RFR: 8293937: x86: Drop LP64 conditions from clearly x86_32 code

[Thomas Stuefe]

On Fri, 16 Sep 2022 11:10:29 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Noticed this when porting Loom on x86_32. There are `*_x86_32.cpp` files that use `_LP64` as if it matters for them. It does not make sense, as in those files we always have `!_LP64`. We can drop the conditionals and clean the code. 
> 
> Proof of completeness:
> 
> 
> $ ack LP64 src/hotspot/ | grep _32
> src/hotspot/cpu/x86/register_x86.hpp:386:                          NOT_LP64( 8 + ) // FILL0-FILL7 in x86_32.ad
> src/hotspot/cpu/x86/vm_version_x86.hpp:733:    return LP64_ONLY(true) NOT_LP64(false); // not implemented on x86_32

Marked as reviewed by stuefe (Reviewer).

Looks good. 

I never really thought about how this bifurcation works in x86. So, this is build magic, it just avoids x86_64 files for 32bit builds and vice versa?

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PR: https://git.openjdk.org/jdk/pull/10305