[Allocator] Make Deallocate() pass alignment and make it use (de)allocate_buffer

This lets it use sized deallocation and make more efficient alignment
decisions. Also adjust BumpPtrAllocator to always allocate at
alignof(std::max_align_t).

include/llvm/ADT/StringMapEntry.h

@@ -125,7 +125,8 @@ public:
     // Free memory referenced by the item.
     size_t AllocSize = sizeof(StringMapEntry) + this->getKeyLength() + 1;
     this->~StringMapEntry();
-    allocator.Deallocate(static_cast<void *>(this), AllocSize);
+    allocator.Deallocate(static_cast<void *>(this), AllocSize,
+                         alignof(StringMapEntry));
   }
 };
 

include/llvm/Support/Allocator.h

@@ -170,7 +170,7 @@ public:
     // If Size is really big, allocate a separate slab for it.
     size_t PaddedSize = SizeToAllocate + Alignment.value() - 1;
     if (PaddedSize > SizeThreshold) {
-      void *NewSlab = Allocator.Allocate(PaddedSize, 0);
+      void *NewSlab = Allocator.Allocate(PaddedSize, alignof(std::max_align_t));
       // We own the new slab and don't want anyone reading anyting other than
       // pieces returned from this method.  So poison the whole slab.
       __asan_poison_memory_region(NewSlab, PaddedSize);
@@ -208,7 +208,7 @@ public:
   // Bump pointer allocators are expected to never free their storage; and
   // clients expect pointers to remain valid for non-dereferencing uses even
   // after deallocation.
-  void Deallocate(const void *Ptr, size_t Size) {
+  void Deallocate(const void *Ptr, size_t Size, size_t /*Alignment*/) {
     __asan_poison_memory_region(Ptr, Size);
   }
 
@@ -332,7 +332,8 @@ private:
   void StartNewSlab() {
     size_t AllocatedSlabSize = computeSlabSize(Slabs.size());
 
-    void *NewSlab = Allocator.Allocate(AllocatedSlabSize, 0);
+    void *NewSlab =
+        Allocator.Allocate(AllocatedSlabSize, alignof(std::max_align_t));
     // We own the new slab and don't want anyone reading anything other than
     // pieces returned from this method.  So poison the whole slab.
     __asan_poison_memory_region(NewSlab, AllocatedSlabSize);
@@ -348,7 +349,7 @@ private:
     for (; I != E; ++I) {
       size_t AllocatedSlabSize =
           computeSlabSize(std::distance(Slabs.begin(), I));
-      Allocator.Deallocate(*I, AllocatedSlabSize);
+      Allocator.Deallocate(*I, AllocatedSlabSize, alignof(std::max_align_t));
     }
   }
 
@@ -357,7 +358,7 @@ private:
     for (auto &PtrAndSize : CustomSizedSlabs) {
       void *Ptr = PtrAndSize.first;
       size_t Size = PtrAndSize.second;
-      Allocator.Deallocate(Ptr, Size);
+      Allocator.Deallocate(Ptr, Size, alignof(std::max_align_t));
     }
   }
 
@@ -434,17 +435,8 @@ void *
 operator new(size_t Size,
              llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold,
                                         GrowthDelay> &Allocator) {
-  struct S {
-    char c;
-    union {
-      double D;
-      long double LD;
-      long long L;
-      void *P;
-    } x;
-  };
-  return Allocator.Allocate(
-      Size, std::min((size_t)llvm::NextPowerOf2(Size), offsetof(S, x)));
+  return Allocator.Allocate(Size, std::min((size_t)llvm::NextPowerOf2(Size),
+                                           alignof(std::max_align_t)));
 }
 
 template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold,

include/llvm/Support/AllocatorBase.h

@@ -48,16 +48,17 @@ public:
 
   /// Deallocate \a Ptr to \a Size bytes of memory allocated by this
   /// allocator.
-  void Deallocate(const void *Ptr, size_t Size) {
+  void Deallocate(const void *Ptr, size_t Size, size_t Alignment) {
 #ifdef __clang__
-    static_assert(static_cast<void (AllocatorBase::*)(const void *, size_t)>(
-                      &AllocatorBase::Deallocate) !=
-                      static_cast<void (DerivedT::*)(const void *, size_t)>(
-                          &DerivedT::Deallocate),
-                  "Class derives from AllocatorBase without implementing the "
-                  "core Deallocate(void *) overload!");
+    static_assert(
+        static_cast<void (AllocatorBase::*)(const void *, size_t, size_t)>(
+            &AllocatorBase::Deallocate) !=
+            static_cast<void (DerivedT::*)(const void *, size_t, size_t)>(
+                &DerivedT::Deallocate),
+        "Class derives from AllocatorBase without implementing the "
+        "core Deallocate(void *) overload!");
 #endif
-    return static_cast<DerivedT *>(this)->Deallocate(Ptr, Size);
+    return static_cast<DerivedT *>(this)->Deallocate(Ptr, Size, Alignment);
   }
 
   // The rest of these methods are helpers that redirect to one of the above
@@ -72,7 +73,7 @@ public:
   template <typename T>
   std::enable_if_t<!std::is_same<std::remove_cv_t<T>, void>::value, void>
   Deallocate(T *Ptr, size_t Num = 1) {
-    Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T));
+    Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T), alignof(T));
   }
 };
 
@@ -80,16 +81,15 @@ class MallocAllocator : public AllocatorBase<MallocAllocator> {
 public:
   void Reset() {}
 
-  LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size,
-                                                size_t /*Alignment*/) {
-    return safe_malloc(Size);
+  LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size, size_t Alignment) {
+    return allocate_buffer(Size, Alignment);
   }
 
   // Pull in base class overloads.
   using AllocatorBase<MallocAllocator>::Allocate;
 
-  void Deallocate(const void *Ptr, size_t /*Size*/) {
-    free(const_cast<void *>(Ptr));
+  void Deallocate(const void *Ptr, size_t Size, size_t Alignment) {
+    deallocate_buffer(const_cast<void *>(Ptr), Size, Alignment);
   }
 
   // Pull in base class overloads.

include/llvm/Support/YAMLParser.h

@@ -139,7 +139,7 @@ public:
 
   void operator delete(void *Ptr, BumpPtrAllocator &Alloc,
                        size_t Size) noexcept {
-    Alloc.Deallocate(Ptr, Size);
+    Alloc.Deallocate(Ptr, Size, 0);
   }
 
   void operator delete(void *) noexcept = delete;

unittests/ADT/StringMapTest.cpp

@@ -230,7 +230,7 @@ TEST_F(StringMapTest, StringMapEntryTest) {
           StringRef(testKeyFirst, testKeyLength), Allocator, 1u);
   EXPECT_STREQ(testKey, entry->first().data());
   EXPECT_EQ(1u, entry->second);
-  free(entry);
+  entry->Destroy(Allocator);
 }
 
 // Test insert() method.

unittests/Support/AllocatorTest.cpp

@@ -206,7 +206,7 @@ public:
     return Slab;
   }
 
-  void Deallocate(void *Slab, size_t Size) {
+  void Deallocate(void *Slab, size_t /*Size*/, size_t /*Alignment*/) {
     free(((void**)Slab)[-1]);
   }