Hi Ian,
2012/4/22 Ian Lance Taylor <i...@google.com>:
> Feng LI <nemoking...@gmail.com> writes:
>
>> Yes, you are right. But how could I reference to a backend defined builtin
>> function in the middle end (I need to generate the builtin function in the
>> middle end and expand it in x86 backend)?
>
> If the function doesn't have a machine-independent definition, then use
> a target hook.
Then I remove the duplicate builtin definition in x86 backend.
I define the builtin function with built_in_class as BUILT_IN_MD in
builtins.def.
So that in the expand_builtin, the target specific hook will be called:
if (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_MD)
return targetm.expand_builtin (exp, target, subtarget, mode, ignore);
Then in the middle end I could reference to this builtin function with
tree tcreate_fn = built_in_decls[BUILT_IN_TCREATE], and it'll call
the target specific expansion in the backend.
The problem happens as the code below shows:
builtin_expand (){
enum built_in_function fcode = DECL_FUNCTION_CODE (fndecl);
}
ix86_expand_builtin{
enum ix86_builtins fcode = DECL_FUNCTION_CODE (fndecl);
}
The builtin codes (enum built_in_function and ix86_builtins_fcode) are
different sets in
both middle end and backend, so I end up with trapping into this code block:
if (ix86_builtins_isa[fcode].isa
&& !(ix86_builtins_isa[fcode].isa & ix86_isa_flags))
{
char *opts = ix86_target_string (ix86_builtins_isa[fcode].isa, 0, NULL,
NULL, NULL, false);
if (!opts)
error ("%qE needs unknown isa option", fndecl);
else
{
gcc_assert (opts != NULL);
error ("%qE needs isa option %s", fndecl, opts);
free (opts);
}
return const0_rtx;
}
Not sure if I'm doing it in the right way, help needed...
Thanks,
Feng
>
> (That said I've thought for a while that we need better mechanisms for
> target-specific optimization passes. If we had those I would tell you
> to write one. E.g., reg-stack.c is a target-specific pass.)
>
> Ian
