[llvm] 8f66f25 - [RDA] Avoid negative shift UB

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2020-04-09T09:47:15+02:00
New Revision: 8f66f25f52f9b4089d216a33283acdb87ea3c250

URL: https://github.com/llvm/llvm-project/commit/8f66f25f52f9b4089d216a33283acdb87ea3c250
DIFF: https://github.com/llvm/llvm-project/commit/8f66f25f52f9b4089d216a33283acdb87ea3c250.diff

LOG: [RDA] Avoid negative shift UB

Avoid "left shift of negative value -1" ubsan errors by casting
to uintptr_t before performing the shift, rather than after.

Added: 
    

Modified: 
    llvm/include/llvm/CodeGen/ReachingDefAnalysis.h

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h b/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h
index f0f6ab0d7e1b..1444d4c295af 100644
--- a/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h
+++ b/llvm/include/llvm/CodeGen/ReachingDefAnalysis.h
@@ -44,7 +44,7 @@ class ReachingDef {
 
 public:
   ReachingDef(std::nullptr_t) : Encoded(0) {}
-  ReachingDef(int Instr) : Encoded((Instr << 2) | 2) {}
+  ReachingDef(int Instr) : Encoded(((uintptr_t) Instr << 2) | 2) {}
   operator int() const { return ((int) Encoded) >> 2; }
 };