UnwindPlan.h revision 68fa4ec4361d1ea5a78a8a7eba2b8015e3dd68f7 
1#ifndef liblldb_UnwindPlan_h
2#define liblldb_UnwindPlan_h
3
4#include "lldb/lldb-private.h"
5#include "lldb/Core/AddressRange.h"
6#include "lldb/Core/Stream.h"
7#include "lldb/Core/ConstString.h"
8
9#include <map>
10#include <vector>
11
12namespace lldb_private {
13
14// The UnwindPlan object specifies how to unwind out of a function - where
15// this function saves the caller's register values before modifying them
16// (for non-volatile aka saved registers) and how to find this frame's
17// Canonical Frame Address (CFA).
18
19// Most commonly, registers are saved on the stack, offset some bytes from
20// the Canonical Frame Address, or CFA, which is the starting address of
21// this function's stack frame (the CFA is same as the eh_frame's CFA,
22// whatever that may be on a given architecture).
23// The CFA address for the stack frame does not change during
24// the lifetime of the function.
25
26// Internally, the UnwindPlan is structured as a vector of register locations
27// organized by code address in the function, showing which registers have been
28// saved at that point and where they are saved.
29// It can be thought of as the expanded table form of the DWARF CFI
30// encoded information.
31
32// Other unwind information sources will be converted into UnwindPlans before
33// being added to a FuncUnwinders object.  The unwind source may be
34// an eh_frame FDE, a DWARF debug_frame FDE, or assembly language based
35// prologue analysis.
36// The UnwindPlan is the canonical form of this information that the unwinder
37// code will use when walking the stack.
38
39class UnwindPlan {
40public:
41
42    class Row {
43    public:
44        class RegisterLocation
45        {
46        public:
47
48            enum RestoreType
49                {
50                    unspecified,        // not specified, we may be able to assume this
51                                        // is the same register. gcc doesn't specify all
52                                        // initial values so we really don't know...
53                    undefined,          // reg is not available, e.g. volatile reg
54                    same,               // reg is unchanged
55                    atCFAPlusOffset,    // reg = deref(CFA + offset)
56                    isCFAPlusOffset,    // reg = CFA + offset
57                    inOtherRegister,    // reg = other reg
58                    atDWARFExpression,  // reg = deref(eval(dwarf_expr))
59                    isDWARFExpression   // reg = eval(dwarf_expr)
60                };
61
62            RegisterLocation() :
63                m_type(unspecified),
64                m_location()
65            {
66            }
67
68            bool
69            operator == (const RegisterLocation& rhs) const;
70
71            bool
72            operator != (const RegisterLocation &rhs) const
73            {
74                return !(*this == rhs);
75            }
76
77            void
78            SetUnspecified()
79            {
80                m_type = unspecified;
81            }
82
83            void
84            SetUndefined()
85            {
86                m_type = undefined;
87            }
88
89            void
90            SetSame()
91            {
92                m_type = same;
93            }
94
95            bool
96            IsSame () const
97            {
98                return m_type == same;
99            }
100
101            bool
102            IsUnspecified () const
103            {
104                return m_type == unspecified;
105            }
106
107            bool
108            IsCFAPlusOffset () const
109            {
110                return m_type == isCFAPlusOffset;
111            }
112
113            bool
114            IsAtCFAPlusOffset () const
115            {
116                return m_type == atCFAPlusOffset;
117            }
118
119            bool
120            IsInOtherRegister () const
121            {
122                return m_type == inOtherRegister;
123            }
124
125            bool
126            IsAtDWARFExpression () const
127            {
128                return m_type == atDWARFExpression;
129            }
130
131            bool
132            IsDWARFExpression () const
133            {
134                return m_type == isDWARFExpression;
135            }
136
137            void
138            SetAtCFAPlusOffset (int32_t offset)
139            {
140                m_type = atCFAPlusOffset;
141                m_location.offset = offset;
142            }
143
144            void
145            SetIsCFAPlusOffset (int32_t offset)
146            {
147                m_type = isCFAPlusOffset;
148                m_location.offset = offset;
149            }
150
151            void
152            SetInRegister (uint32_t reg_num)
153            {
154                m_type = inOtherRegister;
155                m_location.reg_num = reg_num;
