[CodeGen] Introduce MI flag for Live Range split instructionsusers/cdevadas/mi-flag-for-lr-split-insn

For some targets, it is required to identify the COPY instruction
corresponds to the RA inserted live range split. Adding the new
flag `MachineInstr::LRSplit` to serve the purpose.

2 files changed, 4 insertions, 1 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
index 4fcb7f36e023..c270e8d1fb38 100644
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -123,8 +123,9 @@ public:
     NoUSWrap = 1 << 20,      // Instruction supports geps
                              // no unsigned signed wrap.
     SameSign = 1 << 21,      // Both operands have the same sign.
-    InBounds = 1 << 22       // Pointer arithmetic remains inbounds.
+    InBounds = 1 << 22,      // Pointer arithmetic remains inbounds.
                              // Implies NoUSWrap.
+    LRSplit = 1 << 23        // Instruction for live range split.
   };
 
 private:
diff --git a/llvm/lib/CodeGen/SplitKit.cpp b/llvm/lib/CodeGen/SplitKit.cpp
index f9ecb2c97b2e..589b9ca39d63 100644
--- a/llvm/lib/CodeGen/SplitKit.cpp
+++ b/llvm/lib/CodeGen/SplitKit.cpp
@@ -531,6 +531,7 @@ SlotIndex SplitEditor::buildSingleSubRegCopy(
               | getInternalReadRegState(!FirstCopy), SubIdx)
       .addReg(FromReg, 0, SubIdx);
 
+  CopyMI->setFlag(MachineInstr::LRSplit);
   SlotIndexes &Indexes = *LIS.getSlotIndexes();
   if (FirstCopy) {
     Def = Indexes.insertMachineInstrInMaps(*CopyMI, Late).getRegSlot();
@@ -550,6 +551,7 @@ SlotIndex SplitEditor::buildCopy(Register FromReg, Register ToReg,
     // The full vreg is copied.
     MachineInstr *CopyMI =
         BuildMI(MBB, InsertBefore, DebugLoc(), Desc, ToReg).addReg(FromReg);
+    CopyMI->setFlag(MachineInstr::LRSplit);
     return Indexes.insertMachineInstrInMaps(*CopyMI, Late).getRegSlot();
   }