[llvm] [DebugNames] Use hashes to quickly filter false positives (PR #79755)

[Adrian Prantl via llvm-commits]

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@@ -937,9 +937,11 @@ DWARFDebugNames::ValueIterator::findEntryOffsetInCurrentIndex() {
     return std::nullopt; // Empty bucket
 
   for (; Index <= Hdr.NameCount; ++Index) {
-    uint32_t Hash = CurrentIndex->getHashArrayEntry(Index);
-    if (Hash % Hdr.BucketCount != Bucket)
+    uint32_t HashAtIndex = CurrentIndex->getHashArrayEntry(Index);
+    if (HashAtIndex % Hdr.BucketCount != Bucket)
       return std::nullopt; // End of bucket
+    if (HashAtIndex != Hash)
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adrian-prantl wrote:

Maybe add: `// Only do an expensive string comparison if the hashes match.`

https://github.com/llvm/llvm-project/pull/79755