RFR: 8353188: C1: Clean up x86 backend after 32-bit x86 removal [v2]

[Aleksey Shipilev]

On Mon, 31 Mar 2025 21:14:45 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Review comments
>
> src/hotspot/cpu/x86/c1_FrameMap_x86.cpp line 45:
> 
>> 43:     Register reg = r_1->as_Register();
>> 44:     if (r_2->is_Register() && (type == T_LONG || type == T_DOUBLE)) {
>> 45:       Register reg2 = r_2->as_Register();
> 
> FTR `reg2` is unused. (Moreover, `r_2` and `r_2->is_Register()` are redundant on x64.)

Right. Cleaned those up too.

> src/hotspot/cpu/x86/c1_LIRAssembler_x86.cpp line 827:
> 
>> 825:       // compressed klass ptrs: T_METADATA can be a compressed klass
>> 826:       // ptr or a 64 bit method pointer.
>> 827:       ShouldNotReachHere();
> 
> Alternatively, you could drop the whole `T_METADATA` case and defer the handling to default case.

I initially thought leaving the comment there as meaningful, but now I think that comment only relates to 32-bit x86, so now is redundant. So I dropped the `T_METADATA` case completely.

> src/hotspot/cpu/x86/c1_LIRAssembler_x86.cpp line 3063:
> 
>> 3061:              ExternalAddress((address)double_signflip_pool),
>> 3062:              rscratch1);
>> 3063: 
> 
> Is it intentional or just a leftover?

Merge leftover, removed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24301#discussion_r2022343408
PR Review Comment: https://git.openjdk.org/jdk/pull/24301#discussion_r2022344553
PR Review Comment: https://git.openjdk.org/jdk/pull/24301#discussion_r2022344878