From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id NOqwICtfD2VnvBsAWB0awg (envelope-from ) for ; Sat, 23 Sep 2023 17:56:59 -0400 Authentication-Results: simark.ca; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.a=rsa-sha256 header.s=default header.b=qdFf/HZQ; dkim-atps=neutral Received: by simark.ca (Postfix, from userid 112) id 796E51E0C3; Sat, 23 Sep 2023 17:56:59 -0400 (EDT) Received: from server2.sourceware.org (ip-8-43-85-97.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id E21A71E028 for ; Sat, 23 Sep 2023 17:56:56 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 59A163857B9B for ; Sat, 23 Sep 2023 21:56:56 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 59A163857B9B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1695506216; bh=wb3cCiNMe8hE1FsZdR4OmvSw41HAZ3QWs7BgoO27dkM=; h=Date:To:Subject:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=qdFf/HZQR5/EVWog9TxVRlY+kKGMKhoLvmJLoDtehvAxA4XK3oTmx6X6Bjrh7rjO1 rrAR9NdVttZqYibVzwGdgnB/RHHDkNIyImF070vZg9ZsXP5d3Ym0xa0nwqy8qZqhY2 71EYfeQdcawTxD9ylzcT1ubpKZ/oFrajfclxdBho= Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 3C9AC3858CDB for ; Sat, 23 Sep 2023 21:56:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 3C9AC3858CDB Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-302-BJvIgriYMXKXqjaA7Ftlvg-1; Sat, 23 Sep 2023 17:56:32 -0400 X-MC-Unique: BJvIgriYMXKXqjaA7Ftlvg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id EFE5F185A78E for ; Sat, 23 Sep 2023 21:56:31 +0000 (UTC) Received: from f37-zws-nv (unknown [10.22.32.95]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 98847C15BB8; Sat, 23 Sep 2023 21:56:31 +0000 (UTC) Date: Sat, 23 Sep 2023 14:56:30 -0700 To: Guinevere Larsen via Gdb-patches Subject: Re: [PATCH] gdb/record: print frame information when exiting a recursive call Message-ID: <20230923145630.322bf1d5@f37-zws-nv> In-Reply-To: <20230923103457.29768-2-blarsen@redhat.com> References: <20230923103457.29768-2-blarsen@redhat.com> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-10.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Kevin Buettner via Gdb-patches Reply-To: Kevin Buettner Errors-To: gdb-patches-bounces+public-inbox=simark.ca@sourceware.org Sender: "Gdb-patches" Hi Guinevere, Just a few nits. See below... On Sat, 23 Sep 2023 12:34:58 +0200 Guinevere Larsen via Gdb-patches wrote: > Currently, when GDB is reverse stepping out of a function into the same > function due to a recursive call, it doesn't print frame information, as > reported by PR record/29178. This happens because when the inferior > leaves the current frame, GDB decides to refresh the step information, > clobbering the original step_frame_id, making it impossible to figure > out later on that the frame has been changed. > > This commit changes GDB so that, if we notice we're in this exact > situation, we won't refresh the step information. > > Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29178 > --- > gdb/infrun.c | 18 +++++++++ > gdb/testsuite/gdb.reverse/recursion.c | 38 +++++++++++++++++++ > gdb/testsuite/gdb.reverse/recursion.exp | 49 +++++++++++++++++++++++++ > 3 files changed, 105 insertions(+) > create mode 100644 gdb/testsuite/gdb.reverse/recursion.c > create mode 100644 gdb/testsuite/gdb.reverse/recursion.exp > > diff --git a/gdb/infrun.c b/gdb/infrun.c > index 4730d290442..00e6215ebc8 100644 > --- a/gdb/infrun.c > +++ b/gdb/infrun.c > @@ -7679,6 +7679,11 @@ process_event_stop_test (struct execution_control_state *ecs) > } > > bool refresh_step_info = true; > + > + /* shorthand to make if statements smaller. */ Capitalize "shorthand". > + struct frame_id original_frame_id > + = ecs->event_thread->control.step_frame_id; > + struct frame_id curr_frame_id = get_frame_id (get_current_frame ()); I think these could be used to simplify at least one other, already existing, if-statement too. Perhaps post another patch with that change? (Or make it a two-part series with the above addition w/ updates to existing code as part 1.) > if ((ecs->event_thread->stop_pc () == stop_pc_sal.pc) > && (ecs->event_thread->current_line != stop_pc_sal.line > || ecs->event_thread->current_symtab != stop_pc_sal.symtab)) > @@ -7722,6 +7727,19 @@ process_event_stop_test (struct execution_control_state *ecs) > "it's not the start of a statement"); > } > } > + else if (execution_direction == EXEC_REVERSE > + && curr_frame_id != original_frame_id > + && original_frame_id.code_addr_p && curr_frame_id.code_addr_p > + && original_frame_id.code_addr == curr_frame_id.code_addr) > + { > + /* If we enter here, we're leaving a recursive function call. In this > + situation, we shouldn't refresh the step information, because if we > + do, we'll lose the frame_id of when we started stepping, and this > + will make GDB not know we need to print frame information. */ > + refresh_step_info = false; > + infrun_debug_printf ("reverse stepping, left a recursive call, don't " > + "update step info so we remember we left a frame"); > + } > > /* We aren't done stepping. > > diff --git a/gdb/testsuite/gdb.reverse/recursion.c b/gdb/testsuite/gdb.reverse/recursion.c > new file mode 100644 > index 00000000000..747404ce22c > --- /dev/null > +++ b/gdb/testsuite/gdb.reverse/recursion.c > @@ -0,0 +1,38 @@ > +/* This testcase is part of GDB, the GNU debugger. > + > + Copyright 2023 Free Software Foundation, Inc. > + > + This program is free software; you can redistribute it and/or modify > + it under the terms of the GNU General Public License as published by > + the Free Software Foundation; either version 3 of the License, or > + (at your option) any later version. > + > + This program is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + GNU General Public License for more details. > + > + You should have received a copy of the GNU General Public License > + along with this program. If not, see . */ > + > +/* Test GDB's ability to handle recursive functions when executing > + in reverse. */ > + > +int > +foo (int x) { > + if (x) return foo(x-1); > + return 0; > +} > + > +int > +bar(int x){ > + int r = foo(x); > + return 2*r; > +} > + > +int > +main() { > + int i = bar(5); > + int j = foo(5); > + return 0; /* END OF MAIN */ > +} Unless there's a good reason not to do so, I'd like to see the above C code follow the GNU coding standard. > diff --git a/gdb/testsuite/gdb.reverse/recursion.exp b/gdb/testsuite/gdb.reverse/recursion.exp > new file mode 100644 > index 00000000000..331113bee0a > --- /dev/null > +++ b/gdb/testsuite/gdb.reverse/recursion.exp > @@ -0,0 +1,49 @@ > +# Copyright 2008-2023 Free Software Foundation, Inc. > + > +# This program is free software; you can redistribute it and/or modify > +# it under the terms of the GNU General Public License as published by > +# the Free Software Foundation; either version 3 of the License, or > +# (at your option) any later version. > +# > +# This program is distributed in the hope that it will be useful, > +# but WITHOUT ANY WARRANTY; without even the implied warranty of > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > +# GNU General Public License for more details. > +# > +# You should have received a copy of the GNU General Public License > +# along with this program. If not, see . */ > + > +# This file is part of the GDB testsuite. It tests reverse stepping. > +# Lots of code borrowed from "step-test.exp". > + > +# > +# Test step and next in reverse > +# > + > +require supports_reverse > + > +standard_testfile > + > +if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } { > + return -1 > +} > + > +runto_main > + > +if [supports_process_record] { > + # Activate process record/replay > + gdb_test_no_output "record" "turn on process record" > +} > + > +set end_of_program [gdb_get_line_number "END OF MAIN" "$srcfile"] > +gdb_breakpoint $end_of_program > +gdb_continue_to_breakpoint ".*$srcfile/$end_of_program.*" > + > +## test if GDB can reverse over a recursive program > +gdb_test "reverse-next" ".*int j = foo.*" "Skipping recursion from outside" > +## setup and next over a recursion for inside a recursive call > +repeat_cmd_until "reverse-step" ".*" ".*foo .x=4.*" > +gdb_test "reverse-next" ".*return foo.*" "Skipping recursion from inside" > +gdb_test "reverse-next" ".*foo .x=5.*" "print frame when stepping out" > +gdb_test "reverse-next" ".*bar .x=5.*" "stepping into a different function" > +gdb_test "reverse-next" "main .. at .*" "stepping back to main" > -- > 2.41.0 >