I'm back woking on JDK-8351409, and to make progress with the IR tests, I have patched my work with the fix for JDK-8373134 that I've sent a PR for.

I've now tried to expand the reassocation logic and IR test from MaxL to also include MinL, and the IR test fails with:

```
Missed Identity optimization:
Old node:
dist dump
---------------------------------------------
   1 1048 MaxL === _ 124 336 [[ 124 812 374 348 ]] !orig=[300] !jvms: ReductionReassociation::test_2 @ bci:149 (line 38)
   1 336 MinL === _ 324 1000 [[ 348 1048 ]] !orig=[1047] !jvms: Long::min @ bci:2 (line 1961) ReductionReassociation::test_2 @ bci:120 (line 36)
   0 348 MinL === _ 336 1048 [[ 375 812 ]] !jvms: Long::min @ bci:2 (line 1961) ReductionReassociation::test_2 @ bci:128 (line 37)
New node:
dist dump
---------------------------------------------
   1 1000 LoadL === 998 7 251 [[ 336 ]] @aryptr:long[int:>=0] (java/lang/Cloneable,java/io/Serializable):BotPTR:exact+any,iid=bot, idx=6; #long (does not depend only on test, unknown control) !orig=[253] !jvms: ReductionReassociation::test_2 @ bci:57 (line 31)
   1 324 MinL === _ 312 951 [[ 336 ]] !orig=[1046] !jvms: Long::min @ bci:2 (line 1961) ReductionReassociation::test_2 @ bci:111 (line 35)
   0 336 MinL === _ 324 1000 [[ 348 1048 ]] !orig=[1047] !jvms: Long::min @ bci:2 (line 1961) ReductionReassociation::test_2 @ bci:120 (line 36)
```

The IR test that is failing is this (it assumes reassociation logic is in place):

```
  @Test
  @IR(
      counts = {IRNode.MIN_L, "= 4"},
      phase = CompilePhase.AFTER_LOOP_OPTS)
  public Object[] test_2() {
    long result = Integer.MIN_VALUE;
    long result2 = Integer.MIN_VALUE;
    for (int i = 0; i < input_2.length; i += 4) {
      long v0 = input_2[i + 0];
      long v1 = input_2[i + 1];
      long v2 = input_2[i + 2];
      long v3 = input_2[i + 3];
      long u0 = Long.min(v0, result);
      long u1 = Long.min(v1, u0);
      long u2 = Long.min(v2, u1);
      long u3 = Long.min(v3, u2);
      result = u3;
      long t0 = Long.min(v0, v1);
      long t1 = Long.min(v2, t0);
      long t2 = Long.min(v3, t1);
      long t3 = Long.min(result, t2);
      result2 = t3;
    }
    return new Object[] {result, result2};
  }
```

I will try to create a smaller reproducer, and try to understand if the issue should be covered by JDK-8373134 or is a different one.

I need these optimisations to be processed in order to get commoning to kick in. The reassociation IR tests rely on commoning to make 2 different code shapes equal and get deterministic IR node counts.