Re: [PATCH][AARCH64] PR target/84521 Fix frame pointer corruption with -fomit-frame-pointer with __builtin_setjmp

[James Greenhalgh <james dot greenhalgh at arm dot com>]

On Wed, Mar 14, 2018 at 05:40:49PM +0000, Sudi Das wrote:
> Hi
> 
> This patch is another partial fix for PR 84521. This is adding a 
> definition to one of the target hooks used in the SJLJ implemetation so 
> that AArch64 defines the hard_frame_pointer_rtx as the 
> TARGET_BUILTIN_SETJMP_FRAME_VALUE. As pointed out by Wilco there is 
> still a lot more work to be done for these builtins in the future.
> 
> Testing: Bootstrapped and regtested on aarch64-none-linux-gnu and added 
> new test.
> 
> Is this ok for trunk?

OK.

Thanks,
James

> *** gcc/ChangeLog ***
> 
> 2018-03-14  Sudakshina Das  <sudi.das@arm.com>
> 
> 	* builtins.c (expand_builtin_setjmp_receiver): Update condition
> 	to restore frame pointer.
> 	* config/aarch64/aarch64.h (DONT_USE_BUILTIN_SETJMP): Update
> 	comment.
> 	* config/aarch64/aarch64.c (aarch64_builtin_setjmp_frame_value):
> 	New.
> 	(TARGET_BUILTIN_SETJMP_FRAME_VALUE): Define.
> 
> *** gcc/testsuite/ChangeLog ***
> 
> 2018-03-14  Sudakshina Das  <sudi.das@arm.com>
> 
> 	* gcc.c-torture/execute/pr84521.c: New test.

> diff --git a/gcc/builtins.c b/gcc/builtins.c
> index 85affa7..640f1a9 100644
> --- a/gcc/builtins.c
> +++ b/gcc/builtins.c
> @@ -898,7 +898,8 @@ expand_builtin_setjmp_receiver (rtx receiver_label)
>  
>    /* Now put in the code to restore the frame pointer, and argument
>       pointer, if needed.  */
> -  if (! targetm.have_nonlocal_goto ())
> +  if (! targetm.have_nonlocal_goto ()
> +      && targetm.builtin_setjmp_frame_value () != hard_frame_pointer_rtx)
>      {
>        /* First adjust our frame pointer to its actual value.  It was
>  	 previously set to the start of the virtual area corresponding to
> diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
> index e3c52f6..7a21c14 100644
> --- a/gcc/config/aarch64/aarch64.h
> +++ b/gcc/config/aarch64/aarch64.h
> @@ -474,7 +474,9 @@ extern unsigned aarch64_architecture_version;
>  #define EH_RETURN_STACKADJ_RTX	gen_rtx_REG (Pmode, R4_REGNUM)
>  #define EH_RETURN_HANDLER_RTX  aarch64_eh_return_handler_rtx ()
>  
> -/* Don't use __builtin_setjmp until we've defined it.  */
> +/* Don't use __builtin_setjmp until we've defined it.
> +   CAUTION: This macro is only used during exception unwinding.
> +   Don't fall for its name.  */
>  #undef DONT_USE_BUILTIN_SETJMP
>  #define DONT_USE_BUILTIN_SETJMP 1
>  
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index e1fb87f..e7ac0fe 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -12128,6 +12128,13 @@ aarch64_expand_builtin_va_start (tree valist, rtx nextarg ATTRIBUTE_UNUSED)
>    expand_expr (t, const0_rtx, VOIDmode, EXPAND_NORMAL);
>  }
>  
> +/* Implement TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
> +static rtx
> +aarch64_builtin_setjmp_frame_value (void)
> +{
> +  return hard_frame_pointer_rtx;
> +}
> +
>  /* Implement TARGET_GIMPLIFY_VA_ARG_EXPR.  */
>  
>  static tree
> @@ -17505,6 +17512,9 @@ aarch64_run_selftests (void)
>  #undef TARGET_FOLD_BUILTIN
>  #define TARGET_FOLD_BUILTIN aarch64_fold_builtin
>  
> +#undef TARGET_BUILTIN_SETJMP_FRAME_VALUE
> +#define TARGET_BUILTIN_SETJMP_FRAME_VALUE aarch64_builtin_setjmp_frame_value
> +
>  #undef TARGET_FUNCTION_ARG
>  #define TARGET_FUNCTION_ARG aarch64_function_arg
>  
> diff --git a/gcc/testsuite/gcc.c-torture/execute/pr84521.c b/gcc/testsuite/gcc.c-torture/execute/pr84521.c
> new file mode 100644
> index 0000000..76b10d2
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/execute/pr84521.c
> @@ -0,0 +1,49 @@
> +/* { dg-require-effective-target indirect_jumps } */
> +
> +#include <setjmp.h>
> +
> +jmp_buf buf;
> +
> +int uses_longjmp (void)
> +{
> +  __builtin_longjmp (buf, 1);
> +}
> +
> +int gl;
> +void after_longjmp (void)
> +{
> +  gl = 5;
> +}
> +
> +int
> +test_1 (int n)
> +{
> +  volatile int *p = alloca (n);
> +  if (__builtin_setjmp (buf))
> +    {
> +      after_longjmp ();
> +    }
> +  else
> +    {
> +      uses_longjmp ();
> +    }
> +
> +  return 0;
> +}
> +
> +int __attribute__ ((optimize ("no-omit-frame-pointer")))
> +test_2 (int n)
> +{
> +  int i;
> +  int *ptr = (int *)__builtin_alloca (sizeof (int) * n);
> +  for (i = 0; i < n; i++)
> +    ptr[i] = i;
> +  test_1 (n);
> +  return 0;
> +}
> +
> +int main (int argc, const char **argv)
> +{
> +  __builtin_memset (&buf, 0xaf, sizeof (buf));
> +  test_2 (100);
> +}