dmd codegen improvements

[Vladimir Panteleev via Digitalmars-d]

On Tuesday, 18 August 2015 at 21:31:17 UTC, Walter Bright wrote:
> On 8/18/2015 1:24 PM, Vladimir Panteleev wrote:
>> The specific bugs in question have
>> been fixed, but that doesn't change the general problem.
>
> The reason we have regression tests is to make sure things that 
> are fixed stay fixed. Codegen bugs also always had the highest 
> priority.

It doesn't matter. Regression tests protect against the same bugs 
reappearing, not new bugs. I'm talking about the general pattern: 
optimization PR? Regression a few months later.

> Being paralyzed by fear of introducing new bugs is not a way 
> forward with any project.

When the risk outweighs the gain, what's the point of moving 
forward?

> (Switching to ddmd, and eventually put the back end in D, will 
> also help with this. DMC++ is always built with any changes and 
> tested to exactly duplicate itself, and that filters out a lot 
> of problems. Unfortunately, DMC++ is a 32 bit program and 
> doesn't exercise the 64 bit code gen. Again, ddmd will fix 
> that.)

I don't see how switching to D is going to magically reduce the 
number of regressions.