[llvm-dev] opt passes

[Anastasiya Ruzhanskaya via llvm-dev]

Great,
thank you for your help!

2017-07-05 17:06 GMT+02:00 Hal Finkel <hfinkel at anl.gov>:

>
> On 07/05/2017 09:58 AM, Anastasiya Ruzhanskaya wrote:
>
> Oh, yes...strange
> attributes #0 = { noinline nounwind optnone uwtable
> "correctly-rounded-divide-sqrt-fp-math"="false"
> "disable-tail-calls"="false" "less-precise-fpmad"="false"
> "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"
> "no-infs-fp-math"="false" "no-jump-tables"="false"
> "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false"
> "no-trapping-math"="false" "stack-protector-buffer-size"="8"
> "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
> "unsafe-fp-math"="false" "use-soft-float"="false" }
>
> How this can be avoided? it is always so after clang -s -emit-llvm
>
>
> This is because clang defaults to -O0, and in that mode, does not produce
> IR that is intended to be optimized. You probably want to do:
>
> clang -S -emit-llvm -O3 -mllvm -disable-llvm-optzns
>
> to get out the unoptimized IR.
>
>  -Hal
>
>
>
>
>
> 2017-07-05 16:49 GMT+02:00 Hal Finkel <hfinkel at anl.gov>:
>
>>
>> On 07/04/2017 04:25 AM, Anastasiya Ruzhanskaya via llvm-dev wrote:
>>
>> Hello,
>>  I am developing now a compiler, based on llvm infrastructure, so I am
>> building my own sequence of llvm passes with some adjustable options.
>>
>> I can't find really clear info about some cases, so maybe you can help,
>> and write:
>>
>> 0) Why I should always delete attributes before applying optimizations
>> with opt command? With attributes specified no optimization can be applied.
>>
>>
>> You definitely shouldn't delete attributes in general. Does your
>> attribute set include optnone?
>>
>>  -Hal
>>
>>
>> Where I can get real benefit from:
>> 1) Constant Hoisting
>> -only when we have some large reusable constants in program?
>> 2) argpomotion
>> - this option does not always replace all my args by reerence with
>> values, when I specify it.
>>
>>
>> _______________________________________________
>> LLVM Developers mailing listllvm-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>> --
>> Hal Finkel
>> Lead, Compiler Technology and Programming Languages
>> Leadership Computing Facility
>> Argonne National Laboratory
>>
>> --
> Hal Finkel
> Lead, Compiler Technology and Programming Languages
> Leadership Computing Facility
> Argonne National Laboratory
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170706/63c8045c/attachment.html>