From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay1.mentorg.com (relay1.mentorg.com [192.94.38.131]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "relay1.mentorg.com", Issuer "Entrust Certification Authority - L1C" (not verified)) by ozlabs.org (Postfix) with ESMTPS id C0B582C07A5 for ; Tue, 5 Nov 2013 03:53:56 +1100 (EST) Date: Mon, 4 Nov 2013 16:53:50 +0000 From: "Joseph S. Myers" To: Subject: [PATCH 3/6] math-emu: fix floating-point to integer unsigned saturation In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: Joseph Myers Cc: Liu Yu , linux-kernel@vger.kernel.org, Shan Hai List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Joseph Myers The math-emu macros _FP_TO_INT and _FP_TO_INT_ROUND are supposed to saturate their results for out-of-range arguments, except in the case rsigned == 2 (when instead the low bits of the result are taken). However, in the case rsigned == 0 (converting to unsigned integers), they mistakenly produce 0 for positive results and the maximum unsigned integer for negative results, the opposite of correct unsigned saturation. This patch fixes the logic. Signed-off-by: Joseph Myers --- Previous submission: . I have made the corresponding changes to the glibc/libgcc copy of this code, given that it would be desirable to resync the Linux and glibc/libgcc copies (the latter has had many enhancements and bug fixes since it was copied into Linux), although strictly this incorrect saturation is only a bug when trying to emulate particular instruction semantics, not when used in userspace to implement C operations where the results of out-of-range conversions are unspecified or undefined. diff --git a/include/math-emu/op-common.h b/include/math-emu/op-common.h index 9696a5e..70fe5e9 100644 --- a/include/math-emu/op-common.h +++ b/include/math-emu/op-common.h @@ -685,7 +685,7 @@ do { \ else \ { \ r = 0; \ - if (X##_s) \ + if (!X##_s) \ r = ~r; \ } \ FP_SET_EXCEPTION(FP_EX_INVALID); \ @@ -762,7 +762,7 @@ do { \ if (!rsigned) \ { \ r = 0; \ - if (X##_s) \ + if (!X##_s) \ r = ~r; \ } \ else if (rsigned != 2) \ -- Joseph S. Myers joseph@codesourcery.com