RFR: 8272573: Redundant unique_concrete_method_4 dependencies

[Vladimir Kozlov]

On Tue, 17 Aug 2021 11:45:49 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Equivalence checks in `Dependencies::assert_common_4()` are too strong which leads to `unique_concrete_method_4` dependencies being repeatedly recorded and duplicating nmethod dependencies registered.
> 
> The underlying problem is `note_dep_seen()` mutates internal bitmap, but the nested checks fail fast.
> So, multiple requests are required to populate the bit-map for all the arguments in order to make the detection of duplicate assertions work. And it leads to duplicate dependencies registered.
> 
> It turns out `call_site_target_value` is also affected in a similar manner (see `Dependencies::assert_common_2` for dependencies without explicit context argument), so I fix it along the way.
> 
> Testing: hs-tier1 - hs-tier6

src/hotspot/share/code/dependencies.cpp line 242:

> 240:     }
> 241:   } else {
> 242:     if (note_dep_seen(dept, x0)) {

Why `x0` is special in all these cases?
Should we do `||` instead?

  if (note_dep_seen(dept, x0) || note_dep_seen(dept, x1)) {

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PR: https://git.openjdk.java.net/jdk/pull/5141