Re: Fortran sizetype fix

[Zack Weinberg <zack at wolery dot cumb dot org>]

On Sat, Apr 29, 2000 at 10:05:38AM -0400, Richard Kenner wrote:
>     This patch seems to have disappeared into the black lagoon.  It fixes
>     some testsuite failures in Fortran.  It's quite short but I would
>     appreciate if someone who actually _understands_ the sizetype changes
>     would review it.
>
> I certainly understand the sizetype changes, having written them,
> but what I can't figure out is that code in the Fortran front end.
> I can't figure out what the calls *expect* *offset to be!  In at
> least one case, it's being assigned to a variable which is also
> being set in another case to size_zero_node.  If that's correct (and
> he distinction between sizetype and bitsizetype predates my changes
> by quite a while), then your patch is wrong.  If that's incorrect,
> then your patch needs to change it too.  But I can't tell if that's
> wrong or not.

Just going on the number of places where *offset (or the variable it
points to) is assigned, I see one place where it's set to
size_zero_node and three places where it's set to bitsize_zero_node.

Also, the only place *offset is set to anything that's _not_
foo_zero_node are:

	  /* An offset into COMMON.  */
	  *offset = fold (build (PLUS_EXPR, TREE_TYPE (*offset),
				 *offset, TREE_OPERAND (t, 1)));
	  /* Convert offset (presumably in bytes) into canonical units
	     (presumably bits).  */
	  *offset = fold (build (MULT_EXPR, TREE_TYPE (*offset),
				 TYPE_SIZE (TREE_TYPE (TREE_TYPE (t))),
				 *offset));
	  break;

(perhaps this should be using size_binop?) and:

	*offset
	  = size_binop (MULT_EXPR,
			TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))),
			convert (bitsizetype,
				 fold (build (MINUS_EXPR, TREE_TYPE (element),
					      element,
					      TYPE_MIN_VALUE
					      (TYPE_DOMAIN
					       (TREE_TYPE (array)))))));;

	*offset = size_binop (PLUS_EXPR, init_offset, *offset);

both of which, I believe, are meant to come out in bits, and therefore
ought to be in bitsizetype.

I'm now testing this patch:

	* f/com.c (ffecom_overlap_): Set source_offset to
	bitsize_zero_node.
	(ffecom_tree_canonize_ptr_): Use size_binop.  Convert to
	bitsizetype before multiplying by TYPE_SIZE.
	(ffecom_tree_canonize_ref_) [case ARRAY_REF]: Break up offset
	calculation.  Use size_binop throughout.  Convert to
	bitsizetype before multiplying by TYPE_SIZE.

===================================================================
Index: f/com.c
--- f/com.c	2000/03/28 20:37:44	1.83
+++ f/com.c	2000/04/29 16:53:49
@@ -1712,7 +1712,7 @@ ffecom_overlap_ (tree dest_decl, tree de
 	return TRUE;
 
       source_decl = source_tree;
-      source_offset = size_zero_node;
+      source_offset = bitsize_zero_node;
       source_size = TYPE_SIZE (TREE_TYPE (TREE_TYPE (source_tree)));
       break;
 
@@ -9082,13 +9082,12 @@ ffecom_tree_canonize_ptr_ (tree *decl, t
       if (TREE_CODE (TREE_OPERAND (t, 1)) == INTEGER_CST)
 	{
 	  /* An offset into COMMON.  */
-	  *offset = fold (build (PLUS_EXPR, TREE_TYPE (*offset),
-				 *offset, TREE_OPERAND (t, 1)));
+	  *offset = size_binop (PLUS_EXPR, *offset, TREE_OPERAND (t, 1)));
 	  /* Convert offset (presumably in bytes) into canonical units
 	     (presumably bits).  */
-	  *offset = fold (build (MULT_EXPR, TREE_TYPE (*offset),
-				 TYPE_SIZE (TREE_TYPE (TREE_TYPE (t))),
-				 *offset));
+	  *offset = size_binop (MULT_EXPR,
+				convert (bitsizetype, *offset),
+				TYPE_SIZE (TREE_TYPE (TREE_TYPE (t))));
 	  break;
 	}
       /* Not a COMMON reference, so an unrecognized pattern.  */
@@ -9249,18 +9248,17 @@ ffecom_tree_canonize_ref_ (tree *decl, t
 	    || (*decl == error_mark_node))
 	  return;
 
-	*offset
-	  = size_binop (MULT_EXPR,
-			TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))),
-			convert (sizetype,
-				 fold (build (MINUS_EXPR, TREE_TYPE (element),
-					      element,
-					      TYPE_MIN_VALUE
-					      (TYPE_DOMAIN
-					       (TREE_TYPE (array)))))));;
+	/* Calculate ((element - base) * NBBY) + init_offset.  */
+	*offset = size_binop (MINUS_EXPR,
+			      element,
+			      TYPE_MIN_VALUE (TYPE_DOMAIN
+					      (TREE_TYPE (array))));
+
+	*offset = size_binop (MULT_EXPR,
+			      convert (bitsizetype, *offset),
+			      TYPE_SIZE (TREE_TYPE (TREE_TYPE (array))));
 
-	*offset = size_binop (PLUS_EXPR, convert (sizetype, init_offset),
-			      *offset);
+	*offset = size_binop (PLUS_EXPR, init_offset, *offset);
 
 	*size = TYPE_SIZE (TREE_TYPE (t));
 	return;