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Sun, 20 Oct 2024 08:53:50 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHYs5PhMmHMVurLaUGvUD3qQLkrgINiHMsLxe/lrIiMjEMIN9exT2J2RBGEAZcGZ9RUH5GKZg== X-Received: by 2002:adf:9bce:0:b0:374:c3e4:d6de with SMTP id ffacd0b85a97d-37eb47693ebmr5568560f8f.41.1729439629969; Sun, 20 Oct 2024 08:53:49 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: richard.henderson@linaro.org Subject: [PATCH 07/14] target/i386: optimize computation of ZF from CC_OP_DYNAMIC Date: Sun, 20 Oct 2024 17:53:17 +0200 Message-ID: <20241020155324.35273-8-pbonzini@redhat.com> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241020155324.35273-1-pbonzini@redhat.com> References: <20241020155324.35273-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.527, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1729439698580116600 Content-Type: text/plain; charset="utf-8" Most uses of CC_OP_DYNAMIC are for CMP/JB/JE or similar sequences. We can optimize many of them to avoid computation of the flags. This eliminates both TCG ops to set up the new cc_op, and helper instructions because evaluating just ZF is much cheaper. Signed-off-by: Paolo Bonzini --- target/i386/helper.h | 1 + target/i386/tcg/cc_helper.c | 20 ++++++++++++++++++++ target/i386/tcg/translate.c | 10 +++++++--- 3 files changed, 28 insertions(+), 3 deletions(-) diff --git a/target/i386/helper.h b/target/i386/helper.h index eeb8df56eaa..3f67098f11f 100644 --- a/target/i386/helper.h +++ b/target/i386/helper.h @@ -1,5 +1,6 @@ DEF_HELPER_FLAGS_4(cc_compute_all, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int) DEF_HELPER_FLAGS_4(cc_compute_c, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int) +DEF_HELPER_FLAGS_3(cc_compute_nz, TCG_CALL_NO_RWG_SE, tl, tl, tl, int) =20 DEF_HELPER_3(write_eflags, void, env, tl, i32) DEF_HELPER_1(read_eflags, tl, env) diff --git a/target/i386/tcg/cc_helper.c b/target/i386/tcg/cc_helper.c index 40583c04cf9..c24e6a14c07 100644 --- a/target/i386/tcg/cc_helper.c +++ b/target/i386/tcg/cc_helper.c @@ -95,6 +95,26 @@ static target_ulong compute_all_adcox(target_ulong dst, = target_ulong src1, return (src1 & ~(CC_C | CC_O)) | (dst * CC_C) | (src2 * CC_O); } =20 +target_ulong helper_cc_compute_nz(target_ulong dst, target_ulong src1, + int op) +{ + target_ulong mask; + + if (CC_OP_HAS_EFLAGS(op)) { + return ~src1 & CC_Z; + } else { + MemOp size =3D cc_op_size(op); + + if (size =3D=3D MO_TL) { + /* Avoid shift count overflow when computing the mask below. = */ + return dst; + } + + mask =3D (1ull << (8 << size)) - 1; + return dst & mask; + } +} + target_ulong helper_cc_compute_all(target_ulong dst, target_ulong src1, target_ulong src2, int op) { diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index 1a9a2fe709e..5e326ab1aff 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -1008,15 +1008,19 @@ static CCPrepare gen_prepare_eflags_o(DisasContext = *s, TCGv reg) static CCPrepare gen_prepare_eflags_z(DisasContext *s, TCGv reg) { switch (s->cc_op) { - case CC_OP_DYNAMIC: - gen_compute_eflags(s); - /* FALLTHRU */ case CC_OP_EFLAGS: case CC_OP_ADCX: case CC_OP_ADOX: case CC_OP_ADCOX: return (CCPrepare) { .cond =3D TCG_COND_TSTNE, .reg =3D cpu_cc_src, .imm =3D CC_Z }; + case CC_OP_DYNAMIC: + gen_update_cc_op(s); + if (!reg) { + reg =3D tcg_temp_new(); + } + gen_helper_cc_compute_nz(reg, cpu_cc_dst, cpu_cc_src, cpu_cc_op); + return (CCPrepare) { .cond =3D TCG_COND_EQ, .reg =3D reg, .imm =3D= 0 }; default: { MemOp size =3D cc_op_size(s->cc_op); --=20 2.46.2