[X86] detectPMADDUBSW - use SDPatternMatch to handle some of the commutative matching for the zext/sext pairs. NFC. (llvm#165861)

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -54459,6 +54459,7 @@ static SDValue combinePMULH(SDValue Src, EVT VT, const SDLoc &DL,
 static SDValue detectPMADDUBSW(SDValue In, EVT VT, SelectionDAG &DAG,
                                const X86Subtarget &Subtarget,
                                const SDLoc &DL) {
+  using namespace SDPatternMatch;
   if (!VT.isVector() || !Subtarget.hasSSSE3())
     return SDValue();
 
@@ -54468,42 +54469,19 @@ static SDValue detectPMADDUBSW(SDValue In, EVT VT, SelectionDAG &DAG,
     return SDValue();
 
   SDValue SSatVal = detectSSatPattern(In, VT);
-  if (!SSatVal || SSatVal.getOpcode() != ISD::ADD)
-    return SDValue();
-
-  // Ok this is a signed saturation of an ADD. See if this ADD is adding pairs
-  // of multiplies from even/odd elements.
-  SDValue N0 = SSatVal.getOperand(0);
-  SDValue N1 = SSatVal.getOperand(1);
-
-  if (N0.getOpcode() != ISD::MUL || N1.getOpcode() != ISD::MUL)
+  if (!SSatVal)
     return SDValue();
 
-  SDValue N00 = N0.getOperand(0);
-  SDValue N01 = N0.getOperand(1);
-  SDValue N10 = N1.getOperand(0);
-  SDValue N11 = N1.getOperand(1);
-
+  // See if this is a signed saturation of an ADD, adding pairs of multiplies
+  // from even/odd elements, from zero_extend/sign_extend operands.
+  //
   // TODO: Handle constant vectors and use knownbits/computenumsignbits?
-  // Canonicalize zero_extend to LHS.
-  if (N01.getOpcode() == ISD::ZERO_EXTEND)
-    std::swap(N00, N01);
-  if (N11.getOpcode() == ISD::ZERO_EXTEND)
-    std::swap(N10, N11);
-
-  // Ensure we have a zero_extend and a sign_extend.
-  if (N00.getOpcode() != ISD::ZERO_EXTEND ||
-      N01.getOpcode() != ISD::SIGN_EXTEND ||
-      N10.getOpcode() != ISD::ZERO_EXTEND ||
-      N11.getOpcode() != ISD::SIGN_EXTEND)
+  SDValue N00, N01, N10, N11;
+  if (!sd_match(SSatVal,
+                m_Add(m_Mul(m_ZExt(m_Value(N00)), m_SExt(m_Value(N01))),
+                      m_Mul(m_ZExt(m_Value(N10)), m_SExt(m_Value(N11))))))
     return SDValue();
 
-  // Peek through the extends.
-  N00 = N00.getOperand(0);
-  N01 = N01.getOperand(0);
-  N10 = N10.getOperand(0);
-  N11 = N11.getOperand(0);
-
   // Ensure the extend is from vXi8.
   if (N00.getValueType().getVectorElementType() != MVT::i8 ||
       N01.getValueType().getVectorElementType() != MVT::i8 ||