Use a RAII class to track StackOverflowGuard depths

Summary:
`StackOverflowGuard` has two types of heuristics. If
`HERMES_CHECK_NATIVE_STACK` is defined, it will use real stack checking
using the current stack address. Otherwise, it will use a simple depth
count.

In the latter, users of the stack overflow guard are expected to check
for `HERMES_CHECK_NATIVE_STACK`, then increment/decrement the depth
count if necessary.

This change introduces a simple RAII class that will handle this and
makes it simpler to use.

Reviewed By: avp

Differential Revision: D82996952

fbshipit-source-id: d058403c1d86f1a3ca77a5dacc14115e6641b5ef

Author: tsaichien

include/hermes/Support/StackOverflowGuard.h

@@ -115,6 +115,23 @@ class StackOverflowGuard {
   inline bool isOverflowing() {
     return callDepth > maxCallDepth;
   }
+
+  class CallFrameRAII;
+};
+
+/// A simple RAII class to help users increment/decrement frame depth if
+/// necessary.
+class [[nodiscard]] StackOverflowGuard::CallFrameRAII {
+  StackOverflowGuard &guard_;
+
+ public:
+  explicit CallFrameRAII(StackOverflowGuard &guard) : guard_(guard) {
+    ++guard_.callDepth;
+  }
+
+  ~CallFrameRAII() {
+    --guard_.callDepth;
+  }
 };
 
 #endif

include/hermes/VM/Runtime.h

@@ -1733,20 +1733,21 @@ class ScopedNativeDepthTracker {
   Runtime &runtime_;
   /// Whether the stack overflowed when the tracker was constructed.
   bool overflowed_;
+#ifndef HERMES_CHECK_NATIVE_STACK
+  StackOverflowGuard::CallFrameRAII frame_;
+#endif
 
  public:
-  explicit ScopedNativeDepthTracker(Runtime &runtime) : runtime_(runtime) {
-    (void)runtime_;
+  explicit ScopedNativeDepthTracker(Runtime &runtime)
+      : runtime_(runtime)
 #ifndef HERMES_CHECK_NATIVE_STACK
-    ++runtime.overflowGuard_.callDepth;
+        ,
+        frame_(StackOverflowGuard::CallFrameRAII{runtime_.overflowGuard_})
 #endif
+  {
+    (void)runtime_;
     overflowed_ = runtime.isStackOverflowing();
   }
-  ~ScopedNativeDepthTracker() {
-#ifndef HERMES_CHECK_NATIVE_STACK
-    --runtime_.overflowGuard_.callDepth;
-#endif
-  }
 
   /// \return whether we overflowed the native call frame depth.
   bool overflowed() const {

lib/AST/ESTreeJSONDumper.cpp

@@ -202,9 +202,7 @@ class ESTreeJSONDumper {
       return;
     }
 #ifndef HERMES_CHECK_NATIVE_STACK
-    ++stackOverflowGuard_.callDepth;
-    auto decrementDepth =
-        llvh::make_scope_exit([this] { --stackOverflowGuard_.callDepth; });
+    StackOverflowGuard::CallFrameRAII callFrame{stackOverflowGuard_};
 #endif
     if (stackOverflowGuard_.isOverflowing()) {
       json_.emitNullValue();

lib/Regex/Executor.cpp

@@ -999,9 +999,7 @@ auto Context<Traits>::match(State<Traits> *s, bool onlyAtStart)
       "Can only check one location when cursor is backwards");
 
 #ifndef HERMES_CHECK_NATIVE_STACK
-  ++overflowGuard_.callDepth;
-  auto decrement =
-      llvh::make_scope_exit([this] { --overflowGuard_.callDepth; });
+  StackOverflowGuard::CallFrameRAII frame{overflowGuard_};
 #endif
 
   // Make sure we are not exceeding the set limit of the amount of times we can