Re: [Patch] 1/3 Add new builtin __builtin_flush_icache().

[Mark Mitchell <mark at codesourcery dot com>]

David Daney wrote:

> Ok, I think I have come around to your way of thinking.  I still have
> the new predicate __builtin_clear_cache_inline_p() for use in target
> CLEAR_INSN_CACHE definitions, but I leave __clear_cache unchanged.

I don't understand the need for the inline_p function.  It seems to me
there are two scenarios:

1. The back-end has an inline definition of __builtin___clear_cache.  In
that case, it does:

  #define CLEAR_INSN_CACHE(BEG, END) __builtin___clear_cache(BEG, END);

2. The back-end does not have an inline definition of
__builtin_clear_cache.  In that case, it does:

  #define CLEAR_INSN_CACHE(BEG, END) \
    /* Something not involving __builtin___clear_cache */

In both cases, the libgcc __clear_cache routine just does:

  CLEAR_INSN_CACHE (beg, end);

And, in both cases, the user can write either __clear_cache (always an
out-of-line call), or __builtin_clear_cache (may be an out-of-line call,
or may be inline code).

Is your concern that in case (1) the back-end has to do two things:
define the builtin and define CLEAR_INSN_CACHE?  That's a little lame,
but it doesn't seem worse than having to define two builtins.

Am I missing some intermediate case?

Thanks,

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713