Re: [PATCH v3] newlib: add dummy implementations of fe{get, set}prec for Aarch64 Cygwin

Corinna Vinschen <[email protected]> Mon, 7 Jul 2025 10:20:49 +0200
Newsgroups	gmane.comp.lib.newlib
Message-ID	<[email protected]>
On Jul  4 15:49, Radek Barton wrote:
> Hello.
> 
> Sending a new version of the patch that combines both suggestions.

LGTM, Richard?

Thanks,
Corinna


> 
> Radek
> 
> ---
> >From 87aebf36fca923569554b7d95adb4eb5d6c7d8c6 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?Radek=20Barto=C5=88?= <[email protected]>
> Date: Thu, 3 Jul 2025 12:02:03 +0200
> Subject: [PATCH v3] newlib: add dummy implementations of fe{get,set}prec
>  for Aarch64 Cygwin
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
> 
> This patch introduces dummy implementation of fegetprec and fsetprec for Cygwin
> build as those symbols are being exported by cygwin1.dll and AArch64 do not support
> changing floating point precision at runtime.
> 
> Signed-off-by: Radek Bartoň <[email protected]>
> ---
>  newlib/Makefile.in                       | 40 ++++++++++++++++++++++++
>  newlib/libc/machine/aarch64/sys/fenv.h   | 15 +++++++++
>  newlib/libm/machine/aarch64/Makefile.inc |  2 ++
>  newlib/libm/machine/aarch64/fegetprec.c  | 17 ++++++++++
>  newlib/libm/machine/aarch64/fesetprec.c  | 22 +++++++++++++
>  5 files changed, 96 insertions(+)
>  create mode 100644 newlib/libm/machine/aarch64/fegetprec.c
>  create mode 100644 newlib/libm/machine/aarch64/fesetprec.c
> 
> diff --git a/newlib/Makefile.in b/newlib/Makefile.in
> index 5a1987bdd..f1b2252ad 100644
> --- a/newlib/Makefile.in
> +++ b/newlib/Makefile.in
> @@ -3251,11 +3251,13 @@ am__objects_159 = libm/fenv/libm_a-feclearexcept.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-feclearexcept.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fegetenv.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fegetexceptflag.$(OBJEXT) \
> +@HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fegetprec.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fegetround.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-feholdexcept.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-feraiseexcept.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fesetenv.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fesetexceptflag.$(OBJEXT) \
> +@HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fesetprec.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fesetround.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-fetestexcept.$(OBJEXT) \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/libm_a-feupdateenv.$(OBJEXT)
> @@ -5086,11 +5088,13 @@ libm_test_test_LDADD = $(CRT0) libm.a libc.a
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/feclearexcept.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fegetenv.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fegetexceptflag.c \
> +@HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fegetprec.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fegetround.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/feholdexcept.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/feraiseexcept.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fesetenv.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fesetexceptflag.c \
> +@HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fesetprec.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fesetround.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/fetestexcept.c \
>  @HAVE_LIBM_MACHINE_AARCH64_TRUE@	libm/machine/aarch64/feupdateenv.c
> @@ -11081,6 +11085,9 @@ libm/machine/aarch64/libm_a-fegetenv.$(OBJEXT):  \
>  libm/machine/aarch64/libm_a-fegetexceptflag.$(OBJEXT):  \
