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Fri, 22 Nov 2024 10:04:57 -0800 (PST) Received: from [192.168.170.227] ([187.210.107.181]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-2971d5e29ebsm686591fac.14.2024.11.22.10.04.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Nov 2024 10:04:56 -0800 (PST) Message-ID: <1e4bfa65-715a-4ac8-958f-48f0f6301218@linaro.org> Date: Fri, 22 Nov 2024 12:04:53 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 05/43] tcg: Add helper function dispatcher and hook tcg_gen_callN To: Anton Johansson , qemu-devel@nongnu.org Cc: ale@rev.ng, ltaylorsimpson@gmail.com, bcain@quicinc.com, philmd@linaro.org, alex.bennee@linaro.org References: <20241121014947.18666-1-anjo@rev.ng> <20241121014947.18666-6-anjo@rev.ng> Content-Language: en-US From: Richard Henderson In-Reply-To: <20241121014947.18666-6-anjo@rev.ng> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2001:4860:4864:20::34; envelope-from=richard.henderson@linaro.org; helo=mail-oa1-x34.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 11/20/24 19:49, Anton Johansson wrote: > Adds a function pointer to the TCGContext which may be set by targets via > the TARGET_HELPER_DISPATCHER macro. The dispatcher is function > > (void *func, TCGTemp *ret, int nargs, TCGTemp **args) -> bool > > which allows targets to hook the generation of helper calls in TCG and > take over translation. Specifically, this will be used by helper-to-tcg > to replace helper function translation, without having to modify frontends. > > Signed-off-by: Anton Johansson > --- > accel/tcg/translate-all.c | 4 ++++ > include/tcg/tcg.h | 4 ++++ > tcg/tcg.c | 5 +++++ > 3 files changed, 13 insertions(+) I guess I'll have to read further to understand this, but my first reaction is: why would we not modify how the gen_helper_* functions are defined instead? r~ > > diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c > index fdf6d8ac19..814aae93ae 100644 > --- a/accel/tcg/translate-all.c > +++ b/accel/tcg/translate-all.c > @@ -352,6 +352,10 @@ TranslationBlock *tb_gen_code(CPUState *cpu, > tcg_ctx->guest_mo = TCG_MO_ALL; > #endif > > +#if defined(CONFIG_HELPER_TO_TCG) && defined(TARGET_HELPER_DISPATCHER) > + tcg_ctx->helper_dispatcher = TARGET_HELPER_DISPATCHER; > +#endif > + > restart_translate: > trace_translate_block(tb, pc, tb->tc.ptr); > > diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h > index a77ed12b9d..d3e820568f 100644 > --- a/include/tcg/tcg.h > +++ b/include/tcg/tcg.h > @@ -549,6 +549,10 @@ struct TCGContext { > > /* Exit to translator on overflow. */ > sigjmp_buf jmp_trans; > + > + > + bool (*helper_dispatcher)(void *func, TCGTemp *ret_temp, > + int nargs, TCGTemp **args); > }; > > static inline bool temp_readonly(TCGTemp *ts) > diff --git a/tcg/tcg.c b/tcg/tcg.c > index 0babae1b88..5f03bef688 100644 > --- a/tcg/tcg.c > +++ b/tcg/tcg.c > @@ -2252,6 +2252,11 @@ static void tcg_gen_callN(void *func, TCGHelperInfo *info, > } > > total_args = info->nr_out + info->nr_in + 2; > + if (unlikely(tcg_ctx->helper_dispatcher) && > + tcg_ctx->helper_dispatcher(info->func, ret, total_args, args)) { > + return; > + } > + > op = tcg_op_alloc(INDEX_op_call, total_args); > > #ifdef CONFIG_PLUGIN