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[174.21.70.228]) by smtp.gmail.com with ESMTPSA id p65sm40115pfb.62.2021.06.03.14.41.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Jun 2021 14:41:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=j87cuN4oaVGPOQrr81JQNoweh6RR6j9zmHwWvD1f2qc=; b=p++rPMhXyzBlFbk7pzdg7LIjaJw0oMzMDfr+VOHY9KCQo+pI2EP+5cjPY1M78LcIo6 TPP7pSq2L/3dPLXOGL0BJU1/2jEW5uOEo3bG6VzwF/Ru5b213cZOwYgwSzsm/dDqsict 7EdKwClekqJB5s+v8AUPQQZNyXKHZc/mY3g3yAruSuJI7hq8v6vASbwhxOchPEgTb7Id Q4k8XH6t1Sp3tXNoiGP3eDvxxMsBPAlRT9DBTPFnxgCxu1xYneSL4LZO7mp7FqgAp3nV Kww8lUFEsWDzPjuYxetpbYbSdLLYFELQk0HwriI8c+eAAbqkiULiFDex9Km6HnTFpike FNFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=j87cuN4oaVGPOQrr81JQNoweh6RR6j9zmHwWvD1f2qc=; b=jrax/S20T4csW60x3NTmn0oBZP4Z+TLyjIy2JApHVB1Uf9o4vH061RS1Ajx/XSH4+Q oUV8lzqni+105JDhZJwvgDknZEypbKOyti3gIcFS2Fx9e2TZweGX+MJqiZUKjRvkDBkQ S7V5DifHuzkIRGFQax+jqYI5vTIIst0vHhTVG6Vh2I0zsBwIdu+k6uC8/z/Z5AAKgKe5 MphsZL7XKeEnG5XO+5R3ysRWwFYQCjsdIzF5mOijNXgqkuD5hgNhX49qphh11VP4Zi4i 6zxlVFU4KFyQsjFevmM1WPnGDkDjLkKrn4mmzyb2JyuBmfZWE0+97H3AhVLcdiriIQ4R d+0w== X-Gm-Message-State: AOAM533463Xsok7BynInarns27lFGLkNlgmxiGvv/m//0b6op//69dHP bRi8L1pp6TrgG/vG1k5P/AYK6a5hElT5Rw== X-Google-Smtp-Source: ABdhPJz56gmEMK6RPtDkPVXpBJKmFpvPAamDApmxN+npMK09FHZvD5g8L9BotBp2dPkvuOQDyEBYCw== X-Received: by 2002:a17:90a:1150:: with SMTP id d16mr1346065pje.180.1622756500644; Thu, 03 Jun 2021 14:41:40 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PULL 12/29] softfloat: Adjust parts_uncanon_normal for floatx80 Date: Thu, 3 Jun 2021 14:41:14 -0700 Message-Id: <20210603214131.629841-13-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210603214131.629841-1-richard.henderson@linaro.org> References: <20210603214131.629841-1-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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=2607:f8b0:4864:20::102a; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102a.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, 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: =?UTF-8?q?Alex=20Benn=C3=A9e?= Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @linaro.org) With floatx80_precision_x, the rounding happens across the break between words. Notice this case with frac_lsb =3D round_mask + 1 -> 0 and check the bits in frac_hi as needed. In addition, since frac_shift =3D=3D 0, we won't implicitly clear round_mask via the right-shift, so explicitly clear those bits. This fixes rounding for floatx80_precision_[sd]. Reviewed-by: Alex Benn=C3=A9e Signed-off-by: Richard Henderson --- fpu/softfloat-parts.c.inc | 36 ++++++++++++++++++++++++++++++------ 1 file changed, 30 insertions(+), 6 deletions(-) diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc index a026581c33..efb81bbebe 100644 --- a/fpu/softfloat-parts.c.inc +++ b/fpu/softfloat-parts.c.inc @@ -155,7 +155,13 @@ static void partsN(uncanon_normal)(FloatPartsN *p, flo= at_status *s, =20 switch (s->float_rounding_mode) { case float_round_nearest_even: - inc =3D ((p->frac_lo & roundeven_mask) !