1 files changed, 31 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.target/spu/dfcgt-nan.c b/gcc/testsuite/gcc.target/spu/dfcgt-nan.c
new file mode 100644
index 000000000..18ce01356
--- /dev/null
+++ b/gcc/testsuite/gcc.target/spu/dfcgt-nan.c
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-options "-march=celledp -O1" } */
+/* { dg-final { scan-assembler "dfceq" } } */
+
+/* GCC previously transformed an "a <= b" test into "! (a > b)" when
+   compiling with -march=celledp, so that the dfcgt instruction can be
+   used to implement the comparison.
+
+   However, this transformation violates the IEEE-754 standard in the
+   presence of NaN values.  If either a or b is a NaN, a <= b should
+   evaluate to false according to IEEE rules.  However, after the
+   transformation, a > b as implemented by dfcgt itself returns false,
+   so the transformed test returns true.
+
+   Note that the equivalent transformation is valid for single-
+   precision floating-point values on the Cell SPU, because the format
+   does not have NaNs.  It is invalid for double-precision, even on
+   Cell, however.  */
+
+int test (double a, double b) __attribute__ ((noinline));
+int test (double a, double b)
+{
+  return a <= b;
+}
+
+int main (void)
+{
+  double x = 0.0;
+  double y = 0.0/0.0;
+  return test (x, y);
+}