[VPlan] Share PreservesUniformity logic between isSingleScalar and isUniformAcrossVFsAndUFs

Extract the PreservesUniformity logic from isSingleScalar into a shared
static helper function. Update isUniformAcrossVFsAndUFs to use this
logic for VPWidenRecipe and VPInstruction, so that any opcode that
preserves uniformity is considered uniform-across-vf-and-uf if its
operands are.

This unifies the uniformity checking logic and makes it easier to extend
in the future.

This should effectively by NFC currently.

0 files changed, 0 insertions, 0 deletions