Rearrange the emitLiteral register allocation.

This minimizes the diff in a follow-up commit, when manually inlining.

It's not an optimization per se, but for the record:
name              old speed      new speed      delta
WordsEncode1e1-8   698MB/s ± 1%   701MB/s ± 1%   ~     (p=0.165 n=10+10)
WordsEncode1e2-8   428MB/s ± 0%   429MB/s ± 0%   ~       (p=0.489 n=9+9)
WordsEncode1e3-8   446MB/s ± 0%   447MB/s ± 0%   ~       (p=0.476 n=9+9)
WordsEncode1e4-8   321MB/s ± 1%   322MB/s ± 1%   ~     (p=0.593 n=10+10)
WordsEncode1e5-8   267MB/s ± 1%   268MB/s ± 0%   ~       (p=0.287 n=9+9)
WordsEncode1e6-8   313MB/s ± 1%   313MB/s ± 0%   ~       (p=0.190 n=9+8)
RandomEncode-8    14.4GB/s ± 1%  14.4GB/s ± 1%   ~       (p=0.673 n=9+8)
_ZFlat0-8          800MB/s ± 0%   797MB/s ± 2%   ~       (p=0.387 n=9+9)
_ZFlat1-8          436MB/s ± 1%   435MB/s ± 1%   ~       (p=0.169 n=9+9)
_ZFlat2-8         16.2GB/s ± 1%  16.1GB/s ± 2%   ~     (p=0.063 n=10+10)
_ZFlat3-8          633MB/s ± 1%   633MB/s ± 0%   ~      (p=0.661 n=9+10)
_ZFlat4-8         7.96GB/s ± 1%  7.95GB/s ± 1%   ~     (p=0.796 n=10+10)
_ZFlat5-8          771MB/s ± 0%   771MB/s ± 0%   ~     (p=0.929 n=10+10)
_ZFlat6-8          283MB/s ± 1%   283MB/s ± 0%   ~     (p=0.912 n=10+10)
_ZFlat7-8          265MB/s ± 0%   265MB/s ± 0%   ~       (p=0.649 n=9+9)
_ZFlat8-8          299MB/s ± 0%   299MB/s ± 0%   ~       (p=0.748 n=9+9)
_ZFlat9-8          246MB/s ± 1%   246MB/s ± 1%   ~      (p=0.921 n=9+10)
_ZFlat10-8        1.05GB/s ± 1%  1.05GB/s ± 1%   ~     (p=0.089 n=10+10)
_ZFlat11-8         410MB/s ± 0%   411MB/s ± 0%   ~     (p=0.190 n=10+10)
1 file changed