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.

llvm-svn: 206856

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp b/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
index c2337bebe3b..bc3722eb9d4 100644
--- a/llvm/lib/Analysis/BlockFrequencyInfoImpl.cpp
+++ b/llvm/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.