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* [gcc r12-9248] c++: top level bind when rewriting coroutines [PR106188]
@ 2023-03-13 21:38 Arsen Arsenović
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From: Arsen Arsenović @ 2023-03-13 21:38 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:775be7d6cb55173950b62c3b9c11ee208cfff29a
commit r12-9248-g775be7d6cb55173950b62c3b9c11ee208cfff29a
Author: Arsen Arsenović <arsen@aarsen.me>
Date: Sun Sep 4 21:04:23 2022 +0200
c++: top level bind when rewriting coroutines [PR106188]
In the edge case of a coroutine not containing any locals, the ifcd/switch
temporaries would get added to the coroutine frame, corrupting its
layout. To prevent this, we can make sure there is always a BIND_EXPR at
the top of the function body, and thus, always a place for our new
temporaries to go without interfering with the coroutine frame.
PR c++/106188 - Incorrect frame layout after transforming conditional statement without top-level bind expression
PR c++/106713 - if (co_await ...) crashes with a jump to ud2
PR c++/106188
PR c++/106713
gcc/cp/ChangeLog:
* coroutines.cc (coro_rewrite_function_body): Ensure we have a
BIND_EXPR wrapping the function body.
gcc/testsuite/ChangeLog:
* g++.dg/coroutines/pr106188.C: New test.
Diff:
---
gcc/cp/coroutines.cc | 9 ++++++++
gcc/testsuite/g++.dg/coroutines/pr106188.C | 34 ++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 1d886b31c77..64251a4f087 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4095,6 +4095,15 @@ coro_rewrite_function_body (location_t fn_start, tree fnbody, tree orig,
BLOCK_SUPERCONTEXT (replace_blk) = top_block;
BLOCK_SUBBLOCKS (top_block) = replace_blk;
}
+ else
+ {
+ /* We are missing a top level BIND_EXPR. We need one to ensure that we
+ don't shuffle around the coroutine frame and corrupt it. */
+ tree bind_wrap = build3_loc (fn_start, BIND_EXPR, void_type_node,
+ NULL, NULL, NULL);
+ BIND_EXPR_BODY (bind_wrap) = fnbody;
+ fnbody = bind_wrap;
+ }
/* Wrap the function body in a try {} catch (...) {} block, if exceptions
are enabled. */
diff --git a/gcc/testsuite/g++.dg/coroutines/pr106188.C b/gcc/testsuite/g++.dg/coroutines/pr106188.C
new file mode 100644
index 00000000000..9db3778d079
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr106188.C
@@ -0,0 +1,34 @@
+// { dg-do run { target c++20 } }
+// test case from pr106188, w/o workaround
+#include <coroutine>
+
+struct task {
+ struct promise_type {
+ task get_return_object() { return task{}; }
+ void return_void() {}
+ void unhandled_exception() {}
+ auto initial_suspend() noexcept { return std::suspend_never{}; }
+ auto final_suspend() noexcept { return std::suspend_never{}; }
+ };
+};
+
+struct suspend_and_resume {
+ bool await_ready() const { return false; }
+ void await_suspend(std::coroutine_handle<> h) { h.resume(); }
+ void await_resume() {}
+};
+
+task f() {
+ if (co_await suspend_and_resume{}, false) {}
+}
+
+task g() {
+ switch (co_await suspend_and_resume{}, 0) {
+ default: break;
+ }
+}
+
+int main() {
+ f();
+ g();
+}
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