Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -19820,7 +19820,8 @@
 //
 // where Op could be BRCOND or CMOV.
 //
-static SDValue checkBoolTestSetCCCombine(SDValue Cmp, X86::CondCode &CC) {
+static SDValue checkBoolTestSetCCCombine(SDValue Chain, SDValue Cmp,
+                                         X86::CondCode &CC) {
   // Quit if not CMP and SUB with its value result used.
   if (Cmp.getOpcode() != X86ISD::CMP &&
       (Cmp.getOpcode() != X86ISD::SUB || Cmp.getNode()->hasAnyUseOfValue(0)))
@@ -19887,12 +19888,21 @@
     assert(X86::CondCode(SetCC.getConstantOperandVal(0)) == X86::COND_B &&
            "Invalid use of SETCC_CARRY!");
     // FALL THROUGH
-  case X86ISD::SETCC:
+  case X86ISD::SETCC: {
+    // If the operand is CopyFromReg, applying this simplification may create
+    // a situation later where we need to copy EFLAGS. Since this isn't
+    // supported, we will generate incorrect code. To avoid this situation,
+    // we forbid this simplification if the operand is CopyFromReg and it
+    // is not directly chained to us.
+    SDValue Op = SetCC.getOperand(1);
+    if (Chain && Op.getOpcode() == ISD::CopyFromReg && Op.getValue(1) != Chain)
+      break;
     // Set the condition code or opposite one if necessary.
     CC = X86::CondCode(SetCC.getConstantOperandVal(0));
     if (needOppositeCond)
       CC = X86::GetOppositeBranchCondition(CC);
-    return SetCC.getOperand(1);
+    return Op;
+  }
   case X86ISD::CMOV: {
     // Check whether false/true value has canonical one, i.e. 0 or 1.
     ConstantSDNode *FVal = dyn_cast<ConstantSDNode>(SetCC.getOperand(0));
@@ -19965,7 +19975,7 @@
 
   SDValue Flags;
 
-  Flags = checkBoolTestSetCCCombine(Cond, CC);
+  Flags = checkBoolTestSetCCCombine(SDValue(), Cond, CC);
   if (Flags.getNode() &&
       // Extra check as FCMOV only supports a subset of X86 cond.
       (FalseOp.getValueType() != MVT::f80 || hasFPCMov(CC))) {
@@ -21803,7 +21813,7 @@
 
   SDValue Flags;
 
-  Flags = checkBoolTestSetCCCombine(EFLAGS, CC);
+  Flags = checkBoolTestSetCCCombine(SDValue(), EFLAGS, CC);
   if (Flags.getNode()) {
     SDValue Cond = DAG.getConstant(CC, MVT::i8);
     return DAG.getNode(X86ISD::SETCC, DL, N->getVTList(), Cond, Flags);
@@ -21825,7 +21835,7 @@
 
   SDValue Flags;
 
-  Flags = checkBoolTestSetCCCombine(EFLAGS, CC);
+  Flags = checkBoolTestSetCCCombine(Chain, EFLAGS, CC);
   if (Flags.getNode()) {
     SDValue Cond = DAG.getConstant(CC, MVT::i8);
     return DAG.getNode(X86ISD::BRCOND, DL, N->getVTList(), Chain, Dest, Cond,