>  	libm/machine/aarch64/$(am__dirstamp) \
>  	libm/machine/aarch64/$(DEPDIR)/$(am__dirstamp)
> +libm/machine/aarch64/libm_a-fegetprec.$(OBJEXT):  \
> +	libm/machine/aarch64/$(am__dirstamp) \
> +	libm/machine/aarch64/$(DEPDIR)/$(am__dirstamp)
>  libm/machine/aarch64/libm_a-fegetround.$(OBJEXT):  \
>  	libm/machine/aarch64/$(am__dirstamp) \
>  	libm/machine/aarch64/$(DEPDIR)/$(am__dirstamp)
> @@ -11096,6 +11103,9 @@ libm/machine/aarch64/libm_a-fesetenv.$(OBJEXT):  \
>  libm/machine/aarch64/libm_a-fesetexceptflag.$(OBJEXT):  \
>  	libm/machine/aarch64/$(am__dirstamp) \
>  	libm/machine/aarch64/$(DEPDIR)/$(am__dirstamp)
> +libm/machine/aarch64/libm_a-fesetprec.$(OBJEXT):  \
> +	libm/machine/aarch64/$(am__dirstamp) \
> +	libm/machine/aarch64/$(DEPDIR)/$(am__dirstamp)
>  libm/machine/aarch64/libm_a-fesetround.$(OBJEXT):  \
>  	libm/machine/aarch64/$(am__dirstamp) \
>  	libm/machine/aarch64/$(DEPDIR)/$(am__dirstamp)
> @@ -14544,12 +14554,14 @@ distclean-compile:
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-feclearexcept.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fegetenv.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fegetexceptflag.Po@am__quote@
> +@AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fegetprec.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fegetround.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-feholdexcept.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fenv.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-feraiseexcept.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fesetenv.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fesetexceptflag.Po@am__quote@
> +@AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fesetprec.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fesetround.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-fetestexcept.Po@am__quote@
>  @AMDEP_TRUE@@am__include@ @am__quote@libm/machine/aarch64/$(DEPDIR)/libm_a-feupdateenv.Po@am__quote@
> @@ -44362,6 +44374,20 @@ libm/machine/aarch64/libm_a-fegetexceptflag.obj: libm/machine/aarch64/fegetexcep
>  @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
>  @am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -c -o libm/machine/aarch64/libm_a-fegetexceptflag.obj `if test -f 'libm/machine/aarch64/fegetexceptflag.c'; then $(CYGPATH_W) 'libm/machine/aarch64/fegetexceptflag.c'; else $(CYGPATH_W) '$(srcdir)/libm/machine/aarch64/fegetexceptflag.c'; fi`
>  
> +libm/machine/aarch64/libm_a-fegetprec.o: libm/machine/aarch64/fegetprec.c
> +@am__fastdepCC_TRUE@	$(AM_V_CC)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -MT libm/machine/aarch64/libm_a-fegetprec.o -MD -MP -MF libm/machine/aarch64/$(DEPDIR)/libm_a-fegetprec.Tpo -c -o libm/machine/aarch64/libm_a-fegetprec.o `test -f 'libm/machine/aarch64/fegetprec.c' || echo '$(srcdir)/'`libm/machine/aarch64/fegetprec.c
> +@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) libm/machine/aarch64/$(DEPDIR)/libm_a-fegetprec.Tpo libm/machine/aarch64/$(DEPDIR)/libm_a-fegetprec.Po
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='libm/machine/aarch64/fegetprec.c' object='libm/machine/aarch64/libm_a-fegetprec.o' libtool=no @AMDEPBACKSLASH@
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
> +@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -c -o libm/machine/aarch64/libm_a-fegetprec.o `test -f 'libm/machine/aarch64/fegetprec.c' || echo '$(srcdir)/'`libm/machine/aarch64/fegetprec.c
> +
> +libm/machine/aarch64/libm_a-fegetprec.obj: libm/machine/aarch64/fegetprec.c
> +@am__fastdepCC_TRUE@	$(AM_V_CC)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -MT libm/machine/aarch64/libm_a-fegetprec.obj -MD -MP -MF libm/machine/aarch64/$(DEPDIR)/libm_a-fegetprec.Tpo -c -o libm/machine/aarch64/libm_a-fegetprec.obj `if test -f 'libm/machine/aarch64/fegetprec.c'; then $(CYGPATH_W) 'libm/machine/aarch64/fegetprec.c'; else $(CYGPATH_W) '$(srcdir)/libm/machine/aarch64/fegetprec.c'; fi`
