On 9/14/21 11:36, Iain Sandoe wrote:
Hi
Some small code cleanups that allow us to have just one place that
we handle a statement with await expression(s) embedded. Also we
can reduce the work done to figure out whether a statement contains
any such expressions.
tested on x86_64,powerpc64le-linux x86_64-darwin
OK for master?
thanks
Iain
-----
There is no need to make a MODIFY_EXPR for any of the condition
vars that we synthesize.
Expansion of co_return can be carried out independently of any
co_awaits that might be contained which simplifies this.
Where we are rewriting statements to handle await expression
logic, there is no need to carry out any analysis - we just need
to detect the presence of any co_await.
Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
gcc/cp/ChangeLog:
* coroutines.cc (await_statement_walker): Code cleanups.
---
gcc/cp/coroutines.cc | 121 ++++++++++++++++++++-----------------------
1 file changed, 56 insertions(+), 65 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index d2cc2e73c89..27556723b71 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -3412,16 +3412,11 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
return NULL_TREE;
}
- /* We have something to be handled as a single statement. */
- bool has_cleanup_wrapper = TREE_CODE (*stmt) == CLEANUP_POINT_EXPR;
- hash_set<tree> visited;
- awpts->saw_awaits = 0;
- hash_set<tree> truth_aoif_to_expand;
- awpts->truth_aoif_to_expand = &truth_aoif_to_expand;
- awpts->needs_truth_if_exp = false;
- awpts->has_awaiter_init = false;
+ /* We have something to be handled as a single statement. We have to handle
+ a few statements specially where await statements have to be moved out of
+ constructs. */
tree expr = *stmt;
- if (has_cleanup_wrapper)
+ if (TREE_CODE (*stmt) == CLEANUP_POINT_EXPR)
expr = TREE_OPERAND (expr, 0);
STRIP_NOPS (expr);
@@ -3437,6 +3432,8 @@ await_statement_walker (tree *stmt, int *do_subtree, void *d)
transforms can be implemented. */
case IF_STMT:
{
+ tree *await_ptr;
+ hash_set<tree> visited;
/* Transform 'if (cond with awaits) then stmt1 else stmt2' into
bool cond = cond with awaits.
if (cond) then stmt1 else stmt2. */
@@ -3444,10 +3441,8 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
/* We treat the condition as if it was a stand-alone statement,
to see if there are any await expressions which will be analyzed
and registered. */
- if ((res = cp_walk_tree (&IF_COND (if_stmt),
- analyze_expression_awaits, d, &visited)))
- return res;
- if (!awpts->saw_awaits)
+ if (!(cp_walk_tree (&IF_COND (if_stmt),
+ find_any_await, &await_ptr, &visited)))
return NULL_TREE; /* Nothing special to do here. */
gcc_checking_assert (!awpts->bind_stack->is_empty());
@@ -3463,7 +3458,7 @@ await_statement_walker (tree *stmt, int *do_subtree, void
*d)
/* We want to initialize the new variable with the expression
that contains the await(s) and potentially also needs to
have truth_if expressions expanded. */
- tree new_s = build2_loc (sloc, MODIFY_EXPR, boolean_type_node,
+ tree new_s = build2_loc (sloc, INIT_EXPR, boolean_type_node,
newvar, cond_inner);
finish_expr_stmt (new_s);
IF_COND (if_stmt) = newvar;
@@ -3477,25 +3472,25 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
break;
case FOR_STMT:
{
+ tree *await_ptr;
+ hash_set<tree> visited;
/* for loops only need special treatment if the condition or the
iteration expression contain a co_await. */
tree for_stmt = *stmt;
/* Sanity check. */
- if ((res = cp_walk_tree (&FOR_INIT_STMT (for_stmt),
- analyze_expression_awaits, d, &visited)))
- return res;
- gcc_checking_assert (!awpts->saw_awaits);
-
- if ((res = cp_walk_tree (&FOR_COND (for_stmt),
- analyze_expression_awaits, d, &visited)))
- return res;
- bool for_cond_await = awpts->saw_awaits != 0;
- unsigned save_awaits = awpts->saw_awaits;
-
- if ((res = cp_walk_tree (&FOR_EXPR (for_stmt),
- analyze_expression_awaits, d, &visited)))
- return res;
- bool for_expr_await = awpts->saw_awaits > save_awaits;
+ gcc_checking_assert
+ (!(cp_walk_tree (&FOR_INIT_STMT (for_stmt), find_any_await,
+ &await_ptr, &visited)));
What's the rationale for this assert? [expr.await] seems to say
explicitly that an await can appear in the initializer of an init-statement.
