[LLDB] Add type casting to DIL.

lldb/docs/dil-expr-lang.ebnf

@@ -3,10 +3,13 @@
 (* This is currently a subset of the final DIL Language, matching the current
    DIL implementation. *)
 
-expression = unary_expression ;
+expression = cast_expression;
+
+cast_expression = unary_expression
+                | "(" type_id ")" cast_expression;
 
 unary_expression = postfix_expression
-                 | unary_operator expression ;
+                 | unary_operator cast_expression ;
 
 unary_operator = "*" | "&" ;
 
@@ -44,6 +47,31 @@ nested_name_specifier = type_name "::"
                       | namespace_name '::'
                       | nested_name_specifier identifier "::" ;
 
+type_id = type_specifier_seq [abstract_declarator] ;
+
+type_specifier_seq = type_specifier [type_specifier];
+
+type_specifier = ["::"] [nested_name_specifier] type_name;
+               | "char"
+               | "bool"
+               | "short"
+               | "int"
+               | "long"
+               | "signed"
+               | "unsigned"
+               | "float"
+               | "double"
+               | "void" ;
+
+nested_name_specifier = type_name "::"
+                      | namespace_name "::"
+                      | nested_name_specifier identifier "::" ;
+
+abstract_declarator = ptr_operator [abstract_declarator] ;
+
+ptr_operator = "*"
+             | "&";
+
 type_name = class_name
           | enum_name
           | typedef_name;

lldb/include/lldb/ValueObject/DILAST.h

@@ -21,6 +21,7 @@ enum class NodeKind {
   eArraySubscriptNode,
   eBitExtractionNode,
   eBooleanLiteralNode,
+  eCStyleCastNode,
   eErrorNode,
   eFloatLiteralNode,
   eIdentifierNode,
@@ -29,6 +30,21 @@ enum class NodeKind {
   eUnaryOpNode,
 };
 
+/// The C-Style casts allowed by DIL.
+enum class CStyleCastKind {
+  eEnumeration,
+  eNullptr,
+  eReference,
+  eNone,
+};
+
+/// Promotions for C-Style casts in DIL.
+enum class CastPromoKind {
+  eArithmetic,
+  ePointer,
+  eNone,
+};
+
 /// The Unary operators recognized by DIL.
 enum class UnaryOpKind {
   AddrOf, // "&"
@@ -244,6 +260,29 @@ class BooleanLiteralNode : public ASTNode {
   bool m_value;
 };
 
+class CStyleCastNode : public ASTNode {
+public:
+  CStyleCastNode(uint32_t location, CompilerType type, ASTNodeUP operand,
+                 CStyleCastKind kind)
+      : ASTNode(location, NodeKind::eCStyleCastNode), m_type(type),
+        m_operand(std::move(operand)), m_cast_kind(kind) {}
+
+  llvm::Expected<lldb::ValueObjectSP> Accept(Visitor *v) const override;
+
+  CompilerType GetType() const { return m_type; }
+  ASTNode *GetOperand() const { return m_operand.get(); }
+  CStyleCastKind GetCastKind() const { return m_cast_kind; }
+
+  static bool classof(const ASTNode *node) {
+    return node->GetKind() == NodeKind::eCStyleCastNode;
+  }
+
+private:
+  CompilerType m_type;
+  ASTNodeUP m_operand;
+  CStyleCastKind m_cast_kind;
+};
+
 /// This class contains one Visit method for each specialized type of
 /// DIL AST node. The Visit methods are used to dispatch a DIL AST node to
 /// the correct function in the DIL expression evaluator for evaluating that
@@ -267,6 +306,8 @@ class Visitor {
   Visit(const FloatLiteralNode *node) = 0;
   virtual llvm::Expected<lldb::ValueObjectSP>
   Visit(const BooleanLiteralNode *node) = 0;
+  virtual llvm::Expected<lldb::ValueObjectSP>
+  Visit(const CStyleCastNode *node) = 0;
 };
 
 } // namespace lldb_private::dil

lldb/include/lldb/ValueObject/DILEval.h

@@ -60,12 +60,19 @@ class Interpreter : Visitor {
   Visit(const FloatLiteralNode *node) override;
   llvm::Expected<lldb::ValueObjectSP>
   Visit(const BooleanLiteralNode *node) override;
+  llvm::Expected<lldb::ValueObjectSP>
+  Visit(const CStyleCastNode *node) override;
 
   llvm::Expected<CompilerType>
   PickIntegerType(lldb::TypeSystemSP type_system,
                   std::shared_ptr<ExecutionContextScope> ctx,
                   const IntegerLiteralNode *literal);
 
+  llvm::Expected<CompilerType>
+  VerifyCStyleCastType(lldb::ValueObjectSP &operand, CompilerType &op_type,
+                       CompilerType target_type, CastPromoKind &promo_kind,
+                       CStyleCastKind &cast_kind, int location);
+
   // Used by the interpreter to create objects, perform casts, etc.
   lldb::TargetSP m_target;
   llvm::StringRef m_expr;

lldb/include/lldb/ValueObject/DILParser.h

@@ -10,6 +10,7 @@
 #define LLDB_VALUEOBJECT_DILPARSER_H
 
 #include "lldb/Target/ExecutionContextScope.h"
+#include "lldb/Target/StackFrame.h"
 #include "lldb/Utility/DiagnosticsRendering.h"
 #include "lldb/Utility/Status.h"
 #include "lldb/ValueObject/DILAST.h"
@@ -31,6 +32,9 @@ enum class ErrorCode : unsigned char {
   kUnknown,
 };
 
+llvm::Expected<lldb::TypeSystemSP>
+GetTypeSystemFromCU(std::shared_ptr<StackFrame> ctx);
+
 // The following is modeled on class OptionParseError.
 class DILDiagnosticError
     : public llvm::ErrorInfo<DILDiagnosticError, DiagnosticError> {
@@ -101,6 +105,15 @@ class DILParser {
   ASTNodeUP ParseFloatingPointLiteral();
   ASTNodeUP ParseBooleanLiteral();
 
+  ASTNodeUP ParseCastExpression();
+  std::optional<CompilerType> ParseBuiltinType();
+  std::optional<CompilerType> ParseTypeId();
+  void ParseTypeSpecifierSeq(std::string &type_name);
+  bool ParseTypeSpecifier(std::string &user_type_name);
+  std::string ParseTypeName();
+  CompilerType ResolveTypeDeclarators(CompilerType type,
+                                      const std::vector<Token> &ptr_operators);
+
   void BailOut(const std::string &error, uint32_t loc, uint16_t err_len);
 
   void Expect(Token::Kind kind);

lldb/source/ValueObject/DILAST.cpp

@@ -51,4 +51,8 @@ BooleanLiteralNode::Accept(Visitor *v) const {
   return v->Visit(this);
 }
 
+llvm::Expected<lldb::ValueObjectSP> CStyleCastNode::Accept(Visitor *v) const {
+  return v->Visit(this);
+}
+
 } // namespace lldb_private::dil