[newlib-cygwin] Fix error in fdim/f for infinities

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=18b4e0e5187f7e2076661e53747977f21dabedff

commit 18b4e0e5187f7e2076661e53747977f21dabedff
Author: Fabian Schriever <fabian.schriever@gtd-gmbh.de>
Date:   Tue Mar 10 11:24:12 2020 +0100

    Fix error in fdim/f for infinities
    
    The comparison c == FP_INFINITE causes the function to return +inf as it
    expects x = +inf to always be larger than y. This shortcut causes
    several issues as it also returns +inf for the following cases:
     - fdim(+inf, +inf), expected (as per C99): +0.0
     - fdim(-inf, any non NaN), expected: +0.0
    
    I don't see a reason to keep the comparison as all the infinity cases
    return the correct result using just the ternary operation.

Diff:
---
 newlib/libm/common/s_fdim.c  | 5 +----
 newlib/libm/common/sf_fdim.c | 5 +----
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/newlib/libm/common/s_fdim.c b/newlib/libm/common/s_fdim.c
index 73a027953..61a4908f3 100644
--- a/newlib/libm/common/s_fdim.c
+++ b/newlib/libm/common/s_fdim.c
@@ -49,11 +49,8 @@ ANSI C, POSIX.
 	double y;
 #endif
 {
-  int c = __fpclassifyd(x);
-  if (c == FP_NAN)  return(x);
+  if (__fpclassifyd(x) == FP_NAN)  return(x);
   if (__fpclassifyd(y) == FP_NAN)  return(y);
-  if (c == FP_INFINITE)
-    return HUGE_VAL;
 
   return x > y ? x - y : 0.0;
 }
diff --git a/newlib/libm/common/sf_fdim.c b/newlib/libm/common/sf_fdim.c
index fe349098b..8fee57002 100644
--- a/newlib/libm/common/sf_fdim.c
+++ b/newlib/libm/common/sf_fdim.c
@@ -14,11 +14,8 @@
 	float y;
 #endif
 {
-  int c = __fpclassifyf(x);
-  if (c == FP_NAN)  return(x);
+  if (__fpclassifyf(x) == FP_NAN)  return(x);
   if (__fpclassifyf(y) == FP_NAN)  return(y);
-  if (c == FP_INFINITE)
-    return HUGE_VALF;
 
   return x > y ? x - y : 0.0;
 }