RFR: JDK-8323497: On x64, use 32-bit immediate moves for narrow klass base if possible

[Thomas Stuefe]

On Wed, 10 Jan 2024 09:40:26 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/cpu/x86/assembler_x86.cpp line 13369:
>> 
>>> 13367: #ifdef _LP64
>>> 13368: void Assembler::mov32_or_64(Register dst, int64_t imm) {
>>> 13369:   if ((uint64_t)imm < nth_bit(32)) {
>> 
>> Drive-by comments:
>>  a) macro-assembler stuff like this should be in macroAssembler;
>>  b) there is `is_simm32(imm)` for checks like these;
>>  c) I did [JDK-8319406](https://bugs.openjdk.org/browse/JDK-8319406) recently, maybe you could just use that?
>
> [deleted]

God you are fast. 

movptr looks suitable. Why did you name it "ptr" if its not for pointers?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17340#discussion_r1447127069