From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-x441.google.com (mail-wr1-x441.google.com [IPv6:2a00:1450:4864:20::441]) by sourceware.org (Postfix) with ESMTPS id 428043851C12 for ; Thu, 18 Jun 2020 18:04:12 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 428043851C12 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=embecosm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=andrew.burgess@embecosm.com Received: by mail-wr1-x441.google.com with SMTP id t18so7032544wru.6 for ; Thu, 18 Jun 2020 11:04:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=embecosm.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=nMiqjJX2gblHfy1MnJzr+2Tqqls152L5ZOTDiG1fag0=; b=goF7+iEpz7Pz+GqWEMI0J4TSkNtCCyw1VpBYFmu48HIRWMyo62BiH3Cs6LP63tSv5/ rclgrw/RCz6IKWakwr/ei9weLHEd/CTaJ+vPy443jccwCXPL/pcxTft8g3xPLdrj0hf3 14o3Qui5Rk95NTKFZe1bFOgw/Y2g/lH2+TgPEaLrq0nu5xZFSCAAnnWJDNU7fjQiaxHh eauc5OfyrfLI7PY9cO25R3KEDVrW8eNFFRM9hrrHRwG3wXkBOQ6JUODDAYRuYksQCxIA CNnfn2ANXg7kfhEYgKjXTDgO8ExFxj79n7kvFE9EIBtJZ99hbLPfszRoeaL8FFsZ0fc0 Xazw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=nMiqjJX2gblHfy1MnJzr+2Tqqls152L5ZOTDiG1fag0=; b=YDFn7yImiru7+fc+b66s6KrZeZJATD3kb9DQ+r/tlvAUj6WlOtVh1+3li318ivTJIg zg+qJHiCEt5s0hapjLqJOZ5p1q3zlwnoP53sjbmmHlbmy9fmP6A6qvKvu1BaNERRIBNs cZOWYlRXEtuCbZPnNv4Pe4xic+AOA0fLpfLXDz0ZgeHvYM5BefHiiJKFEbuSl4fIylP1 SUdNKmpZltx/StO7pc/x+rmGH1tkfma4bbHVVfyhk6W1U2ZN6hwEgFpWeuMZgiKrblqs oO3kAh2zGdg6zX4kbw1wWNcdfVFaKy0BG3smewliiXqrXN7a8stLKK3sOYp5tSa32upB l5GQ== X-Gm-Message-State: AOAM531FCW6Hfnq+IqhBnEKNMKIwnyVTGNksrdLp3bSCpVMiGy+2ZSBU Qtnn02eFMl8fiAirjdOOBBK5AJVf/2Q= X-Google-Smtp-Source: ABdhPJyhpRoep3hxvjATVRixSG5fAqMTJ56UC4maQXHtHPdtXSZnNhlcaSdNXbpCKR/vxDPt6cyYpA== X-Received: by 2002:a5d:5490:: with SMTP id h16mr6351493wrv.394.1592503451068; Thu, 18 Jun 2020 11:04:11 -0700 (PDT) Received: from localhost (host86-128-12-16.range86-128.btcentralplus.com. [86.128.12.16]) by smtp.gmail.com with ESMTPSA id h188sm4509991wmh.2.2020.06.18.11.04.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jun 2020 11:04:10 -0700 (PDT) Date: Thu, 18 Jun 2020 19:04:09 +0100 From: Andrew Burgess To: Luis Machado Cc: gdb-patches@sourceware.org, tromey@adacore.com Subject: Re: [PATCH] Fix inline frame unwinding breakage Message-ID: <20200618180409.GC2737@embecosm.com> References: <20200414213137.24015-1-luis.machado@linaro.org> <20200414213836.24370-1-luis.machado@linaro.org> <20200618165855.GY2737@embecosm.com> <20200618172922.GZ2737@embecosm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux/5.6.15-200.fc31.x86_64 (x86_64) X-Uptime: 18:48:33 up 10 days, 7:55, X-Editor: GNU Emacs [ http://www.gnu.org/software/emacs ] X-Spam-Status: No, score=-9.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Jun 2020 18:04:15 -0000 * Luis Machado [2020-06-18 14:45:00 -0300]: > On 6/18/20 2:29 PM, Andrew Burgess wrote: > > * Andrew Burgess [2020-06-18 17:58:55 +0100]: > > > > > * Luis Machado via Gdb-patches [2020-04-14 18:38:36 -0300]: > > > > > > > *** re-sending due to the poor choice of characters for the backtrace > > > > annotations. GIT swallowed parts of it. > > > > > > > > There has been some breakage for aarch64-linux, arm-linux and s390-linux in > > > > terms of inline frame unwinding. There may be other targets, but these are > > > > the ones i'm aware of. > > > > > > > > The following testcases started to show numerous failures and trigger internal > > > > errors in GDB after commit 1009d92fc621bc4d017029b90a5bfab16e17fde5, > > > > "Find tailcall frames before inline frames". > > > > > > > > gdb.opt/inline-break.exp > > > > gdb.opt/inline-cmds.exp > > > > gdb.python/py-frame-inline.exp > > > > gdb.reverse/insn-reverse.exp > > > > > > > > The internal errors were of this kind: > > > > > > > > binutils-gdb/gdb/frame.c:579: internal-error: frame_id get_frame_id(frame_info*): Assertion `fi->level == 0' failed. > > > > > > > > After a lengthy investigation to try and find the cause of these assertions, > > > > it seems we're dealing with some fragile/poorly documented code to handle inline > > > > frames and we are attempting to unwind from this fragile section of code. > > > > > > > > Before commit 1009d92fc621bc4d017029b90a5bfab16e17fde5, the tailcall sniffer > > > > was invoked from dwarf2_frame_prev_register. By the time we invoke the > > > > dwarf2_frame_prev_register function, we've probably already calculated the > > > > frame id (via compute_frame_id). > > > > > > > > After said commit, the call to dwarf2_tailcall_sniffer_first was moved to > > > > dwarf2_frame_cache. This is very early in a frame creation process, and > > > > we're still calculating the frame ID (so compute_frame_id is in the call > > > > stack). > > > > > > > > This would be fine for regular frames, but the above testcases all deal > > > > with some inline frames. > > > > > > > > The particularity of inline frames is that their frame ID's depend on > > > > the previous frame's ID, and the previous frame's ID relies in the inline > > > > frame's registers. So it is a bit of a messy situation. > > > > > > > > We have comments in various parts of the code warning about some of these > > > > particularities. > > > > > > > > In the case of dwarf2_tailcall_sniffer_first, we attempt to unwind the PC, > > > > which goes through various functions until we eventually invoke > > > > frame_unwind_got_register. This function will eventually attempt to create > > > > a lazy value for a particular register, and this lazy value will require > > > > a valid frame ID. Since the inline frame doesn't have a valid frame ID > > > > yet (remember we're still calculating the previous frame's ID so we can tell > > > > what the inline frame ID is) we will call compute_frame_id for the inline > > > > frame (level 0). > > > > > > > > We'll eventually hit the assertion above, inside get_frame_id: > > > > > > > > -- > > > > /* If we haven't computed the frame id yet, then it must be that > > > > this is the current frame. Compute it now, and stash the > > > > result. The IDs of other frames are computed as soon as > > > > they're created, in order to detect cycles. See > > > > get_prev_frame_if_no_cycle. */ > > > > gdb_assert (fi->level == 0); > > > > -- > > > > > > > > It seems to me we shouldn't have reached this assertion without having the > > > > inline frame ID already calculated. In fact, it seems we even start recursing > > > > a bit when we invoke get_prev_frame_always within inline_frame_this_id. But > > > > a check makes us quit the recursion and proceed to compute the id. > > > > > > > > Here's the call stack for context: > > > > > > > > #0 get_prev_frame_always_1 (this_frame=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:2109 > > > > RECURSION - #1 0x0000aaaaaae1d098 in get_prev_frame_always (this_frame=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:2124 > > > > #2 0x0000aaaaaae95768 in inline_frame_this_id (this_frame=0xaaaaab85a670, this_cache=0xaaaaab85a688, this_id=0xaaaaab85a6d0) > > > > at ../../../repos/binutils-gdb/gdb/inline-frame.c:165 > > > > #3 0x0000aaaaaae1916c in compute_frame_id (fi=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:550 > > > > #4 0x0000aaaaaae19318 in get_frame_id (fi=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:582 > > > > #5 0x0000aaaaaae13480 in value_of_register_lazy (frame=0xaaaaab85a730, regnum=30) at ../../../repos/binutils-gdb/gdb/findvar.c:296 > > > > #6 0x0000aaaaaae16c00 in frame_unwind_got_register (frame=0xaaaaab85a730, regnum=30, new_regnum=30) at ../../../repos/binutils-gdb/gdb/frame-unwind.c:268 > > > > #7 0x0000aaaaaad52604 in dwarf2_frame_prev_register (this_frame=0xaaaaab85a730, this_cache=0xaaaaab85a748, regnum=30) > > > > at ../../../repos/binutils-gdb/gdb/dwarf2/frame.c:1296 > > > > #8 0x0000aaaaaae1ae68 in frame_unwind_register_value (next_frame=0xaaaaab85a730, regnum=30) at ../../../repos/binutils-gdb/gdb/frame.c:1229 > > > > #9 0x0000aaaaaae1b304 in frame_unwind_register_unsigned (next_frame=0xaaaaab85a730, regnum=30) at ../../../repos/binutils-gdb/gdb/frame.c:1320 > > > > #10 0x0000aaaaaab76574 in aarch64_dwarf2_prev_register (this_frame=0xaaaaab85a730, this_cache=0xaaaaab85a748, regnum=32) > > > > at ../../../repos/binutils-gdb/gdb/aarch64-tdep.c:1114 > > > > #11 0x0000aaaaaad52724 in dwarf2_frame_prev_register (this_frame=0xaaaaab85a730, this_cache=0xaaaaab85a748, regnum=32) > > > > at ../../../repos/binutils-gdb/gdb/dwarf2/frame.c:1316 > > > > #12 0x0000aaaaaae1ae68 in frame_unwind_register_value (next_frame=0xaaaaab85a730, regnum=32) at ../../../repos/binutils-gdb/gdb/frame.c:1229 > > > > #13 0x0000aaaaaae1b304 in frame_unwind_register_unsigned (next_frame=0xaaaaab85a730, regnum=32) at ../../../repos/binutils-gdb/gdb/frame.c:1320 > > > > #14 0x0000aaaaaae16a84 in default_unwind_pc (gdbarch=0xaaaaab81edc0, next_frame=0xaaaaab85a730) at ../../../repos/binutils-gdb/gdb/frame-unwind.c:223 > > > > #15 0x0000aaaaaae32124 in gdbarch_unwind_pc (gdbarch=0xaaaaab81edc0, next_frame=0xaaaaab85a730) at ../../../repos/binutils-gdb/gdb/gdbarch.c:3074 > > > > #16 0x0000aaaaaad4f15c in dwarf2_tailcall_sniffer_first (this_frame=0xaaaaab85a730, tailcall_cachep=0xaaaaab85a830, entry_cfa_sp_offsetp=0x0) > > > > at ../../../repos/binutils-gdb/gdb/dwarf2/frame-tailcall.c:388 > > > > #17 0x0000aaaaaad520c0 in dwarf2_frame_cache (this_frame=0xaaaaab85a730, this_cache=0xaaaaab85a748) at ../../../repos/binutils-gdb/gdb/dwarf2/frame.c:1190 > > > > #18 0x0000aaaaaad52204 in dwarf2_frame_this_id (this_frame=0xaaaaab85a730, this_cache=0xaaaaab85a748, this_id=0xaaaaab85a790) > > > > at ../../../repos/binutils-gdb/gdb/dwarf2/frame.c:1218 > > > > #19 0x0000aaaaaae1916c in compute_frame_id (fi=0xaaaaab85a730) at ../../../repos/binutils-gdb/gdb/frame.c:550 > > > > #20 0x0000aaaaaae1c958 in get_prev_frame_if_no_cycle (this_frame=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:1927 > > > > #21 0x0000aaaaaae1cc44 in get_prev_frame_always_1 (this_frame=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:2006 > > > > FIRST CALL - #22 0x0000aaaaaae1d098 in get_prev_frame_always (this_frame=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:2124 > > > > #23 0x0000aaaaaae18f68 in skip_artificial_frames (frame=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:495 > > > > #24 0x0000aaaaaae193e8 in get_stack_frame_id (next_frame=0xaaaaab85a670) at ../../../repos/binutils-gdb/gdb/frame.c:596 > > > > #25 0x0000aaaaaae87a54 in process_event_stop_test (ecs=0xffffffffefc8) at ../../../repos/binutils-gdb/gdb/infrun.c:6857 > > > > #26 0x0000aaaaaae86bdc in handle_signal_stop (ecs=0xffffffffefc8) at ../../../repos/binutils-gdb/gdb/infrun.c:6381 > > > > #27 0x0000aaaaaae84fd0 in handle_inferior_event (ecs=0xffffffffefc8) at ../../../repos/binutils-gdb/gdb/infrun.c:5578 > > > > #28 0x0000aaaaaae81588 in fetch_inferior_event (client_data=0x0) at ../../../repos/binutils-gdb/gdb/infrun.c:4020 > > > > #29 0x0000aaaaaae5f7fc in inferior_event_handler (event_type=INF_REG_EVENT, client_data=0x0) at ../../../repos/binutils-gdb/gdb/inf-loop.c:43 > > > > #30 0x0000aaaaaae8d768 in infrun_async_inferior_event_handler (data=0x0) at ../../../repos/binutils-gdb/gdb/infrun.c:9377 > > > > #31 0x0000aaaaaabff970 in check_async_event_handlers () at ../../../repos/binutils-gdb/gdb/async-event.c:291 > > > > #32 0x0000aaaaab27cbec in gdb_do_one_event () at ../../../repos/binutils-gdb/gdbsupport/event-loop.cc:194 > > > > #33 0x0000aaaaaaef1894 in start_event_loop () at ../../../repos/binutils-gdb/gdb/main.c:356 > > > > #34 0x0000aaaaaaef1a04 in captured_command_loop () at ../../../repos/binutils-gdb/gdb/main.c:416 > > > > #35 0x0000aaaaaaef3338 in captured_main (data=0xfffffffff1f0) at ../../../repos/binutils-gdb/gdb/main.c:1254 > > > > #36 0x0000aaaaaaef33a0 in gdb_main (args=0xfffffffff1f0) at ../../../repos/binutils-gdb/gdb/main.c:1269 > > > > #37 0x0000aaaaaab6e0dc in main (argc=6, argv=0xfffffffff348) at ../../../repos/binutils-gdb/gdb/gdb.c:32 > > > > > > > > The following patch addresses this by using a function that unwinds the PC > > > > from the next (inline) frame directly as opposed to creating a lazy value > > > > that is bound to the next frame's ID (still not computed). > > > > > > > > I've validated this for aarch64-linux and x86_64-linux by running the > > > > testsuite. > > > > > > > > Tromey, would you mind checking if this suits your problematic core file > > > > tailcall scenario? > > > > > > > > gdb/ChangeLog: > > > > > > > > 2020-04-14 Luis Machado > > > > > > > > * dwarf2/frame-tailcall.c (dwarf2_tailcall_sniffer_first): Use > > > > get_frame_register instead of gdbarch_unwind_pc. > > > > --- > > > > gdb/dwarf2/frame-tailcall.c | 4 +++- > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/gdb/dwarf2/frame-tailcall.c b/gdb/dwarf2/frame-tailcall.c > > > > index 2d219f13f9..01bb134a5c 100644 > > > > --- a/gdb/dwarf2/frame-tailcall.c > > > > +++ b/gdb/dwarf2/frame-tailcall.c > > > > @@ -385,7 +385,9 @@ dwarf2_tailcall_sniffer_first (struct frame_info *this_frame, > > > > prev_gdbarch = frame_unwind_arch (this_frame); > > > > /* Simulate frame_unwind_pc without setting this_frame->prev_pc.p. */ > > > > - prev_pc = gdbarch_unwind_pc (prev_gdbarch, this_frame); > > > > + get_frame_register (this_frame, gdbarch_pc_regnum (prev_gdbarch), > > > > + (gdb_byte *) &prev_pc); > > > > + prev_pc = gdbarch_addr_bits_remove (prev_gdbarch, prev_pc); > > > > /* call_site_find_chain can throw an exception. */ > > > > chain = call_site_find_chain (prev_gdbarch, prev_pc, this_pc); > > > > > > I'm now no longer convinced that this patch is correct, and I'd like > > > to reopen the discussion. > > > > > > Here's what concerns me, we used to make the following call-chain: > > > > > > gdbarch_unwind_pc --> frame_unwind_register_unsigned --> frame_unwind_register_value > > > > > > Now we do this: > > > > > > get_frame_register --> frame_unwind_register --> frame_register_unwind --> frame_unwind_register_value > > > > > > The problem is that gdbarch_unwind_pc' takes an argument 'next_frame', > > > while, get_frame_register takes an argument called frame', but is > > > really 'this_frame', it then passes 'frame->next' to > > > 'frame_unwind_register'. > > > > > > What this means is that if we have a call stack like this: > > > > > > #3 --> #2 --> #1 --> #0 > > > > > > And we invoke the tail-call sniffer in frame #1, previously we figured > > > out the $pc value in frame #2, while now we figure out the $pc value > > > in frame #1. > > > > > > I'm even more convinced that this is an error based on the fix patch > > > you applied later: > > > > > > commit 991a3e2e9944a4b3a27bd989ac03c18285bd545d > > > Date: Sat Apr 25 00:32:44 2020 -0300 > > > > > > Fix remaining inline/tailcall unwinding breakage for x86_64 > > > > > > This basically sent all but a select few cases down the old code path, > > > while restricting just a few cases to the new path. > > > > > > I ran the testsuite (on x86-64/Linux) looking for cases where the new > > > code actually triggers and there are just 2. Remember that this code > > > is use the $pc value to identify tail-call chains. > > > > > > In both of the cases I found, both _before_ and _after_ your change, a > > > tail-call chain was not identified. What this means is that even if > > > your code is returning the wrong value, it's not going to cause a test > > > regression. > > > > > > Finally, if you catch the cases where your new code triggers, and then > > > step into call_site_find_chain (which is called later in the sniffer), > > > you'll see that this function is passed a caller address and a callee > > > address. The callee address passed in is 'this_pc', in our example > > > above, this is the current address in #1. We previously used to > > > compute the address is #2, which makes sense, we're looking for a > > > chain of tail-calls that gets us from #2 to #1. > > > > > > However, after your change we're now simply passing in the address in > > > #1 as both the caller and the callee address, which makes no sense (to > > > me, right now). > > > > > > I'm still investigating at the moment. Right now I have more > > > questions than answer, but I wanted to raise my concerns in case I'm > > > just totally missing something obvious and you can set me straight. > > > > Patch below is a test case that reveals the issue. You'll notice that > > if you revert this patch then there's an extra frame in the backtrace > > that is missing with this patch. > > > > Still looking into what the right fix here is, but would welcome > > discussion. > > Thanks! That's a good assessment of the situation. > > > > > [ It just occurred to me that the test case could end up being target > > and compiler version dependent. I'm on X86-64/Linux with GCC version > > 'gcc (GCC) 9.3.1 20200408 (Red Hat 9.3.1-2)'. ] > > Yeah, x86_64 seems to produce more CFI information from which PC can be > recovered from the *current* frame, unlike AArch64, which assumes SAME_VALUE > and goes to look for PC in the *next* frame. > > From what I recall, we're looking for PC, which translates to fetching LR, > but LR is SAME_VALUE, so we go looking for LR from the *next* frame, and > then run into a frame id assertion. > > For x86_64 we're looking for PC, which, IIRC, translates to another > register. That register, in turn, is available through CFI and we return. We > never attempt to fetch things from the next frame. > > The more general problem is attempting to unwind from within a frame that is > still getting its frame id computed. I can't say that's invalid, but some > targets may support this (x86_64) and others may not (aarch64, s390, riscv, > possibly others in specific situations). I suspect it might be more that for x86-64 the lazy value returned is a lazy memory reference, while for architectures with a link-register we create a lazy register value, and then we're in trouble. I don't think we should ever try to unwind the previous value of a register from a frame that doesn't yet know its frame-id. That just sounds crazy. IIRC the process is: - For each possible unwinder - Install