LiveIntervalAnalysis: Factor out code to update liveness on vreg def removal

This cleans up code and is more in line with the general philosophy of
modifying LiveIntervals through LiveIntervalAnalysis instead of changing
them directly.

This also fixes a case where SplitEditor::removeBackCopies() would miss
the subregister ranges.

llvm-svn: 226690

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 48daf2c..c03773f 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1375,3 +1375,17 @@ void LiveIntervals::removePhysRegDefAt(unsigned Reg, SlotIndex Pos) {
         LR->removeValNo(VNI);
   }
 }
+
+void LiveIntervals::removeVRegDefAt(LiveInterval &LI, SlotIndex Pos) {
+  VNInfo *VNI = LI.getVNInfoAt(Pos);
+  if (VNI == nullptr)
+    return;
+  LI.removeValNo(VNI);
+
+  // Also remove the value in subranges.
+  for (LiveInterval::SubRange &S : LI.subranges()) {
+    if (VNInfo *SVNI = S.getVNInfoAt(Pos))
+      S.removeValNo(SVNI);
+  }
+  LI.removeEmptySubRanges();
+}