Handle regmasks in findRegisterDefOperandIdx().

Only accept register masks when looking for an 'overlapping' def. When
Overlap is not set, the function searches for a proper definition of
Reg.

This means MI->modifiesRegister() considers register masks, but
MI->definesRegister() doesn't.

llvm-svn: 150529

llvm/include/llvm/CodeGen/MachineInstr.h

@@ -702,6 +702,7 @@ public:
   /// that are not dead are skipped. If Overlap is true, then it also looks for
   /// defs that merely overlap the specified register. If TargetRegisterInfo is
   /// non-null, then it also checks if there is a def of a super-register.
+  /// This may also return a register mask operand when Overlap is true.
   int findRegisterDefOperandIdx(unsigned Reg,
                                 bool isDead = false, bool Overlap = false,
                                 const TargetRegisterInfo *TRI = NULL) const;

llvm/lib/CodeGen/MachineInstr.cpp

@@ -1045,6 +1045,10 @@ MachineInstr::findRegisterDefOperandIdx(unsigned Reg, bool isDead, bool Overlap,
   bool isPhys = TargetRegisterInfo::isPhysicalRegister(Reg);
   for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
     const MachineOperand &MO = getOperand(i);
+    // Accept regmask operands when Overlap is set.
+    // Ignore them when looking for a specific def operand (Overlap == false).
+    if (isPhys && Overlap && MO.isRegMask() && MO.clobbersPhysReg(Reg))
+      return i;
     if (!MO.isReg() || !MO.isDef())
       continue;
     unsigned MOReg = MO.getReg();