On 16 July 2015 at 12:39, Richard Biener <rguent...@suse.de> wrote:
> On Wed, 15 Jul 2015, Prathamesh Kulkarni wrote:
>
>> Hi,
>> We allow c_expr to be empty which accepts cases like the following:
>>
>> (simplify
>> match-operand
>> (if ()
>> result-operand))
>>
>> (simplify
>> match-operand
>> {})
>
> Yes we do. We also do not reject various other "bad" forms like
>
> { ( blah! }
>
> so I am not sure treating empty ones specially makes sense. After
> all a c-expr is just a list of preprocessing tokens we re-inject
> into the generated C code.
Well the empty () causes genmatch to segfault.
(simplify
(plus @x @y)
(if ()
@x)))
segfaults here at genmatch.c:2583
output_line_directive (f, ife->cond->code[0].src_loc);
IIUC, since we bail out early from parse_c_expr on "()", code remains
vNULL and accessing code[0] leads to segfault.
backtrace with gdb:
#0 operator[] (ix=0, this=0x6bb628) at ../../src/gcc/vec.h:1180
#1 dt_simplify::gen_1 (this=this@entry=0x6bac30,
f=f@entry=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=indent@entry=10,
gimple=gimple@entry=true, result=0x6bb5e0) at
../../src/gcc/genmatch.c:2583
#2 0x0000000000413430 in dt_simplify::gen (this=0x6bac30,
f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=10, gimple=<optimized out>)
at ../../src/gcc/genmatch.c:2873
#3 0x000000000040de6f in dt_node::gen_kids_1
(this=this@entry=0x6babc0, f=f@entry=0x7ffff7dd4400 <_IO_2_1_stdout_>,
indent=indent@entry=8, gimple=gimple@entry=true,
gimple_exprs=gimple_exprs@entry=...,
generic_exprs=generic_exprs@entry=..., fns=fns@entry=...,
generic_fns=generic_fns@entry=..., preds=preds@entry=...,
others=others@entry=...) at ../../src/gcc/genmatch.c:2510
#4 0x000000000040ecf3 in dt_node::gen_kids (this=0x6babc0,
f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=true) at
../../src/gcc/genmatch.c:2312
#5 0x000000000040f491 in dt_operand::gen (this=0x6babc0,
f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=<optimized out>)
at ../../src/gcc/genmatch.c:2548
#6 0x000000000040e3a2 in dt_node::gen_kids (this=0x6bab80,
f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=true) at
../../src/gcc/genmatch.c:2298
#7 0x000000000040f491 in dt_operand::gen (this=0x6bab80,
f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=<optimized out>)
at ../../src/gcc/genmatch.c:2548
#8 0x000000000040e3a2 in dt_node::gen_kids (this=0x6bab40,
f=0x7ffff7dd4400 <_IO_2_1_stdout_>, indent=8, gimple=true) at
../../src/gcc/genmatch.c:2298
#9 0x000000000040f667 in decision_tree::gen_gimple
(this=0x7fffffffde00, f=0x7ffff7dd4400 <_IO_2_1_stdout_>) at
../../src/gcc/genmatch.c:2913
#10 0x000000000040835e in main (argc=7056432, argv=0x0) at
../../src/gcc/genmatch.c:4135
Thanks,
Prathamesh
>
>> The attached patch rejects empty c_expr.
>> Ok for trunk after bootstrap + test ?
>>
>> Thank you,
>> Prathamesh
>>
>
> --
> Richard Biener <rguent...@suse.de>
> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Dilip Upmanyu, Graham
> Norton, HRB 21284 (AG Nuernberg)
