Update aosp/master LLVM for rebase to r230699.

Change-Id: I2b5be30509658cb8266be782de0ab24f9099f9b9
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 9aef5ed..0a3c926 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -793,19 +793,26 @@
 
     APInt MsbMask = APInt::getHighBitsSet(BitWidth, 1);
     // If we only care about the highest bit, don't bother shifting right.
-    if (MsbMask == DemandedMask) {
+    if (MsbMask == NewMask) {
       unsigned ShAmt = ExVT.getScalarType().getSizeInBits();
       SDValue InOp = Op.getOperand(0);
+      unsigned VTBits = Op->getValueType(0).getScalarType().getSizeInBits();
+      bool AlreadySignExtended =
+        TLO.DAG.ComputeNumSignBits(InOp) >= VTBits-ShAmt+1;
+      // However if the input is already sign extended we expect the sign
+      // extension to be dropped altogether later and do not simplify.
+      if (!AlreadySignExtended) {
+        // Compute the correct shift amount type, which must be getShiftAmountTy
+        // for scalar types after legalization.
+        EVT ShiftAmtTy = Op.getValueType();
+        if (TLO.LegalTypes() && !ShiftAmtTy.isVector())
+          ShiftAmtTy = getShiftAmountTy(ShiftAmtTy);
 
-      // Compute the correct shift amount type, which must be getShiftAmountTy
-      // for scalar types after legalization.
-      EVT ShiftAmtTy = Op.getValueType();
-      if (TLO.LegalTypes() && !ShiftAmtTy.isVector())
-        ShiftAmtTy = getShiftAmountTy(ShiftAmtTy);
-
-      SDValue ShiftAmt = TLO.DAG.getConstant(BitWidth - ShAmt, ShiftAmtTy);
-      return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SHL, dl,
-                                            Op.getValueType(), InOp, ShiftAmt));
+        SDValue ShiftAmt = TLO.DAG.getConstant(BitWidth - ShAmt, ShiftAmtTy);
+        return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SHL, dl,
+                                                 Op.getValueType(), InOp,
+                                                 ShiftAmt));
+      }
     }
 
     // Sign extension.  Compute the demanded bits in the result that are not
@@ -1283,36 +1290,53 @@
     }
 
     // (zext x) == C --> x == (trunc C)
-    if (DCI.isBeforeLegalize() && N0->hasOneUse() &&
-        (Cond == ISD::SETEQ || Cond == ISD::SETNE)) {
+    // (sext x) == C --> x == (trunc C)
+    if ((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
+        DCI.isBeforeLegalize() && N0->hasOneUse()) {
       unsigned MinBits = N0.getValueSizeInBits();
-      SDValue PreZExt;
+      SDValue PreExt;
+      bool Signed = false;
       if (N0->getOpcode() == ISD::ZERO_EXTEND) {
         // ZExt
         MinBits = N0->getOperand(0).getValueSizeInBits();
-        PreZExt = N0->getOperand(0);
+        PreExt = N0->getOperand(0);
       } else if (N0->getOpcode() == ISD::AND) {
         // DAGCombine turns costly ZExts into ANDs
         if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(N0->getOperand(1)))
           if ((C->getAPIntValue()+1).isPowerOf2()) {
             MinBits = C->getAPIntValue().countTrailingOnes();
-            PreZExt = N0->getOperand(0);
+            PreExt = N0->getOperand(0);
           }
+      } else if (N0->getOpcode() == ISD::SIGN_EXTEND) {
+        // SExt
+        MinBits = N0->getOperand(0).getValueSizeInBits();
+        PreExt = N0->getOperand(0);
+        Signed = true;
       } else if (LoadSDNode *LN0 = dyn_cast<LoadSDNode>(N0)) {
-        // ZEXTLOAD
+        // ZEXTLOAD / SEXTLOAD
         if (LN0->getExtensionType() == ISD::ZEXTLOAD) {
           MinBits = LN0->getMemoryVT().getSizeInBits();
-          PreZExt = N0;
+          PreExt = N0;
+        } else if (LN0->getExtensionType() == ISD::SEXTLOAD) {
+          Signed = true;
+          MinBits = LN0->getMemoryVT().getSizeInBits();
+          PreExt = N0;
         }
       }
 
