[PATCH] D118124: [regalloc] Fix assertion error when LiveInterval is empty

[Wang Pengcheng via Phabricator via llvm-commits]

pcwang-thead created this revision.
pcwang-thead added reviewers: asb, craig.topper, jrtc27.
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When evicting interference, it causes an asseertion error
since LiveIntervals::intervalIsInOneMBB assumes that input
is not empty.

This patch fixed bug mentioned in D118020 <https://reviews.llvm.org/D118020>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118124

Files:
  llvm/lib/CodeGen/LiveIntervals.cpp
  llvm/lib/CodeGen/RegAllocGreedy.cpp


Index: llvm/lib/CodeGen/RegAllocGreedy.cpp
===================================================================
--- llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -497,7 +497,7 @@
   if (Matrix->checkInterference(VirtReg, PhysReg) > LiveRegMatrix::IK_VirtReg)
     return false;
 
-  bool IsLocal = LIS->intervalIsInOneMBB(VirtReg);
+  bool IsLocal = VirtReg.empty() || LIS->intervalIsInOneMBB(VirtReg);
 
   // Find VirtReg's cascade number. This will be unassigned if VirtReg was never
   // involved in an eviction before. If a cascade number was assigned, deny
Index: llvm/lib/CodeGen/LiveIntervals.cpp
===================================================================
--- llvm/lib/CodeGen/LiveIntervals.cpp
+++ llvm/lib/CodeGen/LiveIntervals.cpp
@@ -827,6 +827,8 @@
 
 MachineBasicBlock*
 LiveIntervals::intervalIsInOneMBB(const LiveInterval &LI) const {
+  assert(!LI.empty() && "LiveInterval is empty.");
+
   // A local live range must be fully contained inside the block, meaning it is
   // defined and killed at instructions, not at block boundaries. It is not
   // live in or out of any block.


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