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
188 Debugging with GDB
of certain instructions, such as wtop, wexit, and frcpa, which modify the processor
state even when predicated false. In such cases, the debugger stops at the instruc-
tions irrespective of the predicate value of the instructions. Assembly and low-level
programmers, who require the old behavior of the debugger to stop at the instructions
irrespective of the predicate value of these instructions, can explicitly turn off this
feature. To explicitly turn off this feature, enter the following command at the gdb
prompt:
(gdb) set no-predication-handling
The following limitations apply when debugging optimized code:
• Support for high-level loop transformations such as modulo-scheduled loops, or
LNO-optimized loop nests is limited. (This limited support includes all loop opti-
mizations that are enabled at +O3 and above, and some loop optimizations at +O2
or -O.)
• Debug support for local aggregates and arrays is limited.
• Complete debug support for inlined subroutines is not available.
• Values that are not at the current code location will be reported as being un-
available, even if these values can be computed from some other values that are
available.
• Step operations may include occasional "backwards" steps, because of the re-
ordered code during optimization.
• The program stops at asynchronous signal stops even if the reported instruction
is predicated false.
Complete support is available for debugging at the assembly language level. Stepping
by instructions (stepi/nexti) steps as expected and reports the associated source line
numbers for each instruction.
Note: The -ipo compilation implies the +noobjdebug option because the
-ipo object files do not store executable code or debug info.
14.26 Visual Interface for WDB
WDB includes an HP-supported Visual Interface for WDB with both graphical and
terminal modes. The interface is based on Vim 5.7 and WDB. This interface replaces
the -tui mode on Itanium-based systems.
When you use the interface you are actually using vim, which is a vi-compatible editor.
With the interface you can use vi commands to browse in the WDB display.
Most of Visual Interface for WDB functionality is also available for emacs users. Visual
Interface for WDB does not require knowledge of vi commands.
Visual Interface for WDB identifies you as an emacs user by looking at the environment
variable ‘$EDITOR’. If this variable has a value that matches emacs, or gmacs, or xemacs,
then Visual Interface for WDB starts in emacs mode automatically.
Note: If the program expects unbuffered input or uses curses, termcap, or
terminfo, or otherwise transmits escape or control sequences to the termi-
nal, you must use one of the following methods to run Visual Interface for
WDB: