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[81.2.115.148]) by smtp.gmail.com with ESMTPSA id m39sm12114125wms.36.2021.08.20.10.12.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Aug 2021 10:12:21 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Subject: [PATCH] target/i386: Remove unnecessary checks of b2 in SSE decode Date: Fri, 20 Aug 2021 18:12:20 +0100 Message-Id: <20210820171220.15089-1-peter.maydell@linaro.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::433; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x433.google.com X-Spam_score_int: -1 X-Spam_score: -0.2 X-Spam_bar: / X-Spam_report: (-0.2 / 5.0 requ) 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 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: Paolo Bonzini , Richard Henderson , Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" In the SSE decode function gen_sse(), we combine a byte 'b' and a value 'b1' which can be [0..3], and switch on them: b |= (b1 << 8); switch (b) { ... default: unknown_op: gen_unknown_opcode(env, s); return; } In three cases inside this switch, we were then also checking for "if (b1 >= 2) { goto unknown_op; }". However, this can never happen, because the 'case' values in each place are 0x0nn or 0x1nn and the switch will have directed the b1 == (2, 3) cases to the default already. Delete the dead code. This check was added in commit c045af25a52e9 in 2010; the added code was unnecessary then as well. this commit amounts to a revert of c045af25a52e9. Fixes: Coverity CID 1460207 Signed-off-by: Peter Maydell --- Somebody should double-check this, because one assumes Andi added the code for a reason... --- target/i386/tcg/translate.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c index aacb605eee4..3e7afd2620e 100644 --- a/target/i386/tcg/translate.c +++ b/target/i386/tcg/translate.c @@ -3521,9 +3521,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, case 0x171: /* shift xmm, im */ case 0x172: case 0x173: - if (b1 >= 2) { - goto unknown_op; - } val = x86_ldub_code(env, s); if (is_xmm) { tcg_gen_movi_tl(s->T0, val); @@ -3772,9 +3769,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, rm = modrm & 7; reg = ((modrm >> 3) & 7) | REX_R(s); mod = (modrm >> 6) & 3; - if (b1 >= 2) { - goto unknown_op; - } sse_fn_epp = sse_op_table6[b].op[b1]; if (!sse_fn_epp) { @@ -4202,9 +4196,6 @@ static void gen_sse(CPUX86State *env, DisasContext *s, int b, rm = modrm & 7; reg = ((modrm >> 3) & 7) | REX_R(s); mod = (modrm >> 6) & 3; - if (b1 >= 2) { - goto unknown_op; - } sse_fn_eppi = sse_op_table7[b].op[b1]; if (!sse_fn_eppi) { -- 2.20.1