Fortran: improve bounds-checking for array sections [PR30802]

From bb2a765f56b440c8d086329f55c8ff0eaee2b97d Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Thu, 14 Sep 2023 22:08:26 +0200
Subject: [PATCH] Fortran: improve bounds-checking for array sections [PR30802]

gcc/fortran/ChangeLog:

	PR fortran/30802
	* trans-array.cc (trans_array_bound_check): Add optional argument
	COMPNAME for explicit specification of array component name.
	(array_bound_check_elemental): Helper function for generating
	bounds-checking code for elemental dimensions.
	(gfc_conv_expr_descriptor): Use bounds-checking also for elemental
	dimensions, i.e. those not handled by the scalarizer.

gcc/testsuite/ChangeLog:

	PR fortran/30802
	* gfortran.dg/bounds_check_fail_6.f90: New test.
---
 gcc/fortran/trans-array.cc                    | 72 ++++++++++++++++++-
 .../gfortran.dg/bounds_check_fail_6.f90       | 29 ++++++++
 2 files changed, 100 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/bounds_check_fail_6.f90

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 6ca58e98547..71123e37477 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -3452,7 +3452,8 @@  gfc_conv_array_ubound (tree descriptor, int dim)

 static tree
 trans_array_bound_check (gfc_se * se, gfc_ss *ss, tree index, int n,
-			 locus * where, bool check_upper)
+			 locus * where, bool check_upper,
+			 const char *compname = NULL)
 {
   tree fault;
   tree tmp_lo, tmp_up;
@@ -3474,6 +3475,10 @@  trans_array_bound_check (gfc_se * se, gfc_ss *ss, tree index, int n,
   if (VAR_P (descriptor))
     name = IDENTIFIER_POINTER (DECL_NAME (descriptor));

+  /* Use given (array component) name.  */
+  if (compname)
+    name = compname;
+
   /* If upper bound is present, include both bounds in the error message.  */
   if (check_upper)
     {
@@ -3524,6 +3529,67 @@  trans_array_bound_check (gfc_se * se, gfc_ss *ss, tree index, int n,
 }


+/* Generate code for bounds checking for elemental dimensions.  */
+
+static void
+array_bound_check_elemental (gfc_se * se, gfc_ss * ss, gfc_expr * expr)
+{
+  gfc_array_ref *ar;
+  gfc_ref *ref;
+  gfc_symbol *sym;
+  char *var_name = NULL;
+  size_t len;
+  int dim;
+
+  if (!(gfc_option.rtcheck & GFC_RTCHECK_BOUNDS))
+    return;
+
+  if (expr->expr_type == EXPR_VARIABLE)
+    {
+      sym = expr->symtree->n.sym;
+      len = strlen (sym->name) + 1;
+
+      for (ref = expr->ref; ref; ref = ref->next)
+	if (ref->type == REF_COMPONENT)
+	  len += 2 + strlen (ref->u.c.component->name);
+
+      var_name = XALLOCAVEC (char, len);
+      strcpy (var_name, sym->name);
+
+      for (ref = expr->ref; ref; ref = ref->next)
+	{
+	  /* Append component name.  */
+	  if (ref->type == REF_COMPONENT)
+	    {
+	      strcat (var_name, "%%");
+	      strcat (var_name, ref->u.c.component->name);
+	      continue;
+	    }
+
+	  if (ref->type == REF_ARRAY && ref->u.ar.dimen > 0)
+	    {
+	      ar = &ref->u.ar;
+	      for (dim = 0; dim < ar->dimen; dim++)
+		{
+		  if (ar->dimen_type[dim] == DIMEN_ELEMENT)
+		    {
+		      gfc_se indexse;
+		      gfc_init_se (&indexse, NULL);
+		      gfc_conv_expr_type (&indexse, ar->start[dim],
+					  gfc_array_index_type);
+		      trans_array_bound_check (se, ss, indexse.expr, dim,
+					       &ar->where,
+					       ar->as->type != AS_ASSUMED_SIZE
+					       || dim < ar->dimen - 1,
+					       var_name);
+		    }
+		}
+	    }
+	}
+    }
+}
+
+
 /* Return the offset for an index.  Performs bound checking for elemental
    dimensions.  Single element references are processed separately.
    DIM is the array dimension, I is the loop dimension.  */
@@ -7823,6 +7889,10 @@  gfc_conv_expr_descriptor (gfc_se *se, gfc_expr *expr)
   /* Setup the scalarizing loops and bounds.  */
   gfc_conv_ss_startstride (&loop);

+  /* Add bounds-checking for elemental dimensions.  */
+  if ((gfc_option.rtcheck & GFC_RTCHECK_BOUNDS) && !expr->no_bounds_check)
+    array_bound_check_elemental (se, ss, expr);
+
   if (need_tmp)
     {
       if (expr->ts.type == BT_CHARACTER
diff --git a/gcc/testsuite/gfortran.dg/bounds_check_fail_6.f90 b/gcc/testsuite/gfortran.dg/bounds_check_fail_6.f90
new file mode 100644
index 00000000000..90329131158
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/bounds_check_fail_6.f90
@@ -0,0 +1,29 @@ 
+! { dg-do run }
+! { dg-additional-options "-fcheck=bounds -g -fdump-tree-original" }
+! { dg-output "At line 18 .*" }
+! { dg-shouldfail "dimension 3 of array 'u%z' outside of expected range" }
+!
+! PR fortran/30802 - improve bounds-checking for array sections
+
+program test
+  implicit none
+  integer :: k = 0
+  integer, dimension(10,20,30) :: x = 42
+  type t
+     real, dimension(10,20,30) :: z = 23
+  end type t
+  type(t) :: u
+
+  ! pr30802
+  print *, u% z(1,:,k)  ! runtime check only for dimension 3
+
+  ! pr97039
+  call foo (x(k,:,k+1)) ! runtime checks for dimensions 1,3
+contains
+  subroutine foo (a)
+    integer, intent(in) :: a(:)
+  end subroutine foo
+end program test
+
+! { dg-final { scan-tree-dump-times "'u%%z.' outside of expected range" 2 "original" } }
+! { dg-final { scan-tree-dump-times "'x.' outside of expected range" 4 "original" } }
--
2.35.3