[AArch64][SME] Make getRegAllocationHints more specific for multi-vector loads (#123081)

getRegAllocationHints looks for ZPR2StridedOrContiguous load instructions
which are used by FORM_TRANSPOSED_REG_TUPLE pseudos and adds all
strided registers from this class to the list of hints.
This patch changes getRegAllocationHints to restrict this list:
  - If the pseudo uses ZPRMul class, the first load must begin with a register
    which is a multiple of 2 or 4.
  - Only add a hint if it is part of a sequence of registers that do not already
    have any live intervals.

This also contains changes to suggest hints when the load instructions and
the FORM_TRANSPOSED pseudo use multi-vectors of different lengths,
e.g. a pseudo with a 4-vector sequence of registers formed of one column
extracted from four 2-vector loads.

0 files changed, 0 insertions, 0 deletions