Use STRFMON_LDBL_IS_DBL instead of __ldbl_is_dbl.

On platforms where long double used to have the same format as double,
but later switched to a different format (alpha, s390, sparc, and
powerpc), accessing the older behavior is possible and it happens via
__nldbl_* functions (not on the API, but accessible from header
redirection and from compat symbols).  These functions write to the
global flag __ldbl_is_dbl, which tells other functions that long double
variables should be handled as double.  This patch takes the first step
towards removing this global flag and creates __vstrfmon_l_internal,
which takes an explicit flags parameter.

This change arguably makes the generated code slightly worse on
architectures where __ldbl_is_dbl is never true; right now, on those
architectures, it's a compile-time constant; after this change, the
compiler could theoretically prove that __vstrfmon_l_internal was
never called with a nonzero flags argument, but it would probably need
LTO to do it.  This is not performance critical code and I tend to
think that the maintainability benefits of removing action at a
distance are worth it.  However, we _could_ wrap the runtime flag
check with a macro that was defined to ignore its argument and always
return false on architectures where __ldbl_is_dbl is never true, if
people think the codegen benefits are important.

Tested for powerpc and powerpc64le.

1 files changed, 2 insertions, 1 deletions

diff --git a/stdlib/strfmon.c b/stdlib/strfmon.c
index 01980d3e15..3058b3eed1 100644
--- a/stdlib/strfmon.c
+++ b/stdlib/strfmon.c
@@ -30,7 +30,8 @@ __strfmon (char *s, size_t maxsize, const char *format, ...)
 
   va_start (ap, format);
 
-  ssize_t res = __vstrfmon_l (s, maxsize, _NL_CURRENT_LOCALE, format, ap);
+  ssize_t res = __vstrfmon_l_internal (s, maxsize, _NL_CURRENT_LOCALE,
+				       format, ap, 0);
 
   va_end (ap);