[llvm] [GlobalISel] Widen vector loads from aligned ptrs (PR #144309)

[David Green via llvm-commits]

================
@@ -4072,6 +4072,19 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerLoad(GAnyLoad &LoadMI) {
     if (MemTy != DstTy)
       return UnableToLegalize;
 
+    Align Alignment = LoadMI.getAlign();
+    if (Alignment.value() * 8 > MemSizeInBits &&
+        isPowerOf2_64(DstTy.getScalarSizeInBits())) {
+      LLT MoreTy = LLT::fixed_vector(NextPowerOf2(DstTy.getNumElements()),
+                                     DstTy.getElementType());
+      MachineMemOperand *NewMMO = MF.getMachineMemOperand(&MMO, 0, MoreTy);
+      auto NewLoad = MIRBuilder.buildLoad(MoreTy, PtrReg, *NewMMO);
----------------
davemgreen wrote:

I have added a test - it looks like when creating a MMO from another it does not copy the range metadata.
```
MachineMemOperand *MachineFunction::getMachineMemOperand(
    const MachineMemOperand *MMO, const MachinePointerInfo &PtrInfo, LLT Ty) {
  return new (Allocator)
      MachineMemOperand(PtrInfo, MMO->getFlags(), Ty, MMO->getBaseAlign(),
                        AAMDNodes(), nullptr, MMO->getSyncScopeID(),
                        MMO->getSuccessOrdering(), MMO->getFailureOrdering());
}
```

https://github.com/llvm/llvm-project/pull/144309