Hello world,
the attached patch fixes a 9/10/11 regression where we left over
an implicit_pure attribute when a non-implicit_pure procedure was
called.
The fix is explained in the ChangeLog.
If there is a quick review, please also indicate if you think it is
still suitable for gcc 10.2. If the review comes later, then
it obviously will not be :-) On the code side, this should be
fairly safe, because all we are doing is to be more defensive
about our optimizations.
OK for trunk/backporting? This is not something I want to commit
without a review because it is not quite obvious and simple :-)
Best regards
Thomas
Fix handling of implicit_pure by checking if non-pure procedures are called.
Procedures are marked as implicit_pure if they fulfill the criteria of
pure procedures. In this case, a procedure was not marked as not being
implicit_pure which called another procedure, which had not yet been
marked as not being implicit_impure.
Fixed by iterating over all procedures, setting callers of procedures
which are non-pure and non-implicit_pure as non-implicit_pure and
doing this until no more procedure has been changed.
gcc/fortran/ChangeLog:
2020-07-10 Thomas Koenig <tkoe...@gcc.gnu.org>
PR fortran/96018
* frontend-passes.c (gfc_check_externals): Adjust formatting.
(implicit_pure_call): New function.
(implicit_pure_expr): New function.
(gfc_fix_implicit_pure): New function.
* gfortran.h (gfc_fix_implicit_pure): New prototype.
* parse.c (translate_all_program_units): Call gfc_fix_implicit_pure.
diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c
index 69f9ca64c97..4b1d3f2feda 100644
--- a/gcc/fortran/frontend-passes.c
+++ b/gcc/fortran/frontend-passes.c
@@ -5550,7 +5550,8 @@ gfc_check_externals0 (gfc_namespace *ns)
/* Called routine. */
-void gfc_check_externals (gfc_namespace *ns)
+void
+gfc_check_externals (gfc_namespace *ns)
{
gfc_clear_error ();
@@ -5565,3 +5566,76 @@ void gfc_check_externals (gfc_namespace *ns)
gfc_errors_to_warnings (false);
}
+/* Callback function. If there is a call to a subroutine which is
+ neither pure nor implicit_pure, unset the implicit_pure flag for
+ the caller and return -1. */
+
+static int
+implicit_pure_call (gfc_code **c, int *walk_subtrees ATTRIBUTE_UNUSED,
+ void *sym_data)
+{
+ gfc_code *co = *c;
+ gfc_symbol *caller_sym;
+ symbol_attribute *a;
+
+ if (co->op != EXEC_CALL || co->resolved_sym == NULL)
+ return 0;
+
+ a = &co->resolved_sym->attr;
+ if (a->intrinsic || a->pure || a->implicit_pure)
+ return 0;
+
+ caller_sym = (gfc_symbol *) sym_data;
+ gfc_unset_implicit_pure (caller_sym);
+ return 1;
+}
+
+/* Callback function. If there is a call to a function which is
+ neither pure nor implicit_pure, unset the implicit_pure flag for
+ the caller and return 1. */
+
+static int
+implicit_pure_expr (gfc_expr **e, int *walk ATTRIBUTE_UNUSED, void *sym_data)
+{
+ gfc_expr *expr = *e;
+ gfc_symbol *caller_sym;
+ gfc_symbol *sym;
+ symbol_attribute *a;
+
+ if (expr->expr_type != EXPR_FUNCTION || expr->value.function.isym)
+ return 0;
+
+ sym = expr->symtree->n.sym;
+ a = &sym->attr;
+ if (a->pure || a->implicit_pure)
+ return 0;
+
+ caller_sym = (gfc_symbol *) sym_data;
+ gfc_unset_implicit_pure (caller_sym);
+ return 1;
+}
+
+/* Go through all procedures in the namespace and unset the
+ implicit_pure attribute for any procedure that calls something not
+ pure or implicit pure. */
+
+bool
+gfc_fix_implicit_pure (gfc_namespace *ns)
+{
+ bool changed = false;
+ gfc_symbol *proc = ns->proc_name;
+
+ if (proc && proc->attr.flavor == FL_PROCEDURE && proc->attr.implicit_pure
+ && ns->code
+ && gfc_code_walker (&ns->code, implicit_pure_call, implicit_pure_expr,
+ (void *) ns->proc_name))
+ changed = true;
+
+ for (ns = ns->contained; ns; ns = ns->sibling)
+ {
+ if (gfc_fix_implicit_pure (ns))
+ changed = true;
+ }
+
+ return changed;
+}
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 24c5101c4cb..264822ef9f8 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -3623,6 +3623,7 @@ int gfc_expr_walker (gfc_expr **, walk_expr_fn_t, void *);
int gfc_code_walker (gfc_code **, walk_code_fn_t, walk_expr_fn_t, void *);
bool gfc_has_dimen_vector_ref (gfc_expr *e);
void gfc_check_externals (gfc_namespace *);
+bool gfc_fix_implicit_pure (gfc_namespace *);
/* simplify.c */
diff --git a/gcc/fortran/parse.c b/gcc/fortran/parse.c
index 36715134a2c..d30208febb1 100644
--- a/gcc/fortran/parse.c
+++ b/gcc/fortran/parse.c
@@ -6447,6 +6447,11 @@ loop:
gfc_resolve (gfc_current_ns);
+ /* Fix the implicit_pure attribute for those procedures who should
+ not have it. */
+ while (gfc_fix_implicit_pure (gfc_current_ns))
+ ;
+
/* Dump the parse tree if requested. */
if (flag_dump_fortran_original)
gfc_dump_parse_tree (gfc_current_ns, stdout);
@@ -6492,6 +6497,23 @@ done:
/* Do the resolution. */
resolve_all_program_units (gfc_global_ns_list);
+ /* Go through all top-level namespaces and unset the implicit_pure
+ attribute for any procedures that call something not pure or
+ implicit_pure. Because the a procedure marked as not implicit_pure
+ in one sweep may be called by another routine, we repeat this
+ process until there are no more changes. */
+ bool changed;
+ do
+ {
+ changed = false;
+ for (gfc_current_ns = gfc_global_ns_list; gfc_current_ns;
+ gfc_current_ns = gfc_current_ns->sibling)
+ {
+ if (gfc_fix_implicit_pure (gfc_current_ns))
+ changed = true;
+ }
+ }
+ while (changed);
/* Fixup for external procedures. */
for (gfc_current_ns = gfc_global_ns_list; gfc_current_ns;
