one of the reasons I rarely read press releases is that I don't believe in promises -- I believe in _incentives_. In this case, what will Qualcomm be incentivized to do? What are in their interests?
indeed, open sourcing is only half (or even less) of the picture: who is driving the open source community and how it is driven (i.e. governing structure) are probably more important IMHO. There are countless of cases where an open source project is either killed by slow death, or dictated by a single entity. Chris's previous projects like LLVM and MLIR are fortunate enough to grow and thrive organically, and that takes years if not decades to cultivate
> In the end, programs will want probably to stay conservative and will implement only the core ISA
Unlikely, as pointed out in sibling comments the core ISA is too limited. What might prevail is profiles, specifically profiles for application processors like RVA22U64 and RVA23U64, which the latter one makes a lot more sense IMHO.
The article is easy to follow but I think the author missed the e point: branchless programming (a subset of the more known constant time programming) is almost exclusively used in cryptography only nowadays. As shown by the benchmarks in the article, modern branch predictors can easily achieve over 95% if not 99% precision since like a decade ago
yes, the short answer is LLVM uses RegPressureTracker (https://llvm.org/doxygen/classllvm_1_1RegPressureTracker.htm...) to do all those calculations. Slightly longer answer: I should probably be a little more specific that in most cases, Machine Scheduler cares more about register pressure _delta_ caused by a single instruction, either traverses from bottom-up or top-down. In which case it's easier to make an estimation when some of other instructions are not scheduled yet.