On Wed, Apr 13, 2011 at 5:48 PM, Richard Guenther
<richard.guent...@gmail.com> wrote:
> 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.
I'm not sure I understand this, I use define_expand to expand
the builtin function to RTX, and then define_insn * to match the
RTX and generate code. It seems it didn't generate the asm code.
> Do you have any const or pure attributes on the tend builtin?
Do you mean (set_attr "" "") in the define_insn?
Feng
>
> Richard.
>
>> Feng
>>>
>>> Ian
>>>
>>
>
