xref: /external/lldb/include/lldb/Expression/ClangExpressionDeclMap.h

//===-- ClangExpressionDeclMap.h --------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef liblldb_ClangExpressionDeclMap_h_
#define liblldb_ClangExpressionDeclMap_h_

// C Includes
#include <signal.h>
#include <stdint.h>

// C++ Includes
#include <vector>

// Other libraries and framework includes
// Project includes
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/DenseMap.h"
#include "clang/AST/Decl.h"
#include "lldb/lldb-public.h"
#include "lldb/Core/ClangForward.h"
#include "lldb/Core/Value.h"
#include "lldb/Expression/ClangASTSource.h"
#include "lldb/Expression/ClangExpressionVariable.h"
#include "lldb/Expression/Materializer.h"
#include "lldb/Symbol/TaggedASTType.h"
#include "lldb/Symbol/SymbolContext.h"
#include "lldb/Target/ExecutionContext.h"

namespace lldb_private {

//----------------------------------------------------------------------
/// @class ClangExpressionDeclMap ClangExpressionDeclMap.h "lldb/Expression/ClangExpressionDeclMap.h"
/// @brief Manages named entities that are defined in LLDB's debug information.
///
/// The Clang parser uses the ClangASTSource as an interface to request named
/// entities from outside an expression.  The ClangASTSource reports back, listing
/// all possible objects corresponding to a particular name.  But it in turn
/// relies on ClangExpressionDeclMap, which performs several important functions.
///
/// First, it records what variables and functions were looked up and what Decls
/// were returned for them.
///
/// Second, it constructs a struct on behalf of IRForTarget, recording which
/// variables should be placed where and relaying this information back so that
/// IRForTarget can generate context-independent code.
///
/// Third, it "materializes" this struct on behalf of the expression command,
/// finding the current values of each variable and placing them into the
/// struct so that it can be passed to the JITted version of the IR.
///
/// Fourth and finally, it "dematerializes" the struct after the JITted code has
/// has executed, placing the new values back where it found the old ones.
//----------------------------------------------------------------------
class ClangExpressionDeclMap :
    public ClangASTSource
{
public:
    //------------------------------------------------------------------
    /// Constructor
    ///
    /// Initializes class variables.
    ///
    /// @param[in] keep_result_in_memory
    ///     If true, inhibits the normal deallocation of the memory for
    ///     the result persistent variable, and instead marks the variable
    ///     as persisting.
    ///
    /// @param[in] exe_ctx
    ///     The execution context to use when parsing.
    //------------------------------------------------------------------
    ClangExpressionDeclMap (bool keep_result_in_memory,
                            ExecutionContext &exe_ctx);

    //------------------------------------------------------------------
    /// Destructor
    //------------------------------------------------------------------
    ~ClangExpressionDeclMap ();

    //------------------------------------------------------------------
    /// Enable the state needed for parsing and IR transformation.
    ///
    /// @param[in] exe_ctx
    ///     The execution context to use when finding types for variables.
    ///     Also used to find a "scratch" AST context to store result types.
    ///
    /// @param[in] materializer
    ///     If non-NULL, the materializer to populate with information about
    ///     the variables to use
    ///
    /// @return
    ///     True if parsing is possible; false if it is unsafe to continue.
    //------------------------------------------------------------------
    bool
    WillParse (ExecutionContext &exe_ctx,
               Materializer *materializer);

    //------------------------------------------------------------------
    /// [Used by ClangExpressionParser] For each variable that had an unknown
    ///     type at the beginning of parsing, determine its final type now.
    ///
    /// @return
    ///     True on success; false otherwise.
    //------------------------------------------------------------------
    bool
    ResolveUnknownTypes();

    //------------------------------------------------------------------
    /// Disable the state needed for parsing and IR transformation.
    //------------------------------------------------------------------
    void
    DidParse ();

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Add a variable to the list of persistent
    ///     variables for the process.
    ///
    /// @param[in] decl
    ///     The Clang declaration for the persistent variable, used for
    ///     lookup during parsing.
    ///
    /// @param[in] name
    ///     The name of the persistent variable, usually $something.
    ///
    /// @param[in] type
    ///     The type of the variable, in the Clang parser's context.
    ///
    /// @return
    ///     True on success; false otherwise.
    //------------------------------------------------------------------
    bool
    AddPersistentVariable (const clang::NamedDecl *decl,
                           const ConstString &name,
                           TypeFromParser type,
                           bool is_result,
                           bool is_lvalue);

