Cache the fairly expensive last split point computation and provide a fast

inlined path for the common case.

Most basic blocks don't contain a call that may throw, so the last split point
os simply the first terminator.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128874 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 4 deletions

diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index d735f1070b..bf936321d3 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -93,16 +93,20 @@ private:
   // Current live interval.
   const LiveInterval *CurLI;
 
+  /// LastSplitPoint - Last legal split point in each basic block in the current
+  /// function. The first entry is the first terminator, the second entry is the
+  /// last valid split point for a variable that is live in to a landing pad
+  /// successor.
+  SmallVector<std::pair<SlotIndex, SlotIndex>, 8> LastSplitPoint;
+
+  SlotIndex computeLastSplitPoint(unsigned Num);
+
   // Sumarize statistics by counting instructions using CurLI.
   void analyzeUses();
 
   /// calcLiveBlockInfo - Compute per-block information about CurLI.
   bool calcLiveBlockInfo();
 
-  /// canAnalyzeBranch - Return true if MBB ends in a branch that can be
-  /// analyzed.
-  bool canAnalyzeBranch(const MachineBasicBlock *MBB);
-
 public:
   SplitAnalysis(const VirtRegMap &vrm, const LiveIntervals &lis,
                 const MachineLoopInfo &mli);
@@ -118,6 +122,16 @@ public:
   /// getParent - Return the last analyzed interval.
   const LiveInterval &getParent() const { return *CurLI; }
 
+  /// getLastSplitPoint - Return that base index of the last valid split point
+  /// in the basic block numbered Num.
+  SlotIndex getLastSplitPoint(unsigned Num) {
+    // Inline the common simple case.
+    if (LastSplitPoint[Num].first.isValid() &&
+        !LastSplitPoint[Num].second.isValid())
+      return LastSplitPoint[Num].first;
+    return computeLastSplitPoint(Num);
+  }
+
   /// hasUses - Return true if MBB has any uses of CurLI.
   bool hasUses(const MachineBasicBlock *MBB) const {
     return UsingBlocks.lookup(MBB);