From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F214AC433EF for ; Thu, 30 Sep 2021 05:57:57 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B71BD61152 for ; Thu, 30 Sep 2021 05:57:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B71BD61152 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:49632 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mVp4u-0005fX-T8 for qemu-devel@archiver.kernel.org; Thu, 30 Sep 2021 01:57:56 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47312) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mVos9-00011z-Sl; Thu, 30 Sep 2021 01:44:45 -0400 Received: from gandalf.ozlabs.org ([150.107.74.76]:55245) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mVos7-0003VS-Ry; Thu, 30 Sep 2021 01:44:45 -0400 Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4HKhyR1KWqz4xbg; Thu, 30 Sep 2021 15:44:31 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=201602; t=1632980671; bh=qhmA7dMFPqO69K7C9FemWed6fVmEm5KeIrFF6VnDAOk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cTEybkzpvxGJmTbSJAeGPDptPb2ZeILzaWcxAL2OzlJHMqLuJ6NaCAEpewrG6ZcmR jRUJA2DP53iJmvQAu+IZftWulHdyc8RWilXmBZrBDAjAHRULbWQYK1e3coTqfqO4EH 24ONiDgzdIad4IdqYEwZTW33CfhKYZUHpJGY4UTM= From: David Gibson To: peter.maydell@linaro.org Subject: [PULL 13/44] target/ppc: fix setting of CR flags in bcdcfsq Date: Thu, 30 Sep 2021 15:43:55 +1000 Message-Id: <20210930054426.357344-14-david@gibson.dropbear.id.au> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210930054426.357344-1-david@gibson.dropbear.id.au> References: <20210930054426.357344-1-david@gibson.dropbear.id.au> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=150.107.74.76; envelope-from=dgibson@gandalf.ozlabs.org; helo=gandalf.ozlabs.org X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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: Richard Henderson , mark.cave-ayland@ilande.co.uk, qemu-devel@nongnu.org, groug@kaod.org, Luis Pires , hpoussin@reactos.org, clg@kaod.org, qemu-ppc@nongnu.org, philmd@redhat.com, David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Luis Pires According to the ISA, CR should be set based on the source value, and not on the packed decimal result. The way this was implemented would cause GT, LT and EQ to be set incorrectly when the source value was too large and the 31 least significant digits of the packed decimal result ended up being all zero. This would happen for source values of +/-10^31, +/-10^32, etc. The new implementation fixes this and also skips the result calculation altogether in case of src overflow. Signed-off-by: Luis Pires Message-Id: <20210823150235.35759-1-luis.pires@eldorado.org.br> Reviewed-by: Richard Henderson Signed-off-by: David Gibson --- target/ppc/int_helper.c | 61 ++++++++++++++++++++++++++++++++--------- 1 file changed, 48 insertions(+), 13 deletions(-) diff --git a/target/ppc/int_helper.c b/target/ppc/int_helper.c index c2d3248d1e..f5dac3aa87 100644 --- a/target/ppc/int_helper.c +++ b/target/ppc/int_helper.c @@ -2480,10 +2480,26 @@ uint32_t helper_bcdctz(ppc_avr_t *r, ppc_avr_t *b, uint32_t ps) return cr; } +/** + * Compare 2 128-bit unsigned integers, passed in as unsigned 64-bit pairs + * + * Returns: + * > 0 if ahi|alo > bhi|blo, + * 0 if ahi|alo == bhi|blo, + * < 0 if ahi|alo < bhi|blo + */ +static inline int ucmp128(uint64_t alo, uint64_t ahi, + uint64_t blo, uint64_t bhi) +{ + return (ahi == bhi) ? + (alo > blo ? 1 : (alo == blo ? 0 : -1)) : + (ahi > bhi ? 1 : -1); +} + uint32_t helper_bcdcfsq(ppc_avr_t *r, ppc_avr_t *b, uint32_t ps) { int i; - int cr = 0; + int cr; uint64_t lo_value; uint64_t hi_value; ppc_avr_t ret = { .u64 = { 0, 0 } }; @@ -2492,28 +2508,47 @@ uint32_t helper_bcdcfsq(ppc_avr_t *r, ppc_avr_t *b, uint32_t ps) lo_value = -b->VsrSD(1); hi_value = ~b->VsrD(0) + !lo_value; bcd_put_digit(&ret, 0xD, 0); + + cr = CRF_LT; } else { lo_value = b->VsrD(1); hi_value = b->VsrD(0); bcd_put_digit(&ret, bcd_preferred_sgn(0, ps), 0); - } - if (divu128(&lo_value, &hi_value, 1000000000000000ULL) || - lo_value > 9999999999999999ULL) { - cr = CRF_SO; + if (hi_value == 0 && lo_value == 0) { + cr = CRF_EQ; + } else { + cr = CRF_GT; + } } - for (i = 1; i < 16; hi_value /= 10, i++) { - bcd_put_digit(&ret, hi_value % 10, i); - } + /* + * Check src limits: abs(src) <= 10^31 - 1 + * + * 10^31 - 1 = 0x0000007e37be2022 c0914b267fffffff + */ + if (ucmp128(lo_value, hi_value, + 0xc0914b267fffffffULL, 0x7e37be2022ULL) > 0) { + cr |= CRF_SO; - for (; i < 32; lo_value /= 10, i++) { - bcd_put_digit(&ret, lo_value % 10, i); - } + /* + * According to the ISA, if src wouldn't fit in the destination + * register, the result is undefined. + * In that case, we leave r unchanged. + */ + } else { + divu128(&lo_value, &hi_value, 1000000000000000ULL); - cr |= bcd_cmp_zero(&ret); + for (i = 1; i < 16; hi_value /= 10, i++) { + bcd_put_digit(&ret, hi_value % 10, i); + } - *r = ret; + for (; i < 32; lo_value /= 10, i++) { + bcd_put_digit(&ret, lo_value % 10, i); + } + + *r = ret; + } return cr; } -- 2.31.1