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Mon, 06 May 2024 01:10:15 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGi66YCxYNICimuK2yAkJIW/sfeF6+WLeqpWv9m71Kbd0RmmrPg+n6BsB+UhmD3YL48U2c+Jw== X-Received: by 2002:a05:6402:22d7:b0:570:35e:9a09 with SMTP id dm23-20020a05640222d700b00570035e9a09mr7551947edb.7.1714983015032; Mon, 06 May 2024 01:10:15 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: richard.henderson@linaro.org, zhao1.liu@intel.com Subject: [PATCH v2 05/25] target/i386: cleanup cc_op changes for REP/REPZ/REPNZ Date: Mon, 6 May 2024 10:09:37 +0200 Message-ID: <20240506080957.10005-6-pbonzini@redhat.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240506080957.10005-1-pbonzini@redhat.com> References: <20240506080957.10005-1-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=170.10.129.124; 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=-0.431, 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_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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: 1714983505089100001 Content-Type: text/plain; charset="utf-8" gen_update_cc_op must be called before control flow splits. Do it where the jump on ECX!=3D0 is translated. On the other hand, remove the call before gen_jcc1, which takes care of it already, and explain why REPZ/REPNZ need not use CC_OP_DYNAMIC---the translation block ends before any control-flow-dependent cc_op could be observed. Signed-off-by: Paolo Bonzini --- target/i386/tcg/translate.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index 3f1d2858fc9..6b766f5dd3f 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -1242,11 +1242,15 @@ static inline void gen_jcc1(DisasContext *s, int b,= TCGLabel *l1) } =20 /* XXX: does not work with gdbstub "ice" single step - not a - serious problem */ + serious problem. The caller can jump to the returned label + to stop the REP but, if the flags have changed, it has to call + gen_update_cc_op before doing so. */ static TCGLabel *gen_jz_ecx_string(DisasContext *s) { TCGLabel *l1 =3D gen_new_label(); TCGLabel *l2 =3D gen_new_label(); + + gen_update_cc_op(s); gen_op_jnz_ecx(s, l1); gen_set_label(l2); gen_jmp_rel_csize(s, 0, 1); @@ -1342,7 +1346,6 @@ static void gen_repz(DisasContext *s, MemOp ot, void (*fn)(DisasContext *s, MemOp ot)) { TCGLabel *l2; - gen_update_cc_op(s); l2 =3D gen_jz_ecx_string(s); fn(s, ot); gen_op_add_reg_im(s, s->aflag, R_ECX, -1); @@ -1364,11 +1367,13 @@ static void gen_repz2(DisasContext *s, MemOp ot, in= t nz, void (*fn)(DisasContext *s, MemOp ot)) { TCGLabel *l2; - gen_update_cc_op(s); l2 =3D gen_jz_ecx_string(s); + /* + * Only one iteration is done at a time, so there is + * no control flow junction here and cc_op is never dynamic. + */ fn(s, ot); gen_op_add_reg_im(s, s->aflag, R_ECX, -1); - gen_update_cc_op(s); gen_jcc1(s, (JCC_Z << 1) | (nz ^ 1), l2); if (s->repz_opt) { gen_op_jz_ecx(s, l2); --=20 2.45.0