Hi. Sorry for the late reply.
On 03/02, Richard Biener wrote:
> On Thu, Feb 27, 2020 at 6:56 PM Giuliano Belinassi
> <giuliano.belina...@usp.br> wrote:
> >
> > Hi, all.
> >
> > I am tying to fix an issue with a global variable in the parallel gcc
> > project. For this, I am trying to move some global variables from
> > tree-ssa-operands to struct function. One of this variable is a
> > vec<tree*> type, and gengtype doesn't look so happy with it.
>
> I think the solution for this is to not move it to struct function
> but instead have it local to function scope - the state is per
> GIMPLE stmt we process and abstracting what is
> cleaned up in cleanup_build_arrays() into a class we can
> instantiate in the two callers is most appropriate. In theory
> all the functions that access the state could move into the
> class as methods as well but you can pass down the state
> everywhere needed as well.
I implemented this strategy, but the issue remains. Therefore, the
cause of it must be something else.
Just to contextualize, in [1], I also implemented parallelism in
ParallelGcc using a pipeline method for testing, where I split the set
of GIMPLE Intra Procedural Optimizations into multiple sets, and assign
each set to a thread. Then, the function passes through this pipeline.
Now, I am trying to make this version pass the testsuite. There is a test
in particular ('gcc.dg/20031102-1.c') that I am having difficulties
finding the cause of the issue.
if I run:
/tmp/gcc10_parallel/usr/local/bin/gcc --param=num-threads=2 -O2 -c 20031102-1.c
The crash message is:
```
<var_decl 0x7f443363c720 .MEM
type <void_type 0x7f44334fb000 void VOID
align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7f44334fb000
pointer_to_this <pointer_type 0x7f44334fb0b0>>
used static ignored external VOID <built-in>:0:0
align:8 warn_if_not_align:0>
In function ‘main’:
cc1: error: virtual use of statement not up to date
# VUSE <.MEM_1(D)>
_2 = FooBar ();
during GIMPLE pass: walloca
cc1: internal compiler error: verify_ssa failed
0xfdb8fe verify_ssa(bool, bool)
../../gcc/gcc/tree-ssa.c:1208
0xcd3d08 execute_function_todo
../../gcc/gcc/passes.c:2017
0xcd49f2 execute_todo
../../gcc/gcc/passes.c:2064
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
```
Which is triggered by tree-ssa-operands.c:1066 in this branch, checking
if build_vuse != use. Interestingly, this crash does not happens if:
1 - I set the number of threads to 1.
2 - I set the optimization level to O0, O1 or O3.
3 - I disable O2, but enable all flags enabled by O2
(gcc -O2 -Q --help=optimizer).
4 - I left the first 115 passes in the same thread with a parameter I
implmemented (--param=num-threads=2 --param=break=116). Any value
smaller that this causes the issue.
The crash is also consistent, which means that it happens 100% of time.
Any light concerning this issue is welcome. :)
If anyone want to reproduce the issue, you can clone this branch, then compile
with --disable-bootstrap --enable-language=c, and install it like trunk's GCC.
[1] - https://gitlab.com/flusp/gcc/-/tree/giulianob_parallel_pipeline
Thank you,
Giuliano.
>
> Richard.
>
> > In this context, I am trying to add support to vec<tree*> to gengtype.
> > Therefore, I first fixed a problem where gengtype couldn't find the
> > tree union by:
> >
> > diff --git a/gcc/gengtype.c b/gcc/gengtype.c
> > index 53317337cf8..6f4c77020ea 100644
> > --- a/gcc/gengtype.c
> > +++ b/gcc/gengtype.c
> > @@ -638,7 +638,10 @@ create_user_defined_type (const char *type_name,
> > struct fil
> > eloc *pos)
> > /* Strip off the first '*' character (and any subsequent
> > text). */
> > *(field_name + offset_to_star) = '\0';
> >
> > - arg_type = find_structure (field_name, TYPE_STRUCT);
> > + arg_type = resolve_typedef (field_name, pos);
> > + if (!arg_type)
> > + arg_type = find_structure (field_name, TYPE_STRUCT);
> > +
> > arg_type = create_pointer (arg_type);
> > }
> > else
> >
> > After this patch, gengtype seems to correctly detect vec<tree*> types,
> > but then I face linking issues. At first, the compiler could not find
> > gt_ggc_mx (vec<T> *v) and gt_pch_mx (vec<T> *v), therefore I implemented
> > them both in gcc/vec.h:
> >
> > diff --git a/gcc/vec.h b/gcc/vec.h
> > index 091056b37bc..dfa744b684e 100644
> > --- a/gcc/vec.h
> > +++ b/gcc/vec.h
> > @@ -1306,6 +1306,15 @@ vec<T, A, vl_embed>::quick_grow_cleared (unsigned
> > len)
> > vec_default_construct (address () + oldlen, growby);
> > }
> >
> > +template<typename T>
> > +void
> > +gt_ggc_mx (vec<T> *v)
> > +{
> > + extern void gt_ggc_mx (T &);
> > + for (unsigned i = 0; i < v->length (); i++)
> > + gt_ggc_mx ((*v)[i]);
> > +}
> > +
> > /* Garbage collection support for vec<T, A, vl_embed>. */
> >
> > template<typename T>
> > @@ -1328,6 +1337,15 @@ gt_ggc_mx (vec<T, va_gc_atomic, vl_embed> *v
> > ATTRIBUTE_UNUSED)
> >
> > /* PCH support for vec<T, A, vl_embed>. */
> >
> > +template<typename T>
> > +void
> > +gt_pch_nx (vec<T> *v)
> > +{
> > + extern void gt_pch_nx (T &);
> > + for (unsigned i = 0; i < v->length (); i++)
> > + gt_pch_nx ((*v)[i]);
> > +}
> > +
> > template<typename T, typename A>
> > void
> > gt_pch_nx (vec<T, A, vl_embed> *v)
> > @@ -1337,6 +1355,14 @@ gt_pch_nx (vec<T, A, vl_embed> *v)
> > gt_pch_nx ((*v)[i]);
> > }
> >
> > +template<typename T>
> > +void
> > +gt_pch_nx (vec<T *> *v, gt_pointer_operator op, void *cookie)
> > +{
> > + for (unsigned i = 0; i < v->length (); i++)
> > + op (&((*v)[i]), cookie);
> > +}
> > +
> > template<typename T, typename A>
> > void
> > gt_pch_nx (vec<T *, A, vl_embed> *v, gt_pointer_operator op, void *cookie)
> > @@ -1354,6 +1380,15 @@ gt_pch_nx (vec<T, A, vl_embed> *v,
> > gt_pointer_operator op, void *cookie)
> > gt_pch_nx (&((*v)[i]), op, cookie);
> > }
> >
> > +template<typename T>
> > +void
> > +gt_pch_nx (vec<T> *v, gt_pointer_operator op, void *cookie)
> > +{
> > + extern void gt_pch_nx (T *, gt_pointer_operator, void *);
> > + for (unsigned i = 0; i < v->length (); i++)
> > + gt_pch_nx (&((*v)[i]), op, cookie);
> > +}
> > +
> >
> > After that, I get linking errors because the linker can not find
> > gt_ggc_mx (tree *&x) nor void gt_pch_nx (tree *&x). The thing
> > is: it doesn't matter where I implement them, or if I declare
> > them inline. I always get a linking error one way or another.
> >
> > Therefore, what should I do to correctly implement the support
> > for vec<tree*> types?
> >
> > Thank you,
> > Giuliano.
