RFR: 8377726: Remove unused macros in register.hpp

[Manuel Hässig]

On Wed, 18 Feb 2026 10:55:40 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Please review this change to remove some unused (or nearly unused) macros in
>> share/asm/register.hpp. This change also simplifies the zero definition of
>> noreg to render one of the macros no longer used.
>> 
>> Testing: mach5 tier1 and GHA Sanity Tests.
>> The GHA testing failed to build on Alpine Linux because of the unrelated
>> https://bugs.openjdk.org/browse/JDK-8377707
>
> src/hotspot/share/asm/register.hpp line 52:
> 
>> 50: // Macros to help define all kinds of registers
>> 51: 
>> 52: #ifdef USE_POINTERS_TO_REGISTER_IMPL_ARRAY
> 
> Why `ifndef` -> `ifdef`?

Because only the `#else` branch of the original code is left.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29685#discussion_r2822382014