Mark Mitchell wrote:
> David Daney wrote:
>
>   
>> void
>> __clear_cache (char *beg, char *end)
>> {
>>  if (__builtin_clear_cache_inline_p())
>>    __builtin___clear_cache (beg, end);
>>  else
>>    {
>> #ifdef CLEAR_INSN_CACHE
>>      CLEAR_INSN_CACHE (beg, end);
>> #endif /* CLEAR_INSN_CACHE */
>>    }
>> }
>>
>> No changes to any existing  CLEAR_INSN_CACHE definitions are needed. 
>> There is a new target hook that determines the value of
>> __builtin_clear_cache_inline_p().
>>     
>
> I think that's a little bit overly complicated.  Since the target has to
> do something anyhow, to indicate that we should call the builtin here,
> we might as well just have the target define CLEAR_INSN_CACHE that way.
>
> My two cents,
>   

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.

Here is a new version of the target independent portion of the patch.  
Thanks to Mark, Paolo, and Richard for their input.

Currently bootstrapping/testing on x86_64-unknown-linux-gnu, 
mipsel-unknown-linux-gnu (--with-arch=[mips32|mips32r2]).

OK to commit?

2007-07-04  David Daney  <ddaney@avtrex.com>

    * builtins.def (BUILT_IN_CLEAR_CACHE): New builtin.
    (BUILT_IN_CLEAR_CACHE_INLINE_P): Same.
    * builtins.c (expand_builtin_clear_cache): New function.
    (expand_builtin): Call expand_builtin_clear_cache for
    BUILT_IN_CLEAR_CACHE case.  Call gcc_unreachable() for
    BUILT_IN_CLEAR_CACHE_INLINE_P case.
    (fold_builtin_clear_cache_inline_p): New function.
    (fold_builtin_0): Call fold_builtin_clear_cache_inline_p for
    BUILT_IN_CLEAR_CACHE_INLINE_P case.
    * target.h (struct gcc_target):  Add new member
    builtin_clear_cache_inline_p.
    * target-def.h (TARGET_BUILTIN_CLEAR_CACHE_INLINE_P):  New target
    hooks initializer.
    (TARGET_INITIALIZER): Add TARGET_BUILTIN_CLEAR_CACHE_INLINE_P.
    * doc/extend.texi (__builtin___clear_cache): Document new builtin.
    (__builtin_clear_cache_inline_p): Same.
    * doc/tm.texi (TARGET_BUILTIN_CLEAR_CACHE_INLINE_P): Document new
    target hook.
    * testsuite/gcc.dg/builtins-64.c: New test.
    * testsuite/gcc.dg/builtins-65.c: New test.