On Wed, Apr 13, 2011 at 5:45 PM, Feng LI <nemoking...@gmail.com> wrote:
> On Wed, Apr 13, 2011 at 5:32 PM, Ian Lance Taylor <i...@google.com> wrote:
>> Feng LI <nemoking...@gmail.com> writes:
>>
>>> I use unspec_volatile for a function with void arguments and
>>> void return value for some initialization work. But it didn't generate
>>> code in this case. I think probably I need to add more restrictions
>>> some where but I don't know why and how. The code looks like:
>>>
>>> extern __inline void __attribute__((__gnu_inline__, __always_inline__,
>>> __artificial__))
>>> __TEnd (void)
>>> {
>>> __builtin_ia32_tend ();
>>> }
>>>
>>> (define_expand "dta_tend"
>>> [(unspec_volatile [(const_int 0)] UNSPEC_TEND)]
>>> ""
>>> "")
>>>
>>> (define_insn "*dta_tend"
>>> [(unspec_volatile [(const_int 0)] UNSPEC_TEND)]
>>> ""
>>> "tend"
>>> [(set_attr "length" "3")
>>> (set_attr "mode" "none")])
>>
>> In the RTL dumps generated by -da, where does the insn appear and where
>> does it disappear?
>
> It seems that it disappear at the ffork.c.143r.expand at the very beginning.
> I suppose there should be some thing like
> (call_insn ....) generated for __builtin_ia32_tend (); But there isn't.
> instead, it generated:
>
> ;; Generating RTL for gimple basic block 2
> ;; __builtin_ia32_tend ();
> (nil)
You need to expand builtins yourself, a "named" expander doesn't do
that for you.
Richard.
> Feng
>>
>> Ian
>>
>
