Inlining Code Test

[Nick Voronin]

I found this on bugzilla.
http://d.puremagic.com/issues/show_bug.cgi?id=2278

So it's not really a bug. Yet there is no simple workaround. And gap  
between int and double looks strange when stack frame itself is unaligned.

btw, is there no explicit alignment for variables in D at all?
align(8) double d; compiles if d is global, but it does nothing.

import core.stdc.stdio: printf;

align(8) int a;
align(8) double d;

void main() {
     printf("%u %u\n", (cast(size_t)&a) % 8, (cast(size_t)&d) % 8);
}

This _always_ prints "4 4" for me. It seems that globals are not affected  
by environment, but not aligned anyway.

Honestly, I'm lost :) It all works not as expected but then again I can't  
find any evidences that my expectations are valid.

On Sat, 18 Dec 2010 01:57:44 +0300, bearophile <bearophileHUGS at lycos.com>  
wrote:

> Nick Voronin:
>
>> Looks like alignment of local variables is somewhat broken.
>
> This is a very nice bug. If not already present then please add it to  
> Bugzilla. If you don't want to add it, then I will add it myself. I have  
> modified your code like this:
>
> import core.stdc.stdio: printf;
> void main() {
>     int a;
>     double d;
>     printf("%u %u\n", (cast(size_t)&a) % 8, (cast(size_t)&d) % 8);
> }
>
> And this shows the performance difference:
>
> import core.stdc.stdio: printf;
> import std.date: getUTCtime, ticksPerSecond;
> void main() {
>     double d = 0.0;
>     auto t0 = getUTCtime();
>     for (size_t i = 0; i < 100_000_000; i++)
>         d += 1;
>     auto t1 = getUTCtime();
>     printf("%lf\n", d);
>     printf("%u\n", (cast(size_t)&d) % 8);
>     printf("%lf\n", (cast(double)t1 - cast(double)t0) / ticksPerSecond);
> }
>
> Bye,
> bearophile


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