[GlobalISel][NFC] Fix LLT Propagation (#119587)
Retain LLT type information by creating new LLTs from the original LLT
instead of only using the original scalar size.
This PR prepares for the [LLT FPInfo
RFC](https://discourse.llvm.org/t/rfc-globalisel-adding-fp-type-information-to-llt/83349/24)
where LLTs will carry additional floating point type information in
addition to the scalar size.
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index f56be39..83c1d79 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -5347,9 +5347,9 @@
auto [DstReg, DstTy, SrcReg, SrcTy] = MI.getFirst2RegLLTs();
- unsigned SrcScalSize = SrcTy.getScalarSizeInBits();
- LLT SrcNarrowTy =
- LLT::fixed_vector(NarrowTy.getSizeInBits() / SrcScalSize, SrcScalSize);
+ unsigned NewElemCount =
+ NarrowTy.getSizeInBits() / SrcTy.getScalarSizeInBits();
+ LLT SrcNarrowTy = LLT::fixed_vector(NewElemCount, SrcTy.getElementType());
// Split the Src and Dst Reg into smaller registers
SmallVector<Register> SrcVRegs, BitcastVRegs;
