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[200.207.147.180]) by smtp.gmail.com with ESMTPSA id t14-20020a056870638e00b0011dca1bd2cdsm5802609oap.0.2022.09.05.11.19.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Sep 2022 11:19:09 -0700 (PDT) Message-ID: Date: Mon, 5 Sep 2022 15:19:04 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH 03/19] target/ppc: Zero second doubleword in DFP instructions Content-Language: en-US To: =?UTF-8?Q?V=c3=adctor_Colombo?= , qemu-devel@nongnu.org, qemu-ppc@nongnu.org Cc: clg@kaod.org, david@gibson.dropbear.id.au, groug@kaod.org, richard.henderson@linaro.org, matheus.ferst@eldorado.org.br, lucas.araujo@eldorado.org.br, leandro.lupori@eldorado.org.br, lucas.coutinho@eldorado.org.br References: <20220901131756.26060-1-victor.colombo@eldorado.org.br> <20220901131756.26060-4-victor.colombo@eldorado.org.br> From: Daniel Henrique Barboza In-Reply-To: <20220901131756.26060-4-victor.colombo@eldorado.org.br> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2001:4860:4864:20::31; envelope-from=danielhb413@gmail.com; helo=mail-oa1-x31.google.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 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, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, NICE_REPLY_A=-1.716, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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" On 9/1/22 10:17, Víctor Colombo wrote: > Starting at PowerISA v3.1, the second doubleword of the registers > used to store results in DFP instructions are supposed to be zeroed. > > From the ISA, chapter 7.2.1.1 Floating-Point Registers: > """ > Chapter 4. Floating-Point Facility provides 32 64-bit > FPRs. Chapter 5. Decimal Floating-Point also employs > FPRs in decimal floating-point (DFP) operations. When > VSX is implemented, the 32 FPRs are mapped to > doubleword 0 of VSRs 0-31. (...) > All instructions that operate on an FPR are redefined > to operate on doubleword element 0 of the > corresponding VSR. (...) > and the contents of doubleword element 1 of the > VSR corresponding to the target FPR or FPR pair for these > instructions are set to 0. > """ > > Before, the result stored at doubleword 1 was said to be undefined. > > With that, this patch changes the DFP facility to zero doubleword 1 > when using set_dfp64 and set_dfp128. This fixes the behavior for ISA > 3.1 while keeping the behavior correct for previous ones. > > Signed-off-by: Víctor Colombo > --- Reviewed-by: Daniel Henrique Barboza > target/ppc/dfp_helper.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/target/ppc/dfp_helper.c b/target/ppc/dfp_helper.c > index 5ba74b2124..be7aa5357a 100644 > --- a/target/ppc/dfp_helper.c > +++ b/target/ppc/dfp_helper.c > @@ -42,13 +42,16 @@ static void get_dfp128(ppc_vsr_t *dst, ppc_fprp_t *dfp) > > static void set_dfp64(ppc_fprp_t *dfp, ppc_vsr_t *src) > { > - dfp->VsrD(0) = src->VsrD(1); > + dfp[0].VsrD(0) = src->VsrD(1); > + dfp[0].VsrD(1) = 0ULL; > } > > static void set_dfp128(ppc_fprp_t *dfp, ppc_vsr_t *src) > { > dfp[0].VsrD(0) = src->VsrD(0); > dfp[1].VsrD(0) = src->VsrD(1); > + dfp[0].VsrD(1) = 0ULL; > + dfp[1].VsrD(1) = 0ULL; > } > > static void set_dfp128_to_avr(ppc_avr_t *dst, ppc_vsr_t *src)