Conditional iolist_to_binary?

[Loïc Hoguin]

That was it, thanks. And more importantly thanks for the explanations!

Interesting...

On 27/12/2019 22:54, Dániel Szoboszlay wrote:
> Hi,
> 
> My guess the reason is that the iolist_to_binary(Value0) call compiles 
> into a call_ext, while the is_binary(Value0) to a test assembly 
> instruction. This means all live X registers have to be saved to the 
> heap (and restored later) in the first case. Inlining the is_binary 
> check can save you that (and a somewhat expensive external function 
> call) when Value0 is already a binary. But how much a difference this is 
> depends on how many live X registers you have at that point. Maybe try 
> compiling the actual module with erlc -S and compare the generated 
> assembly code with and without the if statement?
> 
> Cheers,
> Daniel
> 
> On Fri, 27 Dec 2019 at 11:07, Loïc Hoguin <essen@REDACTED 
> <mailto:essen@REDACTED>> wrote:
> 
>     Hello,
> 
>     I seem to be getting a small but noticeable performance improvement
>     when
>     I change the following:
> 
>     Value = iolist_to_binary(Value0)
> 
>     Into the following:
> 
>     Value = if
>           is_binary(Value0) -> Value0;
>           true -> iolist_to_binary(Value0)
>     end
> 
>     At least when the input data is mostly binaries. Anyone else seeing
>     this?
> 
>     The only difference between is_binary and iolist_to_binary seems to be
>     that is_binary calls is_binary/binary_bitsize on the same if expression
>     while iolist_to_binary has two if statements.
> 
>     What gives?
> 
>     Cheers,
> 
>     -- 
>     Loïc Hoguin
>     https://ninenines.eu
> 

-- 
Loïc Hoguin
https://ninenines.eu