[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
diff --git a/compiler-rt/lib/builtins/fp_extend_impl.inc b/compiler-rt/lib/builtins/fp_extend_impl.inc
index f6953ff..edcfa8d 100644
--- a/compiler-rt/lib/builtins/fp_extend_impl.inc
+++ b/compiler-rt/lib/builtins/fp_extend_impl.inc
@@ -66,7 +66,9 @@
const src_rep_t sign = aRep & srcSignMask;
dst_rep_t absResult;
- if (aAbs - srcMinNormal < srcInfinity - srcMinNormal) {
+ // If sizeof(src_rep_t) < sizeof(int), the subtraction result is promoted
+ // to (signed) int. To avoid that, explicitly cast to src_rep_t.
+ if ((src_rep_t)(aAbs - srcMinNormal) < srcInfinity - srcMinNormal) {
// a is a normal number.
// Extend to the destination type by shifting the significand and
// exponent into the proper position and rebiasing the exponent.