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.
