[llvm-branch-commits] [llvm] [RISCV] Support memcmp expansion for vectors (PR #114517)

[Luke Lau via llvm-branch-commits]

================
@@ -14520,17 +14520,78 @@ static bool narrowIndex(SDValue &N, ISD::MemIndexType IndexType, SelectionDAG &D
   return true;
 }
 
+/// Try to map an integer comparison with size > XLEN to vector instructions
+/// before type legalization splits it up into chunks.
+static SDValue
+combineVectorSizedSetCCEquality(EVT VT, SDValue X, SDValue Y, ISD::CondCode CC,
+                                const SDLoc &DL, SelectionDAG &DAG,
+                                const RISCVSubtarget &Subtarget) {
+  assert(ISD::isIntEqualitySetCC(CC) && "Bad comparison predicate");
+
+  if (!Subtarget.hasVInstructions())
+    return SDValue();
+
+  MVT XLenVT = Subtarget.getXLenVT();
+  EVT OpVT = X.getValueType();
+  // We're looking for an oversized integer equality comparison.
+  if (OpVT.isScalableVT() || !OpVT.isScalarInteger())
+    return SDValue();
+
+  unsigned OpSize = OpVT.getSizeInBits();
+  // TODO: Support non-power-of-2 types.
+  if (!isPowerOf2_32(OpSize))
+    return SDValue();
----------------
lukel97 wrote:

I think as long as it's byte sized it should be ok right? E.g.
```suggestion
  if (OpSize % 8)
    return SDValue();
```

But happy if you want to leave this as is and do it as a follow on with the TODO in RISCVTargetTransformInfo.cpp

https://github.com/llvm/llvm-project/pull/114517