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Add a variable to the struct that needs to
    ///     be materialized each time the expression runs.
    ///
    /// @param[in] decl
    ///     The Clang declaration for the variable.
    ///
    /// @param[in] name
    ///     The name of the variable.
    ///
    /// @param[in] value
    ///     The LLVM IR value for this variable.
    ///
    /// @param[in] size
    ///     The size of the variable in bytes.
    ///
    /// @param[in] alignment
    ///     The required alignment of the variable in bytes.
    ///
    /// @return
    ///     True on success; false otherwise.
    //------------------------------------------------------------------
    bool
    AddValueToStruct (const clang::NamedDecl *decl,
                      const ConstString &name,
                      llvm::Value *value,
                      size_t size,
                      off_t alignment);

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Finalize the struct, laying out the position
    /// of each object in it.
    ///
    /// @return
    ///     True on success; false otherwise.
    //------------------------------------------------------------------
    bool
    DoStructLayout ();

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Get general information about the laid-out
    /// struct after DoStructLayout() has been called.
    ///
    /// @param[out] num_elements
    ///     The number of elements in the struct.
    ///
    /// @param[out] size
    ///     The size of the struct, in bytes.
    ///
    /// @param[out] alignment
    ///     The alignment of the struct, in bytes.
    ///
    /// @return
    ///     True if the information could be retrieved; false otherwise.
    //------------------------------------------------------------------
    bool
    GetStructInfo (uint32_t &num_elements,
                   size_t &size,
                   off_t &alignment);

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Get specific information about one field
    /// of the laid-out struct after DoStructLayout() has been called.
    ///
    /// @param[out] decl
    ///     The parsed Decl for the field, as generated by ClangASTSource
    ///     on ClangExpressionDeclMap's behalf.  In the case of the result
    ///     value, this will have the name $__lldb_result even if the
    ///     result value ends up having the name $1.  This is an
    ///     implementation detail of IRForTarget.
    ///
    /// @param[out] value
    ///     The IR value for the field (usually a GlobalVariable).  In
    ///     the case of the result value, this will have the correct
    ///     name ($1, for instance).  This is an implementation detail
    ///     of IRForTarget.
    ///
    /// @param[out] offset
    ///     The offset of the field from the beginning of the struct.
    ///     As long as the struct is aligned according to its required
    ///     alignment, this offset will align the field correctly.
    ///
    /// @param[out] name
    ///     The name of the field as used in materialization.
    ///
    /// @param[in] index
    ///     The index of the field about which information is requested.
    ///
    /// @return
    ///     True if the information could be retrieved; false otherwise.
    //------------------------------------------------------------------
    bool
    GetStructElement (const clang::NamedDecl *&decl,
                      llvm::Value *&value,
                      off_t &offset,
                      ConstString &name,
                      uint32_t index);

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Get information about a function given its
    /// Decl.
    ///
    /// @param[in] decl
    ///     The parsed Decl for the Function, as generated by ClangASTSource
    ///     on ClangExpressionDeclMap's behalf.
    ///
    /// @param[out] ptr
    ///     The absolute address of the function in the target.
    ///
    /// @return
    ///     True if the information could be retrieved; false otherwise.
    //------------------------------------------------------------------
    bool
    GetFunctionInfo (const clang::NamedDecl *decl,
                     uint64_t &ptr);

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Get the address of a function given nothing
    /// but its name.  Some functions are needed but didn't get Decls made
    /// during parsing -- specifically, sel_registerName is never called
    /// in the generated IR but we need to call it nonetheless.
    ///
    /// @param[in] name
    ///     The name of the function.
    ///
    /// @param[out] ptr
    ///     The absolute address of the function in the target.
    ///
    /// @return
    ///     True if the address could be retrieved; false otherwise.
    //------------------------------------------------------------------
    bool
    GetFunctionAddress (const ConstString &name,
                        uint64_t &ptr);

