[PATCH] D77584: [X86] Fix to X86LoadValueInjectionRetHardeningPass for possible segfault

[Scott Constable via Phabricator via llvm-commits]

sconstab created this revision.
sconstab added a reviewer: craig.topper.
Herald added a subscriber: hiraditya.

`MBB.back()` could segfault if `MBB.empty()`. Fixed by checking for `MBB.empty()` in the loop.


https://reviews.llvm.org/D77584

Files:
  llvm/lib/Target/X86/X86LoadValueInjectionRetHardening.cpp


Index: llvm/lib/Target/X86/X86LoadValueInjectionRetHardening.cpp
===================================================================
--- llvm/lib/Target/X86/X86LoadValueInjectionRetHardening.cpp
+++ llvm/lib/Target/X86/X86LoadValueInjectionRetHardening.cpp
@@ -99,6 +99,9 @@
 
   bool Modified = false;
   for (auto &MBB : MF) {
+    if (MBB.empty())
+      continue;
+
     MachineInstr &MI = MBB.back();
     if (MI.getOpcode() != X86::RETQ)
       continue;


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