Delete fgMorphGetStructAddr

[SingleAccretion]

After #68986, we do not need it in block morphing.

Includes additional cleanup of dead/unnecessary block morphing code.

Diffs - couple positive ones on x86 where we keep the block copy when assigning to a promoted SIMD.

Sample IR diff

- [000083] -A-X-+----- * COMMA void- [000076] -A-X------- +--* COMMA void- [000071] -A--------- | +--* ASG byref- [000070] D------N--- | | +--* LCL_VAR byref V12 tmp10- [000067] -A--------- | | \--* COMMA byref- [000065] -A--------- | | +--* ASG simd8 (copy)- [000063] D------N--- | | | +--* LCL_VAR simd8 <System.Numerics.Vector2> V11 tmp9- [000011] -----+-N--- | | | \--* CNS_VEC simd8 <0x00000000, 0x00000000>- [000069] ----------- | | \--* ADDR byref- [000066] -------N--- | | \--* LCL_VAR simd8 <System.Numerics.Vector2> V11 tmp9- [000075] -A-X------- | \--* ASG float- [000072] D------N--- | +--* LCL_VAR float V07 tmp5- [000074] ---X------- | \--* IND float- [000073] ----------- | \--* LCL_VAR byref V12 tmp10 Zero Fseq[X]- [000082] -A-X------- \--* ASG float- [000077] D------N--- +--* LCL_VAR float V08 tmp6- [000081] ---X------- \--* IND float- [000080] ----------- \--* ADD byref- [000078] ----------- +--* LCL_VAR byref V12 tmp10- [000079] ----------- \--* CNS_INT int 4 Fseq[Y]+ [000014] -A---+----- * ASG simd8 (copy)+ [000012] D----+-N--- +--* LCL_VAR simd8 <System.Numerics.Vector2>(P) V03 tmp1+ +--* float V03.X (offs=0x00) -> V07 tmp5+ +--* float V03.Y (offs=0x04) -> V08 tmp6+ [000011] -----+----- \--* CNS_VEC simd8 <0x00000000, 0x00000000>

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Issue Details

---

After #68986, we do not need it in block morphing.

Includes additional cleanup of dead/unnecessary block morphing code.

No diffs are expected.

Author:	SingleAccretion
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[SingleAccretion]

@dotnet/jit-contrib

[EgorBo]

Thanks, let's wait for the active CI pipelines to finish