Replace a big gob of old coalescer logic with the new CoalescerPair class.

CoalescerPair can determine if a copy can be coalesced, and which register gets
merged away. The old logic in SimpleRegisterCoalescing had evolved into
something a bit too convoluted.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106701 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 18 insertions, 5 deletions

diff --git a/include/llvm/CodeGen/LiveIntervalAnalysis.h b/include/llvm/CodeGen/LiveIntervalAnalysis.h
index 32fa70970d..8f4de3f026 100644
--- a/include/llvm/CodeGen/LiveIntervalAnalysis.h
+++ b/include/llvm/CodeGen/LiveIntervalAnalysis.h
@@ -133,10 +133,9 @@ namespace llvm {
     bool conflictsWithPhysReg(const LiveInterval &li, VirtRegMap &vrm,
                               unsigned reg);
 
-    /// conflictsWithSubPhysRegRef - Similar to conflictsWithPhysRegRef except
-    /// it checks for sub-register reference and it can check use as well.
-    bool conflictsWithSubPhysRegRef(LiveInterval &li, unsigned Reg,
-                                    bool CheckUse,
+    /// conflictsWithAliasRef - Similar to conflictsWithPhysRegRef except
+    /// it checks for alias uses and defs.
+    bool conflictsWithAliasRef(LiveInterval &li, unsigned Reg,
                                    SmallPtrSet<MachineInstr*,32> &JoinedCopies);
 
     // Interval creation
diff --git a/include/llvm/CodeGen/RegisterCoalescer.h b/include/llvm/CodeGen/RegisterCoalescer.h
index e3d3e79633..7aec10ccb3 100644
--- a/include/llvm/CodeGen/RegisterCoalescer.h
+++ b/include/llvm/CodeGen/RegisterCoalescer.h
@@ -165,9 +165,15 @@ namespace llvm {
     /// virtual register.
     unsigned subIdx_;
 
+    /// origDstReg_ - dstReg_ without subreg adjustments.
+    unsigned origDstReg_;
+
     /// partial_ - True when the original copy was a partial subregister copy.
     bool partial_;
 
+    /// crossClass_ - True when both regs are virtual, and newRC is constrained.
+    bool crossClass_;
+
     /// flipped_ - True when DstReg and SrcReg are reversed from the oriignal copy
     /// instruction.
     bool flipped_;
@@ -186,7 +192,8 @@ namespace llvm {
   public:
     CoalescerPair(const TargetInstrInfo &tii, const TargetRegisterInfo &tri)
       : tii_(tii), tri_(tri), dstReg_(0), srcReg_(0), subIdx_(0),
-        partial_(false), flipped_(false), newRC_(0) {}
+        origDstReg_(0), partial_(false), crossClass_(false), flipped_(false),
+        newRC_(0) {}
 
     /// setRegisters - set registers to match the copy instruction MI. Return
     /// false if MI is not a coalescable copy instruction.
@@ -207,6 +214,9 @@ namespace llvm {
     /// full register, but was a subreg operation.
     bool isPartial() const { return partial_; }
 
+    /// isCrossClass - Return true if DstReg is virtual and NewRC is a smaller register class than DstReg's.
+    bool isCrossClass() const { return crossClass_; }
+
     /// isFlipped - Return true when getSrcReg is the register being defined by
     /// the original copy instruction.
     bool isFlipped() const { return flipped_; }
@@ -222,6 +232,10 @@ namespace llvm {
     /// coalesced into, or 0.
     unsigned getSubIdx() const { return subIdx_; }
 
+    /// getOrigDstReg - Return DstReg as it appeared in the original copy
+    /// instruction before any subreg adjustments.
+    unsigned getOrigDstReg() const { return isPhys() ? origDstReg_ : dstReg_; }
+
     /// getNewRC - Return the register class of the coalesced register.
     const TargetRegisterClass *getNewRC() const { return newRC_; }
   };