Re: Align a variable on the stack.

[TheFlyingFiddle via Digitalmars-d-learn]

On Thursday, 5 November 2015 at 21:24:03 UTC, TheFlyingFiddle 
wrote:
On Thursday, 5 November 2015 at 21:22:18 UTC, TheFlyingFiddle 
wrote:
On Thursday, 5 November 2015 at 11:14:50 UTC, Marc Schütz 
wrote:
~10x slowdown...

I forgot to mention this but I am using DMD 2.069.0-rc2 for x86 
windows.

I reduced it further:

struct A { float x, y, z ,w; }
struct B
{
   float x=float.nan;
   float y=float.nan;
   float z=float.nan;
   float w=float.nan;
}

void initVal(T)(ref T t, ref float k) { pragma(inline, false); }

void benchA()
{
   foreach(float f; 0 .. 1000_000)
   {
      A val = A.init;
      initVal(val, f);
   }
}

void benchB()
{
   foreach(float f; 0 .. 1000_000)
   {
      B val = B.init;
      initVal(val, f);
   }
}

int main(string[] argv)
{
   import std.datetime;
   import std.stdio;

   auto res = benchmark!(benchA, benchB)(1);
   writeln("Default:  ", res[0]);
   writeln("Explicit: ", res[1]);

   readln;
   return 0;
}

also i am using dmd -release -boundcheck=off -inline

The pragma(inline, false) is there to prevent it from removing 
the assignment in the loop.