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From: "ktietz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/51781] New: Missed optimization for ==/!= comparison type-sinking Date: Sat, 07 Jan 2012 11:00:00 -0000 [thread overview] Message-ID: <bug-51781-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51781 Bug #: 51781 Summary: Missed optimization for ==/!= comparison type-sinking Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassigned@gcc.gnu.org ReportedBy: ktietz@gcc.gnu.org Target: *-*-* The following code shows an issue about missed optimization for ==/!= comparisons. extern unsigned char ar[256]; int foo (int x, int y) { int i = (int) ar[x]; return (i == (y & 0xff)); } Compiled with 4.7 using -O2 we get the following optimized tree: ;; Function foo (foo, funcdef_no=0, decl_uid=1600, cgraph_uid=0) foo (int x, int y) { int i; _Bool D.2716; int D.2715; int D.2714; unsigned char D.2713; <bb 2>: D.2713_2 = ar[x_1(D)]; i_3 = (int) D.2713_2; D.2715_5 = y_4(D) & 255; D.2716_6 = D.2715_5 == i_3; D.2714_7 = (int) D.2716_6; return D.2714_7; } But to be expected would be: ;; Function foo (foo, funcdef_no=0, decl_uid=1709, cgraph_uid=0) foo (int x, int y) { unsigned char D.1719; _Bool D.1716; int D.1714; unsigned char D.1713; <bb 2>: D.1713_2 = ar[x_1(D)]; D.1719_9 = (unsigned char) y_4(D); D.1716_6 = D.1713_2 == D.1719_9; D.1714_7 = (int) D.1716_6; return D.1714_7; }
next reply other threads:[~2012-01-07 11:00 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-01-07 11:00 ktietz at gcc dot gnu.org [this message] 2021-06-04 21:55 ` [Bug tree-optimization/51781] " pinskia at gcc dot gnu.org 2023-05-15 4:09 ` pinskia at gcc dot gnu.org
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