2 files changed, 17 insertions, 4 deletions
diff --git a/lib/Support/Allocator.cpp b/lib/Support/Allocator.cpp
index 215b0f249d..8bb07405ec 100644
--- a/lib/Support/Allocator.cpp
+++ b/lib/Support/Allocator.cpp
@@ -87,15 +87,21 @@ void BumpPtrAllocator::Reset() {
 /// Allocate - Allocate space at the specified alignment.
 ///
 void *BumpPtrAllocator::Allocate(size_t Size, size_t Alignment) {
+  // 0-byte alignment means 1-byte alignment.
+  if (Alignment == 0) Alignment = 1;
+
+  size_t PaddedSize = Size + sizeof(MemSlab) + Alignment - 1;
+
+  // If requested size exceeds slab size, increase slab size.
+  while (PaddedSize > SlabSize)
+    SlabSize *= 2;
+
   if (!CurSlab) // Start a new slab if we haven't allocated one already.
     StartNewSlab();
 
   // Keep track of how many bytes we've allocated.
   BytesAllocated += Size;
 
-  // 0-byte alignment means 1-byte alignment.
-  if (Alignment == 0) Alignment = 1;
-
   // Allocate the aligned space, going forwards from CurPtr.
   char *Ptr = AlignPtr(CurPtr, Alignment);
 
@@ -106,7 +112,6 @@ void *BumpPtrAllocator::Allocate(size_t Size, size_t Alignment) {
   }
 
   // If Size is really big, allocate a separate slab for it.
-  size_t PaddedSize = Size + sizeof(MemSlab) + Alignment - 1;
   if (PaddedSize > SizeThreshold) {
     MemSlab *NewSlab = Allocator.Allocate(PaddedSize);
 
diff --git a/unittests/Support/AllocatorTest.cpp b/unittests/Support/AllocatorTest.cpp
index 6c0fca9045..bc5bd3dc40 100644
--- a/unittests/Support/AllocatorTest.cpp
+++ b/unittests/Support/AllocatorTest.cpp
@@ -93,6 +93,14 @@ TEST(AllocatorTest, TestOverflow) {
   EXPECT_EQ(2U, Alloc.GetNumSlabs());
 }
 
+// Test allocating with a size larger than the initial slab size.
+TEST(AllocatorTest, TestSmallSlabSize) {
+  BumpPtrAllocator Alloc(128);
+
+  Alloc.Allocate(200, 0);
+  EXPECT_EQ(1U, Alloc.GetNumSlabs());
+}
+
 // Mock slab allocator that returns slabs aligned on 4096 bytes.  There is no
 // easy portable way to do this, so this is kind of a hack.
 class MockSlabAllocator : public SlabAllocator {