[llvm] 01df04f - [ADT] Reduce the requirements for the simple loop in DenseMap::clear

[Benjamin Kramer via llvm-commits]

Author: Benjamin Kramer
Date: 2020-04-13T19:33:45+02:00
New Revision: 01df04fb5984558d217c7b0cdd4bad67e2c5e5d3

URL: https://github.com/llvm/llvm-project/commit/01df04fb5984558d217c7b0cdd4bad67e2c5e5d3
DIFF: https://github.com/llvm/llvm-project/commit/01df04fb5984558d217c7b0cdd4bad67e2c5e5d3.diff

LOG: [ADT] Reduce the requirements for the simple loop in DenseMap::clear

We can use it when just the value doesn't require destruction. Empty
keys are safe to overwrite always. This gets the important case of
std::pair values.

Added: 
    

Modified: 
    llvm/include/llvm/ADT/DenseMap.h

Removed: 
    


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diff  --git a/llvm/include/llvm/ADT/DenseMap.h b/llvm/include/llvm/ADT/DenseMap.h
index 8d83f7e5507f..df4f02024344 100644
--- a/llvm/include/llvm/ADT/DenseMap.h
+++ b/llvm/include/llvm/ADT/DenseMap.h
@@ -119,9 +119,8 @@ class DenseMapBase : public DebugEpochBase {
     }
 
     const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
-    if (is_trivially_copyable<KeyT>::value &&
-        is_trivially_copyable<ValueT>::value) {
-      // Use a simpler loop when these are trivial types.
+    if (std::is_trivially_destructible<ValueT>::value) {
+      // Use a simpler loop when values don't need destruction.
       for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P)
         P->getFirst() = EmptyKey;
     } else {