From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2140) id 72328385773C; Thu, 8 Jun 2023 10:59:17 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 72328385773C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1686221957; bh=Ew8nKwfP9vGdAgKX23OEJ2sYqd2tH6BaoerEXlyEvnc=; h=From:To:Subject:Date:From; b=UN9Vj5F2G6cEylHBNaXip3gMlEuhKUQ/1V9r6ExxeUk+i3HVza3kNxLexi2stqHZ3 OT471YDQ8YwtvHdns9kirMVqn/7RRUzB2Tp83O63iaRFQuLHZfvi9uBWUK2TbNGzkv 3X2SGwywvW0YGTgK2ULM67XbX44fCYos3VyhCoyE= 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: <20230608105917.72328385773C@sourceware.org> Date: Thu, 8 Jun 2023 10:59:17 +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);