[PATCH] D148218: [BOLT][NFC] Fix UB due to left shift of negative value

[Job Noorman via Phabricator via llvm-commits]

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The following test fails when enabling UBSan due to a left shift of a
negative value:

> runtime error: left shift of negative value -2



  BOLT :: AArch64/ext-island-ref.s

This patch fixes this by using a multiplication instead of a shift.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D148218

Files:
  bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp


Index: bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
===================================================================
--- bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
+++ bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
@@ -265,7 +265,7 @@
         return true;
       }
 
-      DispImm = Inst.getOperand(I).getImm() << 2;
+      DispImm = Inst.getOperand(I).getImm() * 4;
       return true;
     }
     return false;


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