[Bug middle-end/49519] [4.7 Regression] Revision 175272 miscompiled 447.dealII in SPEC CPU 2006

[kirill.yukhin at intel dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49519

--- Comment #16 from Yukhin Kirill <kirill.yukhin at intel dot com> 2011-07-06 10:35:03 UTC ---
Yes.

This is because expander prepares arguments like this:
...
(insn 6 5 7 2 (parallel [
            (set (reg:SI 64)
                (plus:SI (reg/f:SI 53 virtual-incoming-args)
                    (const_int 4 [0x4])))
            (clobber (reg:CC 17 flags))
        ]) 2.cc:103 -1
     (nil))

(insn 7 6 8 2 (set (reg:SI 65)
        (mem/c:SI (plus:SI (reg:SI 64)
                (const_int 12 [0xc])) [0 MEM[(int &)&t + 12]+0 S4 A32]))
2.cc:103 -1
     (nil))

(insn 8 7 9 2 (set (mem:SI (plus:SI (reg/f:SI 53 virtual-incoming-args)
                (const_int 12 [0xc])) [0 S4 A32])
        (reg:SI 65)) 2.cc:103 -1
     (nil))
...

So, calls.c/mem_overlaps_already_clobbered_arg_p unable to determine, that data
come from stack, so it returns true and enables tailcall.