[committed] testcase for pr26483, ia64 libffi denorm failure

[James E Wilson <wilson at specifix dot com>]

I have checked in this testcase.  It reproduces the problem reported in
PR26498, which is a case where denorm values get accidentally rounded by
libffi on IA-64.  I have an unfinished patch in the PR, which I will try
to finish this weekend.  I tested this new testcase on ia64-linux
unpatched, ia64-linux patched, x86_64-linux, and x86_64-linux with
-m32.  It failed for the first one, and worked for the other 3, which is
what I would expect.
-- 
Jim Wilson, GNU Tools Support, http://www.specifix.com

2006-04-07  James E Wilson  <wilson@specifix.com>

	* testsuite/libffi.call/float4.c: New testcase.

Index: testsuite/libffi.call/float4.c
===================================================================
--- testsuite/libffi.call/float4.c	(revision 0)
+++ testsuite/libffi.call/float4.c	(revision 0)
@@ -0,0 +1,60 @@
+/* Area:	ffi_call
+   Purpose:	Check denorm double value.
+   Limitations:	none.
+   PR:		PR26483.
+   Originator:	From the original ffitest.c  */
+
+/* { dg-do run } */
+#include "ffitest.h"
+#include "float.h"
+
+typedef union
+{
+  double d;
+  unsigned char c[sizeof (double)];
+} value_type;
+
+#define CANARY 0xba
+
+static double dblit(double d)
+{
+  return d;
+}
+
+int main (void)
+{
+  ffi_cif cif;
+  ffi_type *args[MAX_ARGS];
+  void *values[MAX_ARGS];
+  double d;
+  value_type result[2];
+  unsigned int i;
+
+  args[0] = &ffi_type_double;
+  values[0] = &d;
+  
+  /* Initialize the cif */
+  CHECK(ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1,
+		     &ffi_type_double, args) == FFI_OK);
+  
+  d = DBL_MIN / 2;
+  
+  /* Put a canary in the return array.  This is a regression test for
+     a buffer overrun.  */
+  memset(result[1].c, CANARY, sizeof (double));
+
+  ffi_call(&cif, FFI_FN(dblit), &result[0].d, values);
+  
+  /* The standard delta check doesn't work for denorms.  Since we didn't do
+     any arithmetic, we should get the original result back, and hence an
+     exact check should be OK here.  */
+ 
+  CHECK(result[0].d == dblit(d));
+
+  /* Check the canary.  */
+  for (i = 0; i < sizeof (double); ++i)
+    CHECK(result[1].c[i] == CANARY);
+
+  exit(0);
+
+}