[gcc r15-11026] fortran: Evaluate class function bounds in the scalarizer [PR121342]
Mikael Morin
mikael@gcc.gnu.org
Tue Mar 31 18:05:53 GMT 2026
https://gcc.gnu.org/g:cadef7a5838c3809d9ea379595393484f3ab0506
commit r15-11026-gcadef7a5838c3809d9ea379595393484f3ab0506
Author: Mikael Morin <morin-mikael@orange.fr>
Date: Wed Jul 30 11:02:27 2025 +0200
fortran: Evaluate class function bounds in the scalarizer [PR121342]
There is code in gfc_conv_procedure_call that, for polymorphic
functions, initializes the scalarization array descriptor
information and forcedfully sets loop bounds. This code is changing
the decisions made by the scalarizer behind his back, and the test shows
an example where the consequences are (badly) visible. In the test, for
one of the actual arguments to an elemental subroutine, an offset to the
loop variable is missing to access the array, as it was the one
originally chosen to set the loop bounds from.
This could theoretically be fixed by just clearing the array of choice
for the loop bounds. This change takes instead the harder path of
adding the missing information to the scalarizer's knowledge so that its
decision doesn't need to be forced to something else after the fact.
The array descriptor information initialisation for polymorphic
functions is moved to gfc_add_loop_ss_code (after the function call
generation), and the loop bounds initialization to a new function called
after that.
As the array chosen to set the loop bounds from is no longer forced
to be the polymorphic function result, we have to let the scalarizer set
a delta for polymorphic function results. For regular non-polymorphic
function result arrays, they are zero-based and the temporary creation
makes the loop zero-based as well, so we can continue to skip the delta
calculation.
In the cases where a temporary is created to store the result of the
array function, the creation of the temporary shifts the loop bounds
to be zero-based. As there was no delta for polymorphic result arrays,
the function result descriptor offset was set to zero in that case for
a zero-based array reference to be correct. Now that the scalarizer
sets a delta, those forced offset updates have to go because they can
make the descriptor invalid and cause erroneous array references.
PR fortran/121342
gcc/fortran/ChangeLog:
* trans-expr.cc (gfc_conv_subref_array_arg): Remove offset
update.
(gfc_conv_procedure_call): For polymorphic functions, move the
scalarizer descriptor information...
* trans-array.cc (gfc_add_loop_ss_code): ... here, and evaluate
the bounds to fresh variables.
(get_class_info_from_ss): Remove offset update.
(gfc_conv_ss_startstride): Don't set a zero value for function
result upper bounds.
(late_set_loop_bounds): New.
(gfc_conv_loop_setup): If the bounds of a function result have
been set, and no other array provided loop bounds for a
dimension, use the function result bounds as loop bounds for
that dimension.
(gfc_set_delta): Don't skip delta setting for polymorphic
function results.
gcc/testsuite/ChangeLog:
* gfortran.dg/class_elemental_1.f90: New test.
(cherry picked from commit 04a1259ffea29718256beeb2aca3f473c1f259e4)
Diff:
---
gcc/fortran/trans-array.cc | 116 +++++++++++++++++++-----
gcc/fortran/trans-expr.cc | 35 +------
gcc/testsuite/gfortran.dg/class_elemental_1.f90 | 35 +++++++
3 files changed, 132 insertions(+), 54 deletions(-)
diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 3e5205e8117b..76fce7ad00f5 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -1426,12 +1426,6 @@ get_class_info_from_ss (stmtblock_t * pre, gfc_ss *ss, tree *eltype,
