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b=bbyNdvPtuUlao1Tk6pLESi+LTqyfMv3jpekiwnzObedjKrKmYDwDvqHi78A9WrHEZ 6LG+cNJH5F4T8MTZE5n3wzWvUJs9hrMxA/Ya/zucGkFnP4rumtXM2uY5vFFT54aFA/ F3/nWjtGYwp3ZGTVKJx8SKi+MnevFaFlfCnF8yrM= Received: from [10.0.0.11] (modemcable238.237-201-24.mc.videotron.ca [24.201.237.238]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id A315C1E091; Tue, 7 Jan 2025 00:34:49 -0500 (EST) Message-ID: <14681618-96db-46d7-bebd-28f1eba64517@simark.ca> Date: Tue, 7 Jan 2025 00:34:49 -0500 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 10/11] gdbserver: refactor the definition and uses of supply_regblock To: Tankut Baris Aktemur , gdb-patches@sourceware.org Cc: simon.marchi@efficios.com References: <20241230-upstream-gdbserver-regcache-v2-0-020a9514fcf0@intel.com> <20241230-upstream-gdbserver-regcache-v2-10-020a9514fcf0@intel.com> Content-Language: en-US From: Simon Marchi In-Reply-To: <20241230-upstream-gdbserver-regcache-v2-10-020a9514fcf0@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org On 2024-12-30 05:49, Tankut Baris Aktemur wrote: > The supply_regblock function takes a pointer to a buffer as an > argument and implements two different behavior based on the pointer > being null. There are three cases where we pass nullptr, all in > tracepoint.cc, where we are essentially doing a reset on the regcache. > > In fast_tracepoint_ctx::get_regcache and > static_tracepoint_ctx::get_regcache, register_status array does not > even exist. Hence, those uses simply boil down to zeroing of register > data. Do this at the time of creating the buffer and remove the calls > to supply_regblock. > > In fetch_traceframe_registers, inline the use with a call to `reset`. > > Hence, there are no more cases left, where a nullptr would be passed > to supply_regblock. Assert that the buffer argument is non-null and > simplify the implementation. > --- > gdbserver/regcache.cc | 14 +++++--------- > gdbserver/tracepoint.cc | 8 +++++--- > 2 files changed, 10 insertions(+), 12 deletions(-) > > diff --git a/gdbserver/regcache.cc b/gdbserver/regcache.cc > index 7e1a722b0f80b9e5641bddfbbe95cbcf2b228df8..562524306dfb36c8be88be5056b2fdddb6ca0b3c 100644 > --- a/gdbserver/regcache.cc > +++ b/gdbserver/regcache.cc > @@ -369,18 +369,14 @@ supply_register_by_name_zeroed (struct regcache *regcache, > void > supply_regblock (struct regcache *regcache, const void *buf) > { > - if (buf) > - { > - const struct target_desc *tdesc = regcache->tdesc; > + gdb_assert (buf != nullptr); > + const struct target_desc *tdesc = regcache->tdesc; > > - memcpy (regcache->registers, buf, tdesc->registers_size); > + memcpy (regcache->registers, buf, tdesc->registers_size); > #ifndef IN_PROCESS_AGENT > - for (int i = 0; i < tdesc->reg_defs.size (); i++) > - regcache->set_register_status (i, REG_VALID); > + for (int i = 0; i < tdesc->reg_defs.size (); i++) > + regcache->set_register_status (i, REG_VALID); > #endif > - } > - else > - regcache->reset (REG_UNAVAILABLE); > } > > #ifndef IN_PROCESS_AGENT > diff --git a/gdbserver/tracepoint.cc b/gdbserver/tracepoint.cc > index 9a00d1f272f905cadbc87265ed0be3d87f7b54df..9e48b1e5afc75c028942212c0f9e788afe025c38 100644 > --- a/gdbserver/tracepoint.cc > +++ b/gdbserver/tracepoint.cc > @@ -4697,7 +4697,6 @@ fast_tracepoint_ctx::get_regcache () > if (!this->regcache.has_value ()) > { > this->regcache.emplace (ipa_tdesc, this->regspace); > - supply_regblock (&this->regcache.value (), nullptr); > supply_fast_tracepoint_registers (&this->regcache.value (), > this->regs); > } > @@ -4714,7 +4713,6 @@ static_tracepoint_ctx::get_regcache () > if (!this->regcache.has_value ()) > { > this->regcache.emplace (ipa_tdesc, this->regspace); > - supply_regblock (&this->regcache.value (), nullptr); > /* Pass down the tracepoint address, because REGS doesn't > include the PC, but we know what it must have been. */ > supply_static_tracepoint_registers (&this->regcache.value (), Nit: can you please leave an empty line before the comment? > @@ -5168,7 +5166,7 @@ fetch_traceframe_registers (int tfnum, struct regcache *regcache, int regnum) > if (dataptr == NULL) > { > /* Mark registers unavailable. */ > - supply_regblock (regcache, NULL); > + regcache->reset (REG_UNAVAILABLE); > > /* We can generally guess at a PC, although this will be > misleading for while-stepping frames and multi-location > @@ -5776,6 +5774,8 @@ gdb_collect (struct tracepoint *tpoint, unsigned char *regs) > return; > } > > + memset (ctx.regspace, 0, ipa_tdesc->registers_size); Alternatively, I guess that the regcache constructor that takes an external buffer could take care of zeroing out the buffer, ensuring the invariant of having the register contents to 0 when unknown/unavailable is respected. Either way: Approved-By: Simon Marchi Simon