x64Emitter: short MOV for 64bit immediates (2)

Prior to this commit, the emitter would unconditionally emit a 10-byte
instruction known as MOVABS when loading a 64-bit immediate to a
register.

0:  48 b8 ef be ad de 00    movabs rax,0xdeadbeef
7:  00 00 00

With this change, it will instead rely on the fact that on x64 writes to
32-bit registers are automatically zero extended to 64-bits, allowing
us to emit a 5 or 6-bytes instruction with the same effect for certain
immediates.

0:  b8 ef be ad de          mov    eax,0xdeadbeef

0 files changed, 0 insertions, 0 deletions