RFR: 8266746: C1: Replace UnsafeGetRaw with UnsafeGetObject when setting up OSR entry block [v4]

[Martin Doerr]

On Tue, 29 Jun 2021 06:21:33 GMT, Yi Yang <yyang at openjdk.org> wrote:

>> After JDK-8150921, most Unsafe{Get,Put}Raw intrinsic methods can be replaced by Unsafe{Get,Put}Object.
>> 
>> There is the only one occurrence where c1 refers UnsafeGetRaw among GraphBuilder::setup_osr_entry_block()
>> 
>> https://github.com/openjdk/jdk/blob/74fecc070a6462e6a2d061525b53a63de15339f9/src/hotspot/share/c1/c1_GraphBuilder.cpp#L3143-L3157
>> 
>> We can replace UnsafeGetRaw with UnsafeGetObject when setting up OSR entry block. After that, Unsafe{Get,Put}Raw can be completely removed  because no one refers to them.
>> 
>> (This patch actually does two things:
>> 1. `Replace UnsafeGetRaw with UnsafeGetObject when setting up OSR entry block` This is the only occurrence where c1 refers UnsafeGetRaw
>> 2. `Cleanup unused Unsafe{Get,Put}Raw code`
>> They are related so I put it together, but I still want to hear your suggestions, I will separate them into two patches if you think it is more reasonable)
>> 
>> Thanks!
>> Yang
>
> Yi Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove unaligned assert

Thanks for taking care of PPC64. I haven't seen errors with this version. But I have some remarks:

- I think the name UnsafeGetObject is confusing, now. It's no longer used for objects only.
- The "unaligned" parameter is unused on all platforms, now. Note that PPC64 and s390 support unaligned accesses, too. I believe it was used by SPARC which has been removed.

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Marked as reviewed by mdoerr (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3917