Ping.
(Sorry for the very aggressive ping; this fixes 764 testsuite failures
on powerpc-linux).
Segher
On Sun, May 28, 2017 at 12:31:12PM +0000, Segher Boessenkool wrote:
> __atomic_add_fetch adds a value to some memory, and returns the result.
> If there is no direct support for this, expand_builtin_atomic_fetch_op
> is asked to implement this as __atomic_fetch_add (which returns the
> original value of the mem), followed by the addition. Now, the
> __atomic_add_fetch could have been a tail call, but we shouldn't
> perform the __atomic_fetch_add as a tail call: following code would
> not be executed, and in fact thrown away because there is a barrier
> after tail calls.
>
> This fixes it.
>
> Tested on powerpc64-linux {-m32,-m64}. Is this okay for trunk?
>
>
> Segher
>
>
> 2017-05-28 Segher Boessenkool <[email protected]>
>
> PR middle-end/80902
> * builtins.c (expand_builtin_atomic_fetch_op): If emitting code after
> a call, force the call to not be a tail call.
>
> ---
> gcc/builtins.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/gcc/builtins.c b/gcc/builtins.c
> index 4f6c9c4..3a70693 100644
> --- a/gcc/builtins.c
> +++ b/gcc/builtins.c
> @@ -6079,6 +6079,12 @@ expand_builtin_atomic_fetch_op (machine_mode mode,
> tree exp, rtx target,
> gcc_assert (TREE_OPERAND (addr, 0) == fndecl);
> TREE_OPERAND (addr, 0) = builtin_decl_explicit (ext_call);
>
> + /* If we will emit code after the call, the call can not be a tail call.
> + If it is emitted as a tail call, a barrier is emitted after it, and
> + then all trailing code is removed. */
> + if (!ignore)
> + CALL_EXPR_TAILCALL (exp) = 0;
> +
> /* Expand the call here so we can emit trailing code. */
> ret = expand_call (exp, target, ignore);
>
> --
> 1.9.3
