coroutines: Replace extra checks for co_yield with asserts.

The lowering of co_yield to a promise method call and a co_await
was moved to the initial analysis phase with the intention of
avoiding the need to handle the two cases later.

Before removing the later checks entirely, this patch replaces
them with checking asserts.

gcc/cp/Changelog:

2020-05-05  Iain Sandoe  <iain@sandoe.co.uk>

	* coroutines.cc (transform_await_wrapper): Check that we have
	no unlowered co_yields.
	(captures_temporary): Likewise.
	(register_awaits): Likewise.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 3dece835650e8a4aabf1f61c74cad4299e0395f3..17e24d269d2ced642ac63c8815a95abb641e95d9 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2020-05-05  Iain Sandoe  <iain@sandoe.co.uk>
+
+       * coroutines.cc (transform_await_wrapper): Check that we have
+       no unlowered co_yields.
+       (captures_temporary): Likewise.
+       (register_awaits): Likewise.
+
 2020-05-05  Nathan Sidwell  <nathan@acm.org>
 
        PR c++/94807

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 0c91abc84f26f4614f5b471fa7db281d2da56c12..ed871e1bab155cdb467cdf03add36ade60c1b260 100644 (file)
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -1743,7 +1743,9 @@ transform_await_wrapper (tree *stmt, int *do_subtree, void *d)
       && DECL_CONTEXT (*stmt) != xform->actor_fn)
     DECL_CONTEXT (*stmt) = xform->actor_fn;
 
-  if (TREE_CODE (*stmt) != CO_AWAIT_EXPR && TREE_CODE (*stmt) != CO_YIELD_EXPR)
+  /* We should have already lowered co_yields to their co_await.  */
+  gcc_checking_assert (TREE_CODE (*stmt) != CO_YIELD_EXPR);
+  if (TREE_CODE (*stmt) != CO_AWAIT_EXPR)
     return NULL_TREE;
 
   tree await_expr = *stmt;
@@ -2612,9 +2614,12 @@ struct susp_frame_data
 static tree
 captures_temporary (tree *stmt, int *do_subtree, void *d)
 {
+  /* We should have already lowered co_yields to their co_await.  */
+  gcc_checking_assert (TREE_CODE (*stmt) != CO_YIELD_EXPR);
+
   /* Stop recursing if we see an await expression, the subtrees
      of that will be handled when it is processed.  */
-  if (TREE_CODE (*stmt) == CO_AWAIT_EXPR || TREE_CODE (*stmt) == CO_YIELD_EXPR)
+  if (TREE_CODE (*stmt) == CO_AWAIT_EXPR)
     {
       *do_subtree = 0;
       return NULL_TREE;
@@ -2732,17 +2737,14 @@ register_awaits (tree *stmt, int *do_subtree ATTRIBUTE_UNUSED, void *d)
 {
   susp_frame_data *data = (susp_frame_data *) d;
 
-  if (TREE_CODE (*stmt) != CO_AWAIT_EXPR && TREE_CODE (*stmt) != CO_YIELD_EXPR)
+  /* We should have already lowered co_yields to their co_await.  */
+  gcc_checking_assert (TREE_CODE (*stmt) != CO_YIELD_EXPR);
+
+  if (TREE_CODE (*stmt) != CO_AWAIT_EXPR)
     return NULL_TREE;
 
   tree aw_expr = *stmt;
   location_t aw_loc = EXPR_LOCATION (aw_expr); /* location of the co_xxxx.  */
-  /* co_yield is syntactic sugar, re-write it to co_await.  */
-  if (TREE_CODE (aw_expr) == CO_YIELD_EXPR)
-    {
-      aw_expr = TREE_OPERAND (aw_expr, 1);
-      *stmt = aw_expr;
-    }
 
   /* If the awaitable is a parm or a local variable, then we already have
      a frame copy, so don't make a new one.  */