    //------------------------------------------------------------------
    /// [Used by IRForTarget] Get the address of a symbol given nothing
    /// but its name.
    ///
    /// @param[in] target
    ///     The target to find the symbol in.  If not provided,
    ///     then the current parsing context's Target.
    ///
    /// @param[in] process
    ///     The process to use.  For Objective-C symbols, the process's
    ///     Objective-C language runtime may be queried if the process
    ///     is non-NULL.
    ///
    /// @param[in] name
    ///     The name of the symbol.
    ///
    /// @return
    ///     Valid load address for the symbol
    //------------------------------------------------------------------
    lldb::addr_t
    GetSymbolAddress (Target &target,
                      Process *process,
                      const ConstString &name,
                      lldb::SymbolType symbol_type);

    lldb::addr_t
    GetSymbolAddress (const ConstString &name,
                      lldb::SymbolType symbol_type);

    //------------------------------------------------------------------
    /// [Used by IRInterpreter] Get basic target information.
    ///
    /// @param[out] byte_order
    ///     The byte order of the target.
    ///
    /// @param[out] address_byte_size
    ///     The size of a pointer in bytes.
    ///
    /// @return
    ///     True if the information could be determined; false
    ///     otherwise.
    //------------------------------------------------------------------
    struct TargetInfo
    {
        lldb::ByteOrder byte_order;
        size_t address_byte_size;

        TargetInfo() :
            byte_order(lldb::eByteOrderInvalid),
            address_byte_size(0)
        {
        }

        bool IsValid()
        {
            return (byte_order != lldb::eByteOrderInvalid &&
                    address_byte_size != 0);
        }
    };
    TargetInfo GetTargetInfo();

    //------------------------------------------------------------------
    /// [Used by ClangASTSource] Find all entities matching a given name,
    /// using a NameSearchContext to make Decls for them.
    ///
    /// @param[in] context
    ///     The NameSearchContext that can construct Decls for this name.
    ///
    /// @return
    ///     True on success; false otherwise.
    //------------------------------------------------------------------
    void
    FindExternalVisibleDecls (NameSearchContext &context);

    //------------------------------------------------------------------
    /// Find all entities matching a given name in a given module/namespace,
    /// using a NameSearchContext to make Decls for them.
    ///
    /// @param[in] context
    ///     The NameSearchContext that can construct Decls for this name.
    ///
    /// @param[in] module
    ///     If non-NULL, the module to query.
    ///
    /// @param[in] namespace_decl
    ///     If valid and module is non-NULL, the parent namespace.
    ///
    /// @param[in] name
    ///     The name as a plain C string.  The NameSearchContext contains
    ///     a DeclarationName for the name so at first the name may seem
    ///     redundant, but ClangExpressionDeclMap operates in RTTI land so
    ///     it can't access DeclarationName.
    ///
    /// @param[in] current_id
    ///     The ID for the current FindExternalVisibleDecls invocation,
    ///     for logging purposes.
    ///
    /// @return
    ///     True on success; false otherwise.
    //------------------------------------------------------------------
    void
    FindExternalVisibleDecls (NameSearchContext &context,
                              lldb::ModuleSP module,
                              ClangNamespaceDecl &namespace_decl,
                              unsigned int current_id);
private:
    ClangExpressionVariableList    m_found_entities;           ///< All entities that were looked up for the parser.
    ClangExpressionVariableList    m_struct_members;           ///< All entities that need to be placed in the struct.
    bool                           m_keep_result_in_memory;    ///< True if result persistent variables generated by this expression should stay in memory.

    //----------------------------------------------------------------------
    /// The following values should not live beyond parsing
    //----------------------------------------------------------------------
    class ParserVars
    {
    public:
        ParserVars(ClangExpressionDeclMap &decl_map) :
            m_exe_ctx(),
            m_sym_ctx(),
            m_persistent_vars(NULL),
            m_enable_lookups(false),
            m_materializer(NULL),
            m_decl_map(decl_map)
        {
        }

        Target *
        GetTarget()
        {
            if (m_exe_ctx.GetTargetPtr())
                return m_exe_ctx.GetTargetPtr();
            else if (m_sym_ctx.target_sp)
                m_sym_ctx.target_sp.get();
            return NULL;
        }

        ExecutionContext            m_exe_ctx;          ///< The execution context to use when parsing.
        SymbolContext               m_sym_ctx;          ///< The symbol context to use in finding variables and types.
        ClangPersistentVariables   *m_persistent_vars;  ///< The persistent variables for the process.
        bool                        m_enable_lookups;   ///< Set to true during parsing if we have found the first "$__lldb" name.
        TargetInfo                  m_target_info;      ///< Basic information about the target.
        Materializer               *m_materializer;     ///< If non-NULL, the materializer to use when reporting used variables.
    private:
        ClangExpressionDeclMap     &m_decl_map;
        DISALLOW_COPY_AND_ASSIGN (ParserVars);
    };

    std::unique_ptr<ParserVars> m_parser_vars;

