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authorBen Cheng <bccheng@google.com>2014-03-26 05:37:19 (GMT)
committerBen Cheng <bccheng@google.com>2014-03-26 05:37:19 (GMT)
commit1bc5aee63eb72b341f506ad058502cd0361f0d10 (patch)
treec607e8252f3405424ff15bc2d00aa38dadbb2518 /gcc-4.9/gcc/testsuite/gcc.target/spu/dfcgt-nan.c
parent283a0bf58fcf333c58a2a92c3ebbc41fb9eb1fdb (diff)
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Initial checkin of GCC 4.9.0 from trunk (r208799).
Change-Id: I48a3c08bb98542aa215912a75f03c0890e497dba
Diffstat (limited to 'gcc-4.9/gcc/testsuite/gcc.target/spu/dfcgt-nan.c')
-rw-r--r--gcc-4.9/gcc/testsuite/gcc.target/spu/dfcgt-nan.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/gcc-4.9/gcc/testsuite/gcc.target/spu/dfcgt-nan.c b/gcc-4.9/gcc/testsuite/gcc.target/spu/dfcgt-nan.c
new file mode 100644
index 0000000..18ce013
--- /dev/null
+++ b/gcc-4.9/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);
+}