[Bug rtl-optimization/40987] Wrong optimization with if-conversion

[Bug rtl-optimization/40987] Wrong optimization with if-conversion

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40987

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|i686                        |
               Host|i686                        |HWI == 32
              Build|i686                        |

--- Comment #11 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-01-21 21:27:18 UTC ---
This bug is now hard to hit on the trunk as i?86 requires host wide word as
64bit.

[Bug rtl-optimization/40987] ifcvt sometimes goes wrong for integer modes > 64bit

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40987

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #11)
> This bug is now hard to hit on the trunk as i?86 requires host wide word as
> 64bit.

HWINT is now required to be 64bit for all targets even.
So this might happen if there is some TImode but then the patch might be best
thing really.

[Bug rtl-optimization/40987] ifcvt sometimes goes wrong for integer modes > 64bit

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40987

--- Comment #13 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is a x86_64-linux-gnu testcase:
```
#include <stdio.h>

typedef __int128_t mytype;
#define value (((__int128_t)(((unsigned long long)__LONG_LONG_MAX__)+1)) |
(((__int128_t)0xffffffffffffffffull)<<64))

mytype func(long arg) __attribute__((noinline,noclone));
mytype func(long arg) {
   mytype val = 0;
   if (arg < 0) {
    // __int128_t t = 0x8000000000000000ull |
(((__int128_t)0xffffffffffffffff)<<64);
      val = value;
   }
   return val;
}

int main() {
   mytype result = func(-1);
   if (result != value) {
      printf("failed.\n");
      return 1;
   } 
   printf("passed.\n");
   return 0;
}
```

It failed until GCC 4.9.0

[Bug rtl-optimization/40987] ifcvt sometimes goes wrong for integer modes > 64bit

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40987

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |4.9.0

--- Comment #14 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looks like this was fixed with r0-127324-ge15eb172b0dd (aka PR 59545).
Basically a signed integer overflow inside the compiler was causing the wrong
code happening.