Use VirtRegMap's Virt2SplitMap to keep track of the original live range before splitting.

All new virtual registers created for spilling or splitting point back to their original.

llvm-svn: 125980

1 files changed, 7 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index 3c7d9f66e74..e23f3828343 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -19,12 +19,18 @@
 
 using namespace llvm;
 
+unsigned LiveRangeEdit::getOriginal(const VirtRegMap &vrm) const {
+  unsigned Orig = vrm.getPreSplitReg(getReg());
+  return Orig ? Orig : getReg();
+}
+
 LiveInterval &LiveRangeEdit::create(MachineRegisterInfo &mri,
                                     LiveIntervals &lis,
                                     VirtRegMap &vrm) {
-  const TargetRegisterClass *RC = mri.getRegClass(parent_.reg);
+  const TargetRegisterClass *RC = mri.getRegClass(getReg());
   unsigned VReg = mri.createVirtualRegister(RC);
   vrm.grow();
+  vrm.setIsSplitFromReg(VReg, getOriginal(vrm));
   LiveInterval &li = lis.getOrCreateInterval(VReg);
   newRegs_.push_back(&li);
   return li;