RFR: 8274130: C2: MulNode::Ideal chained transformations may act on wrong nodes [v2]

[Aleksey Shipilev]

> I was puzzled by it when fixing JDK-8274060. It looks that new optimizations added by [JDK-8273454](https://bugs.openjdk.java.net/browse/JDK-8273454) and [JDK-8263006](https://bugs.openjdk.java.net/browse/JDK-8263006) rewire `in(1)` and `in(2)` in `MulNode::Ideal`, which means the chained transformations should see them? Yet, both inputs and their `Type`-s are cached locally and not refreshed. I have not seen failures due to this yet, but it looks that the current code is subtly incorrect because of this. 
> 
> I thought about doing `return this` instead of `progress = true`, so that we leave `MulNode::Ideal` once we hit any transform and hope to return back, but I wondered if that would expose us to different graph shapes in-between successive `MulNode::Ideal` calls, which might have other unintended consequences. Therefore, I opted to a more conservative patch.
> 
> Additional testing:
>  - [x] `compiler/` tests
>  - [x] `tier1` tests
>  - [x] 100K Fuzzer tests (one unrelated failure)

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Align the stars manually

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5631/files
  - new: https://git.openjdk.java.net/jdk/pull/5631/files/932f039a..c8d3cb12

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5631&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5631&range=00-01

  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5631.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5631/head:pull/5631

PR: https://git.openjdk.java.net/jdk/pull/5631