Hello world,
the attached patch fixes an 8/9/10 regression where, to fix PR 84487
by not putting the initializers and vtabs into the read-only section
(for reasons of size, which could grow enormously) led to a regression
on POWER9 and other non-x86 architectures, where the initializer was
sometimes optimized away, depending on optimization levels.
This was a strange beast to hunt down. This only showed up on
the testresults for gcc 8, so I tried to find out what commit
had fixed this on trunk, in order to backport.
However, bisecting this I found that the test case actually
segfaults all the way up to current trunk when run by hand.
By running the testsuite, I didn't see it. This is strange,
and raises some issues about the testsuite and the possibility
of a latent issue, but I lack the knowledge to hunt this down.
In the meantime, here is this patch, which puts the vtabs and
the initializers where the user actually specified something
into the read-only section again.
Test case: Well, theoretically it is already there, so it makes
little sense to add a new one.
Regression-tested on powerpc64le-unknown-linux-gnu, also
verified by hand that pr51434.f90 now passes with -O2 there.
OK for trunk/9/8?
Regards
Thomas
2019-11-02 Thomas Koenig <tkoe...@gcc.gnu.org>
PR fortran/92133
* trans-decl.c (gfc_get_symbol_decl): If __def_init actually
contains a value, put it into the read-only section.
Index: trans-decl.c
===================================================================
--- trans-decl.c (Revision 277486)
+++ trans-decl.c (Arbeitskopie)
@@ -1911,14 +1911,19 @@ gfc_get_symbol_decl (gfc_symbol * sym)
if (sym->attr.associate_var)
GFC_DECL_ASSOCIATE_VAR_P (decl) = 1;
- /* We no longer mark __def_init as read-only so it does not take up
- space in the read-only section and dan go into the BSS instead,
- see PR 84487. Marking this as artificial means that OpenMP will
- treat this as predetermined shared. */
- if (sym->attr.vtab
- || (sym->name[0] == '_' && gfc_str_startswith (sym->name, "__def_init")))
- DECL_ARTIFICIAL (decl) = 1;
+ /* We only mark __def_init as read-only if it actually has an
+ initializer so it does not needlessly take up space in the
+ read-only section and can go into the BSS instead, see PR 84487.
+ Marking this as artificial means that OpenMP will treat this as
+ predetermined shared. */
+ if (sym->attr.vtab || gfc_str_startswith (sym->name, "__def_init"))
+ {
+ DECL_ARTIFICIAL (decl) = 1;
+ if (sym->attr.vtab || sym->value)
+ TREE_READONLY (decl) = 1;
+ }
+
return decl;
}
