Debugging with GDB (February 2008)
Table Of Contents
- Summary of GDB
- A Sample GDB Session
- Getting In and Out of GDB
- GDB Commands
- Running Programs Under GDB
- Stopping and Continuing
- Examining the Stack
- Examining Source Files
- Examining Data
- Using GDB with Different Languages
- Examining the Symbol Table
- Altering Execution
- GDB Files
- Specifying a Debugging Target
- HP-UX Configuration-Specific Information
- Summary of HP Enhancements to GDB
- HP-UX dependencies
- Supported Platforms and Modes
- HP-UX targets
- Support for Alternate root
- Specifying object file directories
- Fix and continue debugging
- Inline Support
- Debugging Macros
- Debugging Memory Problems
- When to suspect a memory leak
- Memory debugging restrictions
- Memory Debugging Methodologies
- Debugging Memory in Interactive Mode
- Debugging Memory in Batch Mode
- Debugging Memory Interactively After Attaching to a Running Process
- Configuring memory debugging settings
- Scenarios in memory debugging
- Stop when freeing unallocated or deallocated blocks
- Stop when freeing a block if bad writes occurred outside block boundary
- Stop when a specified block address is allocated or deallocated
- Scramble previous memory contents at malloc/free calls
- Detect dangling pointers and dangling blocks
- Detect in-block corruption of freed blocks
- Specify the amount of guard bytes for every block of allocated memory
- Comparison of Memory Debugging Commands in Interactive Mode and Batch Mode
- Heap Profiling
- Memory Checking Analysis for User Defined Memory Management Routines
- Commands to track the change in data segment value
- Thread Debugging Support
- Debugging MPI Programs
- Debugging multiple processes ( programs with fork and vfork calls)
- Debugging Core Files
- Printing the Execution Path Entries for the Current Frame or Thread
- Invoking GDB Before a Program Aborts
- Aborting a Command Line Call
- Instruction Level Stepping
- Enhanced support for watchpoints and breakpoints
- Debugging support for shared libraries
- Language support
- Enhanced Java Debugging Support
- Commands for Examining Java Virtual Machine(JVM) internals
- Support for stack traces in Java, C, and C++ programs
- Support for 64-bit Java, C, aC++ stack unwinding
- Enhanced support for C++ templates
- Support for __fpreg data type on IPF
- Support for _Complex variables in HP C
- Support for debugging namespaces
- Command for evaluating the address of an expression
- Viewing Wide Character Strings
- Support for output logging
- Getting information from a non-debug executable
- Debugging optimized code
- Visual Interface for WDB
- Starting and stopping Visual Interface for WDB
- Navigating the Visual Interface for WDB display
- Specifying foreground and background colors
- Using the X-window graphical interface
- Using the TUI mode
- Changing the size of the source or debugger pane
- Using commands to browse through source files
- Loading source files
- Editing source files
- Editing the command line and command-line history
- Saving the contents of a debugging session to a file
- Support for ddd
- Support for XDB commands
- GNU GDB Logging Commands
- Support for command line calls in a stripped executable
- Displaying the current block scope information
- Linux support
- The HP-UX Terminal User Interface
- XDB to WDB Transition Guide
- By-function lists of XDB commands and HP WDB equivalents
- Overall breakpoint commands
- XDB data formats and HP WDB equivalents
- XDB location syntax and HP WDB equivalents
- XDB special language operators and HP WDB equivalents
- XDB special variables and HP WDB equivalents
- XDB variable identifiers and HP WDB equivalents
- Alphabetical lists of XDB commands and HP WDB equivalents
- Controlling GDB
- Canned Sequences of Commands
- Using GDB under gnu Emacs
- GDB Annotations
- The gdb/mi Interface
- Function and purpose
- Notation and terminology
- gdb/mi Command Syntax
- gdb/mi compatibility with CLI
- gdb/mi output records
- gdb/mi command description format
- gdb/mi breakpoint table commands
- gdb/mi Data manipulation
- gdb/mi program control
- Miscellaneous GDB commands in gdb/mi
- gdb/mi Stack Manipulation Commands
- gdb/mi Symbol query commands
- gdb/mi Target Manipulation Commands
- gdb/mi thread commands
- gdb/mi tracepoint commands
- gdb/mi variable objects
- Reporting Bugs in GDB
- Installing GDB
- Index
Chapter 9: Using GDB with Different Languages 79
9 Using GDB with Different Languages
Although programming languages generally have common aspects, they are rarely ex-
pressed in the same manner. For instance, in ANSI C, dereferencing a pointer p is accom-
plished by *p, but in Modula-2, it is accomplished by p^. Values can also be represented
(and displayed) differently. Hex numbers in C appear as ‘0x1ae’, while in Modula-2 they
appear as ‘1AEH’.
Language-specific information is built into GDB for some languages, allowing you to
express operations like the above in the native language of your program, and allowing
GDB to output values in a manner consistent with the syntax of the native language. The
language you use to build expressions is called the working language.
9.1 Switching between source languages
There are two ways to control the working language. You can have GDB set it automat-
ically, or you can select it manually. You can use the set language command for either
purpose. On startup, GDB sets the default language automatically. The working language
is used to determine how expressions are interpreted, how values are printed, etc.
In addition to the working language, every source file that GDB knows about has its
own working language. For some object file formats, the compiler might indicate which
language a particular source file is in. However, most of the time GDB infers the language
from the name of the file. The language of a source file controls whether C++ names are
demangled—this way backtrace can show each frame appropriately for its own language.
There is no way to set the language of a source file from within GDB, but you can set the
language associated with a filename extension. See Section 9.2 [Displaying the language],
page 80.
This is a common problem when you use a program, such as cfront or f2c, that gen-
erates C but is written in another language. In that case, make the program use #line
directives in its C output; that way GDB will know the correct language of the source code
of the original program, and will display that source code, not the generated C code.
9.1.1 List of filename extensions and languages
If a source file name ends in one of the following extensions, then GDB infers that its
language is the one indicated.
‘.c’ C source file
‘.C’
‘.cc’
‘.cp’
‘.cpp’
‘.cxx’
‘.c++’ C++ source file