tmp2 = gfc_class_len_get (class_expr);
gfc_add_modify (pre, tmp, tmp2);
}
-
- if (rhs_function)
- {
- tmp = gfc_class_data_get (class_expr);
- gfc_conv_descriptor_offset_set (pre, tmp, gfc_index_zero_node);
- }
}
else if (rhs_ss->info->data.array.descriptor)
{
@@ -3372,18 +3366,51 @@ gfc_add_loop_ss_code (gfc_loopinfo * loop, gfc_ss * ss, bool subscript,
break;
case GFC_SS_FUNCTION:
- /* Array function return value. We call the function and save its
- result in a temporary for use inside the loop. */
- gfc_init_se (&se, NULL);
- se.loop = loop;
- se.ss = ss;
- if (gfc_is_class_array_function (expr))
- expr->must_finalize = 1;
- gfc_conv_expr (&se, expr);
- gfc_add_block_to_block (&outer_loop->pre, &se.pre);
- gfc_add_block_to_block (&outer_loop->post, &se.post);
- gfc_add_block_to_block (&outer_loop->post, &se.finalblock);
- ss_info->string_length = se.string_length;
+ {
+ /* Array function return value. We call the function and save its
+ result in a temporary for use inside the loop. */
+ gfc_init_se (&se, NULL);
+ se.loop = loop;
+ se.ss = ss;
+ bool class_func = gfc_is_class_array_function (expr);
+ if (class_func)
+ expr->must_finalize = 1;
+ gfc_conv_expr (&se, expr);
+ gfc_add_block_to_block (&outer_loop->pre, &se.pre);
+ if (class_func
+ && se.expr
+ && GFC_CLASS_TYPE_P (TREE_TYPE (se.expr)))
+ {
+ tree tmp = gfc_class_data_get (se.expr);
+ info->descriptor = tmp;
+ info->data = gfc_conv_descriptor_data_get (tmp);
+ info->offset = gfc_conv_descriptor_offset_get (tmp);
+ for (gfc_ss *s = ss; s; s = s->parent)
+ for (int n = 0; n < s->dimen; n++)
+ {
+ int dim = s->dim[n];
+ tree tree_dim = gfc_rank_cst[dim];
+
+ tree start;
+ start = gfc_conv_descriptor_lbound_get (tmp, tree_dim);
+ start = gfc_evaluate_now (start, &outer_loop->pre);
+ info->start[dim] = start;
+
+ tree end;
+ end = gfc_conv_descriptor_ubound_get (tmp, tree_dim);
+ end = gfc_evaluate_now (end, &outer_loop->pre);
+ info->end[dim] = end;
+
+ tree stride;
+ stride = gfc_conv_descriptor_stride_get (tmp, tree_dim);
+ stride = gfc_evaluate_now (stride, &outer_loop->pre);
+ info->stride[dim] = stride;
+ }
+ }
+ gfc_add_block_to_block (&outer_loop->post, &se.post);
+ gfc_add_block_to_block (&outer_loop->post, &se.finalblock);
+ ss_info->string_length = se.string_length;
+ }
break;
case GFC_SS_CONSTRUCTOR:
@@ -5235,7 +5262,8 @@ done:
int dim = ss->dim[n];
info->start[dim] = gfc_index_zero_node;
- info->end[dim] = gfc_index_zero_node;
+ if (ss_info->type != GFC_SS_FUNCTION)
+ info->end[dim] = gfc_index_zero_node;
info->stride[dim] = gfc_index_one_node;
}
break;
@@ -5920,6 +5948,46 @@ set_loop_bounds (gfc_loopinfo *loop)
}
+/* Last attempt to set the loop bounds, in case they depend on an allocatable
+ function result. */
+
+static void
+late_set_loop_bounds (gfc_loopinfo *loop)
+{
+ int n, dim;
+ gfc_array_info *info;
+ gfc_ss **loopspec;
+
+ loopspec = loop->specloop;
+
+ for (n = 0; n < loop->dimen; n++)
+ {
+ /* Set the extents of this range. */
+ if (loop->from[n] == NULL_TREE
+ || loop->to[n] == NULL_TREE)
+ {
+ /* We should have found the scalarization loop specifier. If not,
+ that's bad news. */
+ gcc_assert (loopspec[n]);
+
+ info = &loopspec[n]->info->data.array;
+ dim = loopspec[n]->dim[n];
+
+ if (loopspec[n]->info->type == GFC_SS_FUNCTION
+ && info->start[dim]
+ && info->end[dim])
+ {
+ loop->from[n] = info->start[dim];
+ loop->to[n] = info->end[dim];
+ }
+ }
+ }
+
+ for (loop = loop->nested; loop; loop = loop->next)
+ late_set_loop_bounds (loop);
+}
+
+
/* Initialize the scalarization loop. Creates the loop variables. Determines
the range of the loop variables. Creates a temporary if required.
