Re: dmd codegen improvements

[deadalnix via Digitalmars-d]

On Wednesday, 19 August 2015 at 09:26:43 UTC, Ola Fosheim Grøstad 
wrote:
On Wednesday, 19 August 2015 at 08:22:58 UTC, Dmitry Olshansky 
wrote:
Also DMD's backend strives to stay fast _and_ generate fine 
machine code. Getting within 10% of GCC/LLVM and being fast is 
IMHO both possible and should be done.

But if iOS/OS-X and others are essentially requiring an 
LLVM-like IR as the object code format then it makes most sense 
to have LLVM as the default backend. If WebAsm et al is 
focusing on mimicing LLVM, then D's backend have to do the 
same. And that is not unlikely giving PNACL being LLVM based. 
Intel is also supportive of LLVM…


Apple is invested in LLVM. For other thing you mention, 
WebAssembly is an AST representation, which is both dumb and do 
not look like anything like LLVM IR.

Replicating a scalar SSA like LLVM does not make a lot of 
sense. What would make a lot of sense would be to start work on 
an experimental SIMD SSA implemented in D that could leverage 
benefits for next gen x86 SIMD and make Phobos target it. That 
could attract new people to D and make D beat LLVM. You could 
even combine LLVM and your own SIMD backend (run both, then 
profile and pick the best code in production on a 
function-by-function base)


WAT ?

Or a high level compile-time oriented IR for D that can boost 
templates semantics and compilation speed.


That's impossible in the state of template right now (I know I've 
been there and dropped it as the return on investement was too 
low).