RFR: 8327964: Simplify BigInteger.implMultiplyToLen intrinsic [v5]

[Dean Long]

On Wed, 17 Apr 2024 12:35:54 GMT, Yudi Zheng <yzheng at openjdk.org> wrote:

>> Moving array construction within BigInteger.implMultiplyToLen intrinsic candidate to its caller simplifies the intrinsic implementation in JIT compiler.
>
> Yudi Zheng has updated the pull request incrementally with one additional commit since the last revision:
> 
>   address comment.

src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp line 4693:

> 4691:     const Register xlen  = r1;
> 4692:     const Register z     = r2;
> 4693:     const Register zlen  = r3;

LibraryCallKit::inline_squareToLen() is still computing zlen and passing it as the 4th arg, even though the value is unused.

src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp line 4702:

> 4700:     const Register tmp5  = r15;
> 4701:     const Register tmp6  = r16;
> 4702:     const Register tmp7  = r17;

No need for r17 or sorting tmps.  Make tmp0 r3, or r6, r7, etc.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18226#discussion_r1569419199
PR Review Comment: https://git.openjdk.org/jdk/pull/18226#discussion_r1569420732