https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90813
Thomas Koenig <tkoenig at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|fortran |rtl-optimization
--- Comment #14 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
So, the code of actually calling the procedure seems to be correct.
(It loads the address of the procedure pointer, then loads
the address from there, and branches).
What appears to be wrong is that the subroutine fs, which assigns
the address of c to the procedure pointer, is never executed.
Data point: -fno-inline restores the correct behavior.
In the .optimized dump, the relevant lines are
MEM[(struct s &)_7].i = 99;
c_ = c;
c_.5_12 = c_;
rhs.2 = c_.5_12 ();
and it seems tat the statement
c_ = c;
is somehow eliminated later.
Ouch, yes, I think I see this now (after some debugging).
This
# proc_ptr_51.f90:35: res => c_()
addis 10,2,.LC1@toc@ha # tmp142,,
ld 10,.LC1@toc@l(10) # tmp142,, tmp142
loads the contents of LC1 (where the procedure
pointer resides) into r10.
This
# proc_ptr_51.f90:26: c_ => c ! This used to ICE
addis 9,2,__f_MOD_c@toc@ha # tmp141,,
# proc_ptr_51.f90:30: end module f
li 8,99 # tmp139,
# proc_ptr_51.f90:26: c_ => c ! This used to ICE
addi 9,9,__f_MOD_c@toc@l # tmp141, tmp141,
puts the address of __f_MOD_c into r9 (and loads another
value in the meantime).
Next lines are
# proc_ptr_51.f90:33: allocate (tgt, source = s(99))
addis 7,2,.LANCHOR0+8@toc@ha # tmp178,,,
addi 30,30,32 # tmp172, tmp171,
# proc_ptr_51.f90:30: end module f
stw 8,0(3) # MEM[(struct s &)_7].i, tmp139
These lines are unrelated.
# proc_ptr_51.f90:35: res => c_()
ld 12,0(10) # c_, c_
This loads the contents of the procedure poitner into r12.
# proc_ptr_51.f90:26: c_ => c ! This used to ICE
addis 10,2,.LANCHOR1@toc@ha # tmp179,,
# proc_ptr_51.f90:33: allocate (tgt, source = s(99))
std 30,.LANCHOR0+8@toc@l(7) # tgt._vptr, tmp172
# proc_ptr_51.f90:26: c_ => c ! This used to ICE
std 9,.LANCHOR1@toc@l(10) # c_, tmp141
This (if I am not mistaken) stores the contents of r9 into the
procedure pointer, but it is too late, because this
# proc_ptr_51.f90:35: res => c_()
mtctr 12 #,
jumps to the NULL pointer.
Interesting question: Why is the store done too late? The tree
dumps look OK; the problem also does not occur if the
call to fs is replaced by a simple pointer assignment.
So, I am going to guess and say this is probably an RTL problem.
