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* [Bug tree-optimization/21001] New: VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR. @ 2005-04-13 19:05 kazu at cs dot umass dot edu 2005-04-13 22:47 ` [Bug tree-optimization/21001] " pinskia at gcc dot gnu dot org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: kazu at cs dot umass dot edu @ 2005-04-13 19:05 UTC (permalink / raw) To: gcc-bugs Consider: int foo (int a) { int b = a != 0; if (b) if (a != 0) return 1; return 0; } With "-O2 -ftree-no-dominator-opts", VRP generates: foo (a) { int b; int D.1153; <bb 0>: b_3 = a_2 != 0; if (b_3 != 0) goto <L0>; else goto <L2>; <L0>:; if (a_2 != 0) goto <L1>; else goto <L2>; <L1>:; D.1153_6 = 1; goto <bb 4> (<L4>); <L2>:; D.1153_5 = 0; # D.1153_1 = PHI <D.1153_6(2), D.1153_5(3)>; <L4>:; return D.1153_1; } Note that the second "if" statement is always true, but VRP does not notice that. Forward-propagating "a_2 != 0" into the first "if" statement will do the desired optimization. -- Summary: VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR. Product: gcc Version: unknown Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P2 Component: tree-optimization AssignedTo: kazu at cs dot umass dot edu ReportedBy: kazu at cs dot umass dot edu CC: gcc-bugs at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21001 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/21001] VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR. 2005-04-13 19:05 [Bug tree-optimization/21001] New: VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR kazu at cs dot umass dot edu @ 2005-04-13 22:47 ` pinskia at gcc dot gnu dot org 2005-04-15 20:32 ` [Bug tree-optimization/21001] VRP is weak when the tested variable in a COND_EXPR is used only " kazu at cs dot umass dot edu ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2005-04-13 22:47 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From pinskia at gcc dot gnu dot org 2005-04-13 22:46 ------- Confirmed. -- What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Ever Confirmed| |1 Last reconfirmed|0000-00-00 00:00:00 |2005-04-13 22:46:53 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21001 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/21001] VRP is weak when the tested variable in a COND_EXPR is used only in the COND_EXPR. 2005-04-13 19:05 [Bug tree-optimization/21001] New: VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR kazu at cs dot umass dot edu 2005-04-13 22:47 ` [Bug tree-optimization/21001] " pinskia at gcc dot gnu dot org @ 2005-04-15 20:32 ` kazu at cs dot umass dot edu 2005-04-18 6:10 ` cvs-commit at gcc dot gnu dot org 2005-04-18 6:11 ` kazu at cs dot umass dot edu 3 siblings, 0 replies; 5+ messages in thread From: kazu at cs dot umass dot edu @ 2005-04-15 20:32 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From kazu at cs dot umass dot edu 2005-04-15 20:32 ------- Patch posted: http://gcc.gnu.org/ml/gcc-patches/2005-04/msg01770.html -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21001 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/21001] VRP is weak when the tested variable in a COND_EXPR is used only in the COND_EXPR. 2005-04-13 19:05 [Bug tree-optimization/21001] New: VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR kazu at cs dot umass dot edu 2005-04-13 22:47 ` [Bug tree-optimization/21001] " pinskia at gcc dot gnu dot org 2005-04-15 20:32 ` [Bug tree-optimization/21001] VRP is weak when the tested variable in a COND_EXPR is used only " kazu at cs dot umass dot edu @ 2005-04-18 6:10 ` cvs-commit at gcc dot gnu dot org 2005-04-18 6:11 ` kazu at cs dot umass dot edu 3 siblings, 0 replies; 5+ messages in thread From: cvs-commit at gcc dot gnu dot org @ 2005-04-18 6:10 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From cvs-commit at gcc dot gnu dot org 2005-04-18 06:10 ------- Subject: Bug 21001 CVSROOT: /cvs/gcc Module name: gcc Changes by: kazu@gcc.gnu.org 2005-04-18 06:10:45 Modified files: gcc : ChangeLog tree-optimize.c gcc/testsuite : ChangeLog Added files: gcc/testsuite/gcc.dg/tree-ssa: pr21001.c Log message: gcc/ PR tree-optimization/21001 * tree-optimize.c (init_tree_optimization_passes): Move the first pass_forwprop immediately before pass_vrp. testsuite/ PR tree-optimization/21001 * gcc.dg/tree-ssa/pr21001.c: New. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.8340&r2=2.8341 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-optimize.c.diff?cvsroot=gcc&r1=2.83&r2=2.84 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.5361&r2=1.5362 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.dg/tree-ssa/pr21001.c.diff?cvsroot=gcc&r1=NONE&r2=1.1 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21001 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/21001] VRP is weak when the tested variable in a COND_EXPR is used only in the COND_EXPR. 2005-04-13 19:05 [Bug tree-optimization/21001] New: VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR kazu at cs dot umass dot edu ` (2 preceding siblings ...) 2005-04-18 6:10 ` cvs-commit at gcc dot gnu dot org @ 2005-04-18 6:11 ` kazu at cs dot umass dot edu 3 siblings, 0 replies; 5+ messages in thread From: kazu at cs dot umass dot edu @ 2005-04-18 6:11 UTC (permalink / raw) To: gcc-bugs ------- Additional Comments From kazu at cs dot umass dot edu 2005-04-18 06:11 ------- Just checked in a patch. -- What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED Target Milestone|--- |4.1.0 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21001 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2005-04-18 6:11 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2005-04-13 19:05 [Bug tree-optimization/21001] New: VRP is weak when the tested variable in a COND_EXPR is used in the COND_EXPR kazu at cs dot umass dot edu 2005-04-13 22:47 ` [Bug tree-optimization/21001] " pinskia at gcc dot gnu dot org 2005-04-15 20:32 ` [Bug tree-optimization/21001] VRP is weak when the tested variable in a COND_EXPR is used only " kazu at cs dot umass dot edu 2005-04-18 6:10 ` cvs-commit at gcc dot gnu dot org 2005-04-18 6:11 ` kazu at cs dot umass dot edu
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