The previous trace is wrong, sorry
A correct place is
else if (tok == '{') {
if (const_wanted)
tcc_error("expected constant");
/* save all registers */
save_regs(0); <<<<<<<<<<<<<<<
/* statement expression : we do not accept break/continue
inside as GCC does */
block(NULL, NULL, NULL, NULL, 0, 1);
skip(')');
} else {
gexpr();
skip(')');
}
This is a save_regs(0) which generate a code when nocode_wanted=1
When
if(!nocode_wanted)
save_regs(0);
then there is no error messages but a test program still hangs
2016-04-03 14:17 GMT+03:00 Sergey Korshunoff <[email protected]>:
> > Or at least fail with an explanatory
> > message if o() is called while nocode_wanted is set?
> I can not grock what is wrong (where is the error). But is starts in
> block.c: 5001 when ({}) is used.
>
> antoo # gdb tcc
> (gdb) set args vla_label_fix_problem.c
> (gdb) b check_nocode_wanted
> Breakpoint 1 at 0x806193a: file i386-gen.c, line 118.
> (gdb) r
> Starting program: /usr/local/bin/tcc vla_label_fix_problem.c
> Breakpoint 1, check_nocode_wanted () at i386-gen.c:118
> 118 if (nocode_wanted)
> (gdb) bt
> #0 check_nocode_wanted () at i386-gen.c:118
> #1 0x08061960 in o (c=184) at i386-gen.c:124
> #2 0x08061dbd in load (r=0, sv=0x80742b8) at i386-gen.c:269
> #3 0x08050c95 in gv (rc=1) at tccgen.c:979
> #4 0x08054882 in vstore () at tccgen.c:2752
> #5 0x08059b06 in init_putv (type=0xbfeb2c18, sec=0x0, c=4294967292, v=0,
> expr_type=2) at tccgen.c:5559
> #6 0x0805a3ce in decl_initializer (type=0xbfeb2c18, sec=0x0,
> c=4294967292, first=1, size_only=0) at tccgen.c:5867
> #7 0x0805a9f7 in decl_initializer_alloc (type=0xbfeb2c18, ad=0xbfeb2bf0,
> r=306, has_init=1, v=1169, scope=50)
> at tccgen.c:6102
> #8 0x0805b7a6 in decl0 (l=50, is_for_loop_init=0) at tccgen.c:6522
> #9 0x0805b80e in decl (l=50) at tccgen.c:6541
> #10 0x08058534 in label_or_decl (l=50) at tccgen.c:4919
> #11 0x08058819 in block (bsym=0x0, csym=0x0, case_sym=0x0, def_sym=0x0,
> case_reg=0, is_expr=0) at tccgen.c:5001
> #12 0x0805ade4 in gen_function (sym=0x8d931c4) at tccgen.c:6216
> #13 0x0805b5a9 in decl0 (l=48, is_for_loop_init=0) at tccgen.c:6468
> #14 0x0805b80e in decl (l=48) at tccgen.c:6541
> #15 0x08068882 in tcc_compile (s1=0x8d86008) at libtcc.c:976
> #16 0x08069374 in tcc_add_file_internal (s1=0x8d86008, filename=0x8d94241
> "vla_label_fix_problem.c", flags=1, filetype=2)
> at libtcc.c:1384
> #17 0x08069581 in tcc_add_file (s=0x8d86008, filename=0x8d94241
> "vla_label_fix_problem.c", filetype=2) at libtcc.c:1476
> #18 0x0806b63a in main (argc=2, argv=0xbfeb31f4) at tcc.c:326
> (gdb).
>
> block.c: 5001
> while (tok != '}') {
> label_or_decl(VT_LOCAL);
> if (tok != '}') {
> if (is_expr)
> vpop();
> block(bsym, csym, case_sym, def_sym, case_reg, is_expr);
> }
> }
>
>
> 2016-04-03 12:13 GMT+03:00 Edmund Grimley Evans <
> [email protected]>:
>
>> > Hi! The following test hangs when compiled with tcc after 737f98421
>> > tccgen.c: Bug fix for 992cbda and 3ff77a1: set nocode_wanted.
>> > tests/tests2/78_vla_label.*: Add test
>>
>> The change introduced at 737f98421 depends on "nocode_wanted" working.
>> But it doesn't work, of course. It's broken probably in lots of ways,
>> but in particular a "do" loop will generate code when it shouldn't. So
>> another instance of the same bug is demonstrated by this:
>>
>> int main()
>> {
>> return sizeof( ({ do { } while (1); }), 0 );
>> }
>>
>> (So the bug perhaps only affects statement expressions, which are not
>> part of standard C.)
>>
>> I wonder, how feasible is it to find every place in tccgen.c where a
>> back-end function like gjmp might be called and ensure that it won't
>> be called when nocode_wanted is set? Could this be done more
>> systematically at a lower level? Or at least fail with an explanatory
>> message if o() is called while nocode_wanted is set?
>>
>> Edmund
>>
>> _______________________________________________
>> Tinycc-devel mailing list
>> [email protected]
>> https://lists.nongnu.org/mailman/listinfo/tinycc-devel
>>
>
>
_______________________________________________
Tinycc-devel mailing list
[email protected]
https://lists.nongnu.org/mailman/listinfo/tinycc-devel