the unwinder on the frame - Sniff frame - If claimed then: - Compute frame-id - Break out of loop Else: - Clean up after failed sniffing - Loop around and try next unwinder - Use frame which has a valid unwinder in place. So if we don't yet have a frame-id then we don't yet know for sure that the unwinder that is in place is actually correct, we're just hoping for the best. I wonder if we should actually assert in all the frame_unwind_got_* functions that the frame we 'got' the value for is not lazy. This might throw up a few issues, but surely anywhere that we might 'frame_unwind_got_memory' (which is fine with no frame-id) some other architecture might do 'frame_unwind_got_register', in which case we're in trouble. As x86-64 is register lite (compared to many others) then it's more likely to do 'frame_unwind_got_memory' and thus dodge bugs that might hit other architectures. Might give that a go and see what it throws up... Additionally I wonder why frame_unwind_register_value doesn't insist that the frame_id be computed before we even try to fetch a register? Might give that a go too... Thanks, Andrew > > > > > Thanks, > > Andrew > > > > --- > > > > commit 566b2b1da20e461cee2798f3eda741c1e31bdff6 > > Author: Andrew Burgess > > Date: Thu Jun 18 18:25:00 2020 +0100 > > > > gdb/testsuite: Test case for inline func, tailcall bug > > > > diff --git a/gdb/testsuite/gdb.opt/inline-frame-tailcall.c b/gdb/testsuite/gdb.opt/inline-frame-tailcall.c > > new file mode 100644 > > index 00000000000..2513c257a29 > > --- /dev/null > > +++ b/gdb/testsuite/gdb.opt/inline-frame-tailcall.c > > @@ -0,0 +1,52 @@ > > +/* Copyright 2020 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 . */ > > + > > +#ifdef __GNUC__ > > +# define ATTR_INLINE __attribute__((gnu_inline)) __attribute__((always_inline)) __attribute__((noclone)) > > +#else > > +# define ATTR_INLINE > > +#endif > > + > > +volatile int global; > > + > > +volatile int counter; > > + > > +static inline ATTR_INLINE int > > +bar () > > +{ > > + /* Just some filler. */ > > + for (counter = 0; counter < 10; ++counter) > > + global = 0; > > + return 0; > > +} > > + > > +__attribute__ ((noinline)) int > > +foo () > > +{ > > + return bar (); > > +} > > + > > +__attribute__ ((noinline)) int > > +test_func () > > +{ > > + return foo (); > > +} > > + > > +int > > +main () > > +{ > > + global = test_func (); > > + return (global * 2); > > +} > > diff --git a/gdb/testsuite/gdb.opt/inline-frame-tailcall.exp b/gdb/testsuite/gdb.opt/inline-frame-tailcall.exp > > new file mode 100644 > > index 00000000000..bac96835d12 > > --- /dev/null > > +++ b/gdb/testsuite/gdb.opt/inline-frame-tailcall.exp > > @@ -0,0 +1,47 @@ > > +# Copyright 2020 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 . > > + > > +# Tests a specific combination, a tailcall into a function, which then > > +# has another function inlined within it. So: > > +# > > +# main --> test_func --> foo --> bar > > +# > > +# main makes a normal call to test_func. > > +# > > +# test_func makes a tail call to foo. > > +# > > +# bar is inlined within foo. > > +# > > +# We should still see test_func in the call stack. > > + > > +standard_testfile > > + > > +if { [prepare_for_testing "failed to prepare" ${testfile} \ > > + [list $srcfile] {debug optimize=-O2}] } { > > + return -1 > > +} > > + > > +if ![runto_main] { > > + return -1 > > +} > > + > > +gdb_breakpoint "bar" > > +gdb_continue_to_breakpoint "bar" > > + > > +gdb_test "bt" \ > > + [multi_line "#0 bar \\(\\).*" \ > > + "#1 foo \\(\\).*" \ > > + "#2 $hex in test_func \\(\\).*" \ > > + "#3 $hex in main \\(\\).*" ] > >