From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47277) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dTWu2-0004zz-R4 for qemu-devel@nongnu.org; Fri, 07 Jul 2017 13:18:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dTWtx-0005Ut-S2 for qemu-devel@nongnu.org; Fri, 07 Jul 2017 13:18:50 -0400 From: =?utf-8?Q?Llu=C3=ADs_Vilanova?= References: <149865219962.17063.10630533069463266646.stgit@frigg.lan> <149865776960.17063.4875279139522061160.stgit@frigg.lan> <2bfdb883-f19b-7fcf-c28b-7ce39115937e@twiddle.net> <87podcebyi.fsf@frigg.lan> <3745ae02-3fb0-1503-9c99-98dce369f697@twiddle.net> Date: Fri, 07 Jul 2017 19:18:28 +0200 In-Reply-To: <3745ae02-3fb0-1503-9c99-98dce369f697@twiddle.net> (Richard Henderson's message of "Fri, 7 Jul 2017 05:26:03 -1000") Message-ID: <87lgo0cgij.fsf@frigg.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v11 23/29] target/arm: [tcg] Port to translate_insn List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: qemu-devel@nongnu.org, Peter Maydell , Peter Crosthwaite , "Emilio G. Cota" , "open list:ARM" , Paolo Bonzini , Alex =?utf-8?Q?Benn=C3=A9e?= Richard Henderson writes: > On 07/07/2017 01:13 AM, Llu=C3=ADs Vilanova wrote: >>>> + if (dc->ss_active && !dc->pstate_ss) { >>>> + /* Singlestep state is Active-pending. >>>> + * If we're in this state at the start of a TB then either >>>> + * a) we just took an exception to an EL which is being debu= gged >>>> + * and this is the first insn in the exception handler >>>> + * b) debug exceptions were masked and we just unmasked them >>>> + * without changing EL (eg by clearing PSTATE.D) >>>> + * In either case we're going to take a swstep exception in t= he >>>> + * "did not step an insn" case, and so the syndrome ISV and EX >>>> + * bits should be zero. >>>> + */ >>>> + assert(dc->base.num_insns =3D=3D 1); >>>> + gen_exception(EXCP_UDEF, syn_swstep(dc->ss_same_el, 0, 0), >>>> + default_exception_el(dc)); >>>> + dc->base.is_jmp =3D DISAS_SKIP; >>=20 >>> This is surely DISAS_EXC -- see gen_step_complete_exception. >>> Why introduce a new name? >>=20 >> The original code goes straight to done_generating here, and that's the = purpose >> of DISAS_SKIP (skip the code executed between the end of the loop and the >> done_generating label). > That is the purpose of DISAS_EXC too. We've called a noreturn helper to = raise > an exception and all following code is unreached. If there *was* any cod= e being > emitted afterward, that is arguably a bug. There was no code being generated after this specific case, but I haven't checked if DISAS_EXC is set in any other place that is not immediately foll= owed by a "goto done_generating". Does this mean DISAS_EXC should be on the generic code and do a "goto done_generating" whenever it is found? And if so, what are the correct plac= es to check for this? After ops->insn_start, ops->translate_insn, ops->tb_stop? Thanks, Lluis