RegisterPresssureTracker: Track live physical register by unit.

This is much simpler to reason about, more efficient, and
fixes some corner cases involving implicit super-register defs.
Fixed rdar://12797931.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169425 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 3 deletions

diff --git a/include/llvm/CodeGen/RegisterPressure.h b/include/llvm/CodeGen/RegisterPressure.h
index 20312be300..edff782f7b 100644
--- a/include/llvm/CodeGen/RegisterPressure.h
+++ b/include/llvm/CodeGen/RegisterPressure.h
@@ -30,7 +30,7 @@ struct RegisterPressure {
   /// Map of max reg pressure indexed by pressure set ID, not class ID.
   std::vector<unsigned> MaxSetPressure;
 
-  /// List of live in registers.
+  /// List of live in virtual registers or physical register units.
   SmallVector<unsigned,8> LiveInRegs;
   SmallVector<unsigned,8> LiveOutRegs;
 
@@ -39,10 +39,16 @@ struct RegisterPressure {
   /// to account for live through (global liveness).
   void increase(const TargetRegisterClass *RC, const TargetRegisterInfo *TRI);
 
+  /// Increase pressure for each pressure set impacted by this register unit.
+  void increase(unsigned RU, const TargetRegisterInfo *TRI);
+
   /// Decrease register pressure for each pressure set impacted by this register
   /// class. This is only useful to account for spilling or rematerialization.
   void decrease(const TargetRegisterClass *RC, const TargetRegisterInfo *TRI);
 
+  /// Decrease pressure for each pressure set impacted by this register unit.
+  void decrease(unsigned RU, const TargetRegisterInfo *TRI);
+
   void dump(const TargetRegisterInfo *TRI) const;
 };
 
@@ -172,8 +178,9 @@ public:
             const LiveIntervals *lis, const MachineBasicBlock *mbb,
             MachineBasicBlock::const_iterator pos);
 
-  /// Force liveness of registers. Particularly useful to initialize the
-  /// livein/out state of the tracker before the first call to advance/recede.
+  /// Force liveness of virtual registers or physical register
+  /// units. Particularly useful to initialize the livein/out state of the
+  /// tracker before the first call to advance/recede.
   void addLiveRegs(ArrayRef<unsigned> Regs);
 
   /// Get the MI position corresponding to this register pressure.