S/390: Do not raise inexact exception in lrint/lround. [BZ #19486]

I get some math test-failures on s390 for float/double/ldouble for
various lrint/lround functions like:
lrint (0x1p64): Exception "Inexact" set
lrint (-0x1p64): Exception "Inexact" set
lround (0x1p64): Exception "Inexact" set
lround (-0x1p64): Exception "Inexact" set
...

GCC emits "convert to fixed" instructions for casting floating point
values to integer values. These instructions raise invalid and inexact
exceptions if the floating point value exceeds the integer type ranges.

This patch enables the various FIX_DBL_LONG_CONVERT_OVERFLOW macros in
order to avoid a cast from floating point to integer type and raise the
invalid exception with feraiseexcept.
The ldbl-128 rint/round functions are now using the same logic.

ChangeLog:

	[BZ #19486]
	* sysdeps/s390/fix-fp-int-convert-overflow.h: New File.
	* sysdeps/generic/fix-fp-int-convert-overflow.h
	(FIX_LDBL_LONG_CONVERT_OVERFLOW,
	FIX_LDBL_LLONG_CONVERT_OVERFLOW): New define.
	* sysdeps/arm/fix-fp-int-convert-overflow.h: Likewise.
	* sysdeps/mips/mips32/fpu/fix-fp-int-convert-overflow.h:
	Likewise.
	* sysdeps/ieee754/ldbl-128/s_lrintl.c (__lrintl):
	Avoid conversions to long int where inexact exceptions
	could be raised.
	* sysdeps/ieee754/ldbl-128/s_lroundl.c (__lroundl):
	Likewise.
	* sysdeps/ieee754/ldbl-128/s_llrintl.c (__llrintl):
	Avoid conversions to long long int where inexact exceptions
	could be raised.
	* sysdeps/ieee754/ldbl-128/s_llroundl.c (__llroundl):
	Likewise.

1 files changed, 9 insertions, 2 deletions

diff --git a/sysdeps/ieee754/ldbl-128/s_lroundl.c b/sysdeps/ieee754/ldbl-128/s_lroundl.c
index 34d226445f..f03262543f 100644
--- a/sysdeps/ieee754/ldbl-128/s_lroundl.c
+++ b/sysdeps/ieee754/ldbl-128/s_lroundl.c
@@ -23,7 +23,7 @@
 #include <math.h>
 
 #include <math_private.h>
-
+#include <fix-fp-int-convert-overflow.h>
 
 long int
 __lroundl (long double x)
@@ -87,7 +87,14 @@ __lroundl (long double x)
 	 FE_INVALID must be raised and the return value is
 	 unspecified.  */
 #ifdef FE_INVALID
-      if (x <= (long double) LONG_MIN - 0.5L)
+      if (FIX_LDBL_LONG_CONVERT_OVERFLOW
+	  && !(sign == -1 && x > (long double) LONG_MIN - 0.5L))
+	{
+	  feraiseexcept (FE_INVALID);
+	  return sign == 1 ? LONG_MAX : LONG_MIN;
+	}
+      else if (!FIX_LDBL_LONG_CONVERT_OVERFLOW
+	       && x <= (long double) LONG_MIN - 0.5L)
 	{
 	  /* If truncation produces LONG_MIN, the cast will not raise
 	     the exception, but may raise "inexact".  */