From patchwork Wed Mar 11 23:59:39 2026 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Bavier X-Patchwork-Id: 131550 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from vm01.sourceware.org (localhost [127.0.0.1]) by sourceware.org (Postfix) with ESMTP id 862664B920F9 for ; Thu, 12 Mar 2026 00:00:30 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 862664B920F9 Authentication-Results: sourceware.org; dkim=pass (2048-bit key, secure) header.d=posteo.net header.i=@posteo.net header.a=rsa-sha256 header.s=2017 header.b=j7yelXRz X-Original-To: newlib@sourceware.org Delivered-To: newlib@sourceware.org Received: from mout01.posteo.de (mout01.posteo.de [185.67.36.65]) by sourceware.org (Postfix) with ESMTPS id 201574B920DC for ; Wed, 11 Mar 2026 23:59:41 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 201574B920DC Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=posteo.net Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=posteo.net ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 201574B920DC Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=185.67.36.65 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1773273586; cv=none; b=bmYYZ2DKf46nuZETfXyYb2KQIfJg2VA+VQsXH7S6AruPUBxPX+SvUBoir0EQnD7Q1CLHwBJEuHGZ/WKC8V3sS9Y8qEwKydLkpXi71/DQBFjkEfFGUkJo8GtI0+ld5kpdTHct1JHevIqwbIq39xbcRCvbOpy9zV4PobzOecaLOJY= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1773273586; c=relaxed/simple; bh=nn7V5UT1qX3NO5SZieDpWFUsCma7DucHKAXTThfxO8s=; h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version; b=Fr90C47WIYIpyvVGPdR59F2M+aM+kINr02idWAvkPnqfaYme655qY8J1QbJDq9uiWN0HxcR70kE8rU8mPN5w8k4GmjiuIcWWIMWdagjIk+fm3whkinQPb2IjWhyw0EIh+rv54WkrR2RUfxJhOoxh2C1KWFkesvYTAmvJDgCg0+o= ARC-Authentication-Results: i=1; server2.sourceware.org DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 201574B920DC Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id B2BC0240027 for ; Thu, 12 Mar 2026 00:59:39 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.net; s=2017; t=1773273579; bh=Ga7Yyxrs5P4wRvkLvC6r4fVF6bISjJcYozHbMEkn0cU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version: Content-Transfer-Encoding:From; b=j7yelXRzUebLH48fvrXBBie7uoDrZKcD/vckTFVSx4s9NN18ynLKAREmStc0vTr1Q /2KW8KjGMzRmWT55u+mSKocY8zYNZoy0fmIQ41U9SQp6LgoaqugTmTCtGXcIVWwXBw UNSDKHM+meu5f+4ZlWUmiaSzchDsYRg2Soz60Ro/PiKZ/GdOQMVRqA3REHA53WLe6F NBPvbGP/ptaEccUSwpqmtUG8arm4sW01NY+b8KnCac9Y2hPPG/InE+9n3LrOW3onMu gAuof5Io2xu+VAIue/loDvaVGmbAb6MkkS2jjYslhwSb1A+RcwZ0k91Fq+sZGAHuxt Vd31rHv9fx3PQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4fWSQy3gWxz6twr; Thu, 12 Mar 2026 00:59:36 +0100 (CET) From: Eric Bavier To: newlib@sourceware.org Cc: Eric Bavier Subject: [PATCH] libm: Fixes scalbnf rounding up to minimum magnitude. Date: Wed, 11 Mar 2026 23:59:39 +0000 Message-ID: <20260311235602.12655-1-bavier@posteo.net> MIME-Version: 1.0 X-Spam-Status: No, score=-10.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_BLOCKED, RCVD_IN_MSPIKE_H2, RCVD_IN_VALIDITY_RPBL_BLOCKED, RCVD_IN_VALIDITY_SAFE_BLOCKED, SPF_HELO_PASS, SPF_PASS, TXREP, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on sourceware.org X-BeenThere: newlib@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Newlib mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: newlib-bounces~patchwork=sourceware.org@sourceware.org Previously, results that should have rounded up to the minimum magnitude floating-point value would instead return zero, in round-to-nearest-even mode. E.g. scalbnf(0x1.000002p0,-150) with subnormal support of scalbnf(0x1.000002p0,-127) without. * newlib/libm/common/fdlibm.h (FLT_SMALLEST_EXP): Adjust down by one. Adjust documentation. --- newlib/libm/common/fdlibm.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/newlib/libm/common/fdlibm.h b/newlib/libm/common/fdlibm.h index 7a49e29e0..595a5206d 100644 --- a/newlib/libm/common/fdlibm.h +++ b/newlib/libm/common/fdlibm.h @@ -101,8 +101,8 @@ The bitmask of |log(REAL_FLT_MIN)|, rounding down. FLT_SMALLEST_EXP - REAL_FLT_MIN's exponent - EXP_BIAS (1 if denormals are not supported, - -22 if they are). + REAL_FLT_MIN's exponent + EXP_BIAS - 1 (0 if denormals are not + supported, -23 if they are). */ #ifdef _FLT_NO_DENORMALS @@ -111,14 +111,14 @@ #define FLT_UWORD_MIN 0x00800000 #define FLT_UWORD_EXP_MIN 0x42fc0000 #define FLT_UWORD_LOG_MIN 0x42aeac50 -#define FLT_SMALLEST_EXP 1 +#define FLT_SMALLEST_EXP 0 #else #define FLT_UWORD_IS_ZERO(x) ((x)==0) #define FLT_UWORD_IS_SUBNORMAL(x) ((x)<0x00800000L) #define FLT_UWORD_MIN 0x00000001 #define FLT_UWORD_EXP_MIN 0x43160000 #define FLT_UWORD_LOG_MIN 0x42cff1b5 -#define FLT_SMALLEST_EXP -22 +#define FLT_SMALLEST_EXP -23 #endif #ifdef __STDC__