IRToDWARF.h revision f285ebcfa3ce0fd200b6a566eb1196927e618fc6 
1//===-- IRToDWARF.h ---------------------------------------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef liblldb_IRToDWARF_h_
11#define liblldb_IRToDWARF_h_
12
13#include "llvm/Pass.h"
14#include "llvm/PassManager.h"
15
16namespace llvm {
17    class BasicBlock;
18    class Module;
19}
20
21namespace lldb_private {
22    class ClangExpressionVariableList;
23    class ClangExpressionDeclMap;
24    class StreamString;
25}
26
27class Relocator;
28
29//----------------------------------------------------------------------
30/// @class IRToDWARF IRToDWARF.h "lldb/Expression/IRToDWARF.h"
31/// @brief Transforms the IR for a function into a DWARF location expression
32///
33/// Once an expression has been parsed and converted to IR, it can run
34/// in two contexts: interpreted by LLDB as a DWARF location expression,
35/// or compiled by the JIT and inserted into the target process for
36/// execution.
37///
38/// IRToDWARF makes the first possible, by traversing the control flow
39/// graph and writing the code for each basic block out as location
40/// expression bytecode.  To ensure that the links between the basic blocks
41/// remain intact, it uses a relocator that records the location of every
42/// location expression instruction that has a relocatable operand, the
43/// target of that operand (as a basic block), and the mapping of each basic
44/// block to an actual location.  After all code has been written out, the
45/// relocator post-processes it and performs all necessary relocations.
46//----------------------------------------------------------------------
47class IRToDWARF : public llvm::ModulePass
48{
49public:
50    //------------------------------------------------------------------
51    /// Constructor
52    ///
53    /// @param[in] pid
54    ///     A unique identifier for this pass.  I'm not sure what this does;
55    ///     it just gets passed down to ModulePass's constructor.
56    ///
57    /// @param[in] variable_list
58    ///     A list of variables to populate with the local variables this
59    ///     expression uses.
60    ///
61    /// @param[in] decl_map
62    ///     The list of externally-referenced variables for the expression,
63    ///     for use in looking up globals.
64    ///
65    /// @param[in] stream
66    ///     The stream to dump DWARF bytecode onto.
67    //------------------------------------------------------------------
68    IRToDWARF(const void *pid,
69              lldb_private::ClangExpressionVariableList &variable_list,
70              lldb_private::ClangExpressionDeclMap *decl_map,
71              lldb_private::StreamString &strm);
72
73    //------------------------------------------------------------------
74    /// Destructor
75    //------------------------------------------------------------------
76    ~IRToDWARF();
77
78    //------------------------------------------------------------------
79    /// Run this IR transformer on a single module
80    ///
81    /// @param[in] M
82    ///     The module to run on.  This module is searched for the function
83    ///     ___clang_expr, and that function is converted to a location
84    ///     expression.
85    ///
86    /// @return
87    ///     True on success; false otherwise
88    //------------------------------------------------------------------
89    bool runOnModule(llvm::Module &M);
90
91    //------------------------------------------------------------------
92    /// Interface stub
93    //------------------------------------------------------------------
94    void assignPassManager(llvm::PMStack &PMS,
95                           llvm::PassManagerType T = llvm::PMT_ModulePassManager);
96
97    //------------------------------------------------------------------
98    /// Returns PMT_ModulePassManager
99    //------------------------------------------------------------------
100    llvm::PassManagerType getPotentialPassManagerType() const;
101private:
102    //------------------------------------------------------------------
103    /// Run this IR transformer on a single basic block
104    ///
105    /// @param[in] BB
106    ///     The basic block to transform.
107    ///
108    /// @param[in] Relocator
109    ///     The relocator to use when registering branches.
110    ///
111    /// @return
112    ///     True on success; false otherwise
113    //------------------------------------------------------------------
114    bool runOnBasicBlock(llvm::BasicBlock &BB, Relocator &Relocator);
115
116    lldb_private::ClangExpressionVariableList &m_variable_list; ///< The list of local variables to populate while transforming
117    lldb_private::ClangExpressionDeclMap *m_decl_map;           ///< The list of external variables
118    lldb_private::StreamString &m_strm;                         ///< The stream to write bytecode to
119};
120
121#endif