hg: jdk7/hotspot-comp/hotspot: 6778657: Casts in SharedRuntime::f2i, f2l, d2i and d2l rely on undefined C++ behaviour

[Florian Weimer]

* vladimir kozlov:

> 6778657: Casts in SharedRuntime::f2i, f2l, d2i and d2l rely on undefined C++ behaviour
> Summary: Replaces SharedRuntime::f2i et al with versions that should work

This:

 JRT_LEAF(jlong, SharedRuntime::f2l(jfloat x))
- if (g_isnan(x)) {return 0;}
- jlong lltmp = (jlong)x;
- if (lltmp != min_jlong) {
- return lltmp;
- } else {
- if (x < 0) {
- return min_jlong;
- } else {
- return max_jlong;
- }
- }
+ if (g_isnan(x))
+ return 0;
+ if (x >= (jfloat) max_jlong)
+ return max_jlong;
+ if (x <= (jfloat) min_jlong)
+ return min_jlong;
+ return (jlong) x;
 JRT_END

doesn't look right because

  (jfloat) max_jlong   and   (jfloat) min_jlong

are not fully specified, either (they can be off by one, and so the
comparison could be false even if the subsequent cast is undefined).