> +@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) libm/machine/aarch64/$(DEPDIR)/libm_a-fegetprec.Tpo libm/machine/aarch64/$(DEPDIR)/libm_a-fegetprec.Po
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='libm/machine/aarch64/fegetprec.c' object='libm/machine/aarch64/libm_a-fegetprec.obj' libtool=no @AMDEPBACKSLASH@
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
> +@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -c -o libm/machine/aarch64/libm_a-fegetprec.obj `if test -f 'libm/machine/aarch64/fegetprec.c'; then $(CYGPATH_W) 'libm/machine/aarch64/fegetprec.c'; else $(CYGPATH_W) '$(srcdir)/libm/machine/aarch64/fegetprec.c'; fi`
> +
>  libm/machine/aarch64/libm_a-fegetround.o: libm/machine/aarch64/fegetround.c
>  @am__fastdepCC_TRUE@	$(AM_V_CC)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -MT libm/machine/aarch64/libm_a-fegetround.o -MD -MP -MF libm/machine/aarch64/$(DEPDIR)/libm_a-fegetround.Tpo -c -o libm/machine/aarch64/libm_a-fegetround.o `test -f 'libm/machine/aarch64/fegetround.c' || echo '$(srcdir)/'`libm/machine/aarch64/fegetround.c
>  @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) libm/machine/aarch64/$(DEPDIR)/libm_a-fegetround.Tpo libm/machine/aarch64/$(DEPDIR)/libm_a-fegetround.Po
> @@ -44432,6 +44458,20 @@ libm/machine/aarch64/libm_a-fesetexceptflag.obj: libm/machine/aarch64/fesetexcep
>  @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
>  @am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -c -o libm/machine/aarch64/libm_a-fesetexceptflag.obj `if test -f 'libm/machine/aarch64/fesetexceptflag.c'; then $(CYGPATH_W) 'libm/machine/aarch64/fesetexceptflag.c'; else $(CYGPATH_W) '$(srcdir)/libm/machine/aarch64/fesetexceptflag.c'; fi`
>  
> +libm/machine/aarch64/libm_a-fesetprec.o: libm/machine/aarch64/fesetprec.c
> +@am__fastdepCC_TRUE@	$(AM_V_CC)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -MT libm/machine/aarch64/libm_a-fesetprec.o -MD -MP -MF libm/machine/aarch64/$(DEPDIR)/libm_a-fesetprec.Tpo -c -o libm/machine/aarch64/libm_a-fesetprec.o `test -f 'libm/machine/aarch64/fesetprec.c' || echo '$(srcdir)/'`libm/machine/aarch64/fesetprec.c
> +@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) libm/machine/aarch64/$(DEPDIR)/libm_a-fesetprec.Tpo libm/machine/aarch64/$(DEPDIR)/libm_a-fesetprec.Po
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='libm/machine/aarch64/fesetprec.c' object='libm/machine/aarch64/libm_a-fesetprec.o' libtool=no @AMDEPBACKSLASH@
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
> +@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -c -o libm/machine/aarch64/libm_a-fesetprec.o `test -f 'libm/machine/aarch64/fesetprec.c' || echo '$(srcdir)/'`libm/machine/aarch64/fesetprec.c
> +
> +libm/machine/aarch64/libm_a-fesetprec.obj: libm/machine/aarch64/fesetprec.c
> +@am__fastdepCC_TRUE@	$(AM_V_CC)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -MT libm/machine/aarch64/libm_a-fesetprec.obj -MD -MP -MF libm/machine/aarch64/$(DEPDIR)/libm_a-fesetprec.Tpo -c -o libm/machine/aarch64/libm_a-fesetprec.obj `if test -f 'libm/machine/aarch64/fesetprec.c'; then $(CYGPATH_W) 'libm/machine/aarch64/fesetprec.c'; else $(CYGPATH_W) '$(srcdir)/libm/machine/aarch64/fesetprec.c'; fi`
> +@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) libm/machine/aarch64/$(DEPDIR)/libm_a-fesetprec.Tpo libm/machine/aarch64/$(DEPDIR)/libm_a-fesetprec.Po
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='libm/machine/aarch64/fesetprec.c' object='libm/machine/aarch64/libm_a-fesetprec.obj' libtool=no @AMDEPBACKSLASH@
