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

[Sudakshina Das <sudi.das@arm.com>]

On 19/03/18 12:11, James Greenhalgh wrote:
> 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 but I realized I marked this wrong as only AArch64 patch. 
This also has a mid change so cc'ing more people for approval.

Sudi

> 
> 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);
>> +}
>