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[174.21.75.75]) by smtp.gmail.com with ESMTPSA id me18sm9392628pjb.33.2021.10.30.14.17.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 30 Oct 2021 14:17:08 -0700 (PDT) Subject: Re: [PATCH v2 07/34] target/ppc: Implement cntlzdm To: matheus.ferst@eldorado.org.br, qemu-devel@nongnu.org, qemu-ppc@nongnu.org References: <20211029202424.175401-1-matheus.ferst@eldorado.org.br> <20211029202424.175401-8-matheus.ferst@eldorado.org.br> From: Richard Henderson Message-ID: <65bd3052-fbe9-33ff-585c-b5259ebd46e0@linaro.org> Date: Sat, 30 Oct 2021 14:17:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211029202424.175401-8-matheus.ferst@eldorado.org.br> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::535; envelope-from=richard.henderson@linaro.org; helo=mail-pg1-x535.google.com X-Spam_score_int: -44 X-Spam_score: -4.5 X-Spam_bar: ---- X-Spam_report: (-4.5 / 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, NICE_REPLY_A=-2.426, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lucas.castro@eldorado.org.br, luis.pires@eldorado.org.br, groug@kaod.org, david@gibson.dropbear.id.au Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 10/29/21 1:23 PM, matheus.ferst@eldorado.org.br wrote: > From: Luis Pires > > Implement the following PowerISA v3.1 instruction: > cntlzdm: Count Leading Zeros Doubleword Under Bit Mask > > Suggested-by: Richard Henderson > Signed-off-by: Luis Pires > Signed-off-by: Matheus Ferst > --- > v2: > - Inline implementation of cntlzdm > --- > target/ppc/insn32.decode | 1 + > target/ppc/translate/fixedpoint-impl.c.inc | 36 ++++++++++++++++++++++ > 2 files changed, 37 insertions(+) > > diff --git a/target/ppc/insn32.decode b/target/ppc/insn32.decode > index 9cb9fc00b8..221cb00dd6 100644 > --- a/target/ppc/insn32.decode > +++ b/target/ppc/insn32.decode > @@ -203,6 +203,7 @@ ADDPCIS 010011 ..... ..... .......... 00010 . @DX > ## Fixed-Point Logical Instructions > > CFUGED 011111 ..... ..... ..... 0011011100 - @X > +CNTLZDM 011111 ..... ..... ..... 0000111011 - @X > > ### Float-Point Load Instructions > > diff --git a/target/ppc/translate/fixedpoint-impl.c.inc b/target/ppc/translate/fixedpoint-impl.c.inc > index 0d9c6e0996..c9e9ae35df 100644 > --- a/target/ppc/translate/fixedpoint-impl.c.inc > +++ b/target/ppc/translate/fixedpoint-impl.c.inc > @@ -413,3 +413,39 @@ static bool trans_CFUGED(DisasContext *ctx, arg_X *a) > #endif > return true; > } > + > +#if defined(TARGET_PPC64) > +static void do_cntlzdm(TCGv_i64 dst, TCGv_i64 src, TCGv_i64 mask) > +{ > + TCGv_i64 tmp; > + TCGLabel *l1; > + > + tmp = tcg_temp_local_new_i64(); > + l1 = gen_new_label(); > + > + tcg_gen_and_i64(tmp, src, mask); > + tcg_gen_clzi_i64(tmp, tmp, 64); > + > + tcg_gen_brcondi_i64(TCG_COND_EQ, tmp, 0, l1); > + > + tcg_gen_subfi_i64(tmp, 64, tmp); > + tcg_gen_shr_i64(tmp, mask, tmp); > + tcg_gen_ctpop_i64(tmp, tmp); > + > + gen_set_label(l1); > + > + tcg_gen_mov_i64(dst, tmp); This works, but a form without brcond would be better (due to how poorly tcg handles basic blocks). How about tcg_gen_clzi_i64(tmp, tmp, 0); tcg_gen_xori_i64(tmp, tmp, 63); tcg_gen_shr_i64(tmp, mask, tmp); tcg_gen_shri_i64(tmp, tmp, 1); tcg_gen_ctpop_i64(dst, tmp); The middle 3 operations perform a shift between [1-64], such that we are assured of 0 for 64. Either way, Reviewed-by: Richard Henderson r~