[BumpPtrAllocator] Move DefaultSlabAllocator to a member of BumpPtrAllocator,...

[BumpPtrAllocator] Move DefaultSlabAllocator to a member of BumpPtrAllocator, instead of a static variable.

The problem with having DefaultSlabAllocator being a global static is that it is undefined if BumpPtrAllocator
will be usable during global initialization because it is not guaranteed that DefaultSlabAllocator will be
initialized before BumpPtrAllocator is created and used.

llvm-svn: 189433

llvm/include/llvm/Support/Allocator.h

@@ -99,6 +99,9 @@ class BumpPtrAllocator {
   /// allocate a separate slab.
   size_t SizeThreshold;
 
+  /// \brief the default allocator used if one is not provided
+  MallocSlabAllocator DefaultSlabAllocator;
+
   /// Allocator - The underlying allocator we use to get slabs of memory.  This
   /// defaults to MallocSlabAllocator, which wraps malloc, but it could be
   /// changed to use a custom allocator.
@@ -133,12 +136,10 @@ class BumpPtrAllocator {
   /// one.
   void DeallocateSlabs(MemSlab *Slab);
 
-  static MallocSlabAllocator DefaultSlabAllocator;
-
   template<typename T> friend class SpecificBumpPtrAllocator;
 public:
-  BumpPtrAllocator(size_t size = 4096, size_t threshold = 4096,
-                   SlabAllocator &allocator = DefaultSlabAllocator);
+  BumpPtrAllocator(size_t size = 4096, size_t threshold = 4096);
+  BumpPtrAllocator(size_t size, size_t threshold, SlabAllocator &allocator);
   ~BumpPtrAllocator();
 
   /// Reset - Deallocate all but the current slab and reset the current pointer
@@ -189,8 +190,10 @@ template <typename T>
 class SpecificBumpPtrAllocator {
   BumpPtrAllocator Allocator;
 public:
-  SpecificBumpPtrAllocator(size_t size = 4096, size_t threshold = 4096,
-              SlabAllocator &allocator = BumpPtrAllocator::DefaultSlabAllocator)
+  SpecificBumpPtrAllocator(size_t size = 4096, size_t threshold = 4096)
+    : Allocator(size, threshold) {}
+  SpecificBumpPtrAllocator(size_t size, size_t threshold,
+                           SlabAllocator &allocator)
     : Allocator(size, threshold, allocator) {}
 
   ~SpecificBumpPtrAllocator() {

llvm/lib/Support/Allocator.cpp

@@ -26,6 +26,10 @@ BumpPtrAllocator::BumpPtrAllocator(size_t size, size_t threshold,
     : SlabSize(size), SizeThreshold(std::min(size, threshold)),
       Allocator(allocator), CurSlab(0), BytesAllocated(0) { }
 
+BumpPtrAllocator::BumpPtrAllocator(size_t size, size_t threshold)
+    : SlabSize(size), SizeThreshold(std::min(size, threshold)),
+      Allocator(DefaultSlabAllocator), CurSlab(0), BytesAllocated(0) { }
+
 BumpPtrAllocator::~BumpPtrAllocator() {
   DeallocateSlabs(CurSlab);
 }
@@ -167,9 +171,6 @@ void BumpPtrAllocator::PrintStats() const {
          << " (includes alignment, etc)\n";
 }
 
-MallocSlabAllocator BumpPtrAllocator::DefaultSlabAllocator =
-  MallocSlabAllocator();
-
 SlabAllocator::~SlabAllocator() { }
 
 MallocSlabAllocator::~MallocSlabAllocator() { }