156            }
157
158            uint32_t
159            GetRegisterNumber () const
160            {
161                if (m_type == inOtherRegister)
162                    return m_location.reg_num;
163                return LLDB_INVALID_REGNUM;
164            }
165
166            RestoreType
167            GetLocationType () const
168            {
169                return m_type;
170            }
171
172            int32_t
173            GetOffset () const
174            {
175                if (m_type == atCFAPlusOffset || m_type == isCFAPlusOffset)
176                    return m_location.offset;
177                return 0;
178            }
179
180            void
181            GetDWARFExpr (const uint8_t **opcodes, uint16_t& len) const
182            {
183                if (m_type == atDWARFExpression || m_type == isDWARFExpression)
184                {
185                    *opcodes = m_location.expr.opcodes;
186                    len = m_location.expr.length;
187                }
188                else
189                {
190                    *opcodes = NULL;
191                    len = 0;
192                }
193            }
194
195            void
196            SetAtDWARFExpression (const uint8_t *opcodes, uint32_t len);
197
198            void
199            SetIsDWARFExpression (const uint8_t *opcodes, uint32_t len);
200
201            const uint8_t *
202            GetDWARFExpressionBytes ()
203            {
204                if (m_type == atDWARFExpression || m_type == isDWARFExpression)
205                    return m_location.expr.opcodes;
206                return NULL;
207            }
208
209            int
210            GetDWARFExpressionLength ()
211            {
212                if (m_type == atDWARFExpression || m_type == isDWARFExpression)
213                    return m_location.expr.length;
214                return 0;
215            }
216
217            void
218            Dump (Stream &s,
219                  const UnwindPlan* unwind_plan,
220                  const UnwindPlan::Row* row,
221                  Thread* thread,
222                  bool verbose) const;
223
224        private:
225            RestoreType m_type;            // How do we locate this register?
226            union
227            {
228                // For m_type == atCFAPlusOffset or m_type == isCFAPlusOffset
229                int32_t offset;
230                // For m_type == inOtherRegister
231                uint32_t reg_num; // The register number
232                // For m_type == atDWARFExpression or m_type == isDWARFExpression
233                struct {
234                    const uint8_t *opcodes;
235                    uint16_t length;
236                } expr;
237            } m_location;
238        };
239
240    public:
241        Row ();
242
243        Row (const UnwindPlan::Row& rhs) :
244            m_offset(rhs.m_offset), m_cfa_reg_num(rhs.m_cfa_reg_num), m_cfa_offset(rhs.m_cfa_offset)
245        {
246            for (collection::const_iterator idx = rhs.m_register_locations.begin(); idx != rhs.m_register_locations.end(); ++idx)
247            {
248                m_register_locations[idx->first] = idx->second;
249            }
250        }
251
252        bool
253        GetRegisterInfo (uint32_t reg_num, RegisterLocation& register_location) const;
254
255        void
256        SetRegisterInfo (uint32_t reg_num, const RegisterLocation register_location);
257
258        lldb::addr_t
259        GetOffset() const
260        {
261            return m_offset;
262        }
263
264        void
265        SetOffset(lldb::addr_t offset)
266        {
267            m_offset = offset;
268        }
269
270        void
271        SlideOffset(lldb::addr_t offset)
272        {
273            m_offset += offset;
274        }
275
276        uint32_t
277        GetCFARegister () const
278        {
279            return m_cfa_reg_num;
280        }
281
282        bool
283        SetRegisterLocationToAtCFAPlusOffset (uint32_t reg_num,
284                                              int32_t offset,
285                                              bool can_replace);
286
287        bool
288        SetRegisterLocationToIsCFAPlusOffset (uint32_t reg_num,
289                                              int32_t offset,
290                                              bool can_replace);
291
292        bool
293        SetRegisterLocationToUndefined (uint32_t reg_num,
294                                        bool can_replace,
295                                        bool can_replace_only_if_unspecified);
296
297        bool
298        SetRegisterLocationToUnspecified (uint32_t reg_num,
299                                          bool can_replace);
300
301        bool
302        SetRegisterLocationToRegister (uint32_t reg_num,
303                                       uint32_t other_reg_num,
304                                       bool can_replace);
305
306        bool
