http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55719
Aldy Hernandez <aldyh at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rsandifo at gcc dot gnu.org
--- Comment #5 from Aldy Hernandez <aldyh at gcc dot gnu.org> 2013-01-09
18:45:34 UTC ---
I'm out of my depth here, but perhaps someone can give me a hint on how to
debug this further.
As alluded to earlier, this ICE only happens with sched-pressure scheduling.
The actual ICE happens in find_reloads_address_part(), where we have are
analyzing X=:
(const:DI (plus:DI (symbol_ref:DI ("glob_b"))
(const_int 3 [0x3])))
prefer_reload_class() returns NO_REGS, because legitimate_reload_constant_p()
returns false for the X above. So when we call force_const_mem() in
find_reloads_address_part...
if (CONSTANT_P (x)
&& (!targetm.legitimate_constant_p (mode, x)
|| targetm.preferred_reload_class (x, rclass) == NO_REGS))
{
x = force_const_mem (mode, x); <-- HERE
force_const_mem() returns NULL because s390_cannot_force_const_mem() returns
true for the SYMBOL_REF in -fPIC mode.
Bottom line-- force_const_mem() returns NULL for a (const (plus SYMBOL_REF
CONST)) with -fPIC, and then we dereference this NULL.
Is the RTL correct?
Any hints?
