[LLDB][Expression] Allow instantiation of IR Entity from ValueObject

This is required in preparation for the follow-up patch which adds support for evaluating expressions from within C++ lambdas. In such cases we need to materialize variables which are not part of the current frame but instead are ivars on a 'this' pointer of the current frame.
intel · Jul 22, 2022 · 317c8bf · 317c8bf
1 parent fcf4e25
commit 317c8bf
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Showing 6 changed files with 290 additions and 37 deletions.
diff --git a/lldb/include/lldb/Expression/Materializer.h b/lldb/include/lldb/Expression/Materializer.h
@@ -78,6 +78,28 @@ class Materializer {
   AddPersistentVariable(lldb::ExpressionVariableSP &persistent_variable_sp,
                         PersistentVariableDelegate *delegate, Status &err);
   uint32_t AddVariable(lldb::VariableSP &variable_sp, Status &err);
+
+  /// Create entity from supplied ValueObject and count it as a member
+  /// of the materialized struct.
+  ///
+  /// Behaviour is undefined if 'valobj_provider' is empty.
+  ///
+  /// \param[in] name Name of variable to materialize
+  ///
+  /// \param[in] valobj_provider When materializing values multiple
+  ///            times, this callback gets used to fetch a fresh
+  ///            ValueObject corresponding to the supplied frame.
+  ///            This is mainly used for conditional breakpoints
+  ///            that re-apply an expression whatever the frame
+  ///            happens to be when the breakpoint got hit.
+  ///
+  /// \param[out] err Error status that gets set on error.
+  ///
+  /// \returns Offset in bytes of the member we just added to the
+  ///          materialized struct.
+  uint32_t AddValueObject(ConstString name,
+                          ValueObjectProviderTy valobj_provider, Status &err);
+
   uint32_t AddResultVariable(const CompilerType &type, bool is_lvalue,
                              bool keep_in_memory,
                              PersistentVariableDelegate *delegate, Status &err);

diff --git a/lldb/include/lldb/lldb-private-types.h b/lldb/include/lldb/lldb-private-types.h
@@ -106,6 +106,12 @@ struct OptionValidator {
 typedef struct type128 { uint64_t x[2]; } type128;
 typedef struct type256 { uint64_t x[4]; } type256;
 
+/// Functor that returns a ValueObjectSP for a variable given its name
+/// and the StackFrame of interest. Used primarily in the Materializer
+/// to refetch a ValueObject when the ExecutionContextScope changes.
+using ValueObjectProviderTy =
+    std::function<lldb::ValueObjectSP(ConstString, StackFrame *)>;
+
 } // namespace lldb_private
 
 #endif // #if defined(__cplusplus)