Thanks Thomas - haven't run into any issues. There wasn't any measurable 
performance uplift when using -mtail-call though, which is probably because 
my workload (FFmpeg) may not use it much.  

That being said, I previously played around with the -menable-tail-call  
linker flag. And unlike -mtail-call, it does two things: firstly, it does 
produce a small (~1%), but consistent performance uplift. At the same time, 
it doesn't seem to make use of the new WebAssembly opcodes (didn't require 
me to enable those in V8). Not sure what -menable-tail-call actually does, 
but it seems different from -mtail-call. Also, it cannot be used as a 
compiler flag, ie. only the linker will accept it.

Any ideas?

Soeren

On Wednesday, November 24, 2021 at 10:57:46 AM UTC+10 [email protected] 
wrote:

> Hi Soeren,
>
> The compiler flag -mtail-call is what you want. This support has been in 
> upstream LLVM for a while, but it hasn't been used very much, so if you run 
> into bugs with it, please let us know!
>
> Best,
>
> Thomas
>
> On Tue, Nov 23, 2021 at 6:14 PM Soeren Balko <[email protected]> wrote:
>
>> I was wondering about the state of WebAssembly tail call support in 
>> Emscripten. It's available as an experimental V8 feature in Chrome and will 
>> hopefully be mainstreamed in the not-too distant future.
>>
>> Couldn't find much information on how to build with tail call support in 
>> Emscripten, but I suspect that adding the -menable-tail-call linker flag 
>> does the trick? Or is there more to it?
>>
>> @Alon - can you please confirm?
>>
>> Thank you!
>> Soeren
>>
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