=3D frac_lsbm1 ? frac_lsbm= 1 : 0); + if (N > 64 && frac_lsb =3D=3D 0) { + inc =3D ((p->frac_hi & 1) || (p->frac_lo & round_mask) !=3D fr= ac_lsbm1 + ? frac_lsbm1 : 0); + } else { + inc =3D ((p->frac_lo & roundeven_mask) !=3D frac_lsbm1 + ? frac_lsbm1 : 0); + } break; case float_round_ties_away: inc =3D frac_lsbm1; @@ -176,7 +182,11 @@ static void partsN(uncanon_normal)(FloatPartsN *p, flo= at_status *s, overflow_norm =3D true; /* fall through */ case float_round_to_odd_inf: - inc =3D p->frac_lo & frac_lsb ? 0 : round_mask; + if (N > 64 && frac_lsb =3D=3D 0) { + inc =3D p->frac_hi & 1 ? 0 : round_mask; + } else { + inc =3D p->frac_lo & frac_lsb ? 0 : round_mask; + } break; default: g_assert_not_reached(); @@ -191,8 +201,8 @@ static void partsN(uncanon_normal)(FloatPartsN *p, floa= t_status *s, p->frac_hi |=3D DECOMPOSED_IMPLICIT_BIT; exp++; } + p->frac_lo &=3D ~round_mask; } - frac_shr(p, frac_shift); =20 if (fmt->arm_althp) { /* ARM Alt HP eschews Inf and NaN for a wider exponent. */ @@ -201,18 +211,21 @@ static void partsN(uncanon_normal)(FloatPartsN *p, fl= oat_status *s, flags =3D float_flag_invalid; exp =3D exp_max; frac_allones(p); + p->frac_lo &=3D ~round_mask; } } else if (unlikely(exp >=3D exp_max)) { flags |=3D float_flag_overflow | float_flag_inexact; if (overflow_norm) { exp =3D exp_max - 1; frac_allones(p); + p->frac_lo &=3D ~round_mask; } else { p->cls =3D float_class_inf; exp =3D exp_max; frac_clear(p); } } + frac_shr(p, frac_shift); } else if (s->flush_to_zero) { flags |=3D float_flag_output_denormal; p->cls =3D float_class_zero; @@ -232,18 +245,29 @@ static void partsN(uncanon_normal)(FloatPartsN *p, fl= oat_status *s, /* Need to recompute round-to-even/round-to-odd. */ switch (s->float_rounding_mode) { case float_round_nearest_even: - inc =3D ((p->frac_lo & roundeven_mask) !=3D frac_lsbm1 - ? frac_lsbm1 : 0); + if (N > 64 && frac_lsb =3D=3D 0) { + inc =3D ((p->frac_hi & 1) || + (p->frac_lo & round_mask) !=3D frac_lsbm1 + ? frac_lsbm1 : 0); + } else { + inc =3D ((p->frac_lo & roundeven_mask) !=3D frac_lsbm1 + ? frac_lsbm1 : 0); + } break; case float_round_to_odd: case float_round_to_odd_inf: - inc =3D p->frac_lo & frac_lsb ? 0 : round_mask; + if (N > 64 && frac_lsb =3D=3D 0) { + inc =3D p->frac_hi & 1 ? 0 : round_mask; + } else { + inc =3D p->frac_lo & frac_lsb ? 0 : round_mask; + } break; default: break; } flags |=3D float_flag_inexact; frac_addi(p, p, inc); + p->frac_lo &=3D ~round_mask; } =20 exp =3D (p->frac_hi & DECOMPOSED_IMPLICIT_BIT) !=3D 0; --=20 2.25.1