- assert(getOperand(DefOpIdx).isDef() && "DefOpIdx is not a def!");
- const MCInstrDesc &MCID = getDesc();
- for (unsigned i = 0, e = MCID.getNumOperands(); i != e; ++i) {
- const MachineOperand &MO = getOperand(i);
- if (MO.isReg() && MO.isUse() &&
- MCID.getOperandConstraint(i, MCOI::TIED_TO) == (int)DefOpIdx) {
- if (UseOpIdx)
- *UseOpIdx = (unsigned)i;
- return true;
+/// tieOperands - Mark operands at DefIdx and UseIdx as tied to each other.
+///
+/// Use and def operands can be tied together, indicated by a non-zero TiedTo
+/// field. TiedTo can have these values:
+///
+/// 0: Operand is not tied to anything.
+/// 1 to TiedMax-1: Tied to getOperand(TiedTo-1).
+/// TiedMax: Tied to an operand >= TiedMax-1.
+///
+/// The tied def must be one of the first TiedMax operands on a normal
+/// instruction. INLINEASM instructions allow more tied defs.
+///
+void MachineInstr::tieOperands(unsigned DefIdx, unsigned UseIdx) {
+ 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");
+
+ if (DefIdx < TiedMax)
+ UseMO.TiedTo = DefIdx + 1;
+ else {
+ // Inline asm can use the group descriptors to find tied operands, but on
+ // normal instruction, the tied def must be within the first TiedMax
+ // operands.
+ assert(isInlineAsm() && "DefIdx out of range");
+ UseMO.TiedTo = TiedMax;
+ }
+
+ // UseIdx can be out of range, we'll search for it in findTiedOperandIdx().
+ DefMO.TiedTo = std::min(UseIdx + 1, TiedMax);
+}
+
+/// 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.
+unsigned MachineInstr::findTiedOperandIdx(unsigned OpIdx) const {
+ const MachineOperand &MO = getOperand(OpIdx);
+ assert(MO.isTied() && "Operand isn't tied");
+
+ // Normally TiedTo is in range.
+ if (MO.TiedTo < TiedMax)
+ return MO.TiedTo - 1;
+
+ // Uses on normal instructions can be out of range.
+ if (!isInlineAsm()) {
+ // Normal tied defs must be in the 0..TiedMax-1 range.
+ if (MO.isUse())
+ return TiedMax - 1;
+ // MO is a def. Search for the tied use.
+ for (unsigned i = TiedMax - 1, e = getNumOperands(); i != e; ++i) {
+ const MachineOperand &UseMO = getOperand(i);
+ if (UseMO.isReg() && UseMO.isUse() && UseMO.TiedTo == OpIdx + 1)
+ return i;