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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/65425] code optimization leads to spurious FP exception Date: Wed, 18 Mar 2015 12:10:00 -0000 [thread overview] Message-ID: <bug-65425-4-C2lEQvJ3ve@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-65425-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65425 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |wrong-code Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2015-03-18 CC| |jsm28 at gcc dot gnu.org Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- I think we have a duplicate bug for this - if-conversion transforms the loop body to execute the log10 unconditionally: iftmp.0_11 = log10 (_10); iftmp.0_2 = _10 > 0.0 ? iftmp.0_11 : -9.9999e+4; it's static bool if_convertible_stmt_p (gimple stmt, vec<data_reference_p> refs, bool *any_mask_load_store) { ... case GIMPLE_CALL: { tree fndecl = gimple_call_fndecl (stmt); if (fndecl) { int flags = gimple_call_flags (stmt); if ((flags & ECF_CONST) && !(flags & ECF_LOOPING_CONST_OR_PURE) /* We can only vectorize some builtins at the moment, so restrict if-conversion to those. */ && DECL_BUILT_IN (fndecl)) return true; } return false; which fails to check whether the call may trap. I have a patch for that issue, but log10 is also using ATTR_NOTHROW_* thus it is declared as never trapping. It looks like _all_ functions will have this issue. Then the canonical helper gimple_could_trap_p doesn't consider the _body_ of the call but only the call instruction itself. So we have to "abuse" gimple_call_nothrow_p here. I'm not sure about how to deal with this (adding another layer distinguishing flag_trapping_math in builtins.def)?
prev parent reply other threads:[~2015-03-18 12:10 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-03-14 17:14 [Bug tree-optimization/65425] New: " p.vanhoof at oma dot be 2015-03-18 12:10 ` [Bug tree-optimization/65425] " rguenth at gcc dot gnu.org 2015-03-18 12:10 ` rguenth at gcc dot gnu.org [this message]
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