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
84 Debugging with GDB
9.4.1 C and C++
Since C and C++ are so closely related, many features of GDB apply to both languages.
Whenever this is the case, we discuss those languages together.
The C++ debugging facilities are jointly implemented by the C++ compiler and GDB.
Therefore, to debug your C++ code effectively, you must compile your C++ programs with
a supported C++ compiler, such as gnu g++, or the HP ANSI C++ compiler (aCC).
For best results when using gnu C++, use the stabs debugging format. You can select
that format explicitly with the g++ command-line options ‘-gstabs’ or ‘-gstabs+’. Refer
to section “Options for Debugging Your Program or gnu CC” in Using gnu CC, for more
information.
9.4.1.1 C and C++ operators
Operators must be defined on values of specific types. For instance, + is defined on
numbers, but not on structures. Operators are often defined on groups of types.
For the purposes of C and C++, the following definitions hold:
• Integral types include int with any of its storage-class specifiers; char; enum; and, for
C++, bool.
• Floating-point types include float, double, and long double (if supported by the
target platform).
• Pointer types include all types defined as (type *).
• Scalar types include all of the above.
The following operators are supported. They are listed here in order of increasing prece-
dence:
, The comma or sequencing operator. Expressions in a comma-separated list are
evaluated from left to right, with the result of the entire expression being the
last expression evaluated.
= Assignment. The value of an assignment expression is the value assigned. De-
fined on scalar types.
op = Used in an expression of the form a op = b , and translated to a = a op b . op =
and = have the same precedence. op is any one of the operators |, ^, &, <<, >>,
+, -, *, /, %.
?: The ternary operator. a ? b : c can be thought of as: if a then b else c. a
should be of an integral type.
|| Logical or. Defined on integral types.
&& Logical and. Defined on integral types.
| Bitwise or. Defined on integral types.
^ Bitwise exclusive-or. Defined on integral types.
& Bitwise and. Defined on integral types.