trans-expr.c (gfc_conv_expr, [...]): Update comments.

2005-08-04  Paul Brook  <paul@codesourcery.com>

	* trans-expr.c (gfc_conv_expr, gfc_conv_expr_type): Update comments.
	(gfc_conv_expr_lhs): Fix assertion.
	(gfc_conv_expr_val): Merge post block.  Set se.expr to new value.
	* trans.h: Move and update comments.

From-SVN: r102729

3 files changed, 22 insertions, 11 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index b2a7452..f626559 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2005-08-04  Paul Brook  <paul@codesourcery.com>
+
+	* trans-expr.c (gfc_conv_expr, gfc_conv_expr_type): Update comments.
+	(gfc_conv_expr_lhs): Fix assertion.
+	(gfc_conv_expr_val): Merge post block.  Set se.expr to new value.
+
 2005-08-02  David Edelsohn  <edelsohn@gnu.org>
 
 	PR fortran/22491
diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c
index 0cd8741..a3846f3 100644
--- a/gcc/fortran/trans-expr.c
+++ b/gcc/fortran/trans-expr.c
@@ -1867,7 +1867,9 @@ gfc_conv_substring_expr (gfc_se * se, gfc_expr * expr)
 }
 
 
-/* Entry point for expression translation.  */
+/* Entry point for expression translation.  Evaluates a scalar quantity.
+   EXPR is the expression to be translated, and SE is the state structure if
+   called from within the scalarized.  */
 
 void
 gfc_conv_expr (gfc_se * se, gfc_expr * expr)
@@ -1923,15 +1925,20 @@ gfc_conv_expr (gfc_se * se, gfc_expr * expr)
     }
 }
 
+/* Like gfc_conv_expr_val, but the value is also suitable for use in the lhs
+   of an assignment.  */
 void
 gfc_conv_expr_lhs (gfc_se * se, gfc_expr * expr)
 {
   gfc_conv_expr (se, expr);
-  /* AFAICS all numeric lvalues have empty post chains.  If not we need to
+  /* All numeric lvalues should have empty post chains.  If not we need to
      figure out a way of rewriting an lvalue so that it has no post chain.  */
-  gcc_assert (expr->ts.type != BT_CHARACTER || !se->post.head);
+  gcc_assert (expr->ts.type == BT_CHARACTER || !se->post.head);
 }
 
+/* Like gfc_conv_expr, but the POST block is guaranteed to be empty for
+   numeric expressions.  Used for scalar values whee inserting cleanup code
+   is inconvenient.  */
 void
 gfc_conv_expr_val (gfc_se * se, gfc_expr * expr)
 {
@@ -1943,9 +1950,12 @@ gfc_conv_expr_val (gfc_se * se, gfc_expr * expr)
     {
       val = gfc_create_var (TREE_TYPE (se->expr), NULL);
       gfc_add_modify_expr (&se->pre, val, se->expr);
+      se->expr = val;
+      gfc_add_block_to_block (&se->pre, &se->post);
     }
 }
 
+/* Helper to translate and expression and convert it to a particular type.  */
 void
 gfc_conv_expr_type (gfc_se * se, gfc_expr * expr, tree type)
 {
diff --git a/gcc/fortran/trans.h b/gcc/fortran/trans.h
index c4099a9..9678ff8 100644
--- a/gcc/fortran/trans.h
+++ b/gcc/fortran/trans.h
@@ -275,20 +275,15 @@ tree gfc_chainon_list (tree, tree);
    when a POST chain may be created, and what the returned expression may be
    used for.  Note that character strings have special handling.  This
    should not be a problem as most statements/operations only deal with
-   numeric/logical types.  */
+   numeric/logical types.  See the implementations in trans-expr.c
+   for details of the individual functions.  */
 
-/* Entry point for expression translation.  */
 void gfc_conv_expr (gfc_se * se, gfc_expr * expr);
-/* Like gfc_conv_expr, but the POST block is guaranteed to be empty for
-   numeric expressions.  */
 void gfc_conv_expr_val (gfc_se * se, gfc_expr * expr);
-/* Like gfc_conv_expr_val, but the value is also suitable for use in the lhs of
-   an assignment.  */
 void gfc_conv_expr_lhs (gfc_se * se, gfc_expr * expr);
-/* Converts an expression so that it can be passed be reference.  */
 void gfc_conv_expr_reference (gfc_se * se, gfc_expr *);
-/* Equivalent to convert(type, gfc_conv_expr_val(se, expr)).  */
 void gfc_conv_expr_type (gfc_se * se, gfc_expr *, tree);
+
 /* Find the decl containing the auxiliary variables for assigned variables.  */
 void gfc_conv_label_variable (gfc_se * se, gfc_expr * expr);
 /* If the value is not constant, Create a temporary and copy the value.  */