Skip a binary search when possible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129293 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/SlotIndexes.h b/include/llvm/CodeGen/SlotIndexes.h
index dc247132c8f238f7a478e148caa3948b070e837e..7bbb7521e54a7ed3d697ea03f55b145f4af1aae2 100644 (file)
--- a/include/llvm/CodeGen/SlotIndexes.h
+++ b/include/llvm/CodeGen/SlotIndexes.h
@@ -545,6 +545,8 @@ namespace llvm {
 
     /// Returns the basic block which the given index falls in.
     MachineBasicBlock* getMBBFromIndex(SlotIndex index) const {
+      if (MachineInstr *MI = getInstructionFromIndex(index))
+        return MI->getParent();
       SmallVectorImpl<IdxMBBPair>::const_iterator I =
         std::lower_bound(idx2MBBMap.begin(), idx2MBBMap.end(), index);
       // Take the pair containing the index