This patch improves the support of DWARF5 by lldb.
Imagine we have the following code,
(compiled with clang++ test.cpp -g -o test -gdwarf-5):
struct XXX {
int A;
};
int main() {
XXX Obj;
Obj.A = 1;
return Obj.A;
}Without this patch when lldb stops on a breakpoint or dump variables
the output is:
(lldb) b main
warning: (x86_64) /home/umb/tests_2018/95_lldb/repro/dwarf5_nosplit/test unsupported DW_FORM value: 0x25
Breakpoint 1: where = test`main, address = 0x0000000000400550
(lldb) run
Process 5589 launched: '/home/umb/tests_2018/95_lldb/repro/dwarf5_nosplit/test' (x86_64)
Process 5589 stopped
* thread #1, name = 'test', stop reason = breakpoint 1.1
frame #0: 0x0000000000400550 test`main
test`main:
-> 0x400550 <+0>: pushq %rbp
0x400551 <+1>: movq %rsp, %rbp
0x400554 <+4>: movl $0x0, -0x4(%rbp)
0x40055b <+11>: movl $0x1, -0x8(%rbp)
(lldb) script
Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
>>> print lldb.frame.GetVariables(True, True, True, True)
<empty> lldb.SBValueList()Note that it complains about unknown forms,
there is no code source lines and output from the print
call is empty.
With the patch applied output becomes:
umb@umb-virtual-machine:~/LLVM/build_lldb/bin$ ./lldb ~/tests_2018/95_lldb/repro/dwarf5_nosplit/test
(lldb) target create "/home/umb/tests_2018/95_lldb/repro/dwarf5_nosplit/test"
Current executable set to '/home/umb/tests_2018/95_lldb/repro/dwarf5_nosplit/test' (x86_64).
(lldb) b main
Breakpoint 1: where = test`main + 11 at test.cpp:7, address = 0x000000000040055b
(lldb) run
Process 63624 launched: '/home/umb/tests_2018/95_lldb/repro/dwarf5_nosplit/test' (x86_64)
Process 63624 stopped
* thread #1, name = 'test', stop reason = breakpoint 1.1
frame #0: 0x000000000040055b test`main at test.cpp:7
4
5 int main() {
6 XXX Obj;
-> 7 Obj.A = 1;
8
9 return Obj.A;
10 }
(lldb) script
Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
>>> print lldb.frame.GetVariables(True, True, True, True)
(XXX) Obj = (A = 0)Note there is no test case yet, I am going to add it to this revision soon.
This is my first patch for lldb and I did not yet learn how to write the
test for the code written.
I would be happy to see any comments/suggestions.