[llvm] GlobalISel: Match loads by pointer operand in CombinerHelper (PR #216672)

[Tim Gymnich via llvm-commits]

================
@@ -1153,24 +1154,21 @@ bool CombinerHelper::matchSextInRegOfLoad(
   if (!isPowerOf2_32(NewSizeBits))
     return false;
 
-  const MachineMemOperand &MMO = LoadDef->getMMO();
-  LegalityQuery::MemDesc MMDesc(MMO);
+  LegalityQuery::MemDesc MMDesc(*MMO);
 
   // Don't modify the memory access size if this is atomic/volatile, but we can
   // still adjust the opcode to indicate the high bit behavior.
-  if (LoadDef->isSimple())
+  if (!MMO->isAtomic() && !MMO->isVolatile())
     MMDesc.MemoryTy = LLT::scalar(NewSizeBits);
   else if (MemBits > NewSizeBits || MemBits == RegTy.getSizeInBits())
     return false;
 
   // TODO: Could check if it's legal with the reduced or original memory size.
-  if (!isLegalOrBeforeLegalizer({TargetOpcode::G_SEXTLOAD,
-                                 {MRI.getType(LoadDef->getDstReg()),
-                                  MRI.getType(LoadDef->getPointerReg())},
-                                 {MMDesc}}))
+  if (!isLegalOrBeforeLegalizer(
+          {TargetOpcode::G_SEXTLOAD, {RegTy, MRI.getType(PtrReg)}, {MMDesc}}))
     return false;
 
-  MatchInfo = std::make_tuple(LoadDef->getDstReg(), NewSizeBits);
+  MatchInfo = std::make_tuple(SrcReg, NewSizeBits);
----------------
tgymnich wrote:

shouldn't this be `PtrReg`?

```suggestion
  MatchInfo = std::make_tuple(PtrReg, NewSizeBits);
```

https://github.com/llvm/llvm-project/pull/216672