PowerPC64 support in safe_address function

[gustavotemple]

Add a ppc64-specific implementation of the safe_address
function with overflow checking.

[gustavotemple]

@remicollet, @smalyshev, @datibbaw, @laruence: the PR #734 has been rebased in this one.

[remicollet]

Tried against master on

 POWER8 (architected), altivec supported
 Linux foo 3.10.0-123.el7.ppc64 #1 SMP Mon May 5 11:18:37 EDT 2014 ppc64 ppc64 ppc64 GNU/Linux

This make ext/spl/tests/bug67247.phpt segfault:

Without the patch

size: 1
Fatal error: Possible integer overflow in memory allocation (2305843009213693953 * 16 + 0) in /home/remi/php-src/ext/spl/tests/bug67247.php on line 4

With:

size: 1
size: 2305843009213693953
Segfault

[remicollet]

FYI, we now have 0 failed tests on ppc64, so testing will be easier (build with --disable-all, so no extension tested)

[gustavotemple]

@remicollet, thank you very much :)

[remicollet]

Any update on this one ? (still segfault)

[gustavotemple]

Sorry @remicollet, not yet, I and my teammates (@caioso, @lbianc) we're still checking.

[remicollet]

@gustavotemple no urgency ;)
I have return the ppc64 machine used to check these PR, but will be able to request another later.

[gustavotemple]

@remicollet, done, fixed.

[remicollet]

Tested on

 POWER7 (architected), altivec supported
 Linux xxx 3.10.0-216.el7.ppc64 #1 SMP Tue Dec 9 15:02:02 EST 2014 ppc64 ppc64 ppc64 GNU/Linux

No regression detected. Fine :)

[php-pulls]

Comment on behalf of remi at php.net:

merged, thanks for improving PHP on PowerPC :)