[Builtins] Implement half-precision conversions.

Mostly uninteresting, except:
- in __extendXfYf2, when checking if the number is normal, the old
  code relied on the unsignedness of src_rep_t, which is a problem
  when sizeof(src_rep_t) < sizeof(int): the result gets promoted to
  int, the signedness of which breaks the comparison.
  I added an explicit cast; it shouldn't affect other types.
- we can't pass __fp16, so src_t and src_rep_t are the same.
- the gnu_*_ieee symbols are simply duplicated definitions, as aliases
  are problematic on mach-o (where only weak aliases are supported;
  that's not what we want).

Differential Revision: http://reviews.llvm.org/D9693

llvm-svn: 237161

1 files changed, 111 insertions, 0 deletions

diff --git a/compiler-rt/test/builtins/Unit/truncdfhf2_test.c b/compiler-rt/test/builtins/Unit/truncdfhf2_test.c
new file mode 100644
index 00000000000..98c5c9dac2e
--- /dev/null
+++ b/compiler-rt/test/builtins/Unit/truncdfhf2_test.c
@@ -0,0 +1,111 @@
+//===--------------- truncdfhf2_test.c - Test __truncdfhf2 ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file tests __truncdfhf2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h>
+
+#include "fp_test.h"
+
+uint16_t __truncdfhf2(double a);
+
+int test__truncdfhf2(double a, uint16_t expected)
+{
+    uint16_t x = __truncdfhf2(a);
+    int ret = compareResultH(x, expected);
+
+    if (ret){
+        printf("error in test__truncdfhf2(%f) = %#.4x, "
+               "expected %#.4x\n", a, x, fromRep16(expected));
+    }
+    return ret;
+}
+
+char assumption_1[sizeof(__fp16) * CHAR_BIT == 16] = {0};
+
+int main()
+{
+    // qNaN
+    if (test__truncdfhf2(makeQNaN64(),
+                         UINT16_C(0x7e00)))
+        return 1;
+    // NaN
+    if (test__truncdfhf2(makeNaN64(UINT64_C(0x8000)),
+                         UINT16_C(0x7e00)))
+        return 1;
+    // inf
+    if (test__truncdfhf2(makeInf64(),
+                         UINT16_C(0x7c00)))
+        return 1;
+    if (test__truncdfhf2(-makeInf64(),
+                         UINT16_C(0xfc00)))
+        return 1;
+    // zero
+    if (test__truncdfhf2(0.0, UINT16_C(0x0)))
+        return 1;
+    if (test__truncdfhf2(-0.0, UINT16_C(0x8000)))
+        return 1;
+
+    if (test__truncdfhf2(3.1415926535,
+                         UINT16_C(0x4248)))
+        return 1;
+    if (test__truncdfhf2(-3.1415926535,
+                         UINT16_C(0xc248)))
+        return 1;
+    if (test__truncdfhf2(0x1.987124876876324p+1000,
+                         UINT16_C(0x7c00)))
+        return 1;
+    if (test__truncdfhf2(0x1.987124876876324p+12,
+                         UINT16_C(0x6e62)))
+        return 1;
+    if (test__truncdfhf2(0x1.0p+0,
+                         UINT16_C(0x3c00)))
+        return 1;
+    if (test__truncdfhf2(0x1.0p-14,
+                         UINT16_C(0x0400)))
+        return 1;
+    // denormal
+    if (test__truncdfhf2(0x1.0p-20,
+                         UINT16_C(0x0010)))
+        return 1;
+    if (test__truncdfhf2(0x1.0p-24,
+                         UINT16_C(0x0001)))
+        return 1;
+    if (test__truncdfhf2(-0x1.0p-24,
+                         UINT16_C(0x8001)))
+        return 1;
+    if (test__truncdfhf2(0x1.5p-25,
+                         UINT16_C(0x0001)))
+        return 1;
+    // and back to zero
+    if (test__truncdfhf2(0x1.0p-25,
+                         UINT16_C(0x0000)))
+        return 1;
+    if (test__truncdfhf2(-0x1.0p-25,
+                         UINT16_C(0x8000)))
+        return 1;
+    // max (precise)
+    if (test__truncdfhf2(65504.0,
+                         UINT16_C(0x7bff)))
+        return 1;
+    // max (rounded)
+    if (test__truncdfhf2(65519.0,
+                         UINT16_C(0x7bff)))
+        return 1;
+    // max (to +inf)
+    if (test__truncdfhf2(65520.0,
+                         UINT16_C(0x7c00)))
+        return 1;
+    if (test__truncdfhf2(-65520.0,
+                         UINT16_C(0xfc00)))
+        return 1;
+    return 0;
+}