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[173.197.98.125]) by smtp.gmail.com with ESMTPSA id z8-20020a63c048000000b005c6e8fa9f24sm1926558pgi.49.2024.03.15.00.41.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 Mar 2024 00:41:54 -0700 (PDT) Message-ID: Date: Thu, 14 Mar 2024 21:41:51 -1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH for 9.0 v15 04/10] target/riscv: always clear vstart in whole vec move insns Content-Language: en-US To: Daniel Henrique Barboza , qemu-devel@nongnu.org Cc: qemu-riscv@nongnu.org, alistair.francis@wdc.com, bmeng@tinylab.org, liwei1518@gmail.com, zhiwei_liu@linux.alibaba.com, palmer@rivosinc.com, max.chou@sifive.com References: <20240314175704.478276-1-dbarboza@ventanamicro.com> <20240314175704.478276-5-dbarboza@ventanamicro.com> From: Richard Henderson In-Reply-To: <20240314175704.478276-5-dbarboza@ventanamicro.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::32e; envelope-from=richard.henderson@linaro.org; helo=mail-ot1-x32e.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, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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 3/14/24 07:56, Daniel Henrique Barboza wrote: > These insns have 2 paths: we'll either have vstart already cleared if > vstart_eq_zero or we'll do a brcond to check if vstart >= maxsz to call > the 'vmvr_v' helper. The helper will clear vstart if it executes until > the end, or if vstart >= vl. > > For starters, the check itself is wrong: we're checking vstart >= maxsz, > when in fact we should use vstart in bytes, or 'startb' like 'vmvr_v' is > calling, to do the comparison. But even after fixing the comparison we'll > still need to clear vstart in the end, which isn't happening too. > > We want to make the helpers responsible to manage vstart, including > these corner cases, precisely to avoid these situations: > > - remove the wrong vstart >= maxsz cond from the translation; > - add a 'startb >= maxsz' cond in 'vmvr_v', and clear vstart if that > happens. > > This way we're now sure that vstart is being cleared in the end of the > execution, regardless of the path taken. > > Fixes: f714361ed7 ("target/riscv: rvv-1.0: implement vstart CSR") > Signed-off-by: Daniel Henrique Barboza > --- > target/riscv/insn_trans/trans_rvv.c.inc | 3 --- > target/riscv/vector_helper.c | 5 +++++ > 2 files changed, 5 insertions(+), 3 deletions(-) Reviewed-by: Richard Henderson r~