Hi!
While usually the order of vars in block scope isn't that significant,
e.g. on the following testcase with -fopenmp -fstack-arrays it does matter
if we have local declaration of a temporary and then local declaration of
a VLA that uses that other temporary as the TYPE_SIZE_UNIT, or the other way
around (we ICE if we first see the VLA and firstprivatize the variable, only
to later on discover it is a local var). pushdecl is called on them in the
right order (scalar temporary first, then VLA that uses it), but the names
chain is LIFO.
Actually, with gfc_merge_block_scope it seems we end up in quite randomish
order.
So, is it intentional that pushdecl / getdecls acts like a LIFO?
Though, it seems user vars are pushdecled in the reverse order of
declarations, but gfc_add_decl_to_function is called in the user declared
order, so perhaps for the following patch we'd also need to
decl = nreverse (saved_function_decls);
in gfc_generate_function_code and similarly in gfc_process_block_locals
decl = nreverse (saved_local_decls);
What do you think about this?
Note, nreverse is fairly cheap, it is linear in the chain length.
2016-06-30 Jakub Jelinek <ja...@redhat.com>
PR fortran/71687
* f95-lang.c (struct binding_level): Add reversed field.
(clear_binding_level): Adjust initializer.
(getdecls): If reversed is clear, set it and nreverse the names
chain before returning it.
(poplevel): Use getdecls.
* gfortran.dg/gomp/pr71687.f90: New test.
--- gcc/fortran/f95-lang.c.jj 2016-06-29 10:46:33.000000000 +0200
+++ gcc/fortran/f95-lang.c 2016-06-30 17:11:44.350240191 +0200
@@ -286,6 +286,9 @@ binding_level {
tree blocks;
/* The binding level containing this one (the enclosing binding level). */
struct binding_level *level_chain;
+ /* True if nreverse has been already called on names; if false, names
+ are ordered from newest declaration to oldest one. */
+ bool reversed;
};
/* The binding level currently in effect. */
@@ -296,7 +299,7 @@ static GTY(()) struct binding_level *cur
static GTY(()) struct binding_level *global_binding_level;
/* Binding level structures are initialized by copying this one. */
-static struct binding_level clear_binding_level = { NULL, NULL, NULL };
+static struct binding_level clear_binding_level = { NULL, NULL, NULL, false };
/* Return true if we are in the global binding level. */
@@ -310,6 +313,11 @@ global_bindings_p (void)
tree
getdecls (void)
{
+ if (!current_binding_level->reversed)
+ {
+ current_binding_level->reversed = true;
+ current_binding_level->names = nreverse (current_binding_level->names);
+ }
return current_binding_level->names;
}
@@ -347,7 +355,7 @@ poplevel (int keep, int functionbody)
binding level that we are about to exit and which is returned by this
routine. */
tree block_node = NULL_TREE;
- tree decl_chain = current_binding_level->names;
+ tree decl_chain = getdecls ();
tree subblock_chain = current_binding_level->blocks;
tree subblock_node;
--- gcc/testsuite/gfortran.dg/gomp/pr71687.f90.jj 2016-06-30
17:12:27.279702475 +0200
+++ gcc/testsuite/gfortran.dg/gomp/pr71687.f90 2016-06-30 17:12:53.480374296
+0200
@@ -0,0 +1,11 @@
+! PR fortran/71687
+! { dg-do compile }
+! { dg-additional-options "-fstack-arrays -O2" }
+
+subroutine s (n, x)
+ integer :: n
+ real :: x(n)
+!$omp parallel
+ x(1:n) = x(n:1:-1)
+!$omp end parallel
+end
Jakub
