[llvm] r290768 - [LVI] Remove count/erase idiom in favor of checking result value of erase

[Philip Reames via llvm-commits]

Author: reames
Date: Fri Dec 30 16:09:10 2016
New Revision: 290768

URL: http://llvm.org/viewvc/llvm-project?rev=290768&view=rev
Log:
[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.


Modified:
    llvm/trunk/lib/Analysis/LazyValueInfo.cpp

Modified: llvm/trunk/lib/Analysis/LazyValueInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LazyValueInfo.cpp?rev=290768&r1=290767&r2=290768&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LazyValueInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/LazyValueInfo.cpp Fri Dec 30 16:09:10 2016
@@ -462,8 +462,7 @@ void LazyValueInfoCache::eraseValue(Valu
   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(
 
     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;