[llvm] [ADT] DenseMapInfo<unsigned long>::getHashValue - avoid MSVC out of bounds shift warning (PR #96173)

via llvm-commits llvm-commits at lists.llvm.org
Thu Jun 20 04:38:43 PDT 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-adt

Author: Simon Pilgrim (RKSimon)

<details>
<summary>Changes</summary>

Fixes MSVC warning after #<!-- -->95734 - despite it taking the `sizeof(Val) == 4` path, it still warns that the 32-bit unsigned long shift by 32 is out of bounds, so avoid it by converting the hard coded shift amount to be based off sizeof() instead.

---
Full diff: https://github.com/llvm/llvm-project/pull/96173.diff


1 Files Affected:

- (modified) llvm/include/llvm/ADT/DenseMapInfo.h (+1-1) 


``````````diff
diff --git a/llvm/include/llvm/ADT/DenseMapInfo.h b/llvm/include/llvm/ADT/DenseMapInfo.h
index 4f0aaa1ad48bb..3d83a2c1473f5 100644
--- a/llvm/include/llvm/ADT/DenseMapInfo.h
+++ b/llvm/include/llvm/ADT/DenseMapInfo.h
@@ -142,7 +142,7 @@ template<> struct DenseMapInfo<unsigned long> {
     if constexpr (sizeof(Val) == 4)
       return DenseMapInfo<unsigned>::getHashValue(Val);
     else
-      return detail::combineHashValue(Val >> 32, Val);
+      return detail::combineHashValue(Val >> (4 * sizeof(Val)), Val);
   }
 
   static bool isEqual(const unsigned long& LHS, const unsigned long& RHS) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/96173


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