Debugging support for JIT code

[llvmbot]

Bugzilla Link	1129
Resolution	FIXED
Resolved on	Oct 13, 2009 16:46
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@asl,@nunoplopes

Extended Description

When debugging JIT code, I'd like to have some means to either step through code
using GDB or see a trace of JITed code.

[llvmbot]

As I mentioned to Leonard on IRC, one way to do the trace feature is to:

1. Add a -jit-trace-debug option.
2. Have IntrinsicLowering lower intrinsics into function calls if that option
   is set.
3. Implement those functions in lli to print out the trace of the program.

It might also be possible to specify a breakpoint from the debugger by calling a
special lli function with the file name and line number. Then the trace would
stop printing out until the break point was hit.

[lattner]

It would be far better to make the JIT emit DWARF information to memory, then inform GDB about it. I
have no idea if GDB has such a feature. Do you know how tcc works?

[asl]

tcc uses stabs. I don't know how to inform gdb to load something from memory.
Leonard, do you have some example code with tcc & jit'ed debugging?

[nunoplopes]

I believe this is done by now. There's now support for both gdb and oprofile.

[lhames]

mentioned in issue llvm/llvm-bugzilla-archive#21523

[lhames]

mentioned in issue llvm/llvm-bugzilla-archive#45208