+      // Figure out how many bits we need to preserve this constant.
+      unsigned ReqdBits = Signed ?
+        C1.getBitWidth() - C1.getNumSignBits() + 1 :
+        C1.getActiveBits();
+
       // Make sure we're not losing bits from the constant.
       if (MinBits > 0 &&
-          MinBits < C1.getBitWidth() && MinBits >= C1.getActiveBits()) {
+          MinBits < C1.getBitWidth() &&
+          MinBits >= ReqdBits) {
         EVT MinVT = EVT::getIntegerVT(*DAG.getContext(), MinBits);
         if (isTypeDesirableForOp(ISD::SETCC, MinVT)) {
           // Will get folded away.
-          SDValue Trunc = DAG.getNode(ISD::TRUNCATE, dl, MinVT, PreZExt);
+          SDValue Trunc = DAG.getNode(ISD::TRUNCATE, dl, MinVT, PreExt);
           SDValue C = DAG.getConstant(C1.trunc(MinBits), MinVT);
           return DAG.getSetCC(dl, VT, Trunc, C, Cond);
         }
@@ -2163,9 +2187,10 @@
   }
 }
 
-std::pair<unsigned, const TargetRegisterClass*> TargetLowering::
-getRegForInlineAsmConstraint(const std::string &Constraint,
-                             MVT VT) const {
+std::pair<unsigned, const TargetRegisterClass *>
+TargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *RI,
+                                             const std::string &Constraint,
+                                             MVT VT) const {
   if (Constraint.empty() || Constraint[0] != '{')
     return std::make_pair(0u, static_cast<TargetRegisterClass*>(nullptr));
   assert(*(Constraint.end()-1) == '}' && "Not a brace enclosed constraint?");
@@ -2177,8 +2202,6 @@
     std::make_pair(0u, static_cast<const TargetRegisterClass*>(nullptr));
 
   // Figure out which register class contains this reg.
-  const TargetRegisterInfo *RI =
-      getTargetMachine().getSubtargetImpl()->getRegisterInfo();
   for (TargetRegisterInfo::regclass_iterator RCI = RI->regclass_begin(),
        E = RI->regclass_end(); RCI != E; ++RCI) {
     const TargetRegisterClass *RC = *RCI;
@@ -2231,8 +2254,9 @@
 /// and also tie in the associated operand values.
 /// If this returns an empty vector, and if the constraint string itself
 /// isn't empty, there was an error parsing.
-TargetLowering::AsmOperandInfoVector TargetLowering::ParseConstraints(
-    ImmutableCallSite CS) const {
+TargetLowering::AsmOperandInfoVector
+TargetLowering::ParseConstraints(const TargetRegisterInfo *TRI,
+                                 ImmutableCallSite CS) const {
   /// ConstraintOperands - Information about all of the constraints.
   AsmOperandInfoVector ConstraintOperands;
   const InlineAsm *IA = cast<InlineAsm>(CS.getCalledValue());
@@ -2323,7 +2347,7 @@
   }
 
   // If we have multiple alternative constraints, select the best alternative.
-  if (ConstraintOperands.size()) {
+  if (!ConstraintOperands.empty()) {
     if (maCount) {
       unsigned bestMAIndex = 0;
       int bestWeight = -1;
@@ -2394,12 +2418,12 @@
       AsmOperandInfo &Input = ConstraintOperands[OpInfo.MatchingInput];
 
       if (OpInfo.ConstraintVT != Input.ConstraintVT) {
-        std::pair<unsigned, const TargetRegisterClass*> MatchRC =
-          getRegForInlineAsmConstraint(OpInfo.ConstraintCode,
-                                       OpInfo.ConstraintVT);
-        std::pair<unsigned, const TargetRegisterClass*> InputRC =
-          getRegForInlineAsmConstraint(Input.ConstraintCode,
-                                       Input.ConstraintVT);
+        std::pair<unsigned, const TargetRegisterClass *> MatchRC =
+            getRegForInlineAsmConstraint(TRI, OpInfo.ConstraintCode,
+                                         OpInfo.ConstraintVT);
+        std::pair<unsigned, const TargetRegisterClass *> InputRC =
+            getRegForInlineAsmConstraint(TRI, Input.ConstraintCode,
+                                         Input.ConstraintVT);
         if ((OpInfo.ConstraintVT.isInteger() !=
              Input.ConstraintVT.isInteger()) ||
             (MatchRC.second != InputRC.second)) {