From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2140) id C1E03385735E; Thu, 8 Jun 2023 09:17:46 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C1E03385735E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1686215866; bh=Ew8nKwfP9vGdAgKX23OEJ2sYqd2tH6BaoerEXlyEvnc=; h=From:To:Subject:Date:From; b=aRSz6oD/TC5AWnM62bbxV12FlaSsBhWZqLNo/Y4biqzwomDOTnTgGqmWJF2B5zxGO TJwtRb9Mai3VsJkDcwVmWzy2edxJpv8SQyzR4VMKFednDOvp1I0J3nNux5DPYJz2Vo faGxh54RbMbcOBmTKSvA6SM7xf+2GhzE6sNxqAPs= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Alexandre Oliva To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/users/aoliva/heads/testme)] detect infinite loops earlier in returning_call_p X-Act-Checkin: gcc X-Git-Author: Alexandre Oliva X-Git-Refname: refs/users/aoliva/heads/testme X-Git-Oldrev: c4d4a9fe2bf270ca93c0b545997226cb9b153d6c X-Git-Newrev: 4e561e98ef85bf1962a03ddc2dd570ccdeacfd07 Message-Id: <20230608091746.C1E03385735E@sourceware.org> Date: Thu, 8 Jun 2023 09:17:46 +0000 (GMT) List-Id: https://gcc.gnu.org/g:4e561e98ef85bf1962a03ddc2dd570ccdeacfd07 commit 4e561e98ef85bf1962a03ddc2dd570ccdeacfd07 Author: Alexandre Oliva Date: Thu Jun 8 05:39:16 2023 -0300 detect infinite loops earlier in returning_call_p An infinite loop could create a path as long as the block count in returning_call_p, and then fail the backwards check if a call is found before emptying the path. Return as soon as the path exceeds the block count, and search for duplicate blocks before allocating more memory for the path, so as to cut the looping short. for gcc/ChangeLog * gimple-harden-control-flow.cc (returning_call_p): Detect infinite loops sooner. Diff: --- gcc/gimple-harden-control-flow.cc | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/gcc/gimple-harden-control-flow.cc b/gcc/gimple-harden-control-flow.cc index 3998fd0d293..044671cab79 100644 --- a/gcc/gimple-harden-control-flow.cc +++ b/gcc/gimple-harden-control-flow.cc @@ -19,6 +19,7 @@ along with GCC; see the file COPYING3. If not see . */ #include "config.h" +#define INCLUDE_ALGORITHM /* find */ #include "system.h" #include "coretypes.h" #include "backend.h" @@ -211,14 +212,19 @@ returning_call_p (gcall *call) return false; /* Quickly check that there's a path to exit compatible with a - returning call. Detect infinite loops through the counter. */ - basic_block bb = gimple_bb (call); + returning call. Detect infinite loops by limiting the path + length to the basic block count, and by looking for duplicate + blocks before allocating more memory for the path, for amortized + O(n). */ auto_vec path; - for (int i = n_basic_blocks_for_fn (cfun); - bb != EXIT_BLOCK_PTR_FOR_FN (cfun) && i--; + for (basic_block bb = gimple_bb (call); + bb != EXIT_BLOCK_PTR_FOR_FN (cfun); bb = single_succ (bb)) if (!single_succ_p (bb) - || (single_succ_edge (bb)->flags & EDGE_EH) != 0) + || (single_succ_edge (bb)->flags & EDGE_EH) != 0 + || n_basic_blocks_for_fn (cfun) - path.length () <= NUM_FIXED_BLOCKS + || (path.length () == path.allocated () + && std::find (path.begin (), path.end (), bb) != path.end ())) return false; else path.safe_push (bb);