+ visited.empty ();
+ bool for_cond_await
+ = cp_walk_tree (&FOR_COND (for_stmt), find_any_await,
+ &await_ptr, &visited);
+
+ visited.empty ();
+ bool for_expr_await
+ = cp_walk_tree (&FOR_EXPR (for_stmt), find_any_await,
+ &await_ptr, &visited);
/* If the condition has an await, then we will need to rewrite the
loop as
@@ -3538,7 +3533,12 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
= create_named_label_with_ctx (sloc, buf, NULL_TREE);
free (buf);
add_stmt (build_stmt (sloc, LABEL_EXPR, it_expr_label));
- add_stmt (FOR_EXPR (for_stmt));
+ tree for_expr = FOR_EXPR (for_stmt);
+ /* Present the iteration expression as a statement. */
+ if (TREE_CODE (for_expr) == CLEANUP_POINT_EXPR)
+ for_expr = TREE_OPERAND (for_expr, 0);
+ STRIP_NOPS (for_expr);
+ finish_expr_stmt (for_expr);
FOR_EXPR (for_stmt) = NULL_TREE;
FOR_BODY (for_stmt) = pop_stmt_list (insert_list);
/* rewrite continue statements to goto label. */
@@ -3565,11 +3565,11 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
break;
stmt..
} */
+ tree *await_ptr;
+ hash_set<tree> visited;
tree while_stmt = *stmt;
- if ((res = cp_walk_tree (&WHILE_COND (while_stmt),
- analyze_expression_awaits, d, &visited)))
- return res;
- if (!awpts->saw_awaits)
+ if (!(cp_walk_tree (&WHILE_COND (while_stmt),
+ find_any_await, &await_ptr, &visited)))
return NULL_TREE; /* Nothing special to do here. */
tree insert_list = push_stmt_list ();
@@ -3595,10 +3595,10 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
break;
} while (true); */
tree do_stmt = *stmt;
- if ((res = cp_walk_tree (&DO_COND (do_stmt),
- analyze_expression_awaits, d, &visited)))
- return res;
- if (!awpts->saw_awaits)
+ tree *await_ptr;
+ hash_set<tree> visited;
+ if (!(cp_walk_tree (&DO_COND (do_stmt),
+ find_any_await, &await_ptr, &visited)))
return NULL_TREE; /* Nothing special to do here. */
tree insert_list = push_stmt_list ();
@@ -3621,10 +3621,10 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
switch_type cond = cond with awaits
switch (cond) stmt. */
tree sw_stmt = *stmt;
- if ((res = cp_walk_tree (&SWITCH_STMT_COND (sw_stmt),
- analyze_expression_awaits, d, &visited)))
- return res;
- if (!awpts->saw_awaits)
+ tree *await_ptr;
+ hash_set<tree> visited;
+ if (!(cp_walk_tree (&SWITCH_STMT_COND (sw_stmt),
+ find_any_await, &await_ptr, &visited)))
return NULL_TREE; /* Nothing special to do here. */
gcc_checking_assert (!awpts->bind_stack->is_empty());
@@ -3665,9 +3665,6 @@ await_statement_walker (tree *stmt, int *do_subtree, void
*d)
{ expr; p.return_void(); goto final_suspend;}
- for co_return [non void expr];
{ p.return_value(expr); goto final_suspend; } */
- if ((res = cp_walk_tree (stmt, analyze_expression_awaits,
- d, &visited)))
- return res;
location_t loc = EXPR_LOCATION (expr);
tree call = TREE_OPERAND (expr, 1);
expr = TREE_OPERAND (expr, 0);
@@ -3675,39 +3672,33 @@ await_statement_walker (tree *stmt, int *do_subtree,
void *d)
/* [stmt.return.coroutine], 2.2
If expr is present and void, it is placed immediately before
the call for return_void; */
- tree *maybe_await_stmt = NULL;
if (expr && VOID_TYPE_P (TREE_TYPE (expr)))
- {
- finish_expr_stmt (expr);
- /* If the return argument was a void expression, then any
- awaits must be contained in that. */
- maybe_await_stmt = tsi_stmt_ptr (tsi_last (ret_list));
- }
+ finish_expr_stmt (expr);
/* Insert p.return_{void,value(expr)}. */
finish_expr_stmt (call);
- /* Absent a return of a void expression, any awaits must be in
- the parameter to return_value(). */
- if (!maybe_await_stmt)
- maybe_await_stmt = tsi_stmt_ptr (tsi_last (ret_list));
TREE_USED (awpts->fs_label) = 1;
add_stmt (build_stmt (loc, GOTO_EXPR, awpts->fs_label));
*stmt = pop_stmt_list (ret_list);
+ res = cp_walk_tree (stmt, await_statement_walker, d, NULL);
/* Once this is complete, we will have processed subtrees. */
*do_subtree = 0;
- if (awpts->saw_awaits)
- {
- gcc_checking_assert (maybe_await_stmt);
- res = cp_walk_tree (maybe_await_stmt, await_statement_walker,
- d, NULL);
- if (res)
- return res;
- }
- return NULL_TREE; /* Done. */
+ return res;
}
break;
}
else if (EXPR_P (expr))
{
+ hash_set<tree> visited;
+ tree *await_ptr;
+ if (!(cp_walk_tree (stmt, find_any_await, &await_ptr, &visited)))
+ return NULL_TREE; /* Nothing special to do here. */
+
+ visited.empty ();
+ awpts->saw_awaits = 0;
+ hash_set<tree> truth_aoif_to_expand;
+ awpts->truth_aoif_to_expand = &truth_aoif_to_expand;
+ awpts->needs_truth_if_exp = false;
+ awpts->has_awaiter_init = false;
if ((res = cp_walk_tree (stmt, analyze_expression_awaits, d, &visited)))
return res;
*do_subtree = 0; /* Done subtrees. */
