[llvm] r322595 - Specify inline for isWhitespace in CommandLine.cpp

[Rui Ueyama via llvm-commits]

This change was made by a wrong assumption that
-DCMAKE_BUILD_TYPE=RelWithDebugInfo would produce the same executable as
-DCMAKE_BUILD_TYPE=Release modulo debug info. Turned out that's not true --
it at least disables some optimizations such as function inlining. This
change doesn't do any harm, but I'll revert it to avoid confusion.

On Mon, Jan 22, 2018 at 1:45 PM, Chandler Carruth <chandlerc at gmail.com>
wrote:

> Yeah, this really shouldn't be necessary and seems really questionable...
> I cannot imagine a way that LLVM requires this, and if it LLVM doesn't
> require this I wonder if we should just move to benchmarking a self-hosted
> LLD rather than worrying about the very detailed performance
> characteristics with MSCV-built LLD. This seems like a pretty glaring
> deficiency in the MSVC inliner that we're papering over.
>
> On Mon, Jan 22, 2018 at 9:57 AM David Blaikie <dblaikie at gmail.com> wrote:
>
>> Is this with a selfhost build? (ie: is clang failing to inline this
>> function where it should) - should we look into why the compiler is failing
>> to catch this case?
>>
>>
>> On Tue, Jan 16, 2018 at 12:53 PM Rui Ueyama via llvm-commits <
>> llvm-commits at lists.llvm.org> wrote:
>>
>>> Author: ruiu
>>> Date: Tue Jan 16 12:52:32 2018
>>> New Revision: 322595
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=322595&view=rev
>>> Log:
>>> Specify inline for isWhitespace in CommandLine.cpp
>>>
>>> Patch by Takuto Ikuta.
>>>
>>> In chromium's component build, there are many directive sections and
>>> commandline parsing takes much time.
>>> This patch is for speed up of lld in RelWithDebInfo build by forcing
>>> inline heavily called isWhitespace function.
>>>
>>> 10 times link perf stats of blink_core.dll changed like below.
>>>
>>> master:
>>> TotalSeconds: 9.8764878
>>> TotalSeconds: 10.1455242
>>> TotalSeconds: 10.075279
>>> TotalSeconds: 10.3397347
>>> TotalSeconds: 9.8361665
>>> TotalSeconds: 9.9544441
>>> TotalSeconds: 9.8960686
>>> TotalSeconds: 9.8877865
>>> TotalSeconds: 10.0551879
>>> TotalSeconds: 10.0492254
>>> Avg: 10.01159047
>>>
>>> with this patch:
>>> TotalSeconds: 8.8696762
>>> TotalSeconds: 9.1021585
>>> TotalSeconds: 9.0233893
>>> TotalSeconds: 9.1886175
>>> TotalSeconds: 9.156954
>>> TotalSeconds: 9.0978564
>>> TotalSeconds: 9.1316824
>>> TotalSeconds: 8.8354606
>>> TotalSeconds: 9.2549431
>>> TotalSeconds: 9.4473085
>>> Avg: 9.11080465
>>>
>>> Modified:
>>>     llvm/trunk/lib/Support/CommandLine.cpp
>>>
>>> Modified: llvm/trunk/lib/Support/CommandLine.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
>>> Support/CommandLine.cpp?rev=322595&r1=322594&r2=322595&view=diff
>>> ============================================================
>>> ==================
>>> --- llvm/trunk/lib/Support/CommandLine.cpp (original)
>>> +++ llvm/trunk/lib/Support/CommandLine.cpp Tue Jan 16 12:52:32 2018
>>> @@ -688,7 +688,7 @@ static bool EatsUnboundedNumberOfValues(
>>>           O->getNumOccurrencesFlag() == cl::OneOrMore;
>>>  }
>>>
>>> -static bool isWhitespace(char C) {
>>> +static inline bool isWhitespace(char C) {
>>>    return C == ' ' || C == '\t' || C == '\r' || C == '\n';
>>>  }
>>>
>>>
>>>
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>>>
>>
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