blockfreq: Implement clear() explicitly

This was implicitly with copy assignment before, which fails to actually
clear `std::vector<>`'s heap storage.  Move assignment would work, but
since MSVC can't imply those anyway, explicitly `clear()`-ing members
makes more sense.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206856 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/BlockFrequencyInfoImpl.cpp b/lib/Analysis/BlockFrequencyInfoImpl.cpp
index c2337bebe3bde587c9993ee155d27fa0b565d8de..bc3722eb9d4e78f186965e9cecac5f4d38652dc5 100644 (file)
--- a/lib/Analysis/BlockFrequencyInfoImpl.cpp
+++ b/lib/Analysis/BlockFrequencyInfoImpl.cpp
@@ -598,7 +598,11 @@ void Distribution::normalize() {
 }
 
 void BlockFrequencyInfoImplBase::clear() {
-  *this = BlockFrequencyInfoImplBase();
+  // Swap with a default-constructed std::vector, since std::vector<>::clear()
+  // does not actually clear heap storage.
+  std::vector<FrequencyData>().swap(Freqs);
+  std::vector<WorkingData>().swap(Working);
+  std::vector<LoopData>().swap(PackagedLoops);
 }
 
 /// \brief Clear all memory not needed downstream.