[Bug 82828] Regression: Crash in 3Dmark2001

[bugzilla-daemon at freedesktop.org]

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

--- Comment #6 from Connor Abbott <cwabbott0 at gmail.com> ---
(In reply to comment #5)
> Created attachment 105451 [details]
> 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.

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, then
it's supposed to be assigned a register already).

(In reply to comment #5)
> Created attachment 105451 [details]
> 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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