From a C++/JS benchmark

[bearophile]

Trass3r:

> > are you willing and able to show me the asm before it gets assembled?  
> > (with gcc you do it with the -S switch). (I also suggest to use only the  
> > C standard library, with time() and printf() to produce a smaller asm  
> > output: http://codepad.org/12EUo16J ).

You are a person of few words :-) Thank you for the asm.

Apparently the program was not compiled in release mode (or with nobounds. With DMD it's the same thing, maybe with gdc it's not the same thing). It contains the calls, but they aren't to the next line, they were for the array bounds:

    call    _d_assert
    call    _d_array_bounds
    call    _d_array_bounds
    call    _d_assert_msg
    call    _d_array_bounds
    call    _d_array_bounds
    call    _d_array_bounds
    call    _d_array_bounds
    call    _d_array_bounds
    call    _d_array_bounds
	call	_d_assert_msg

But I think this doesn't fully explain the low performance, I have seen too many instructions like:

	movss	DWORD PTR [rsp+32], xmm1
	movss	DWORD PTR [rsp+16], xmm2
	movss	DWORD PTR [rsp+48], xmm3

If you want to go on with this exploration, then I suggest you to find a way to disable bound tests.

Bye,
bearophile