> +@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
> +@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -c -o libm/machine/aarch64/libm_a-fesetprec.obj `if test -f 'libm/machine/aarch64/fesetprec.c'; then $(CYGPATH_W) 'libm/machine/aarch64/fesetprec.c'; else $(CYGPATH_W) '$(srcdir)/libm/machine/aarch64/fesetprec.c'; fi`
> +
>  libm/machine/aarch64/libm_a-fesetround.o: libm/machine/aarch64/fesetround.c
>  @am__fastdepCC_TRUE@	$(AM_V_CC)$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libm_a_CPPFLAGS) $(CPPFLAGS) $(libm_a_CFLAGS) $(CFLAGS) -MT libm/machine/aarch64/libm_a-fesetround.o -MD -MP -MF libm/machine/aarch64/$(DEPDIR)/libm_a-fesetround.Tpo -c -o libm/machine/aarch64/libm_a-fesetround.o `test -f 'libm/machine/aarch64/fesetround.c' || echo '$(srcdir)/'`libm/machine/aarch64/fesetround.c
>  @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) libm/machine/aarch64/$(DEPDIR)/libm_a-fesetround.Tpo libm/machine/aarch64/$(DEPDIR)/libm_a-fesetround.Po
> diff --git a/newlib/libc/machine/aarch64/sys/fenv.h b/newlib/libc/machine/aarch64/sys/fenv.h
> index 1f97791a7..369cc4850 100644
> --- a/newlib/libc/machine/aarch64/sys/fenv.h
> +++ b/newlib/libc/machine/aarch64/sys/fenv.h
> @@ -123,6 +123,21 @@ fegetexcept(void)
>  
>  #endif /* __BSD_VISIBLE */
>  
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#ifdef __CYGWIN__
> +
> +#if __MISC_VISIBLE
> +int fegetprec (void);
> +int fesetprec (int __prec);
> +#endif
> +
> +#endif /* __CYGWIN__ */
>  
> +#ifdef __cplusplus
> +}
> +#endif
>  
>  #endif	/* !_FENV_H_ */
> diff --git a/newlib/libm/machine/aarch64/Makefile.inc b/newlib/libm/machine/aarch64/Makefile.inc
> index 478aaeed8..0064363e7 100644
> --- a/newlib/libm/machine/aarch64/Makefile.inc
> +++ b/newlib/libm/machine/aarch64/Makefile.inc
> @@ -33,11 +33,13 @@
>  	%D%/feclearexcept.c \
>  	%D%/fegetenv.c \
>  	%D%/fegetexceptflag.c \
> +	%D%/fegetprec.c \
>  	%D%/fegetround.c \
>  	%D%/feholdexcept.c \
>  	%D%/feraiseexcept.c \
>  	%D%/fesetenv.c \
>  	%D%/fesetexceptflag.c \
> +	%D%/fesetprec.c \
>  	%D%/fesetround.c \
>  	%D%/fetestexcept.c \
>  	%D%/feupdateenv.c
> diff --git a/newlib/libm/machine/aarch64/fegetprec.c b/newlib/libm/machine/aarch64/fegetprec.c
> new file mode 100644
> index 000000000..82e08fb96
> --- /dev/null
> +++ b/newlib/libm/machine/aarch64/fegetprec.c
> @@ -0,0 +1,17 @@
> +#if defined(__CYGWIN__)
> +
> +/* Returns the currently selected precision, represented by one of the
> +   values of the defined precision macros. */
> +int
> +fegetprec (void)
> +{
> +  /* AArch64 doesn't have configurable precision.
> +     Return a fixed value indicating double precision (most common). */
> +  return -1;
> +}
> +
> +#else
> +
> +#include "../../fenv/fenv_stub.c"
> +
> +#endif
> diff --git a/newlib/libm/machine/aarch64/fesetprec.c b/newlib/libm/machine/aarch64/fesetprec.c
> new file mode 100644
> index 000000000..dd507001c
> --- /dev/null
> +++ b/newlib/libm/machine/aarch64/fesetprec.c
> @@ -0,0 +1,22 @@
> +#if defined(__CYGWIN__)
> +
> +/* http://www.open-std.org/jtc1/sc22//WG14/www/docs/n752.htm:
> +
> +   The fesetprec function establishes the precision represented by its
> +   argument prec.  If the argument does not match a precision macro, the
> +   precision is not changed.
> +
> +   The fesetprec function returns a nonzero value if and only if the
> +   argument matches a precision macro (that is, if and only if the requested
> +   precision can be established). */
> +int
> +fesetprec (int prec)
> +{
> +  /* Aarch64 doesn't support changing precision at runtime. */
> +  return 0; // return failure
> +}
> +#else
> +
> +#include "../../fenv/fenv_stub.c"
> +
> +#endif
> -- 
> 2.49.0.vfs.0.4