runtime: Add matherr function when appropriate.

From-SVN: r184024

1 files changed, 88 insertions, 0 deletions

diff --git a/libgo/runtime/go-matherr.c b/libgo/runtime/go-matherr.c
new file mode 100644
index 0000000..786f316
--- /dev/null
+++ b/libgo/runtime/go-matherr.c
@@ -0,0 +1,88 @@
+/* go-matherr.c -- a Go version of the matherr function.
+
+   Copyright 2012 The Go Authors. All rights reserved.
+   Use of this source code is governed by a BSD-style
+   license that can be found in the LICENSE file.  */
+
+/* The gccgo version of the math library calls libc functions.  On
+   some systems, such as Solaris, those functions will call matherr on
+   exceptional conditions.  This is a version of matherr appropriate
+   for Go, one which returns the values that the Go math library
+   expects.  This is fine for pure Go programs.  For mixed Go and C
+   programs this will be problematic if the C programs themselves use
+   matherr.  Normally the C version of matherr will override this, and
+   the Go code will just have to cope.  If this turns out to be too
+   problematic we can change to run pure Go code in the math library
+   on systems that use matherr.  */
+
+#include <math.h>
+#include <stdint.h>
+
+#include "config.h"
+
+#if defined(HAVE_MATHERR) && defined(HAVE_STRUCT_EXCEPTION)
+
+#define PI 3.14159265358979323846264338327950288419716939937510582097494459
+
+int
+matherr (struct exception* e)
+{
+  const char *n;
+
+  if (e->type != DOMAIN)
+    return 0;
+
+  n = e->name;
+  if (__builtin_strcmp (n, "acos") == 0
+      || __builtin_strcmp (n, "asin") == 0)
+    e->retval = NAN;
+  else if (__builtin_strcmp (n, "atan2") == 0)
+    {
+      if (e->arg1 == 0 && e->arg2 == 0)
+	{
+	  double nz;
+
+	  nz = -0.0;
+	  if (__builtin_memcmp (&e->arg2, &nz, sizeof (double)) != 0)
+	    e->retval = e->arg1;
+	  else
+	    e->retval = copysign (PI, e->arg1);
+	}
+      else
+	return 0;
+    }
+  else if (__builtin_strcmp (n, "log") == 0
+	   || __builtin_strcmp (n, "log10") == 0)
+    e->retval = NAN;
+  else if (__builtin_strcmp (n, "pow") == 0)
+    {
+      if (e->arg1 < 0)
+	e->retval = NAN;
+      else if (e->arg1 == 0 && e->arg2 == 0)
+	e->retval = 1.0;
+      else if (e->arg1 == 0 && e->arg2 < 0)
+	{
+	  double i;
+
+	  if (modf (e->arg2, &i) == 0 && ((int64_t) i & 1) == 1)
+	    e->retval = copysign (INFINITY, e->arg1);
+	  else
+	    e->retval = INFINITY;
+	}
+      else
+	return 0;
+    }
+  else if (__builtin_strcmp (n, "sqrt") == 0)
+    {
+      if (e->arg1 < 0)
+	e->retval = NAN;
+      else
+	return 0;
+    }
+  else
+    return 0;
+
+  return 1;
+}
+
+#endif