[RyuJIT] Refactor the codegen/emitter for MOVD/MODQ

[fiigii]

The codegen/emitter of MOVD/MODQ is very messy in the current backend.
It has several "instructions" to generate MOVD/MODQ (e.g., mov_i2xmm, mov_xmm2i, movd, and movd), but the codegen is not consistent.
For example, mov_i2xmm can generate MOVD and MOVQ based on different emit-size, but it just accepts some of the valid sizes.

INST3( mov_i2xmm,   "movd"        , 0, IUM_WR, 0, 0, BAD_CODE,     BAD_CODE, PCKDBL(0x6E)) 
INST3( mov_xmm2i,   "movd"        , 0, IUM_WR, 0, 0, BAD_CODE,     BAD_CODE, PCKDBL(0x7E)) 
INST3( movd,        "movd"        , 0, IUM_WR, 0, 0, PCKDBL(0x7E), BAD_CODE, PCKDBL(0x6E))
INST3( movq,        "movq"        , 0, IUM_WR, 0, 0, PCKDBL(0xD6), BAD_CODE, SSEFLT(0x7E))

cc @CarolEidt @tannergooding

[mikedn]

For example, mov_i2xmm can generate MOVD and MOVQ based on different emit-size, but it just accepts some of the valid sizes.

What do you mean? It sounds like a contradiction, either it can generate based on different emit-size or it can't because there are only 2 valid sizes.

[fiigii]

For example, mov_i2xmm + 64-bit can generate MOVQ xmm, rax, but mov_i2xmm + 32-bit does not work, we need mov_i2xmm + 128-bit to generate MOVD xmm, eax.

[mikedn]

For example, mov_i2xmm + 64-bit can generate MOVQ xmm, rax, but mov_i2xmm + 32-bit does not work, we need mov_i2xmm + 128-bit to generate MOVD xmm, eax.

Seems to be working fine for me:

getEmitter()->emitIns_R_R(INS_mov_i2xmm, EA_4BYTE, REG_XMM6, REG_RDX);
getEmitter()->emitIns_R_R(INS_mov_i2xmm, EA_8BYTE, REG_XMM5, REG_RBX);
getEmitter()->emitIns_R_R(INS_mov_xmm2i, EA_4BYTE, REG_XMM4, REG_RCX);
getEmitter()->emitIns_R_R(INS_mov_xmm2i, EA_8BYTE, REG_XMM3, REG_RAX);

generates

C4E1796EF2           vmovd    xmm6, edx
C4E1F96EEB           vmovd    xmm5, rbx
C4E1797EE1           vmovd    ecx, xmm4
C4E1F97ED8           vmovd    rax, xmm3

[fiigii]

@mikedn Oh, you are right! I used the wrong emit-size in dotnet/coreclr#17030 (should be emitActualTypeSize rather than emitTypeSize). Thank you!