Re: Mixin in Inline Assembly

[Chris M via Digitalmars-d-learn]

On Tuesday, 10 January 2017 at 13:13:17 UTC, Basile B. wrote:
On Tuesday, 10 January 2017 at 11:38:43 UTC, Guillaume Piolat 
wrote:
On Tuesday, 10 January 2017 at 10:41:54 UTC, Basile B. wrote:

don't forget to flag

asm pure nothrow {}

otherwise it's slow.

Why?

It's an empirical observation. In september I tried to get why 
an inline asm function was slow. What happened was that I 
didn't mark the asm block as nothrow

https://forum.dlang.org/post/xznocpxtalpayvkrw...@forum.dlang.org

I opened an issue asking the specifications to explain that 
clearly.

Huh, that's really interesting, thanks for posting. I guess my 
other question would be how do I determine if a block of assembly 
is pure?

I also figured out moving *op1 directly into RAX, guess it makes 
sense that a 64-bit value would need a 64-bit register :)

private void rot(string ins)(int *op1, int op2)
{
    mixin("
    asm
    {
        mov RAX, op1;
        mov ECX, op2[EBP];" ~
        ins ~ " [RAX], CL;
    }
    ");
}