Add MachineInstr::tieOperands, remove setIsTied().

Manage tied operands entirely internally to MachineInstr. This makes it
possible to change the representation of tied operands, as I will do
shortly.

The constraint that tied uses and defs must be in the same order was too
restrictive.

llvm-svn: 163021

1 files changed, 16 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index ae205f6d106..5a395fddeed 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/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.