i386 define_asm_attributes question

[H.J. Lu]

On Mon, May 7, 2012 at 3:02 PM, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
> Hi,
>
> I noticed gcc predicts huge sizes for asm statements on ix86. This is
> due to define_asm_attributes in i386.md, where the length *per single
> instruction* in the asm is set to 128. That doesn't look realistic to
> me. Is there a good reason for this large value? Or should something
> like the patch below be tested? (I choose 16 but I don't know if there
> are larger insns for x86 - I assume you do ;-)
>
> Ciao!
> Steven
>
>
> Index: config/i386/i386.md
> ===================================================================
> --- config/i386/i386.md (revision 187257)
> +++ config/i386/i386.md (working copy)
> @@ -661,7 +661,7 @@
>
>  ;; Describe a user's asm statement.
>  (define_asm_attributes
> -  [(set_attr "length" "128")
> +  [(set_attr "length" "16")
>    (set_attr "type" "multi")])
>
>  (define_code_iterator plusminus [plus minus])

I checked with our people.  The maximum insn length on Intel
processor is 15byte.

-- 
H.J.