llvm dev - Sep 2016 - Mark code from source to IR

Hi everyone,

I am looking at a way to mark part of a source code for an optimisation pass (or
how to transfert information from source code to IR).

I want to work on C / C++ / Objective-c and Swift.

Something like:

...
//Begin Optimisation 
if(i % 2){
	printf(“Something”);
}
//End Optimisation

for(int i = 0; i < 10; ++i){
	printf("%d, “, i);
}
printf("\n”);
…

I have found several informations here:
http://clang-analyzer.llvm.org/annotations.html
<http://clang-analyzer.llvm.org/annotations.html>. I was thinking about
using #pragma or annotate attribute but this is not working on Swift.

Does anyone has an hint to begin with?

Greetings,

Johan


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Hi,

I am looking at a way to mark part of a source code for an
optimisation
> pass (or how to transfert information from source code to IR).
>
Does it have to be comments, or could you do something like this?

if (optimize_me(i%2)) {
  ...
}

You could look at how __builtin_expect is handled inside the compiler. In
lib/Transforms/Scalar/LowerExpectIntrinsic.cpp, branch weight metadata is
generated based on that function. You could probably adapt this to generate
the metadata that you need.

Best,
Jonas
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Hi Jonas,
> Does it have to be comments, or could you do something like this?
Not at all, it was just an example, it can pragma or builtin function or
anything else.
> You could look at how __builtin_expect is handled inside the compiler. In
lib/Transforms/Scalar/LowerExpectIntrinsic.cpp, branch weight metadata is
generated based on that function. You could probably adapt this to generate the
metadata that you need.
I will take a look at it thanks.

Greetings.

Johan
> On 23 Sep 2016, at 11:52, Jonas Wagner <jonas.wagner at epfl.ch>
wrote:
> 
> Hi,
> 
> I am looking at a way to mark part of a source code for an optimisation
pass (or how to transfert information from source code to IR).
> 
> Does it have to be comments, or could you do something like this?
> 
> if (optimize_me(i%2)) {
>   ...
> }
> 
> You could look at how __builtin_expect is handled inside the compiler. In
lib/Transforms/Scalar/LowerExpectIntrinsic.cpp, branch weight metadata is
generated based on that function. You could probably adapt this to generate the
metadata that you need.
> 
> Best,
> Jonas
> 
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