[PATCH] D33084: [GISel]: Fix undefined behavior while accessing DefaultAction map

[Aditya Nandakumar via Phabricator via llvm-commits]

aditya_nandakumar created this revision.

We end up dereferencing the end iterator here when the Aspect doesn't exist in the DefaultAction map.
Check for end iterator.


Repository:
  rL LLVM

https://reviews.llvm.org/D33084

Files:
  include/llvm/CodeGen/GlobalISel/LegalizerInfo.h


Index: include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
===================================================================
--- include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
+++ include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
@@ -153,8 +153,12 @@
     do {
       Ty = NextType(Ty);
       auto ActionIt = Map.find(Ty);
-      if (ActionIt == Map.end())
-        Action = DefaultActions.find(Aspect.Opcode)->second;
+      if (ActionIt == Map.end()) {
+        auto DefaultIt = DefaultActions.find(Aspect.Opcode);
+        if (DefaultIt == DefaultActions.end())
+          return LLT();
+        Action = DefaultIt->second;
+      }
       else
         Action = ActionIt->second;
     } while(Action != Legal);


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