dmd 1.053 and 2.037 release

[Don]

Walter Bright wrote:
> Don wrote:
>> Yeah. Actually the CPU problem is an accepts-invalid bug. It worked on 
>> my Pentium M, but it shouldn't have.
>> The problem is what DMD does to the "uninitialized assignments".
>>
>> float x;
>>
>> gets changed into
>>
>> float x = double.snan;
>>
>> and is implemented with
>> fld float.snan; fstp x;
>>
>> The FLD is triggering the snan. They should be changed into mov EAX, 
>> reinterpret_cast<int>(float.snan); mov x, EAX;
> 
> Sounds like a good idea.
> 
>> There's another reason for doing this. On Pentium 4, x87 NaNs are 
>> incredibly slow. More than 250 cycles!!! On AMD and on Pentium 4 SSE2, 
>> they are the same as any other value (about 0.5 cycles). Yet another 
>> reason to hate the P4. But still, this is such a horrific performance 
>> killer that we ought to avoid it.
> 
> I had no idea that was the case!

I only just discovered it. Every documentation I've seen just said 
"These [cycle count] values are for normal operands. NaNs, infinities, 
and denormals may increase cycle counts considerably." I found a blog of 
someone who'd actually measured it.