[PATCH 1/2] gdi32/tests: Add locale-dependent face matching test.

[Rémi Bernon]

On 11/23/20 3:12 PM, Rémi Bernon wrote:
> On 11/23/20 2:40 PM, Rémi Bernon wrote:
>> On 11/23/20 2:16 PM, Alexandre Julliard wrote:
>>> Rémi Bernon <rbernon at codeweavers.com> writes:
>>>
>>>> Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
>>>> ---
>>>>
>>>> This brings another ~200ms prefix startup time improvement, from ~1.2s
>>>> to ~1s for "wine cmd /c exit" execution time on average, as well as a
>>>> ~50ms process startup time improvement, from ~0.25s to ~0.2s execution
>>>> time when prefix is already started.
>>>>
>>>> The test shows that using wcsicmp is incorrect for face name 
>>>> comparison,
>>>> or at least that we should not rely on the current locale, and perf
>>>> also reports a high number of CPU cache miss coming from the locale
>>>> refcounting, which is the main source of improvement here.
>>>>
>>>> IIUC RtlDowncaseUnicodeChar also does locale dependent case folding,
>>>> but I'm not sure to see how it's controlled (it's the system default
>>>> locale that defines the loaded tables right?), and we should probably
>>>> check if case matching depends on it. If not, is there any canonical
>>>> normalized unicode case folding that should be used instead?
>>>
>>> Unicode case mapping in ntdll is not locale-dependent. You can use
>>> CompareStringOrdinal() for that sort of thing.
>>>
>>
>> I also wanted to avoid iterating the whole strings as much as 
>> possible. RtlCompareUnicodeStrings (and so CompareStringOrdinal too) 
>> needs the actual strings length, or at least one of the two strings 
>> length to stop the iteration. This starts to add up as these 
>> comparisons are done quite a lot, specially when there's a lot of fonts.
>>
>> Using CompareStringOrdinal, with strlenW calls to get the actual 
>> lengths, instead adds ~50ms to the results above when prefix is not 
>> start, and ~15ms to the process execution time when prefix is already 
>> started.
>>
>> Of course the results depends on how many system fonts are installed, 
>> and I'm testing it with the debian fonts-noto package which brings a 
>> lot, but I don't think it's so unusual (I didn't even install it for 
>> the test, for some reason I've got it installed for a while).
> 
> Well nevermind, it looks like that RtlCompareUnicodeStrings should 
> support -1 length and stop the comparison on first EOS, according to:
> 
>    https://testbot.winehq.org/JobDetails.pl?Key=82338

Or not, it just compares lengths... so what I initially said.
-- 
Rémi Bernon <rbernon at codeweavers.com>