[IR] Avoid linear scan in MDNode::intersect() (NFC)

00940fb8544767ba5217922c4ba96677aabe9eb3 changed this code to
construct a set for the B metadata. However, it still performs a
linear is_contained query, rather than making use of the set
structure.

diff --git a/llvm/lib/IR/Metadata.cpp b/llvm/lib/IR/Metadata.cpp
index cdd544040f528eeb09f3be70e387acf6e11547cd..ce89009e86ebab386ade5d8b57acca05d63c42a0 100644 (file)
--- a/llvm/lib/IR/Metadata.cpp
+++ b/llvm/lib/IR/Metadata.cpp
@@ -914,7 +914,7 @@ MDNode *MDNode::intersect(MDNode *A, MDNode *B) {
 
   SmallSetVector<Metadata *, 4> MDs(A->op_begin(), A->op_end());
   SmallPtrSet<Metadata *, 4> BSet(B->op_begin(), B->op_end());
-  MDs.remove_if([&](Metadata *MD) { return !is_contained(BSet, MD); });
+  MDs.remove_if([&](Metadata *MD) { return !BSet.count(MD); });
 
   // FIXME: This preserves long-standing behaviour, but is it really the right
   // behaviour?  Or was that an unintended side-effect of node uniquing?