compiler, runtime: Fix complex division of NaN / 0.

From-SVN: r203331

1 files changed, 46 insertions, 0 deletions

diff --git a/libgo/runtime/go-cdiv.c b/libgo/runtime/go-cdiv.c
new file mode 100644
index 0000000..0a81e45
--- /dev/null
+++ b/libgo/runtime/go-cdiv.c
@@ -0,0 +1,46 @@
+/* go-cdiv.c -- complex division routines
+
+   Copyright 2013 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.  */
+
+/* Calls to these functions are generated by the Go frontend for
+   division of complex64 or complex128.  We use these because Go's
+   complex division expects slightly different results from the GCC
+   default.  When dividing NaN+1.0i / 0+0i, Go expects NaN+NaNi but
+   GCC generates NaN+Infi.  NaN+Infi seems wrong seems the rules of
+   C99 Annex G specify that if either side of a complex number is Inf,
+   the the whole number is Inf, but an operation involving NaN ought
+   to result in NaN, not Inf.  */
+
+__complex float
+__go_complex64_div (__complex float a, __complex float b)
+{
+  if (__builtin_expect (b == 0+0i, 0))
+    {
+      if (!__builtin_isinff (__real__ a)
+	  && !__builtin_isinff (__imag__ a)
+	  && (__builtin_isnanf (__real__ a) || __builtin_isnanf (__imag__ a)))
+	{
+	  /* Pass "1" to nanf to match math/bits.go.  */
+	  return __builtin_nanf("1") + __builtin_nanf("1")*1i;
+	}
+    }
+  return a / b;
+}
+
+__complex double
+__go_complex128_div (__complex double a, __complex double b)
+{
+  if (__builtin_expect (b == 0+0i, 0))
+    {
+      if (!__builtin_isinf (__real__ a)
+	  && !__builtin_isinf (__imag__ a)
+	  && (__builtin_isnan (__real__ a) || __builtin_isnan (__imag__ a)))
+	{
+	  /* Pass "1" to nan to match math/bits.go.  */
+	  return __builtin_nan("1") + __builtin_nan("1")*1i;
+	}
+    }
+  return a / b;
+}