Comment=
# 6
on bug 82828<=
/a>
from Connor Abbott
(In reply to comment #5=
)
> Created attachment 105451 [details]
> full backtrace from piglit crash
>=20
> (In reply to comment #4)
> > All the crashes are in the same place, right?
> >=20
> > Can you run it under gdb and print out n2 and the contents of
> > g->nodes[n].adjacency_list (it's an array with g->nodes[n].=
adjacency_count
> > elements) after the segfault? How about the former before the ra_=
simplify()
> > call in the ra_allocate() call that's segfaulting? (If you don't =
know how to
> > do this, see
> > http://stackoverflow.com/questions/2956889/how-to-set-=
a-counter-for-a-gdb-
> > breakpoint)
> >=20
> > I'm guessing that it's segfaulting because n2 is some bogus value=
. n2 comes
> > from the adjacency_list, which is something generated before the =
allocator
> > actually runs by code I didn't touch and then never modified afte=
rward, and
> > the code that's segfaulting wasn't modified by the commit in ques=
tion, so
> > the two most likely options I see are that either this is exposin=
g a bug
> > somewhere else (like in r300g) or the new ra_simplify() is somehow
> > corrupting the adjacency_list. I don't know how r300g sets up the=
register
> > conflicts and register classes, though, so I can't guess why it w=
orks fine
> > on i965 but fails for r300g.
>=20
> OK, so not sure if I know what I'm doing but selecting one random cras=
hing
> piglit test
>=20
> /bin/shader_runner tests/shaders/glsl-fs-loop-continue.shader_test -au=
to
>=20
> Program received signal SIGSEGV, Segmentation fault.
> 0xb76391a9 in ra_select (g=3D0x80c2058) at
> ../../src/mesa/program/register_allocate.c:525
> 525 BITSET_TEST(g->regs->regs[r].conflicts, g->nodes[n2].re=
g)) {
>=20
> print n2
> $2 =3D 0
>=20
> print n
> $7 =3D 1
>=20
> print g->nodes[n].adjacency_count
> $1 =3D 3
>=20
> print g->nodes[n].adjacency_list
> $3 =3D (unsigned int *) 0x80c1b58
>=20
> print g->nodes[n].adjacency_list[0]
> $4 =3D 1
>=20
> print g->nodes[n].adjacency_list[1]
> $5 =3D 0
>=20
> print g->nodes[n].adjacency_list[2]
> $6 =3D 2
>=20
> full backtrace attached.
Can you print out the value of g->nodes[n2].reg? I think it may be NO_REG
(0xffffffff), even though it shouldn't be (if a node is not on the stack, t=
hen
it's supposed to be assigned a register already).
(In reply to comment #5)
> Created attachment 105451 [details]
> full backtrace from piglit crash
>=20
> (In reply to comment #4)
> > All the crashes are in the same place, right?
> >=20
> > Can you run it under gdb and print out n2 and the contents of
> > g->nodes[n].adjacency_list (it's an array with g->nodes[n].=
adjacency_count
> > elements) after the segfault? How about the former before the ra_=
simplify()
> > call in the ra_allocate() call that's segfaulting? (If you don't =
know how to
> > do this, see
> > http://stackoverflow.com/questions/2956889/how-to-set-=
a-counter-for-a-gdb-
> > breakpoint)
> >=20
> > I'm guessing that it's segfaulting because n2 is some bogus value=
. n2 comes
> > from the adjacency_list, which is something generated before the =
allocator
> > actually runs by code I didn't touch and then never modified afte=
rward, and
> > the code that's segfaulting wasn't modified by the commit in ques=
tion, so
> > the two most likely options I see are that either this is exposin=
g a bug
> > somewhere else (like in r300g) or the new ra_simplify() is somehow
> > corrupting the adjacency_list. I don't know how r300g sets up the=
register
> > conflicts and register classes, though, so I can't guess why it w=
orks fine
> > on i965 but fails for r300g.
>=20
> OK, so not sure if I know what I'm doing but selecting one random cras=
hing
> piglit test
>=20
> /bin/shader_runner tests/shaders/glsl-fs-loop-continue.shader_test -au=
to
>=20
> Program received signal SIGSEGV, Segmentation fault.
> 0xb76391a9 in ra_select (g=3D0x80c2058) at
> ../../src/mesa/program/register_allocate.c:525
> 525 BITSET_TEST(g->regs->regs[r].conflicts, g->nodes[n2].re=
g)) {
>=20
> print n2
> $2 =3D 0
>=20
> print n
> $7 =3D 1
>=20
> print g->nodes[n].adjacency_count
> $1 =3D 3
>=20
> print g->nodes[n].adjacency_list
> $3 =3D (unsigned int *) 0x80c1b58
>=20
> print g->nodes[n].adjacency_list[0]
> $4 =3D 1
>=20
> print g->nodes[n].adjacency_list[1]
> $5 =3D 0
>=20
> print g->nodes[n].adjacency_list[2]
> $6 =3D 2
>=20
> full backtrace attached.