Fix PR10277.

Remat during spilling triggers dead code elimination. If a phi-def
becomes unused, that may also cause live ranges to split into separate
connected components.

This type of splitting is different from normal live range splitting. In
particular, there may not be a common original interval.

When the split range is its own original, make sure that the new
siblings are also their own originals. The range being split cannot be
used as an original since it doesn't cover the new siblings.

llvm-svn: 134413

2 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/InlineSpiller.cpp b/llvm/lib/CodeGen/InlineSpiller.cpp
index 0273891d690..4bd35c3812a 100644
--- a/llvm/lib/CodeGen/InlineSpiller.cpp
+++ b/llvm/lib/CodeGen/InlineSpiller.cpp
@@ -425,6 +425,7 @@ void InlineSpiller::analyzeSiblingValues() {
       // Check possible sibling copies.
       if (VNI->isPHIDef() || VNI->getCopy()) {
         VNInfo *OrigVNI = OrigLI.getVNInfoAt(VNI->def);
+        assert(OrigVNI && "Def outside original live range");
         if (OrigVNI->def != VNI->def)
           DefMI = traceSiblingValue(Reg, VNI, OrigVNI);
       }
diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index 052abad57e1..b385fb36bbf 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -298,10 +298,16 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
     if (NumComp <= 1)
       continue;
     ++NumFracRanges;
+    bool IsOriginal = VRM.getOriginal(LI->reg) == LI->reg;
     DEBUG(dbgs() << NumComp << " components: " << *LI << '\n');
     SmallVector<LiveInterval*, 8> Dups(1, LI);
     for (unsigned i = 1; i != NumComp; ++i) {
       Dups.push_back(&createFrom(LI->reg, LIS, VRM));
+      // If LI is an original interval that hasn't been split yet, make the new
+      // intervals their own originals instead of referring to LI. The original
+      // interval must contain all the split products, and LI doesn't.
+      if (IsOriginal)
+        VRM.setIsSplitFromReg(Dups.back()->reg, 0);
       if (delegate_)
         delegate_->LRE_DidCloneVirtReg(Dups.back()->reg, LI->reg);
     }