PowerPC: Update long double IEEE 128-bit tests.

[Michael Meissner <meissner@linux.ibm.com>]

PowerPC: Update long double IEEE 128-bit tests.

I have split all of these patches into separate patches to hopefully get them
into the tree.

This patch fixes 3 tests in the testsuite that fail if long double is set
to IEEE 128-bit.

I have tested this patch with bootstrap builds on a little endian power9 system
running Linux.  With the other patches, I have built two full bootstrap builds
using this patch and the patches after this patch.  One build used the current
default for long double (IBM extended double) and the other build switched the
default to IEEE 128-bit.  I used the Advance Toolchain AT 14.0 compiler as the
library used by this compiler.  There are no regressions between the tests.
There are 3 fortran benchmarks (ieee/large_2.f90, default_format_2.f90, and
default_format_denormal_2.f90) that now pass.

Can I install this into the trunk?

We have gotten some requests to back port these changes to GCC 10.x.  At the
moment, I am not planning to do the back port, but I may need to in the future.

gcc/testsuite/
2020-10-22  Michael Meissner  <meissner@linux.ibm.com>

	* c-c++-common/dfp/convert-bfp-11.c: If long double is IEEE
	128-bit, skip the test.
	* gcc.dg/nextafter-2.c: On PowerPC, if long double is IEEE
	128-bit, include math.h to get the built-in mapped correctly.
	* gcc.target/powerpc/pr70117.c: Add support for long double being
	IEEE 128-bit.
---
 gcc/testsuite/c-c++-common/dfp/convert-bfp-11.c |  7 +++++++
 gcc/testsuite/gcc.dg/nextafter-2.c              | 10 ++++++++++
 gcc/testsuite/gcc.target/powerpc/pr70117.c      |  6 ++++--
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/c-c++-common/dfp/convert-bfp-11.c b/gcc/testsuite/c-c++-common/dfp/convert-bfp-11.c
index 95c433d2c24..6ee0c1c6ae9 100644
--- a/gcc/testsuite/c-c++-common/dfp/convert-bfp-11.c
+++ b/gcc/testsuite/c-c++-common/dfp/convert-bfp-11.c
@@ -5,6 +5,7 @@
    Don't force 128-bit long doubles because runtime support depends
    on glibc.  */
 
+#include <float.h>
 #include "convert.h"
 
 volatile _Decimal32 sd;
@@ -39,6 +40,12 @@ main ()
   if (sizeof (long double) != 16)
     return 0;
 
+  /* This test is written to test IBM extended double, which is a pair of
+     doubles.  If long double can hold a larger value than a double can, such
+     as when long double is IEEE 128-bit, just exit immediately.  */
+  if (LDBL_MAX_10_EXP > DBL_MAX_10_EXP)
+    return 0;
+
   convert_101 ();
   convert_102 ();
 
diff --git a/gcc/testsuite/gcc.dg/nextafter-2.c b/gcc/testsuite/gcc.dg/nextafter-2.c
index e51ae94be0c..64e9e3c485f 100644
--- a/gcc/testsuite/gcc.dg/nextafter-2.c
+++ b/gcc/testsuite/gcc.dg/nextafter-2.c
@@ -13,4 +13,14 @@
 #  define NO_LONG_DOUBLE 1
 # endif
 #endif
+
+#if defined(_ARCH_PPC) && defined(__LONG_DOUBLE_IEEE128__)
+/* On PowerPC systems, long double uses either the IBM long double format, or
+   IEEE 128-bit format.  The compiler switches the long double built-in
+   function names and glibc switches the names when math.h is included.
+   Because this test is run with -fno-builtin, include math.h so that the
+   appropriate nextafter functions are called.  */
+#include <math.h>
+#endif
+
 #include "nextafter-1.c"
diff --git a/gcc/testsuite/gcc.target/powerpc/pr70117.c b/gcc/testsuite/gcc.target/powerpc/pr70117.c
index 3bbd2c595e0..928efe39c7b 100644
--- a/gcc/testsuite/gcc.target/powerpc/pr70117.c
+++ b/gcc/testsuite/gcc.target/powerpc/pr70117.c
@@ -9,9 +9,11 @@
    128-bit floating point, because the type is not enabled on those
    systems.  */
 #define LDOUBLE __ibm128
+#define IBM128_MAX ((__ibm128) 1.79769313486231580793728971405301199e+308L)
 
 #elif defined(__LONG_DOUBLE_IBM128__)
 #define LDOUBLE long double
+#define IBM128_MAX LDBL_MAX
 
 #else
 #error "long double must be either IBM 128-bit or IEEE 128-bit"
@@ -75,10 +77,10 @@ main (void)
   if (__builtin_isnormal (ld))
     __builtin_abort ();
 
-  ld = LDBL_MAX;
+  ld = IBM128_MAX;
   if (!__builtin_isnormal (ld))
     __builtin_abort ();
-  ld = -LDBL_MAX;
+  ld = -IBM128_MAX;
   if (!__builtin_isnormal (ld))
     __builtin_abort ();
 
-- 
2.22.0


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797