[PATCH] D23302: LiveIntervalAnalysis: add an assertion in repairOldRegInRange

[Nicolai Hähnle via llvm-commits]

nhaehnle created this revision.
nhaehnle added reviewers: MatzeB, kparzysz.
nhaehnle added a subscriber: llvm-commits.
Herald added a subscriber: MatzeB.

This is triggered by a test case I have, which otherwise leads to
non-deterministic crashes making it rather harder to even
bugpoint-reduce...

https://reviews.llvm.org/D23302

Files:
  lib/CodeGen/LiveIntervalAnalysis.cpp

Index: lib/CodeGen/LiveIntervalAnalysis.cpp
===================================================================
--- lib/CodeGen/LiveIntervalAnalysis.cpp
+++ lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1398,8 +1398,10 @@
   SlotIndex lastUseIdx;
   if (LII != LR.end() && LII->start < endIdx)
     lastUseIdx = LII->end;
-  else
+  else {
+    assert(LII != LR.begin());
     --LII;
+  }
 
   for (MachineBasicBlock::iterator I = End; I != Begin;) {
     --I;


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