Auto-compute live intervals on demand.

When new virtual registers are created during splitting/spilling, defer
creation of the live interval until we need to use the live interval.

Along with the recent commits to notify LiveRangeEdit when new virtual
registers are created, this makes it possible for functions like
TargetInstrInfo::loadRegFromStackSlot() and
TargetInstrInfo::storeRegToStackSlot() to create multiple virtual
registers as part of the process of generating loads/stores for
different register classes, and then have the live intervals for those
new registers computed when they are needed.

llvm-svn: 188437

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/StrongPHIElimination.cpp b/llvm/lib/CodeGen/StrongPHIElimination.cpp
index b337c539334..d8b287f737a 100644
--- a/llvm/lib/CodeGen/StrongPHIElimination.cpp
+++ b/llvm/lib/CodeGen/StrongPHIElimination.cpp
@@ -772,7 +772,7 @@ void StrongPHIElimination::InsertCopiesForPHI(MachineInstr *PHI,
 
   // Add the region from the beginning of MBB to the copy instruction to
   // CopyReg's live interval, and give the VNInfo the phidef flag.
-  LiveInterval &CopyLI = LI->getOrCreateInterval(CopyReg);
+  LiveInterval &CopyLI = LI->createEmptyInterval(CopyReg);
   SlotIndex MBBStartIndex = LI->getMBBStartIdx(MBB);
   SlotIndex DestCopyIndex = LI->getInstructionIndex(CopyInstr);
   VNInfo *CopyVNI = CopyLI.getNextValue(MBBStartIndex,
@@ -783,7 +783,7 @@ void StrongPHIElimination::InsertCopiesForPHI(MachineInstr *PHI,
 
   // Adjust DestReg's live interval to adjust for its new definition at
   // CopyInstr.
-  LiveInterval &DestLI = LI->getOrCreateInterval(DestReg);
+  LiveInterval &DestLI = LI->createEmptyInterval(DestReg);
   SlotIndex PHIIndex = LI->getInstructionIndex(PHI);
   DestLI.removeRange(PHIIndex.getRegSlot(), DestCopyIndex.getRegSlot());