[lldb] Introduce Language::AreEqualForFrameComparison

This allows languages to provide an opinion on whether two symbol contexts are
equivalent (i.e. belong to the same function).

It is useful to drive the comparisons done by stepping plans that need to ensure
symbol contexts obtained from different points in time are actually the same.

Author: felipepiovezan

lldb/include/lldb/Target/Language.h

@@ -363,6 +363,15 @@ class Language : public PluginInterface {
     return false;
   }
 
+  /// Returns a boolean indicating whether two symbol contexts are equal for the
+  /// purposes of frame comparison. If the plugin has no opinion, it should
+  /// return nullopt.
+  virtual std::optional<bool>
+  AreEqualForFrameComparison(const SymbolContext &sc1,
+                             const SymbolContext &sc2) const {
+    return {};
+  }
+
   /// Returns true if this Language supports exception breakpoints on throw via
   /// a corresponding LanguageRuntime plugin.
   virtual bool SupportsExceptionBreakpointsOnThrow() const { return false; }

lldb/source/Target/ThreadPlanStepOverRange.cpp

@@ -11,6 +11,7 @@
 #include "lldb/Symbol/CompileUnit.h"
 #include "lldb/Symbol/Function.h"
 #include "lldb/Symbol/LineTable.h"
+#include "lldb/Target/Language.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/RegisterContext.h"
 #include "lldb/Target/Target.h"
@@ -103,6 +104,10 @@ void ThreadPlanStepOverRange::SetupAvoidNoDebug(
 
 bool ThreadPlanStepOverRange::IsEquivalentContext(
     const SymbolContext &context) {
+  if (Language *language = Language::FindPlugin(context.GetLanguage()))
+    if (std::optional<bool> maybe_equivalent =
+            language->AreEqualForFrameComparison(context, m_addr_context))
+      return *maybe_equivalent;
   // Match as much as is specified in the m_addr_context: This is a fairly
   // loose sanity check.  Note, sometimes the target doesn't get filled in so I
   // left out the target check.  And sometimes the module comes in as the .o