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1 //===- llvm/Support/PrettyStackTrace.h - Pretty Crash Handling --*- 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 // This file defines the PrettyStackTraceEntry class, which is used to make
11 // crashes give more contextual information about what the program was doing
12 // when it crashed.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_SUPPORT_PRETTYSTACKTRACE_H
17 #define LLVM_SUPPORT_PRETTYSTACKTRACE_H
18 
19 #include "llvm/Support/Compiler.h"
20 
21 namespace llvm {
22   class raw_ostream;
23 
24   void EnablePrettyStackTrace();
25 
26   /// PrettyStackTraceEntry - This class is used to represent a frame of the
27   /// "pretty" stack trace that is dumped when a program crashes. You can define
28   /// subclasses of this and declare them on the program stack: when they are
29   /// constructed and destructed, they will add their symbolic frames to a
30   /// virtual stack trace.  This gets dumped out if the program crashes.
31   class PrettyStackTraceEntry {
32     const PrettyStackTraceEntry *NextEntry;
33     PrettyStackTraceEntry(const PrettyStackTraceEntry &) = delete;
34     void operator=(const PrettyStackTraceEntry&) = delete;
35   public:
36     PrettyStackTraceEntry();
37     virtual ~PrettyStackTraceEntry();
38 
39     /// print - Emit information about this stack frame to OS.
40     virtual void print(raw_ostream &OS) const = 0;
41 
42     /// getNextEntry - Return the next entry in the list of frames.
getNextEntry()43     const PrettyStackTraceEntry *getNextEntry() const { return NextEntry; }
44   };
45 
46   /// PrettyStackTraceString - This object prints a specified string (which
47   /// should not contain newlines) to the stream as the stack trace when a crash
48   /// occurs.
49   class PrettyStackTraceString : public PrettyStackTraceEntry {
50     const char *Str;
51   public:
PrettyStackTraceString(const char * str)52     PrettyStackTraceString(const char *str) : Str(str) {}
53     void print(raw_ostream &OS) const override;
54   };
55 
56   /// PrettyStackTraceProgram - This object prints a specified program arguments
57   /// to the stream as the stack trace when a crash occurs.
58   class PrettyStackTraceProgram : public PrettyStackTraceEntry {
59     int ArgC;
60     const char *const *ArgV;
61   public:
PrettyStackTraceProgram(int argc,const char * const * argv)62     PrettyStackTraceProgram(int argc, const char * const*argv)
63       : ArgC(argc), ArgV(argv) {
64       EnablePrettyStackTrace();
65     }
66     void print(raw_ostream &OS) const override;
67   };
68 
69   /// Returns the topmost element of the "pretty" stack state.
70   const void* SavePrettyStackState();
71 
72   /// Restores the topmost element of the "pretty" stack state to State, which
73   /// should come from a previous call to SavePrettyStackState().  This is
74   /// useful when using a CrashRecoveryContext in code that also uses
75   /// PrettyStackTraceEntries, to make sure the stack that's printed if a crash
76   /// happens after a crash that's been recovered by CrashRecoveryContext
77   /// doesn't have frames on it that were added in code unwound by the
78   /// CrashRecoveryContext.
79   void RestorePrettyStackState(const void* State);
80 
81 } // end namespace llvm
82 
83 #endif
84