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Date:      Sun, 28 Jul 2024 21:38:12 GMT
From:      Ed Maste <emaste@FreeBSD.org>
To:        src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org
Subject:   git: 34f746cc7f8a - main - libm: fma: correct zero sign with small inputs
Message-ID:  <202407282138.46SLcCkF069579@gitrepo.freebsd.org>

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The branch main has been updated by emaste:

URL: https://cgit.FreeBSD.org/src/commit/?id=34f746cc7f8a8dd261027a8b392b76e70adc8438

commit 34f746cc7f8a8dd261027a8b392b76e70adc8438
Author:     Steve Kargl <kargl@FreeBSD.org>
AuthorDate: 2024-06-16 23:41:38 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2024-07-28 21:37:45 +0000

    libm: fma: correct zero sign with small inputs
    
    This is a fixed version of 888796ade284.
    
    PR:             277783
    Reported by:    Victor Stinner
    Reviewed by:    emaste
    MFC after:      1 week
---
 lib/msun/src/s_fma.c  | 4 ++--
 lib/msun/src/s_fmal.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/msun/src/s_fma.c b/lib/msun/src/s_fma.c
index 6c889a6a46ca..23a84491dd2a 100644
--- a/lib/msun/src/s_fma.c
+++ b/lib/msun/src/s_fma.c
@@ -260,14 +260,14 @@ fma(double x, double y, double z)
 
 	spread = ex + ey;
 
-	if (r.hi == 0.0) {
+	if (r.hi == 0.0 && xy.lo == 0) {
 		/*
 		 * When the addends cancel to 0, ensure that the result has
 		 * the correct sign.
 		 */
 		fesetround(oround);
 		volatile double vzs = zs; /* XXX gcc CSE bug workaround */
-		return (xy.hi + vzs + ldexp(xy.lo, spread));
+		return (xy.hi + vzs);
 	}
 
 	if (oround != FE_TONEAREST) {
diff --git a/lib/msun/src/s_fmal.c b/lib/msun/src/s_fmal.c
index 80c835d09c2b..2fca20610157 100644
--- a/lib/msun/src/s_fmal.c
+++ b/lib/msun/src/s_fmal.c
@@ -241,14 +241,14 @@ fmal(long double x, long double y, long double z)
 
 	spread = ex + ey;
 
-	if (r.hi == 0.0) {
+	if (r.hi == 0.0 && xy.lo == 0) {
 		/*
 		 * When the addends cancel to 0, ensure that the result has
 		 * the correct sign.
 		 */
 		fesetround(oround);
 		volatile long double vzs = zs; /* XXX gcc CSE bug workaround */
-		return (xy.hi + vzs + ldexpl(xy.lo, spread));
+		return (xy.hi + vzs);
 	}
 
 	if (oround != FE_TONEAREST) {



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