Re: Feature request: Set the direction flag on x86/x64 register->register operations

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Dec 18, 2008 at 10:52 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Dec 18, 2008 at 9:16 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Tue, Dec 9, 2008 at 4:51 AM, Stefan Dösinger <stefan@codeweavers.com> wrote:
>>> Hi,
>>>
>>> Here is another version of my patch to set the direction flag on
>>> register->register operations.
>>>
>>> The main change is that it is now controlled by a per-instruction suffix
>>> instead of a command line switch. Alexandre Julliard didn't like the idea of
>>> the command line switch, he prefers gcc to control the bit. I have to modify
>>> gcc to make it generate a "movl %edi, %edi" like Windows has it anyway, so
>>> going this route is ok for me.
>>>
>>> I added a test for this feature which specifically tests the instructions
>>> that are important to me(mov %edi, %edi and mov %esp, %ebp) and a few more.
>>> I ran the existing tests with the flag forced on for all instructions, and
>>> they pass. There are a few false positives obviously because the patch
>>> changes the encoding, but I checked all of those cases and the code works
>>> correctly.
>>>
>>> I verified the behavior against msvc, and it does set the flag on 8, 16 and
>>> 32 bit operations for sure. I didn't check 64 bit ones because I do not have
>>> a 64 bit Windows installation to test, but this is moot now anyway because
>>> gcc controls the flag. It doesn't affect this patch any longer.
>>>
>>
>> Please use "movl.r" instead of "movlr".
>
> That is what I have in mind:
>

Here is my patch. Is it useful?



-- 
H.J.

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