4 files changed, 31 insertions, 20 deletions

diff --git a/include/llvm/CodeGen/MachineInstr.h b/include/llvm/CodeGen/MachineInstr.h
index d636dfd441..67ae3f9289 100644
--- a/include/llvm/CodeGen/MachineInstr.h
+++ b/include/llvm/CodeGen/MachineInstr.h
@@ -782,6 +782,14 @@ public:
                         const TargetInstrInfo *TII,
                         const TargetRegisterInfo *TRI) const;
 
+  /// tieOperands - Add a tie between the register operands at DefIdx and
+  /// UseIdx. The tie will cause the register allocator to ensure that the two
+  /// operands are assigned the same physical register.
+  ///
+  /// Tied operands are managed automatically for explicit operands in the
+  /// MCInstrDesc. This method is for exceptional cases like inline asm.
+  void tieOperands(unsigned DefIdx, unsigned UseIdx);
+
   /// findTiedOperandIdx - Given the index of a tied register operand, find the
   /// operand it is tied to. Defs are tied to uses and vice versa. Returns the
   /// index of the tied operand which must exist.
@@ -942,9 +950,11 @@ private:
 
   /// untieRegOperand - Break any tie involving OpIdx.
   void untieRegOperand(unsigned OpIdx) {
-    const MachineOperand &MO = getOperand(OpIdx);
-    if (MO.isReg() && MO.isTied())
-      getOperand(findTiedOperandIdx(OpIdx)).setIsTied(false);
+    MachineOperand &MO = getOperand(OpIdx);
+    if (MO.isReg() && MO.isTied()) {
+      getOperand(findTiedOperandIdx(OpIdx)).IsTied = false;
+      MO.IsTied = false;
+    }
   }
 
   /// addImplicitDefUseOperands - Add all implicit def and use operands to
diff --git a/include/llvm/CodeGen/MachineOperand.h b/include/llvm/CodeGen/MachineOperand.h
index 594dc276b0..baec8822c6 100644
--- a/include/llvm/CodeGen/MachineOperand.h
+++ b/include/llvm/CodeGen/MachineOperand.h
@@ -390,11 +390,6 @@ public:
     IsEarlyClobber = Val;
   }
 
-  void setIsTied(bool Val = true) {
-    assert(isReg() && "Wrong MachineOperand accessor");
-    IsTied = Val;
-  }
-
   void setIsDebug(bool Val = true) {
     assert(isReg() && IsDef && "Wrong MachineOperand accessor");
     IsDebug = Val;
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index ae205f6d10..5a395fddee 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -728,12 +728,8 @@ void MachineInstr::addOperand(const MachineOperand &Op) {
       // Set the IsTied bit if MC indicates this use is tied to a def.
       if (Operands[OpNo].isUse()) {
         int DefIdx = MCID->getOperandConstraint(OpNo, MCOI::TIED_TO);
-        if (DefIdx != -1) {
-          MachineOperand &DefMO = getOperand(DefIdx);
-          assert(DefMO.isDef() && "Use tied to operand that isn't a def");
-          DefMO.IsTied = true;
-          Operands[OpNo].IsTied = true;
-        }
+        if (DefIdx != -1)
+          tieOperands(DefIdx, OpNo);
       }
       // If the register operand is flagged as early, mark the operand as such.
       if (MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
@@ -1140,6 +1136,20 @@ int MachineInstr::findFirstPredOperandIdx() const {
   return -1;
 }
 
+/// Mark operands at DefIdx and UseIdx as tied to each other.
+void MachineInstr::tieOperands(unsigned DefIdx, unsigned UseIdx) {
+  assert(DefIdx < UseIdx && "Tied defs must precede the use");
+  MachineOperand &DefMO = getOperand(DefIdx);
+  MachineOperand &UseMO = getOperand(UseIdx);
+  assert(DefMO.isDef() && "DefIdx must be a def operand");
+  assert(UseMO.isUse() && "UseIdx must be a use operand");
+  assert(!DefMO.isTied() && "Def is already tied to another use");
+  assert(!UseMO.isTied() && "Use is already tied to another def");
+
+  DefMO.IsTied = true;
+  UseMO.IsTied = true;
+}
+
 /// Given the index of a tied register operand, find the operand it is tied to.
 /// Defs are tied to uses and vice versa. Returns the index of the tied operand
 /// which must exist.
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 5399a51557..46ddab0d76 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -945,12 +945,8 @@ EmitSpecialNode(SDNode *Node, bool IsClone, bool IsCloned,
           if (InlineAsm::isUseOperandTiedToDef(Flags, DefGroup)) {
             unsigned DefIdx = GroupIdx[DefGroup] + 1;
             unsigned UseIdx = GroupIdx.back() + 1;
-            for (unsigned j = 0; j != NumVals; ++j) {
-              assert(!MI->getOperand(DefIdx + j).isTied() &&
-                     "Def is already tied to another use");
-              MI->getOperand(DefIdx + j).setIsTied();
-              MI->getOperand(UseIdx + j).setIsTied();
-            }
+            for (unsigned j = 0; j != NumVals; ++j)
+              MI->tieOperands(DefIdx + j, UseIdx + j);
           }
         }
         break;