[LVI] Remove count/erase idiom in favor of checking result value of erase

Minor compile time win.  Avoids an additional O(N) scan in the case where we are removing an element and costs nothing when we aren't.

llvm-svn: 290768

1 files changed, 2 insertions, 6 deletions

diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index cd1f25090d6..4f635523687 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -462,8 +462,7 @@ void LazyValueInfoCache::eraseValue(Value *V) {
   SmallVector<AssertingVH<BasicBlock>, 4> ToErase;
   for (auto &I : OverDefinedCache) {
     SmallPtrSetImpl<Value *> &ValueSet = I.second;
-    if (ValueSet.count(V))
-      ValueSet.erase(V);
+    ValueSet.erase(V);
     if (ValueSet.empty())
       ToErase.push_back(I.first);
   }
@@ -533,12 +532,9 @@ void LazyValueInfoCache::threadEdgeImpl(BasicBlock *OldSucc,
 
     bool changed = false;
     for (Value *V : ValsToClear) {
-      // TODO: count and erase can be converted to a find/erase(itr) pattern
-      if (!ValueSet.count(V))
+      if (!ValueSet.erase(V))
         continue;
 
-      ValueSet.erase(V);
-
       // If we removed anything, then we potentially need to update
       // blocks successors too.
       changed = true;