Add the ability to "intern" FoldingSetNodeID data into a

BumpPtrAllocator-allocated region to allow it to be stored in a more
compact form and to avoid the need for a non-trivial destructor call.

Use this new mechanism in ScalarEvolution instead of
FastFoldingSetNode to avoid leaking memory in the case where a
FoldingSetNodeID uses heap storage, and to reduce overall memory
usage.

llvm-svn: 98829

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Support/FoldingSet.cpp b/llvm/lib/Support/FoldingSet.cpp
index 954dc77dff1..3f467fe1b69 100644
--- a/llvm/lib/Support/FoldingSet.cpp
+++ b/llvm/lib/Support/FoldingSet.cpp
@@ -15,6 +15,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/FoldingSet.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
 #include <cassert>
@@ -130,6 +131,15 @@ bool FoldingSetNodeID::operator==(const FoldingSetNodeID &RHS)const{
   return memcmp(&Bits[0], &RHS.Bits[0], Bits.size()*sizeof(Bits[0])) == 0;
 }
 
+/// Intern - Copy this node's data to a memory region allocated from the
+/// given allocator and return a FoldingSetNodeIDRef describing the
+/// interned data.
+FoldingSetNodeIDRef
+FoldingSetNodeID::Intern(BumpPtrAllocator &Allocator) const {
+  unsigned *New = Allocator.Allocate<unsigned>(Bits.size());
+  std::uninitialized_copy(Bits.begin(), Bits.end(), New);
+  return FoldingSetNodeIDRef(New, Bits.size());
+}
 
 //===----------------------------------------------------------------------===//
 /// Helper functions for FoldingSetImpl.