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From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/31178] VRP can infer a range for b in a >> b and a << b Date: Thu, 15 Mar 2007 14:43:00 -0000 [thread overview] Message-ID: <20070315144336.21305.qmail@sourceware.org> (raw) In-Reply-To: <bug-31178-10053@http.gcc.gnu.org/bugzilla/> ------- Comment #1 from rguenth at gcc dot gnu dot org 2007-03-15 14:43 ------- This is blocked by the same fact as PR30317 in that ASSERT_EXPRs can only assert half-ranges or single valued ranges. This makes the following prototype not assert [0, prec) but [-INF, prec) instead :( Index: tree-vrp.c =================================================================== *** tree-vrp.c (revision 122953) --- tree-vrp.c (working copy) *************** infer_value_range (tree stmt, tree op, e *** 3113,3118 **** --- 3113,3134 ---- } } + /* We can assume that the shift argument of a left or right shift + is within zero and the type precision of the shifted operand. */ + if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT + && (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == RSHIFT_EXPR + || TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == LSHIFT_EXPR) + && TREE_OPERAND (GIMPLE_STMT_OPERAND (stmt, 1), 1) == op) + { + tree lop = TREE_OPERAND (GIMPLE_STMT_OPERAND (stmt, 1), 0); + tree lop_type = TREE_TYPE (lop); + + /* Unfortunately we only can infer half-ranges here. */ + *val_p = build_int_cst (lop_type, TYPE_PRECISION (lop_type) - 1); + *comp_code_p = LE_EXPR; + return true; + } + return false; } -- rguenth at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- BugsThisDependsOn| |30317 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31178
next prev parent reply other threads:[~2007-03-15 14:43 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2007-03-14 21:13 [Bug tree-optimization/31178] New: " rguenth at gcc dot gnu dot org 2007-03-15 14:43 ` rguenth at gcc dot gnu dot org [this message] 2009-02-08 14:21 ` [Bug tree-optimization/31178] " steven at gcc dot gnu dot org 2009-02-08 14:47 ` rguenth at gcc dot gnu dot org [not found] <bug-31178-4@http.gcc.gnu.org/bugzilla/> 2013-02-11 7:48 ` rguenth at gcc dot gnu.org 2013-02-11 8:00 ` jakub at gcc dot gnu.org 2022-03-22 14:21 ` amacleod at redhat dot com 2022-03-22 17:03 ` amacleod at redhat dot com 2022-03-23 8:08 ` rguenther at suse dot de 2022-03-23 8:26 ` jakub at gcc dot gnu.org 2022-03-23 8:31 ` jakub at gcc dot gnu.org 2022-04-05 17:58 ` amacleod at redhat dot com 2022-04-05 18:06 ` jakub at gcc dot gnu.org 2022-04-05 18:24 ` amacleod at redhat dot com 2022-04-06 6:00 ` rguenth at gcc dot gnu.org 2022-04-06 8:16 ` vincent-gcc at vinc17 dot net 2022-04-06 8:22 ` rguenther at suse dot de 2022-04-06 8:45 ` vincent-gcc at vinc17 dot net 2022-04-06 13:10 ` amacleod at redhat dot com 2022-04-06 13:13 ` jakub at gcc dot gnu.org 2022-04-06 13:16 ` rguenther at suse dot de 2024-06-20 16:07 ` pinskia at gcc dot gnu.org 2024-06-26 5:44 ` pinskia at gcc dot gnu.org
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