On Fri, 6 Nov 2020 04:25:40 GMT, Dean Long <dl...@openjdk.org> wrote:
>> src/hotspot/share/opto/library_call.cpp line 1015:
>>
>>> 1013: Deoptimization::Action_make_not_entrant);
>>> 1014: }
>>> 1015:
>>
>> A comment here explaining what the code below is doing would be helpful.
>
> This code wasn't here before, so I'm guessing it's needed for T_LONG. For
> T_INT is it just wasted work?
Code in IdealLoopTree::is_range_check_if() uses this check:
if (range->Opcode() != Op_LoadRange && !iff->is_RangeCheck()) {
const TypeInt* tint = phase->_igvn.type(range)->isa_int();
if (tint == NULL || tint->empty() || tint->_lo < 0) {
// Allow predication on positive values that aren't LoadRanges.
// This allows optimization of loops where the length of the
// array is a known value and doesn't need to be loaded back
// from the array.
return false;
that is it assumes that everything that's on the right hand size of the a
RangeCheck test is positive. I think it's cleaner and less dangerous to
explicitly cast the length to >= 0 when the intrinsic is built. In a subsequent
patch I intend to drop the && !iff->is_RangeCheck() check above.
-------------
PR: https://git.openjdk.java.net/jdk/pull/1003
