Thanks to the hints of Gopal and Paolo, I added a simple stabs generator
for JIT code. As we currently don't have line numbers, the code assumes,
there are no comments and no empty lines, just one op per line.
Here is a sample debug session (the important thing happens after
build_asm where symbols got built):
$ gdb parrot
GNU gdb 4.18
....
(gdb) b runops_jit
Breakpoint 1 at 0x8049ca7: file interpreter.c, line 227.
(gdb) r -j -d mops.pbc
Starting program: /home/lt/src/parrot-leo/parrot -j mops.pbc
Breakpoint 1, runops_jit (interpreter=0x812eab0, pc=0x81466b0)
at interpreter.c:227
227
code_start = interpreter->code->byte_code;
(gdb) n
228
code_size = interpreter->code->byte_code_size / sizeof(opcode_t);
(gdb)
229
code_end = interpreter->code->byte_code + code_size;
(gdb)
231
jit_code = build_asm(interpreter, pc, code_start, code_end);
(gdb)
232
(jit_code) (interpreter, pc);
(gdb) add-symbol-file mops.o 0
add symbol table from file "mops.o" at text_addr = 0x0?
(y or n) y
Reading symbols from mops.o...done.
(gdb) s
jit_func () at mops.pasm:1
1
set I2, 0
(gdb)
2
set I3, 1
(gdb) l
1
set I2, 0
2
set I3, 1
3
set I4, 100000000
4
print "Iterations: "
5
print I4
6
print "\n"
7
set I1, 2
8
mul I5, I4, I1
9
print "Estimated ops: "
10
print I5
(gdb) l
11
print "\n"
12
time N1
13
REDO: sub I4, I4, I3
14
if I4, REDO
15
DONE: time N5
16
sub N2, N5, N1
17
print "Elapsed time: "
18
print N2
19
print "\n"
20
if I4, BUG
(gdb) b 13
Breakpoint 2 at 0x814ecc6: file mops.pasm, line 13.
(gdb) c
Continuing.
Iterations: 100000000
Estimated ops: 200000000
Breakpoint 2, jit_func () at mops.pasm:13
13
REDO: sub I4, I4, I3
(gdb) n
14
if I4, REDO
(gdb)
14
if I4, REDO
(gdb)
14
if I4, REDO
(gdb) b 15
Breakpoint 3 at 0x814ecdc: file mops.pasm, line 15.
(gdb) c
Continuing.
Breakpoint 3, jit_func () at mops.pasm:15
15
DONE: time N5
(gdb) c
Continuing.
Elapsed time: 9.725663
M op/s: 20.564151
Program exited normally.
(gdb) q
Have fun,
leo
