dmd codegen improvements

[Vladimir Panteleev via Digitalmars-d]

On Tuesday, 18 August 2015 at 20:24:31 UTC, Vladimir Panteleev 
wrote:
> On Tuesday, 18 August 2015 at 19:02:20 UTC, Walter Bright wrote:
>> On 8/18/2015 5:37 AM, Vladimir Panteleev wrote:
>>> IIRC, I have had three releases affected by 
>>> optimization/inlining DMD bugs (two
>>> of Digger and one of RABCDAsm). These do not speak well for D 
>>> when end-users ask
>>> me what the cause of the bug is, and I have to say "Yeah, 
>>> it's a bug in the
>>> official D compiler".
>>
>> Are they filed in bugzilla?
>
> Yep, just search for wrong-code regressions. The specific bugs 
> in question have been fixed, but that doesn't change the 
> general problem.

I would like to add that fixing the regression does not make it 
go away. Even though it's fixed in git, and even after the fix 
ships with a new DMD release, there is still a D version out 
there that has the bug, and that will never change until the end 
of time. The consequence of this is that affected programs cannot 
be built with certain versions of DMD (e.g. RABCDAsm's build tool 
checks for the compiler bug and asks users to use another 
compiler version or disable optimizations). This affects users 
who get DMD by some other means than downloading it from 
dlang.org themselves, e.g. via their OS package repository 
(especially LTS OS release users).

Fixing regressions is not enough. We need to try harder to 
prevent them from ending up in DMD releases at all.