[newlib-cygwin/main] RISC-V: Use the new libm code if possible

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=97d483c2f81c0865bead701f4d2824a21fae4938

commit 97d483c2f81c0865bead701f4d2824a21fae4938
Author:     Hau Hsu <hau.hsu@sifive.com>
AuthorDate: Wed Feb 22 09:59:07 2023 +0800
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Wed Feb 22 12:20:57 2023 +0100

    RISC-V: Use the new libm code if possible
    
    Set  __OBSOLETE_MATH_DEFAULT to 0 if 'd' extension is supported (i.e.
    __riscv_flen == 64).
    
    Base on the comment for  __OBSOLETE_MATH_DEFAULT:
    
    > ... it assumes that the toolchain has ISO C99 support (hexfloat
    > literals, standard fenv semantics), the target has IEEE-754 conforming
    > binary32 float and binary64 double (not mixed endian) representation,
    > standard SNaN representation, double and single precision arithmetics
    > has similar latency and it has no legacy SVID matherr support, only
    > POSIX errno and fenv exception based error handling.
    
    Signed-off-by: Hau Hsu <hau.hsu@sifive.com>

Diff:
---
 newlib/libc/include/machine/ieeefp.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/newlib/libc/include/machine/ieeefp.h b/newlib/libc/include/machine/ieeefp.h
index 9bb8af02f455..a29557a6d00c 100644
--- a/newlib/libc/include/machine/ieeefp.h
+++ b/newlib/libc/include/machine/ieeefp.h
@@ -221,6 +221,11 @@
 #ifdef __riscv_flen
 # define _SUPPORTS_ERREXCEPT
 #endif
+#if __riscv_flen == 64
+# define __OBSOLETE_MATH_DEFAULT 0
+#else
+# define __OBSOLETE_MATH_DEFAULT 1
+#endif
 #endif
 
 #ifdef __i960__