[llvm] [LLVM][DAGCombiner] Port calculateByteProvider to TypeSize. (PR #148425)

[Ricardo Jesus via llvm-commits]

================
@@ -9149,11 +9149,12 @@ calculateByteProvider(SDValue Op, unsigned Index, unsigned Depth,
   if (Op.getOpcode() != ISD::LOAD && VectorIndex.has_value())
     return std::nullopt;
 
-  unsigned BitWidth = Op.getValueSizeInBits();
-  if (BitWidth % 8 != 0)
+  TypeSize BitWidth = Op.getValueSizeInBits();
+  if (!BitWidth.isKnownMultipleOf(8))
     return std::nullopt;
-  unsigned ByteWidth = BitWidth / 8;
-  assert(Index < ByteWidth && "invalid index requested");
+  TypeSize ByteWidth = BitWidth.divideCoefficientBy(8);
+  assert(TypeSize::isKnownLT(TypeSize::getFixed(Index), ByteWidth) &&
+         "invalid index requested");
----------------
rj-jesus wrote:

Apologies if this is obvious, but is there a benefit to using TypeSize here rather than taking `BitWidth`'s `getKnownMinValue()`? (In case it isn't intentional, it also seems that `ByteWidth` may be implicitly converted to unsigned a few lines below in `case ISD::BSWAP`. Once again, I'm sorry if this is obvious and intentional.)

https://github.com/llvm/llvm-project/pull/148425