RFR: 8354231: x86: Purge FPU support from (Macro)Assembler after 32-bit x86 removal

[Aleksey Shipilev]

On Wed, 9 Apr 2025 19:14:06 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> There are lots of cleanups possible in (Macro)Assembler after 32-bit x86 removal. This cleanup is focused on removing the large parts of x87 FPU support that are no longer needed. Note that _some_ math stubs are actually using x87 FPU in a very limited manner, but the implementations use separate definitions (under `LP64`). Those are left alone, and we clean up x86_32 code here.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `all`

Resolved a simple merge conflict.

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PR Comment: https://git.openjdk.org/jdk/pull/24558#issuecomment-2796146672