y > 10 ) printf("%d%d", x, y); } void amp(int x, int y) { if ((x < 3) & (y > 10) ) printf("%d%d", x, y); } the assembly code generated by g++ (all versions I tested with optimization flag `-O3'), is not optimal (see the link on the bottom of this message). Basically, for both methods, the generated assembly code is identical. For the method "amp" (with single `&') there should be generated only one jump, as branch misprediction penalty is very high otherwise! As a side note: the code by intel's compiler (ICC) is however generating optimal code for such scenarios, at least for versions icc13, and icc15 that I've tested. See: http://goo.gl/oiTPX5
next reply other threads:[~2015-06-12 11:52 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-06-12 11:52 fkastrati at gmail dot com [this message] 2015-06-13 10:13 ` [Bug c++/66520] " ebotcazou at gcc dot gnu.org 2015-06-13 23:21 ` fkastrati at gmail dot com 2015-06-14 7:23 ` ebotcazou at gcc dot gnu.org 2015-06-14 10:44 ` fkastrati at gmail dot com 2015-06-14 10:57 ` ebotcazou at gcc dot gnu.org 2015-06-14 10:58 ` schwab@linux-m68k.org 2015-06-14 11:26 ` fkastrati at gmail dot com 2015-06-14 11:34 ` fkastrati at gmail dot com 2015-06-14 12:26 ` redi at gcc dot gnu.org
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