From e72fbb6915c1dd1a52ecef55e10329e353cc3072 Mon Sep 17 00:00:00 2001
From: Mikael Morin <mikael@gcc.gnu.org>
Date: Fri, 22 Apr 2022 22:52:26 +0200
Subject: [PATCH] fortran: Update index extraction code. [PR102043]
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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.
---
 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 732221f..9f86815 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);
 }
-- 
2.7.4