From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2140) id F1A04385701B; Fri, 9 Jun 2023 08:07:23 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org F1A04385701B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1686298043; bh=+l2RPZsKu0XjiRqwqZCziF4C9Gp4xu9V3ry+Jn8Hato=; h=From:To:Subject:Date:From; b=BOjxhgcDiDTdZOWtqYJmSabR8u1ASQzq9fcN38fOV0x4fiGF5vkkeE6JIxXHmszmM gxl+5PQfVggxyd1oelfhGFSxP+ASy/6st2AfLcly7GoTvrUj4UOW9IT5qoJQ6ZE0hE x1oJ/MBweZDIwgahu5zfvKQhdNgBHRBzMRzkV38o= 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: a7fea6132089e9e2475eded5572fd5a53d9cb5b5 X-Git-Newrev: 4ddfd19c07a6b949b03072d7998833f5d3a4f680 Message-Id: <20230609080723.F1A04385701B@sourceware.org> Date: Fri, 9 Jun 2023 08:07:23 +0000 (GMT) List-Id: https://gcc.gnu.org/g:4ddfd19c07a6b949b03072d7998833f5d3a4f680 commit 4ddfd19c07a6b949b03072d7998833f5d3a4f680 Author: Alexandre Oliva Date: Thu Jun 8 05:55:04 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);