[llvm] [AMDGPU][SDAG] Support source modifiers as integer on select (PR #147325)

[Janek van Oirschot via llvm-commits]

================
@@ -4830,6 +4830,65 @@ AMDGPUTargetLowering::foldFreeOpFromSelect(TargetLowering::DAGCombinerInfo &DCI,
   return SDValue();
 }
 
+static EVT IntToFloatVT(EVT VT) {
+  return VT = VT.isVector() ? MVT::getVectorVT(MVT::getFloatingPointVT(
+                                                   VT.getScalarSizeInBits()),
+                                               VT.getVectorNumElements())
+                            : MVT::getFloatingPointVT(VT.getFixedSizeInBits());
+}
+
+static SDValue BitwiseToSrcModifierOp(SDValue N,
+                                      TargetLowering::DAGCombinerInfo &DCI) {
+
+  unsigned Opc = N.getNode()->getOpcode();
+  if (Opc != ISD::AND && Opc != ISD::XOR && Opc != ISD::AND)
+    return SDValue();
+
+  SelectionDAG &DAG = DCI.DAG;
+  SDValue LHS = N.getNode()->getOperand(0);
+  SDValue RHS = N.getNode()->getOperand(1);
+  ConstantSDNode *CRHS = isConstOrConstSplat(RHS);
+
+  if (!CRHS)
+    return SDValue();
+
+  EVT VT = RHS.getValueType();
+
+  assert((VT == MVT::i32 || VT == MVT::v2i32 || VT == MVT::i64) &&
+         "Expected i32, v2i32 or i64 value type.");
+
+  uint64_t Mask = 0;
+  if (VT.isVector()) {
+    SDValue Splat = DAG.getSplatValue(RHS);
+    const ConstantSDNode *C = dyn_cast<ConstantSDNode>(Splat);
+    Mask = C->getZExtValue();
+  } else
+    Mask = CRHS->getZExtValue();
+
+  EVT FVT = IntToFloatVT(VT);
+  SDValue BC = DAG.getNode(ISD::BITCAST, SDLoc(N), FVT, LHS);
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JanekvO wrote:

nit: can `SDLoc SL(N);` and reuse SL 

https://github.com/llvm/llvm-project/pull/147325