1 files changed, 78 insertions, 0 deletions
diff --git a/lib/AST/Interp/InterpStack.cpp b/lib/AST/Interp/InterpStack.cpp
new file mode 100644
index 000000000000..5c803f3d9424
--- /dev/null
+++ b/lib/AST/Interp/InterpStack.cpp
@@ -0,0 +1,78 @@
+//===--- InterpStack.cpp - Stack implementation for the VM ------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cassert>
+#include <cstdlib>
+#include "InterpStack.h"
+
+using namespace clang;
+using namespace clang::interp;
+
+InterpStack::~InterpStack() {
+  clear();
+}
+
+void InterpStack::clear() {
+  if (Chunk && Chunk->Next)
+    free(Chunk->Next);
+  if (Chunk)
+    free(Chunk);
+  Chunk = nullptr;
+  StackSize = 0;
+}
+
+void *InterpStack::grow(size_t Size) {
+  assert(Size < ChunkSize - sizeof(StackChunk) && "Object too large");
+
+  if (!Chunk || sizeof(StackChunk) + Chunk->size() + Size > ChunkSize) {
+    if (Chunk && Chunk->Next) {
+      Chunk = Chunk->Next;
+    } else {
+      StackChunk *Next = new (malloc(ChunkSize)) StackChunk(Chunk);
+      if (Chunk)
+        Chunk->Next = Next;
+      Chunk = Next;
+    }
+  }
+
+  auto *Object = reinterpret_cast<void *>(Chunk->End);
+  Chunk->End += Size;
+  StackSize += Size;
+  return Object;
+}
+
+void *InterpStack::peek(size_t Size) {
+  assert(Chunk && "Stack is empty!");
+
+  StackChunk *Ptr = Chunk;
+  while (Size > Ptr->size()) {
+    Size -= Ptr->size();
+    Ptr = Ptr->Prev;
+    assert(Ptr && "Offset too large");
+  }
+
+  return reinterpret_cast<void *>(Ptr->End - Size);
+}
+
+void InterpStack::shrink(size_t Size) {
+  assert(Chunk && "Chunk is empty!");
+
+  while (Size > Chunk->size()) {
+    Size -= Chunk->size();
+    if (Chunk->Next) {
+      free(Chunk->Next);
+      Chunk->Next = nullptr;
+    }
+    Chunk->End = Chunk->start();
+    Chunk = Chunk->Prev;
+    assert(Chunk && "Offset too large");
+  }
+
+  Chunk->End -= Size;
+  StackSize -= Size;
+}