cmd/asm: add ordered CASP variants for arm64#79930
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The arm64 assembler supports the LSE compare-and-swap-pair instructions only in their relaxed form (CASPD, CASPW). Add the acquire, release, and acquire-release variants: CASPAD, CASPAW, CASPLD, CASPLW, CASPALD, CASPALW. The single-register CAS family already supports all four orderings; the pair instructions were the only members limited to the relaxed variant, forcing code that needs an ordered 128-bit compare-and-swap to hand-encode the instruction with WORD directives. Fixes golang#79929
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The arm64 assembler supports the LSE compare-and-swap-pair instructions only in their relaxed form (CASPD, CASPW). Add the acquire, release, and acquire-release variants: CASPAD, CASPAW, CASPLD, CASPLW, CASPALD, CASPALW.
The single-register CAS family already supports all four orderings; the pair instructions were the only members limited to the relaxed variant, forcing code that needs an ordered 128-bit compare-and-swap to hand-encode the instruction with WORD directives.
Fixes #79929