307        SetRegisterLocationToSame (uint32_t reg_num,
308                                   bool must_replace);
309
310
311
312        void
313        SetCFARegister (uint32_t reg_num);
314
315        int32_t
316        GetCFAOffset () const
317        {
318            return m_cfa_offset;
319        }
320
321        void
322        SetCFAOffset (int32_t offset)
323        {
324            m_cfa_offset = offset;
325        }
326
327        // Return the number of registers we have locations for
328        int
329        GetRegisterCount () const
330        {
331            return m_register_locations.size();
332        }
333
334        void
335        Clear ();
336
337        void
338        Dump (Stream& s, const UnwindPlan* unwind_plan, Thread* thread, lldb::addr_t base_addr) const;
339
340        bool
341        operator == (const Row &rhs) const
342        {
343            if (m_offset == rhs.m_offset &&
344                m_cfa_reg_num != rhs.m_cfa_reg_num &&
345                m_cfa_offset != rhs.m_cfa_offset)
346                return m_register_locations == rhs.m_register_locations;
347            return false;
348        }
349
350        bool
351        operator != (const Row &rhs) const
352        {
353            if (m_offset != rhs.m_offset ||
354                m_cfa_reg_num != rhs.m_cfa_reg_num ||
355                m_cfa_offset != rhs.m_cfa_offset)
356                return true;
357
358            return m_register_locations != rhs.m_register_locations;
359        }
360
361    protected:
362        typedef std::map<uint32_t, RegisterLocation> collection;
363        lldb::addr_t m_offset;      // Offset into the function for this row
364        uint32_t m_cfa_reg_num;     // The Call Frame Address register number
365        int32_t  m_cfa_offset;      // The offset from the CFA for this row
366        collection m_register_locations;
367
368    }; // class Row
369
370public:
371
372    typedef STD_SHARED_PTR(Row) RowSP;
373
374    UnwindPlan (lldb::RegisterKind reg_kind) :
375        m_row_list (),
376        m_plan_valid_address_range (),
377        m_register_kind (reg_kind),
378        m_source_name ()
379    {
380    }
381
382    ~UnwindPlan ()
383	{
384	}
385
386    void
387    Dump (Stream& s, Thread* thread, lldb::addr_t base_addr) const;
388
389    void
390    AppendRow (RowSP row);
391
392    // Returns a pointer to the best row for the given offset into the function's instructions.
393    // If offset is -1 it indicates that the function start is unknown - the final row in the UnwindPlan is returned.
394    // In practice, the UnwindPlan for a function with no known start address will be the architectural default
395    // UnwindPlan which will only have one row.
396    UnwindPlan::RowSP
397    GetRowForFunctionOffset (int offset) const;
398
399    lldb::RegisterKind
400    GetRegisterKind () const
401    {
402        return m_register_kind;
403    }
404
405    void
406    SetRegisterKind (lldb::RegisterKind kind)
407    {
408        m_register_kind = kind;
409    }
410
411    uint32_t
412    GetInitialCFARegister () const
413    {
414        if (m_row_list.empty())
415            return LLDB_INVALID_REGNUM;
416        return m_row_list.front()->GetCFARegister();
417    }
418
419    // This UnwindPlan may not be valid at every address of the function span.
420    // For instance, a FastUnwindPlan will not be valid at the prologue setup
421    // instructions - only in the body of the function.
422    void
423    SetPlanValidAddressRange (const AddressRange& range);
424
425    const AddressRange &
426    GetAddressRange () const
427    {
428        return m_plan_valid_address_range;
429    }
430
431    bool
432    PlanValidAtAddress (Address addr);
433
434    bool
435    IsValidRowIndex (uint32_t idx) const;
436
437    const UnwindPlan::RowSP
438    GetRowAtIndex (uint32_t idx) const;
439
440    const UnwindPlan::RowSP
441    GetLastRow () const;
442
443    lldb_private::ConstString
444    GetSourceName () const;
445
446    void
447    SetSourceName (const char *);
448
449    int
450    GetRowCount () const;
451
452    void
453    Clear()
454    {
455        m_row_list.clear();
456        m_plan_valid_address_range.Clear();
457        m_register_kind = lldb::eRegisterKindDWARF;
458        m_source_name.Clear();
459    }
460
461    const RegisterInfo *
462    GetRegisterInfo (Thread* thread, uint32_t reg_num) const;
463
464private:
465
466
467    typedef std::vector<RowSP> collection;
468    collection m_row_list;
469    AddressRange m_plan_valid_address_range;
470    lldb::RegisterKind m_register_kind;   // The RegisterKind these register numbers are in terms of - will need to be
471                                // translated to lldb native reg nums at unwind time
472    lldb_private::ConstString m_source_name;  // for logging, where this UnwindPlan originated from
473}; // class UnwindPlan
474
475} // namespace lldb_private
476
477#endif //liblldb_UnwindPlan_h
478