1 files changed, 23 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/TargetRegisterInfo.cpp b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
index 5db1c58..8b5cd3e 100644
--- a/llvm/lib/CodeGen/TargetRegisterInfo.cpp
+++ b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
@@ -472,6 +472,29 @@ unsigned TargetRegisterInfo::getRegSizeInBits(unsigned Reg,
   return getRegSizeInBits(*RC);
 }
 
+unsigned
+TargetRegisterInfo::lookThruCopyLike(unsigned SrcReg,
+                                     const MachineRegisterInfo *MRI) const {
+  while (true) {
+    const MachineInstr *MI = MRI->getVRegDef(SrcReg);
+    if (!MI->isCopyLike())
+      return SrcReg;
+
+    unsigned CopySrcReg;
+    if (MI->isCopy())
+      CopySrcReg = MI->getOperand(1).getReg();
+    else {
+      assert(MI->isSubregToReg() && "Bad opcode for lookThruCopyLike");
+      CopySrcReg = MI->getOperand(2).getReg();
+    }
+
+    if (!isVirtualRegister(CopySrcReg))
+      return CopySrcReg;
+
+    SrcReg = CopySrcReg;
+  }
+}
+
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 LLVM_DUMP_METHOD
 void TargetRegisterInfo::dumpReg(unsigned Reg, unsigned SubRegIndex,