From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1666) id 21C043858D28; Thu, 29 Sep 2022 08:24:01 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 21C043858D28 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1664439841; bh=rqpYxcFD2lL2xx+NEyNwbXz0OSKmBGJhUCkG3B9cmag=; h=From:To:Subject:Date:From; b=RDBEbq2fpxqzSLq/EGP9guGJnyelTz2hjmpttdbBTEpbQBwYWpaiy0xal+DK5ItNZ hUTQAWUy1Aiu9Lu1+hhDCuxydwZurxhMntjkn+ns8rIW9yWcrM6a4Y+ykTv4mFjm8w yA7zn67w50DdSrF2YPUIqodOblXOFCPZWy+suwwM= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Richard Biener To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-2926] tree-optimization/105646 - re-interpret always executed in uninit diag X-Act-Checkin: gcc X-Git-Author: Richard Biener X-Git-Refname: refs/heads/master X-Git-Oldrev: f758d447d7f4699253c9f8ee345ba9b8357cdb22 X-Git-Newrev: a1cd4d52d6ef90b977fb2d80c1cf17f3efa5b01d Message-Id: <20220929082401.21C043858D28@sourceware.org> Date: Thu, 29 Sep 2022 08:24:01 +0000 (GMT) List-Id: https://gcc.gnu.org/g:a1cd4d52d6ef90b977fb2d80c1cf17f3efa5b01d commit r13-2926-ga1cd4d52d6ef90b977fb2d80c1cf17f3efa5b01d Author: Richard Biener Date: Fri Aug 19 15:11:14 2022 +0200 tree-optimization/105646 - re-interpret always executed in uninit diag The following fixes PR105646, not diagnosing int f1(); int f3(){ auto const & a = f1(); bool v3{v3}; return a; } with optimization because the early uninit diagnostic pass only diagnoses always executed cases. The patch does this by re-interpreting what always executed means and choosing to ignore exceptional and abnormal control flow for this. At the same time it improves things as suggested in a comment - when the value-numbering run done without optimizing figures there's a fallthru path, consider blocks on it as always executed. PR tree-optimization/105646 * tree-ssa-uninit.cc (warn_uninitialized_vars): Pre-compute the set of fallthru reachable blocks from function entry and use that to determine wlims.always_executed. * g++.dg/uninit-pr105646.C: New testcase. Diff: --- gcc/testsuite/g++.dg/uninit-pr105646.C | 17 +++++++++++++++++ gcc/tree-ssa-uninit.cc | 10 ++++++++-- 2 files changed, 25 insertions(+), 2 deletions(-) diff --git a/gcc/testsuite/g++.dg/uninit-pr105646.C b/gcc/testsuite/g++.dg/uninit-pr105646.C new file mode 100644 index 00000000000..48ceb986ec6 --- /dev/null +++ b/gcc/testsuite/g++.dg/uninit-pr105646.C @@ -0,0 +1,17 @@ +// { dg-do compile } +// { dg-require-effective-target c++11 } +// { dg-options "-O2 -Wuninitialized" } + +int f1(); +int f2(){ + bool v2{v2}; // { dg-warning "is used uninitialized" } + auto const & a = f1(); + return a; +} +int f3(){ + auto const & a = f1(); + // Diagnose the following when optimizing and as unconditional + // uninitialized use despite f1 possibly throwing + bool v3{v3}; // { dg-warning "is used uninitialized" } + return a; +} diff --git a/gcc/tree-ssa-uninit.cc b/gcc/tree-ssa-uninit.cc index eae29f88f9d..bde23997a0a 100644 --- a/gcc/tree-ssa-uninit.cc +++ b/gcc/tree-ssa-uninit.cc @@ -991,14 +991,20 @@ warn_uninitialized_vars (bool wmaybe_uninit) auto_bb_flag ft_reachable (cfun); /* Mark blocks that are always executed when we ignore provably - not executed edges. */ + not executed and EH and abnormal edges. */ basic_block bb = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)); while (!(bb->flags & ft_reachable)) { bb->flags |= ft_reachable; + edge e = find_fallthru_edge (bb->succs); + if (e && e->flags & EDGE_EXECUTABLE) + { + bb = e->dest; + continue; + } /* Find a single executable edge. */ edge_iterator ei; - edge e, ee = NULL; + edge ee = NULL; FOR_EACH_EDGE (e, ei, bb->succs) if (e->flags & EDGE_EXECUTABLE) {