[Bug middle-end/89303] [8 Regression] memory leak with shared_ptr and enable_shared_from_this

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89303

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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  Attachment #45682|0                           |1
        is obsolete|                            |

--- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Created attachment 45684
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45684&action=edit
Testcase for both bugs

This new attachment can be used to reproduce both bugs, for any GCC version
from 5.1.0 onwards, with -O1.

By default it shows the memory leak, but when BAD_WEAK_PTR_BUG is defined it
demonstrates the unexpected exception.

Defining FIXME makes both bugs go away.

I've confirmed that the original bug is caused by
_M_weak_this._M_refcount._M_pi being null:

(gdb) p tg
$1 = {_M_ptr = 0x614e80, _M_refcount = {_M_pi = 0x614e70}}
(gdb) p *tg._M_ptr
$2 = {<std::__enable_shared_from_this<blob, 0>> = {_M_weak_this = {_M_ptr =
0x614e80, _M_refcount = {_M_pi = 0x0}}}, data = 0x614ea0}

Bisecting from 4.9 to 5.1 shows the bug started with r221859:

2015-04-03  Jan Hubicka

       PR ipa/65076
       * ipa-inline.c (edge_badness): Add combined size to the denominator.