Update LiveDebugVariables after live range splitting.

After a virtual register is split, update any debug user variables that resided
in the old register. This ensures that the LiveDebugVariables are still correct
after register allocation.

This may create DBG_VALUE instructions that place a user variable in a register
in parts of the function and in a stack slot in other parts. DwarfDebug
currently doesn't support that.

llvm-svn: 130998

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/LiveDebugVariables.h b/llvm/lib/CodeGen/LiveDebugVariables.h
index a6e40a19845..3ce3c398bd4 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.h
+++ b/llvm/lib/CodeGen/LiveDebugVariables.h
@@ -21,10 +21,12 @@
 #ifndef LLVM_CODEGEN_LIVEDEBUGVARIABLES_H
 #define LLVM_CODEGEN_LIVEDEBUGVARIABLES_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 
 namespace llvm {
 
+class LiveInterval;
 class VirtRegMap;
 
 class LiveDebugVariables : public MachineFunctionPass {
@@ -42,6 +44,11 @@ public:
   ///               register.
   void renameRegister(unsigned OldReg, unsigned NewReg, unsigned SubIdx);
 
+  /// splitRegister - Move any user variables in OldReg to the live ranges in
+  /// NewRegs where they are live. Mark the values as unavailable where no new
+  /// register is live.
+  void splitRegister(unsigned OldReg, ArrayRef<LiveInterval*> NewRegs);
+
   /// emitDebugValues - Emit new DBG_VALUE instructions reflecting the changes
   /// that happened during register allocation.
   /// @param VRM Rename virtual registers according to map.