On Mon, Jan 8, 2024 at 3:35 AM Kewen.Lin <li...@linux.ibm.com> wrote:
>
> Hi,
>
> As PR113100 shows, the unbiasing introduced by r14-6737 can
> cause the scrubbing to overrun and screw some critical data
> on stack like saved toc base consequently cause segfault on
> Power.
>
> By checking PR112917, IMHO we should keep this unbiasing
> guarded under SPARC_STACK_BOUNDARY_HACK (TARGET_ARCH64 &&
> TARGET_STACK_BIAS), similar to some existing code special
> treating SPARC stack bias.
>
> Bootstrapped and regtested on x86_64-redhat-linux and
> powerpc64{,le}-linux-gnu. All reported failures in
> PR113100 are gone. I also expect the culprit commit can
> affect those ports with nonzero STACK_POINTER_OFFSET.
>
> Is it ok for trunk?
OK
> BR,
> Kewen
> -----
> PR middle-end/113100
>
> gcc/ChangeLog:
>
> * builtins.cc (expand_builtin_stack_address): Guard stack point
> adjustment with SPARC_STACK_BOUNDARY_HACK.
> ---
> gcc/builtins.cc | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/builtins.cc b/gcc/builtins.cc
> index 125ea158ebf..9bad1e962b4 100644
> --- a/gcc/builtins.cc
> +++ b/gcc/builtins.cc
> @@ -5450,6 +5450,7 @@ expand_builtin_stack_address ()
> rtx ret = convert_to_mode (ptr_mode, copy_to_reg (stack_pointer_rtx),
> STACK_UNSIGNED);
>
> +#ifdef SPARC_STACK_BOUNDARY_HACK
> /* Unbias the stack pointer, bringing it to the boundary between the
> stack area claimed by the active function calling this builtin,
> and stack ranges that could get clobbered if it called another
> @@ -5476,7 +5477,9 @@ expand_builtin_stack_address ()
> (caller) function's active area as well, whereas those pushed or
> allocated temporarily for a call are regarded as part of the
> callee's stack range, rather than the caller's. */
> - ret = plus_constant (ptr_mode, ret, STACK_POINTER_OFFSET);
> + if (SPARC_STACK_BOUNDARY_HACK)
> + ret = plus_constant (ptr_mode, ret, STACK_POINTER_OFFSET);
> +#endif
>
> return force_reg (ptr_mode, ret);
> }
> --
> 2.39.3
