[gcc r12-8228] fortran: Update index extraction code. [PR102043]

[gcc r12-8228] fortran: Update index extraction code. [PR102043]

[Mikael Morin]

https://gcc.gnu.org/g:e72fbb6915c1dd1a52ecef55e10329e353cc3072

commit r12-8228-ge72fbb6915c1dd1a52ecef55e10329e353cc3072
Author: Mikael Morin <mikael@gcc.gnu.org>
Date:   Fri Apr 22 22:52:26 2022 +0200

    fortran: Update index extraction code. [PR102043]
    
    This avoids a regression on hollerith4.f90 and hollerith6.f90 later in
    the patch series when code generation for array references is changed
    to use pointer arithmetic.
    
    The problem comes from the extraction of the array index from an
    ARRAY_REF tree, which doesn’t work if the tree is not an ARRAY_REF
    any more.
    
    This updates the code generated for remaining size evaluation to work
    with a source tree that uses either array indexing or pointer
    arithmetic.
    
            PR fortran/102043
    
    gcc/fortran/ChangeLog:
    
            * trans-io.cc: Add handling for the case where the array
            is referenced using pointer arithmetic.

Diff:
---
 gcc/fortran/trans-io.cc | 48 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 11 deletions(-)

diff --git a/gcc/fortran/trans-io.cc b/gcc/fortran/trans-io.cc
index 732221f848b..9f86815388c 100644
--- a/gcc/fortran/trans-io.cc
+++ b/gcc/fortran/trans-io.cc
@@ -737,7 +737,6 @@ set_parameter_ref (stmtblock_t *block, stmtblock_t *postblock,
 static void
 gfc_convert_array_to_string (gfc_se * se, gfc_expr * e)
 {
-  tree size;
 
   if (e->rank == 0)
     {
@@ -755,12 +754,13 @@ gfc_convert_array_to_string (gfc_se * se, gfc_expr * e)
       array = sym->backend_decl;
       type = TREE_TYPE (array);
 
+      tree elts_count;
       if (GFC_ARRAY_TYPE_P (type))
-	size = GFC_TYPE_ARRAY_SIZE (type);
+	elts_count = GFC_TYPE_ARRAY_SIZE (type);
       else
 	{
 	  gcc_assert (GFC_DESCRIPTOR_TYPE_P (type));
-	  size = gfc_conv_array_stride (array, rank);
+	  tree stride = gfc_conv_array_stride (array, rank);
 	  tmp = fold_build2_loc (input_location, MINUS_EXPR,
 				 gfc_array_index_type,
 				 gfc_conv_array_ubound (array, rank),
@@ -768,23 +768,49 @@ gfc_convert_array_to_string (gfc_se * se, gfc_expr * e)
 	  tmp = fold_build2_loc (input_location, PLUS_EXPR,
 				 gfc_array_index_type, tmp,
 				 gfc_index_one_node);
+	  elts_count = fold_build2_loc (input_location, MULT_EXPR,
+					gfc_array_index_type, tmp, stride);
+	}
+      gcc_assert (elts_count);
+
+      tree elt_size = TYPE_SIZE_UNIT (gfc_get_element_type (type));
+      elt_size = fold_convert (gfc_array_index_type, elt_size);
+
+      tree size;
+      if (TREE_CODE (se->expr) == ARRAY_REF)
+	{
+	  tree index = TREE_OPERAND (se->expr, 1);
+	  index = fold_convert (gfc_array_index_type, index);
+
+	  elts_count = fold_build2_loc (input_location, MINUS_EXPR,
+					gfc_array_index_type,
+					elts_count, index);
+
 	  size = fold_build2_loc (input_location, MULT_EXPR,
-				  gfc_array_index_type, tmp, size);
+				  gfc_array_index_type, elts_count, elt_size);
+	}
+      else
+	{
+	  gcc_assert (TREE_CODE (se->expr) == INDIRECT_REF);
+	  tree ptr = TREE_OPERAND (se->expr, 0);
+
+	  gcc_assert (TREE_CODE (ptr) == POINTER_PLUS_EXPR);
+	  tree offset = fold_convert_loc (input_location, gfc_array_index_type,
+					  TREE_OPERAND (ptr, 1));
+
+	  size = fold_build2_loc (input_location, MULT_EXPR,
+				  gfc_array_index_type, elts_count, elt_size);
+	  size = fold_build2_loc (input_location, MINUS_EXPR,
+				  gfc_array_index_type, size, offset);
 	}
       gcc_assert (size);
 
-      size = fold_build2_loc (input_location, MINUS_EXPR,
-			      gfc_array_index_type, size,
-			      TREE_OPERAND (se->expr, 1));
       se->expr = gfc_build_addr_expr (NULL_TREE, se->expr);
-      tmp = TYPE_SIZE_UNIT (gfc_get_element_type (type));
-      size = fold_build2_loc (input_location, MULT_EXPR,
-			      gfc_array_index_type, size,
-			      fold_convert (gfc_array_index_type, tmp));
       se->string_length = fold_convert (gfc_charlen_type_node, size);
       return;
     }
 
+  tree size;
   gfc_conv_array_parameter (se, e, true, NULL, NULL, &size);
   se->string_length = fold_convert (gfc_charlen_type_node, size);
 }