[Bug middle-end/36255] -fstrict-aliasing breaks __builtin_va_args

[pinskia at gcc dot gnu dot org]

--- Comment #6 from pinskia at gcc dot gnu dot org  2008-05-17 13:42 ---
Hmm, va_arg actually expands to use aliasing set 0.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36255

[Bug middle-end/36255] -fstrict-aliasing breaks __builtin_va_args

[rguenth at gcc dot gnu dot org]

--- Comment #7 from rguenth at gcc dot gnu dot org  2008-05-17 13:52 ---
Created an attachment (id=15652)
 -- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15652action=view)
single-file testcase


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36255

[Bug middle-end/36255] -fstrict-aliasing breaks __builtin_va_args

[rguenth at gcc dot gnu dot org]

--- Comment #8 from rguenth at gcc dot gnu dot org  2008-05-17 13:52 ---
Confirmed.


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rguenth at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
 Ever Confirmed|0   |1
   Keywords||wrong-code
   Last reconfirmed|-00-00 00:00:00 |2008-05-17 13:52:50
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36255

[Bug middle-end/36255] -fstrict-aliasing breaks __builtin_va_args

[rguenth at gcc dot gnu dot org]

--- Comment #9 from rguenth at gcc dot gnu dot org  2008-05-17 18:03 ---
Hmm, if I properly add va_end (args) the bug is gone.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36255

[Bug middle-end/36255] -fstrict-aliasing breaks __builtin_va_args

[rguenth at gcc dot gnu dot org]

--- Comment #10 from rguenth at gcc dot gnu dot org  2008-05-17 18:15 
---
Reduced testcase, works with -fno-strict-aliasing.

unsigned long __attribute__((noinline)) foo (int narg, ...)
{
  unsigned long V1;
  __builtin_va_list args;
  __builtin_va_start (args, narg);
  V1 = (unsigned long)__builtin_va_arg(args, void *);
  /*__builtin_va_end (args);*/
  return V1;
}
extern void abort (void);
int main(int argc, char**argv)
{
  unsigned long x = foo (1, 0x2688612UL);
  if (x != 0x2688612UL)
abort ();
  return 0;
}


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36255

[Bug middle-end/36255] -fstrict-aliasing breaks __builtin_va_args

[rguenth at gcc dot gnu dot org]

--- Comment #11 from rguenth at gcc dot gnu dot org  2008-05-17 18:21 
---
Note that the missing va_end makes the testcase strictly invalid.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36255

[Bug middle-end/36255] -fstrict-aliasing breaks __builtin_va_args

[pinskia at gcc dot gnu dot org]

--- Comment #12 from pinskia at gcc dot gnu dot org  2008-05-17 18:23 
---
This is undefined code without va_end. 


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pinskia at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|NEW |RESOLVED
 Resolution||INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36255