    //----------------------------------------------------------------------
    /// Activate parser-specific variables
    //----------------------------------------------------------------------
    void
    EnableParserVars()
    {
        if (!m_parser_vars.get())
            m_parser_vars.reset(new ParserVars(*this));
    }

    //----------------------------------------------------------------------
    /// Deallocate parser-specific variables
    //----------------------------------------------------------------------
    void
    DisableParserVars()
    {
        m_parser_vars.reset();
    }

    //----------------------------------------------------------------------
    /// The following values contain layout information for the materialized
    /// struct, but are not specific to a single materialization
    //----------------------------------------------------------------------
    struct StructVars {
        StructVars() :
            m_struct_alignment(0),
            m_struct_size(0),
            m_struct_laid_out(false),
            m_result_name(),
            m_object_pointer_type(NULL, NULL)
        {
        }

        off_t                       m_struct_alignment;         ///< The alignment of the struct in bytes.
        size_t                      m_struct_size;              ///< The size of the struct in bytes.
        bool                        m_struct_laid_out;          ///< True if the struct has been laid out and the layout is valid (that is, no new fields have been added since).
        ConstString                 m_result_name;              ///< The name of the result variable ($1, for example)
        TypeFromUser                m_object_pointer_type;      ///< The type of the "this" variable, if one exists
    };

    std::unique_ptr<StructVars> m_struct_vars;

    //----------------------------------------------------------------------
    /// Activate struct variables
    //----------------------------------------------------------------------
    void
    EnableStructVars()
    {
        if (!m_struct_vars.get())
            m_struct_vars.reset(new struct StructVars);
    }

    //----------------------------------------------------------------------
    /// Deallocate struct variables
    //----------------------------------------------------------------------
    void
    DisableStructVars()
    {
        m_struct_vars.reset();
    }

    //----------------------------------------------------------------------
    /// Get this parser's ID for use in extracting parser- and JIT-specific
    /// data from persistent variables.
    //----------------------------------------------------------------------
    uint64_t
    GetParserID()
    {
        return (uint64_t)this;
    }

    //------------------------------------------------------------------
    /// Given a target, find a data symbol that has the given name.
    ///
    /// @param[in] target
    ///     The target to use as the basis for the search.
    ///
    /// @param[in] name
    ///     The name as a plain C string.
    ///
    /// @return
    ///     The LLDB Symbol found, or NULL if none was found.
    //---------------------------------------------------------
    const Symbol *
    FindGlobalDataSymbol (Target &target,
                          const ConstString &name);

    //------------------------------------------------------------------
    /// Given a target, find a variable that matches the given name and
    /// type.
    ///
    /// @param[in] target
    ///     The target to use as a basis for finding the variable.
    ///
    /// @param[in] module
    ///     If non-NULL, the module to search.
    ///
    /// @param[in] name
    ///     The name as a plain C string.
    ///
    /// @param[in] namespace_decl
    ///     If non-NULL and module is non-NULL, the parent namespace.
    ///
    /// @param[in] type
    ///     The required type for the variable.  This function may be called
    ///     during parsing, in which case we don't know its type; hence the
    ///     default.
    ///
    /// @return
    ///     The LLDB Variable found, or NULL if none was found.
    //------------------------------------------------------------------
    lldb::VariableSP
    FindGlobalVariable (Target &target,
                        lldb::ModuleSP &module,
                        const ConstString &name,
                        ClangNamespaceDecl *namespace_decl,
                        TypeFromUser *type = NULL);

    //------------------------------------------------------------------
    /// Get the value of a variable in a given execution context and return
    /// the associated Types if needed.
    ///
    /// @param[in] var
    ///     The variable to evaluate.
    ///
    /// @param[out] var_location
    ///     The variable location value to fill in
    ///
    /// @param[out] found_type
    ///     The type of the found value, as it was found in the user process.
    ///     This is only useful when the variable is being inspected on behalf
    ///     of the parser, hence the default.
    ///
    /// @param[out] parser_type
    ///     The type of the found value, as it was copied into the parser's
    ///     AST context.  This is only useful when the variable is being
    ///     inspected on behalf of the parser, hence the default.
    ///
    /// @param[in] decl
    ///     The Decl to be looked up.
    ///
    /// @return
    ///     Return true if the value was successfully filled in.
    //------------------------------------------------------------------
    bool
    GetVariableValue (lldb::VariableSP &var,
                      lldb_private::Value &var_location,
                      TypeFromUser *found_type = NULL,
                      TypeFromParser *parser_type = NULL);

