Re: [Qemu-devel] [PATCH] w64: Fix calls of TCG helper functions with 5 arguments

[Stefan Weil <sw@weilnetz.de>]

Am 12.09.2012 21:14, schrieb Aurelien Jarno:
> On Wed, Sep 12, 2012 at 07:12:47PM +0100, Peter Maydell wrote:
>> On 12 September 2012 19:03, Stefan Weil<sw@weilnetz.de>  wrote:
>>> diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
>>> index da17bba..43b5572 100644
>>> --- a/tcg/i386/tcg-target.c
>>> +++ b/tcg/i386/tcg-target.c
>>> @@ -118,7 +118,7 @@ static void patch_reloc(uint8_t *code_ptr, int type,
>>>   static inline int tcg_target_get_call_iarg_regs_count(int flags)
>>>   {
>>>       if (TCG_TARGET_REG_BITS == 64) {
>>> -        return 6;
>>> +        return ARRAY_SIZE(tcg_target_call_iarg_regs);
>>>       }
>>>
>>>       return 0;
>>
>> Hmm. Why can't we just return the array size in all cases?
>> Is there something special about 32 bit x86? I checked, and
>> all our other TCG targets return the same value as the size of
>> the iarg_regs array (either using ARRAY_SIZE or by just returning
>> the right number)...
>>
>
> On 32-bit x86, all arguments are now being passed on the stack, that's
> why the function returns 0. On the other hand when the change has been
> done, the registers haven't been removed from tcg_target_call_iarg_regs.
>
> I think this patch is fine enough for 1.2, but a better patch is needed
> for master.

As soon as the special case x86 with 32 bit is fixed or eliminated,
it should be possible that all TCG targets share the same code for
tcg_target_get_call_iarg_regs_count. That function could be
removed from the target specific implementations and moved
to tcg.c.