From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=57232 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Q5fNL-0002n9-Mw for qemu-devel@nongnu.org; Fri, 01 Apr 2011 10:31:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Q5fNJ-0004tb-3y for qemu-devel@nongnu.org; Fri, 01 Apr 2011 10:30:59 -0400 Received: from mnementh.archaic.org.uk ([81.2.115.146]:45963) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Q5fNI-0004or-RS for qemu-devel@nongnu.org; Fri, 01 Apr 2011 10:30:57 -0400 From: Peter Maydell Date: Fri, 1 Apr 2011 15:30:38 +0100 Message-Id: <1301668243-29886-6-git-send-email-peter.maydell@linaro.org> In-Reply-To: <1301668243-29886-1-git-send-email-peter.maydell@linaro.org> References: <1301668243-29886-1-git-send-email-peter.maydell@linaro.org> Subject: [Qemu-devel] [PATCH 05/10] target-arm: Correct ABD's handling of negative zeroes List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori , qemu-devel@nongnu.org Cc: Aurelien Jarno Implement ABD by taking the absolute value of the difference of the operands (as the ARM ARM specifies) rather than by flipping the order of the operands to the subtract based on the results of a comparison. The latter approch gives the wrong answers for some edge cases like negative zero. Signed-off-by: Peter Maydell --- target-arm/neon_helper.c | 4 +--- 1 files changed, 1 insertions(+), 3 deletions(-) diff --git a/target-arm/neon_helper.c b/target-arm/neon_helper.c index 8eb4cef..1905545 100644 --- a/target-arm/neon_helper.c +++ b/target-arm/neon_helper.c @@ -1788,9 +1788,7 @@ uint32_t HELPER(neon_abd_f32)(CPUState *env, uint32_t a, uint32_t b) { float32 f0 = make_float32(a); float32 f1 = make_float32(b); - return float32_val((float32_compare_quiet(f0, f1, NFS) == 1) - ? float32_sub(f0, f1, NFS) - : float32_sub(f1, f0, NFS)); + return float32_val(float32_abs(float32_sub(f0, f1, NFS))); } uint32_t HELPER(neon_add_f32)(CPUState *env, uint32_t a, uint32_t b) -- 1.7.1