[newlib-cygwin] Aarch32/64: Support __FLT_EVAL_METHOD__ values other than 0, 1, 2

[Jeff Johnston]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=27f0913c17c216548b2f5eea79037ee90038f375

commit 27f0913c17c216548b2f5eea79037ee90038f375
Author: Andrea Corallo <andrea.corallo@arm.com>
Date:   Wed Mar 30 15:40:59 2022 +0200

    Aarch32/64: Support __FLT_EVAL_METHOD__ values other than 0, 1, 2
    
    2022-03-30  Andrea Corallo  <andrea.corallo@arm.com>
    
            * libc/include/machine/ieeefp.h (__FLOAT_TYPE, __DOUBLE_TYPE): New
            macros.
            * libc/include/math.h: Uses __DOUBLE_TYPE __FLOAT_TYPE to define
            double_t float_t if possible.

Diff:
---
 newlib/libc/include/machine/ieeefp.h | 14 ++++++++++++++
 newlib/libc/include/math.h           |  9 +++++++++
 2 files changed, 23 insertions(+)

diff --git a/newlib/libc/include/machine/ieeefp.h b/newlib/libc/include/machine/ieeefp.h
index 3c1f41e03..9bb8af02f 100644
--- a/newlib/libc/include/machine/ieeefp.h
+++ b/newlib/libc/include/machine/ieeefp.h
@@ -90,6 +90,13 @@
 #ifndef __SOFTFP__
 # define _SUPPORTS_ERREXCEPT
 #endif
+/* As per ISO/IEC TS 18661 '__FLT_EVAL_METHOD__' will be defined to 16
+   (if compiling with +fp16 support) so it can't be used by math.h to
+   define float_t and double_t.  For values of '__FLT_EVAL_METHOD__'
+   other than 0, 1, 2 the definition of float_t and double_t is
+   implementation-defined.  */
+#define __DOUBLE_TYPE double
+#define __FLOAT_TYPE float
 #endif
 
 #if defined (__aarch64__)
@@ -102,6 +109,13 @@
 #ifdef __ARM_FP
 # define _SUPPORTS_ERREXCEPT
 #endif
+/* As per ISO/IEC TS 18661 '__FLT_EVAL_METHOD__' will be defined to 16
+   (if compiling with +fp16 support) so it can't be used by math.h to
+   define float_t and double_t.  For values of '__FLT_EVAL_METHOD__'
+   other than 0, 1, 2 the definition of float_t and double_t is
+   implementation-defined.  */
+#define __DOUBLE_TYPE double
+#define __FLOAT_TYPE float
 #endif
 
 #ifdef __epiphany__
diff --git a/newlib/libc/include/math.h b/newlib/libc/include/math.h
index 799ac494a..54e30ef82 100644
--- a/newlib/libc/include/math.h
+++ b/newlib/libc/include/math.h
@@ -168,6 +168,15 @@ extern int isnan (double);
    #else
     /* Implementation-defined.  Assume float_t and double_t have been
      * defined previously for this configuration (e.g. config.h). */
+
+   /* If __DOUBLE_TYPE is defined (__FLOAT_TYPE is then supposed to be
+      defined as well) float_t and double_t definition is suggested by
+      an arch specific header.  */
+   #ifdef __DOUBLE_TYPE
+    typedef __DOUBLE_TYPE double_t;
+    typedef __FLOAT_TYPE float_t;
+   #endif
+   /* Assume config.h has provided these types.  */
   #endif
 #else
     /* Assume basic definitions.  */