Merge pull request #27 from nikolaperic/ins-opt-revert

Revert "NanoMips: Support for 16bit masks in OR to INS combine"

Author: cme

llvm/lib/Target/Mips/MipsISelLowering.cpp

@@ -1046,26 +1046,8 @@ static SDValue attemptOrToIns(SDValue &And, SDValue &Right, SDNode *N,
   if (!(CN = dyn_cast<ConstantSDNode>(And.getOperand(1))))
     return SDValue();
   unsigned Mask0 = ~CN->getZExtValue();
-
-  KnownBits KnownMaskBits = DAG.computeKnownBits(SDValue(CN, 0));
-  APInt maxValue = KnownMaskBits.getMaxValue();
-  unsigned int MaxNumOfActiveBitsInMask = maxValue.getActiveBits();
-
-  // If the mask value fits into 16 bits, trim the leading ones.
-  // Leading ones were made after negating zero expanded 16 bit value.
-  // This enables the function isShiftedMask() to recognize 16 bit masks as
-  // valid.
-  // TODO: Support the case when there are two two consecutive OR instructions
-  // and two masks whose value fits in 16 bits.
-  if (MaxNumOfActiveBitsInMask <= 16) {
-    uint16_t Mask0_16 = Mask0;
-    if (!isShiftedMask(Mask0_16, SMPos0, SMSize0))
-      return SDValue();
-  } else if (MaxNumOfActiveBitsInMask <= 32) {
-    uint32_t Mask0_32 = Mask0;
-    if (!isShiftedMask(Mask0_32, SMPos0, SMSize0))
-      return SDValue();
-  }
+  if (!isShiftedMask(Mask0, SMPos0, SMSize0))
+    return SDValue();
 
   SDLoc DL(N);
   EVT ValTy = N->getValueType(0);