misched: Fix RegisterPressureTracker handling of DebugVals.

Assertion failed: (TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker").
rdar://12790302.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169072 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 1 deletions

diff --git a/include/llvm/CodeGen/RegisterPressure.h b/include/llvm/CodeGen/RegisterPressure.h
index 30326d05df..cc9b1c4643 100644
--- a/include/llvm/CodeGen/RegisterPressure.h
+++ b/include/llvm/CodeGen/RegisterPressure.h
@@ -150,7 +150,8 @@ class RegPressureTracker {
   bool RequireIntervals;
 
   /// Register pressure corresponds to liveness before this instruction
-  /// iterator. It may point to the end of the block rather than an instruction.
+  /// iterator. It may point to the end of the block or a DebugValue rather than
+  /// an instruction.
   MachineBasicBlock::const_iterator CurrPos;
 
   /// Pressure map indexed by pressure set ID, not class ID.
@@ -184,6 +185,10 @@ public:
   // position changes while pressure does not.
   void setPos(MachineBasicBlock::const_iterator Pos) { CurrPos = Pos; }
 
+  /// \brief Get the SlotIndex for the first nondebug instruction including or
+  /// after the current position.
+  SlotIndex getCurrSlot() const;
+
   /// Recede across the previous instruction.
   bool recede();