[Bug 82828] Regression: Crash in 3Dmark2001

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=82828

--- Comment #5 from Pavel Ondračka <pavel.ondracka at email.cz> ---
Created attachment 105451
  --> https://bugs.freedesktop.org/attachment.cgi?id=105451&action=edit
full backtrace from piglit crash

(In reply to comment #4)
> All the crashes are in the same place, right?
> 
> 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)
> 
> 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 afterward, and
> the code that's segfaulting wasn't modified by the commit in question, so
> the two most likely options I see are that either this is exposing 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 works fine
> on i965 but fails for r300g.

OK, so not sure if I know what I'm doing but selecting one random crashing
piglit test

/bin/shader_runner tests/shaders/glsl-fs-loop-continue.shader_test -auto

Program received signal SIGSEGV, Segmentation fault.
0xb76391a9 in ra_select (g=0x80c2058) at
../../src/mesa/program/register_allocate.c:525
525            BITSET_TEST(g->regs->regs[r].conflicts, g->nodes[n2].reg)) {

print n2
$2 = 0

print n
$7 = 1

print g->nodes[n].adjacency_count
$1 = 3

print g->nodes[n].adjacency_list
$3 = (unsigned int *) 0x80c1b58

print g->nodes[n].adjacency_list[0]
$4 = 1

print g->nodes[n].adjacency_list[1]
$5 = 0

print g->nodes[n].adjacency_list[2]
$6 = 2

full backtrace attached.

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