Also generates code for scalar expressions which have been
@@ -5938,6 +6006,8 @@ gfc_conv_loop_setup (gfc_loopinfo * loop, locus * where)
allocating the temporary. */
gfc_add_loop_ss_code (loop, loop->ss, false, where);
+ late_set_loop_bounds (loop);
+
tmp_ss = loop->temp_ss;
/* If we want a temporary then create it. */
if (tmp_ss != NULL)
@@ -5994,9 +6064,11 @@ gfc_set_delta (gfc_loopinfo *loop)
gfc_ss_type ss_type;
ss_type = ss->info->type;
- if (ss_type != GFC_SS_SECTION
- && ss_type != GFC_SS_COMPONENT
- && ss_type != GFC_SS_CONSTRUCTOR)
+ if (!(ss_type == GFC_SS_SECTION
+ || ss_type == GFC_SS_COMPONENT
+ || ss_type == GFC_SS_CONSTRUCTOR
+ || (ss_type == GFC_SS_FUNCTION
+ && gfc_is_class_array_function (ss->info->expr))))
continue;
info = &ss->info->data.array;
diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 00ba563c00bb..ffe86539a0fd 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -5454,16 +5454,6 @@ gfc_conv_subref_array_arg (gfc_se *se, gfc_expr * expr, int g77,
/* Translate the expression. */
gfc_conv_expr (&rse, expr);
- /* Reset the offset for the function call since the loop
- is zero based on the data pointer. Note that the temp
- comes first in the loop chain since it is added second. */
- if (gfc_is_class_array_function (expr))
- {
- tmp = loop.ss->loop_chain->info->data.array.descriptor;
- gfc_conv_descriptor_offset_set (&loop.pre, tmp,
- gfc_index_zero_node);
- }
-
gfc_conv_tmp_array_ref (&lse);
if (intent != INTENT_OUT)
@@ -8843,28 +8833,9 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
&& se->expr && GFC_CLASS_TYPE_P (TREE_TYPE (se->expr))
&& expr->must_finalize)
{
- int n;
- if (se->ss && se->ss->loop)
- {
- gfc_add_block_to_block (&se->ss->loop->pre, &se->pre);
- se->expr = gfc_evaluate_now (se->expr, &se->ss->loop->pre);
- tmp = gfc_class_data_get (se->expr);
- info->descriptor = tmp;
- info->data = gfc_conv_descriptor_data_get (tmp);
- info->offset = gfc_conv_descriptor_offset_get (tmp);
- for (n = 0; n < se->ss->loop->dimen; n++)
- {
- tree dim = gfc_rank_cst[n];
- se->ss->loop->to[n] = gfc_conv_descriptor_ubound_get (tmp, dim);
- se->ss->loop->from[n] = gfc_conv_descriptor_lbound_get (tmp, dim);
- }
- }
- else
- {
- /* TODO Eliminate the doubling of temporaries. This
- one is necessary to ensure no memory leakage. */
- se->expr = gfc_evaluate_now (se->expr, &se->pre);
- }
+ /* TODO Eliminate the doubling of temporaries. This
+ one is necessary to ensure no memory leakage. */
+ se->expr = gfc_evaluate_now (se->expr, &se->pre);
/* Finalize the result, if necessary. */
attr = expr->value.function.esym
diff --git a/gcc/testsuite/gfortran.dg/class_elemental_1.f90 b/gcc/testsuite/gfortran.dg/class_elemental_1.f90
new file mode 100644
index 000000000000..547ae989218a
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/class_elemental_1.f90
@@ -0,0 +1,35 @@
+! { dg-do run }
+!
+! PR fortran/121342
+! The polymorphic function result as actual argument used to force the loop
+! bounds around the elemental call, altering access to the other arrays.
+
+program p
+ implicit none
+ type :: t
+ integer :: i
+ end type
+ type :: u
+ integer :: i, a
+ end type
+ type(u) :: accum(5)
+ integer :: a(3:7), k
+ a = [ (k*k, k=1,5) ]
+ call s(accum, f(), a)
+ ! print *, accum%i
+ ! print *, accum%a
+ if (any(accum%i /= accum%a)) error stop 1
+contains
+ elemental subroutine s(l, c, a)
+ type(u) , intent(out) :: l
+ class(t) , intent(in) :: c
+ integer , intent(in) :: a
+ l%i = c%i
+ l%a = a
+ end subroutine
+ function f()
+ class(t), allocatable :: f(:)
+ allocate(f(-1:3))
+ f%i = [ (k*k, k=1,5) ]
+ end function
+end program
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