How to use compile & execute function in GDB

How to use compile & execute function in GDB

[高国胜]

I have install gcc-5.0, and copy libcc1.so to current work space.
When I try the compile & execute function in gdb, The following error occurred:

(gdb) b main
Breakpoint 1 at 0x80483dd: file test.c, line 5.
(gdb) r
Starting program: /home/guosheng_gao/gdb-7.9/obj/test

Breakpoint 1, main () at test.c:5
5         a = 1;
(gdb) compile code int z=5;c=z;
cc1: error: unrecognized command line option "-std=gnu11"
cc1: error: unrecognized command line option "-fplugin=libcc1plugin"
cc1: error: unrecognized command line option "-fplugin-arg-libcc1plugin-fd=6"
Compilation failed.
(gdb)

Any advices will be wonderful!

Re: How to use compile & execute function in GDB

[Jan Kratochvil]

On Wed, 15 Apr 2015 07:45:19 +0200, 高国胜 wrote:
> I have install gcc-5.0, and copy libcc1.so to current work space.

GDB apparently found libcc1.so but the gcc commmand GDB found is not gcc-5.0,
otherwise it would not complain for '-std=gnu11' etc.

GDB does not search for 'cc' or 'gcc', it uses more complicated pattern:
	https://sourceware.org/gdb/current/onlinedocs/gdb/Compiling-and-Injecting-Code.html#Compiling-and-Injecting-Code
	17.7.3 Compiler search for the compile command
For example on my system it found (not easy to find out, used 'strace -f -p'
for running GDB during the 'compile code' command):
	/usr/lib64/ccache/x86_64-redhat-linux-gcc

I will add there some debug output + filename-enforcing commands.


Thanks for testing compile,
Jan

Re: 答复: How to use compile & execute function in GDB

[Jan Kratochvil]

On Thu, 16 Apr 2015 05:35:04 +0200, 高国胜 wrote:
> Ok，it works now. 

Great.


> Can the compile & execute function be used for cross debugging in embed
> system?

You do not say the target triple.  It requires gdbarch_infcall_mmap() which is
currently implemented only by linux-tdep.c, by looking up the "mmap64" symbol.
If you do not have it you should get
	This target does not support inferior memory allocation by mmap.
or
	evaluation of this expression requires the program to have a function "mmap64".

Either your target uses linux-tdep.c and it is enough to provide suitable
"mmap64" function in your target inferior or you need to implement appropriate
gdbarch_infcall_mmap() in your tdep GDB file.


Jan