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From: "spop at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/64878] [5 Regression] Miscompilation of nntpgrab Date: Mon, 02 Feb 2015 17:25:00 -0000 [thread overview] Message-ID: <bug-64878-4-lPteMXkfLH@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-64878-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64878 --- Comment #4 from Sebastian Pop <spop at gcc dot gnu.org> --- The problem is in the recursion step of fsm_find_control_statement_thread_paths: for (i = 0; i < gimple_phi_num_args (phi); i++) { tree arg = gimple_phi_arg_def (phi, i); basic_block bbi = gimple_phi_arg_edge (phi, i)->src; [...] if (TREE_CODE (arg) == SSA_NAME) { vec_safe_push (path, bbi); /* Recursively follow SSA_NAMEs looking for a constant definition. */ fsm_find_control_statement_thread_paths (arg, visited_phis, path); path->pop (); continue; } We are not supposed to register a jump-thread following only one of the PHI arguments, as the other arguments may resolve into a non-constant or a different constant. In the current case, we have c = x->c1[x->c2]; switch (a) { case 0: if (c == ' ') x->c2++; else if (c == '/') { a = 4; // here is the first argument of the phi node j = x->c2++; } else a = b; // recursive call will follow b and resolve into 15 // here the phi node looks like // a0 = phi (4, b) break; case 1: switch (c) { case '{': a = 0; b = 15; f = f10 (); x->c2++; break;
next prev parent reply other threads:[~2015-02-02 17:25 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-01-30 17:29 [Bug tree-optimization/64878] New: " jakub at gcc dot gnu.org 2015-01-30 17:29 ` [Bug tree-optimization/64878] " jakub at gcc dot gnu.org 2015-01-30 17:30 ` jakub at gcc dot gnu.org 2015-01-30 20:15 ` spop at gcc dot gnu.org 2015-01-30 20:19 ` spop at gcc dot gnu.org 2015-01-30 20:27 ` spop at gcc dot gnu.org 2015-02-02 17:25 ` spop at gcc dot gnu.org [this message] 2015-02-04 17:30 ` spop at gcc dot gnu.org 2015-02-04 17:41 ` jakub at gcc dot gnu.org 2015-02-06 21:08 ` spop at gcc dot gnu.org 2015-02-06 21:16 ` jakub at gcc dot gnu.org 2015-03-05 14:28 ` yroux at gcc dot gnu.org
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