[PATCH] D81632: Fix undefined behavior in PeepholeOptimizer.

[zuojian lin via Phabricator via llvm-commits]

linzj created this revision.
Herald added subscribers: llvm-commits, hiraditya.
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Caused by optimizeExtInstr function uses uninitialized SubIdx.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D81632

Files:
  llvm/lib/CodeGen/PeepholeOptimizer.cpp


Index: llvm/lib/CodeGen/PeepholeOptimizer.cpp
===================================================================
--- llvm/lib/CodeGen/PeepholeOptimizer.cpp
+++ llvm/lib/CodeGen/PeepholeOptimizer.cpp
@@ -458,7 +458,7 @@
 optimizeExtInstr(MachineInstr &MI, MachineBasicBlock &MBB,
                  SmallPtrSetImpl<MachineInstr*> &LocalMIs) {
   Register SrcReg, DstReg;
-  unsigned SubIdx;
+  unsigned SubIdx = 0;
   if (!TII->isCoalescableExtInstr(MI, SrcReg, DstReg, SubIdx))
     return false;
 


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