2 files changed, 66 insertions, 0 deletions
diff --git a/include/llvm/CodeGen/MachineInstrBundle.h b/include/llvm/CodeGen/MachineInstrBundle.h
index f6525a827b..9552e21fca 100644
--- a/include/llvm/CodeGen/MachineInstrBundle.h
+++ b/include/llvm/CodeGen/MachineInstrBundle.h
@@ -107,6 +107,39 @@ public:
     advance();
   }
 
+  /// getOperandNo - Returns the number of the current operand relative to its
+  /// instruction.
+  ///
+  unsigned getOperandNo() const {
+    return OpI - InstrI->operands_begin();
+  }
+
+  /// RegInfo - Information about a virtual register used by a set of operands.
+  ///
+  struct RegInfo {
+    /// Reads - One of the operands read the virtual register.  This does not
+    /// include <undef> or <internal> use operands, see MO::readsReg().
+    bool Reads;
+
+    /// Writes - One of the operands writes the virtual register.
+    bool Writes;
+
+    /// Tied - Uses and defs must use the same register. This can be because of
+    /// a two-address constraint, or there may be a partial redefinition of a
+    /// sub-register.
+    bool Tied;
+  };
+
+  /// analyzeVirtReg - Analyze how the current instruction or bundle uses a
+  /// virtual register.  This function should not be called after operator++(),
+  /// it expects a fresh iterator.
+  ///
+  /// @param Reg The virtual register to analyze.
+  /// @param Ops When set, this vector will receive an (MI, OpNum) entry for
+  ///            each operand referring to Reg.
+  /// @returns A filled-in RegInfo struct.
+  RegInfo analyzeVirtReg(unsigned Reg,
+                 SmallVectorImpl<std::pair<MachineInstr*, unsigned> > *Ops = 0);
 };
 
 /// MIOperands - Iterate over operands of a single instruction.
diff --git a/lib/CodeGen/MachineInstrBundle.cpp b/lib/CodeGen/MachineInstrBundle.cpp
index d8b2b3a6ce..81d2abeb1d 100644
--- a/lib/CodeGen/MachineInstrBundle.cpp
+++ b/lib/CodeGen/MachineInstrBundle.cpp
@@ -241,3 +241,36 @@ bool llvm::finalizeBundles(MachineFunction &MF) {
 
   return Changed;
 }
+
+//===----------------------------------------------------------------------===//
+// MachineOperand iterator
+//===----------------------------------------------------------------------===//
+
+MachineOperandIteratorBase::RegInfo
+MachineOperandIteratorBase::analyzeVirtReg(unsigned Reg,
+                    SmallVectorImpl<std::pair<MachineInstr*, unsigned> > *Ops) {
+  RegInfo RI = { false, false, false };
+  for(; isValid(); ++*this) {
+    MachineOperand &MO = deref();
+    if (!MO.isReg() || MO.getReg() != Reg)
+      continue;
+
+    // Remember each (MI, OpNo) that refers to Reg.
+    if (Ops)
+      Ops->push_back(std::make_pair(MO.getParent(), getOperandNo()));
+
+    // Both defs and uses can read virtual registers.
+    if (MO.readsReg()) {
+      RI.Reads = true;
+      if (MO.isDef())
+        RI.Tied = true;
+    }
+
+    // Only defs can write.
+    if (MO.isDef())
+      RI.Writes = true;
+    else if (!RI.Tied && MO.getParent()->isRegTiedToDefOperand(getOperandNo()))
+      RI.Tied = true;
+  }
+  return RI;
+}