The Linux Development Platform Configuring, Using, and ... - Classes
The Linux Development Platform Configuring, Using, and ... - Classes
The Linux Development Platform Configuring, Using, and ... - Classes
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CH03.fm Page 63 Monday, October 7, 2002 8:33 PM<br />
Compiling a Program 63<br />
3.3.4 Compilation with Debug Support<br />
If you want to debug a program after compiling with gcc, you have to include debug<br />
information in the compiled program. <strong>The</strong> debug information is included in object file using the<br />
–g comm<strong>and</strong> line switch with gcc. <strong>The</strong> following comm<strong>and</strong> creates the hello.o file that contains<br />
debug information.<br />
[rr@conformix 4]$ gcc -g -c hello.c<br />
[rr@conformix 4]$<br />
Note that when you compile a program with debug information, the size may be quite<br />
large as compared to a file compiled without debug information. In the example program of<br />
hello.c, the size of hello.o is 908 bytes when compiled without debug information. <strong>The</strong><br />
size of hello.o is 10780 bytes when it is compiled with debug information.<br />
You can use multiple debug levels with –g option. <strong>The</strong> default debug level is 2 which is<br />
equivalent to using –g2 comm<strong>and</strong> line option. If you use –g3 comm<strong>and</strong> line option, information<br />
about macros is also included which makes it easier to debug macros.<br />
N O T E You can use the debug option with optimization<br />
options. Optimization options are discussed later in this chapter.<br />
With the –a option on the comm<strong>and</strong> line, you can also include some profiling information<br />
in the object code.<br />
You can also use some comm<strong>and</strong> line switches to provide extra information. For example,<br />
one useful thing is to print out a list of directories that the gcc comm<strong>and</strong> searches to find files.<br />
<strong>The</strong> following comm<strong>and</strong> will print all directories that gcc uses to search libraries, programs <strong>and</strong><br />
so on.<br />
[rr@conformix 4]$ gcc -print-search-dirs hello.c -o hello<br />
install: /usr/lib/gcc-lib/i386-redhat-linux/2.96/<br />
programs: =/usr/lib/gcc-lib/i386-redhat-linux/2.96/:/usr/lib/<br />
gcc-lib/i386-redhat-linux/2.96/:/usr/lib/gcc-lib/i386-redhat-<br />
linux/:/usr/lib/gcc/i386-redhat-linux/2.96/:/usr/lib/gcc/i386-<br />
redhat-linux/:/usr/lib/gcc-lib/i386-redhat-linux/2.96/../../<br />
../../i386-redhat-linux/bin/i386-redhat-linux/2.96/:/usr/lib/<br />
gcc-lib/i386-redhat-linux/2.96/../../../../i386-redhat-linux/<br />
bin/<br />
libraries: =/usr/lib/gcc-lib/i386-redhat-linux/2.96/:/usr/lib/<br />
gcc/i386-redhat-linux/2.96/:/usr/lib/gcc-lib/i386-redhatlinux/2.96/../../../../i386-redhat-linux/lib/i386-redhatlinux/2.96/:/usr/lib/gcc-lib/i386-redhat-linux/2.96/../../../<br />
../i386-redhat-linux/lib/:/usr/lib/gcc-lib/i386-redhat-linux/<br />
2.96/../../../i386-redhat-linux/2.96/:/usr/lib/gcc-lib/i386-<br />
redhat-linux/2.96/../../../:/lib/i386-redhat-linux/2.96/:/lib/<br />
:/usr/lib/i386-redhat-linux/2.96/:/usr/lib/<br />
[rr@conformix 4]$
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