[newlib-cygwin] libm: Detect fast fmaf support

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=0c1989070ee1d849c7a25ad2eb6c8e3fb1df6393

commit 0c1989070ee1d849c7a25ad2eb6c8e3fb1df6393
Author: Keith Packard via Newlib <newlib@sourceware.org>
Date:   Sat Aug 8 15:34:12 2020 -0700

    libm: Detect fast fmaf support
    
    Anything with fast FMA is assumed to have fast FMAF, along with
    32-bit arms that advertise 32-bit FP support and __ARM_FEATURE_FMA
    
    Signed-off-by: Keith Packard <keithp@keithp.com>

Diff:
---
 newlib/libm/common/math_config.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/newlib/libm/common/math_config.h b/newlib/libm/common/math_config.h
index df8f8d6e4..e7a8bb7fe 100644
--- a/newlib/libm/common/math_config.h
+++ b/newlib/libm/common/math_config.h
@@ -79,6 +79,14 @@
 # endif
 #endif
 
+#ifndef HAVE_FAST_FMAF
+# if HAVE_FAST_FMA || (__ARM_FEATURE_FMA && (__ARM_FP & 4))
+#  define HAVE_FAST_FMAF 1
+# else
+#  define HAVE_FAST_FMAF 0
+# endif
+#endif
+
 #if HAVE_FAST_ROUND
 /* When set, the roundtoint and converttoint functions are provided with
    the semantics documented below.  */