RFR: 8256655: rework long counted loop handling [v2]

[Tobias Hartmann]

On Fri, 20 Nov 2020 11:57:13 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> This fails to build on Windows:
>> `
>> [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2065: 'ulong': undeclared identifier
>> [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2146: syntax error: missing ')' before identifier 'iters_limit'
>> [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2146: syntax error: missing ';' before identifier 'iters_limit'
>> [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2065: 'ulong': undeclared identifier
>> [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2059: syntax error: ')'`
>
>> This fails to build on Windows:
>> ` [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2065: 'ulong': undeclared identifier [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2146: syntax error: missing ')' before identifier 'iters_limit' [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2146: syntax error: missing ';' before identifier 'iters_limit' [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2065: 'ulong': undeclared identifier [2020-11-20T08:11:03,704Z] ./open/src/hotspot/share/opto/loopnode.cpp(821): error C2059: syntax error: ')'`
> 
> Build issues should be fixed now.

Did some quick sanity testing and `compiler/regalloc/TestC1OverlappingRegisterHint` fails with `assert(init_n->get_int() + cl->stride_con() >= cl->limit()->get_int()) failed: should be one iteration`.

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PR: https://git.openjdk.java.net/jdk/pull/1316