    //------------------------------------------------------------------
    /// Use the NameSearchContext to generate a Decl for the given LLDB
    /// Variable, and put it in the Tuple list.
    ///
    /// @param[in] context
    ///     The NameSearchContext to use when constructing the Decl.
    ///
    /// @param[in] var
    ///     The LLDB Variable that needs a Decl.
    ///
    /// @param[in] valobj
    ///     The LLDB ValueObject for that variable.
    //------------------------------------------------------------------
    void
    AddOneVariable (NameSearchContext &context,
                    lldb::VariableSP var,
                    lldb::ValueObjectSP valobj,
                    unsigned int current_id);

    //------------------------------------------------------------------
    /// Use the NameSearchContext to generate a Decl for the given
    /// persistent variable, and put it in the list of found entities.
    ///
    /// @param[in] context
    ///     The NameSearchContext to use when constructing the Decl.
    ///
    /// @param[in] pvar
    ///     The persistent variable that needs a Decl.
    ///
    /// @param[in] current_id
    ///     The ID of the current invocation of FindExternalVisibleDecls
    ///     for logging purposes.
    //------------------------------------------------------------------
    void
    AddOneVariable (NameSearchContext &context,
                    lldb::ClangExpressionVariableSP &pvar_sp,
                    unsigned int current_id);

    //------------------------------------------------------------------
    /// Use the NameSearchContext to generate a Decl for the given LLDB
    /// symbol (treated as a variable), and put it in the list of found
    /// entities.
    ///
    /// @param[in] context
    ///     The NameSearchContext to use when constructing the Decl.
    ///
    /// @param[in] var
    ///     The LLDB Variable that needs a Decl.
    //------------------------------------------------------------------
    void
    AddOneGenericVariable (NameSearchContext &context,
                           const Symbol &symbol,
                           unsigned int current_id);

    //------------------------------------------------------------------
    /// Use the NameSearchContext to generate a Decl for the given
    /// function.  (Functions are not placed in the Tuple list.)  Can
    /// handle both fully typed functions and generic functions.
    ///
    /// @param[in] context
    ///     The NameSearchContext to use when constructing the Decl.
    ///
    /// @param[in] fun
    ///     The Function that needs to be created.  If non-NULL, this is
    ///     a fully-typed function.
    ///
    /// @param[in] sym
    ///     The Symbol that corresponds to a function that needs to be
    ///     created with generic type (unitptr_t foo(...)).
    //------------------------------------------------------------------
    void
    AddOneFunction (NameSearchContext &context,
                    Function *fun,
                    Symbol *sym,
                    unsigned int current_id);

    //------------------------------------------------------------------
    /// Use the NameSearchContext to generate a Decl for the given
    /// register.
    ///
    /// @param[in] context
    ///     The NameSearchContext to use when constructing the Decl.
    ///
    /// @param[in] reg_info
    ///     The information corresponding to that register.
    //------------------------------------------------------------------
    void
    AddOneRegister (NameSearchContext &context,
                    const RegisterInfo *reg_info,
                    unsigned int current_id);

    //------------------------------------------------------------------
    /// Use the NameSearchContext to generate a Decl for the given
    /// type.  (Types are not placed in the Tuple list.)
    ///
    /// @param[in] context
    ///     The NameSearchContext to use when constructing the Decl.
    ///
    /// @param[in] type
    ///     The type that needs to be created.
    //------------------------------------------------------------------
    void
    AddOneType (NameSearchContext &context,
                TypeFromUser &type,
                unsigned int current_id);

    //------------------------------------------------------------------
    /// Copy a C++ class type into the parser's AST context and add a
    /// member function declaration to it for the expression.
    ///
    /// @param[in] type
    ///     The type that needs to be created.
    //------------------------------------------------------------------

    TypeFromParser
    CopyClassType(TypeFromUser &type,
                  unsigned int current_id);
};

} // namespace lldb_private

#endif  // liblldb_ClangExpressionDeclMap_h_