> There are theoretical benefits, but in practice, LLVM does pretty well with it's current scheme.
I think having a decoupled spilling phase is nice feature of the SSA-based scheme. However, I don't say that LLVM (or GCC) should switch to the SSA-based scheme. I just appreciate that the Go compiler switched to the SSA-based scheme, because it may bring some new insights to the research community.
SSA is not a pre-req to a decoupled spilling phase :)
In fact, the guy who wrote LLVM's current register allocation did his thesis on decoupled SSA register allocation - http://www.theses.fr/2012ENSL0777
But he still decided not to go that way in LLVM when decoupling regalloc from spilling.
"because it may bring some new insights to the research community."
No offense, but this seems pretty unlikely. It's been 10 years and the number of production optimizing compilers that use SSA based regalloc (for example) is still hovering close to 0.
Sad (because i helped fund a ton of that research), but true.
The same thing is sadly true of libfirm. While a really impressive piece of work, it hasn't spurred much that i can see ...
I think having a decoupled spilling phase is nice feature of the SSA-based scheme. However, I don't say that LLVM (or GCC) should switch to the SSA-based scheme. I just appreciate that the Go compiler switched to the SSA-based scheme, because it may bring some new insights to the research community.