[llvm-branch-commits] [llvm] [LoongArch] Custom legalizing build_vector with same constant elements (PR #150584)

[Lu Weining via llvm-branch-commits]

================
@@ -2495,26 +2492,47 @@ SDValue LoongArchTargetLowering::lowerBUILD_VECTOR(SDValue Op,
   if (DAG.isSplatValue(Op, /*AllowUndefs=*/false))
     return Op;
 
-  if (!isConstantBUILD_VECTOR(Node)) {
+  for (unsigned i = 0; i < NumElts; ++i) {
+    SDValue Opi = Node->getOperand(i);
+    if (isIntOrFPConstant(Opi)) {
+      IsConstant = true;
+      if (!ConstantValue.getNode())
+        ConstantValue = Opi;
+      else if (ConstantValue != Opi)
+        UseSameConstant = false;
+    }
+  }
+
+  if (IsConstant && UseSameConstant) {
+    SDValue Result = DAG.getSplatBuildVector(ResTy, DL, ConstantValue);
+    for (unsigned i = 0; i < NumElts; ++i) {
+      SDValue Opi = Node->getOperand(i);
+      if (!isIntOrFPConstant(Opi))
+        Result = DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, ResTy, Result, Opi,
+                             DAG.getConstant(i, DL, Subtarget.getGRLenVT()));
+    }
+    return Result;
+  }
+
+  if (!IsConstant) {
     // Use INSERT_VECTOR_ELT operations rather than expand to stores.
     // The resulting code is the same length as the expansion, but it doesn't
     // use memory operations.
     assert(ResTy.isVector());
 
-    unsigned NumElts = ResTy.getVectorNumElements();
     SDValue Op0 = Node->getOperand(0);
-    SDValue Vector = DAG.getUNDEF(ResTy);
+    SDValue Result = DAG.getUNDEF(ResTy);
----------------
SixWeining wrote:

The naming change is unnecessary.

https://github.com/llvm/llvm-project/pull/150584