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

1 files changed, 13 insertions, 3 deletions

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)
 {