[newlib-cygwin/cygwin-3_5-branch] libm/common: Fix nextafter and nextafterf when x == y

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bbf8484a5b4fb5bcae024c04a8d84e53834e8b79

commit bbf8484a5b4fb5bcae024c04a8d84e53834e8b79
Author:     Kito Cheng <kito.cheng@sifive.com>
AuthorDate: Thu Dec 5 16:39:56 2024 +0800
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Thu Dec 5 11:57:37 2024 +0100

    libm/common: Fix nextafter and nextafterf when x == y
    
    That according to C99/POSIX, nextafter(x,y) should return y if x==y.
    
    [1] NetBSD fix for this: https://github.com/IIJ-NetBSD/netbsd-src/commit/3bc685224189d2b7dfb68da52d9725a256a667bd
    [2] glibc fix for this: https://github.com/bminor/glibc/commit/bc9f6000f6752153e5e1902259d5f491a88a1ae5#diff-bcc0628a39c3c2003047dcb5a40a8b50c00f01a74b1c8c1100d770a8e48b1ce2
    [3] Linux man page: https://man7.org/linux/man-pages/man3/nextafter.3.html
    
    (cherry picked from commit 7ccfe49e8ce908c581f82c8dbf0f9064df488a24)

Diff:
---
 newlib/libm/common/s_nextafter.c  | 2 +-
 newlib/libm/common/sf_nextafter.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/newlib/libm/common/s_nextafter.c b/newlib/libm/common/s_nextafter.c
index 9453a0a0015d..356c79f3de22 100644
--- a/newlib/libm/common/s_nextafter.c
+++ b/newlib/libm/common/s_nextafter.c
@@ -70,7 +70,7 @@ PORTABILITY
 	if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) ||   /* x is nan */ 
 	   ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0))     /* y is nan */ 
 	   return x+y;				
-	if(x==y) return x;		/* x=y, return x */
+	if(x==y) return y;		/* x=y, return y */
 	if((ix|lx)==0) {			/* x == 0 */
 	    INSERT_WORDS(x,hy&0x80000000,1);	/* return +-minsubnormal */
 	    y = x*x;
diff --git a/newlib/libm/common/sf_nextafter.c b/newlib/libm/common/sf_nextafter.c
index cea4da58ddcf..cdc7c663dfc2 100644
--- a/newlib/libm/common/sf_nextafter.c
+++ b/newlib/libm/common/sf_nextafter.c
@@ -32,7 +32,7 @@
 	if(FLT_UWORD_IS_NAN(ix) ||
 	   FLT_UWORD_IS_NAN(iy))
 	   return x+y;
-	if(x==y) return x;		/* x=y, return x */
+	if(x==y) return y;		/* x=y, return y */
 	if(FLT_UWORD_IS_ZERO(ix)) {		/* x == 0 */
 	    SET_FLOAT_WORD(x,(hy&0x80000000)|FLT_UWORD_MIN);
 	    y = x*x;