Re: [PATCH v2] rs6000: Fix some issues in rs6000_can_inline_p [PR102059]

["Martin Liška" <mliska@suse.cz>]

On 12/4/21 00:23, Peter Bergner wrote:
> On 12/2/21 9:46 PM, Kewen.Lin via Gcc-patches wrote:
>> on 2021/11/30 上午12:57, Segher Boessenkool wrote:
>>> On Wed, Sep 01, 2021 at 02:55:51PM +0800, Kewen.Lin wrote:
>>>> This patch is to fix the inconsistent behaviors for non-LTO mode
>>>> and LTO mode.  As Martin pointed out, currently the function
>>>> rs6000_can_inline_p simply makes it inlinable if callee_tree is
>>>> NULL, but it's wrong, we should use the command line options
>>>> from target_option_default_node as default.
>>>
>>> This is not documented.
>>>
>>
>> Yeah, but according to the document for the target attribute [1],
>> "Multiple target back ends implement the target attribute to specify
>> that a function is to be compiled with different target options than
>> specified on the command line. The original target command-line options
>> are ignored. ", it seems to say the function without any target
>> attribute/pragma will be compiled with target options specified on the
>> command line.  I think it's a normal expectation for users.
>>
>> Excepting for the inconsistent behaviors between LTO and non-LTO,
>> it can also make the below case different.
> 
> I thought Martin and richi mentioned that target attribute options
> are treated as if they are appended to the end of the command line
> options, so they can potentially override earlier options, but they
> don't actually ignore them?

No, the described behavior is true for optimize attribute:

optimize (string, …)
...
The optimize attribute arguments of a function behave behave as if appended to the command-line.

but:

target (string, …)
...
The original target command-line options are ignored.

As seen here:
https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes

Cheers,
Martin

> 
> Peter
>