Tree Borrows

> On the one hand, compilers would like to exploit the strong guarantees of the type system—particularly those pertaining to aliasing of pointers—in order to unlock powerful intraprocedural optimizations.

How true is this really?

Torvalds has argued for a long time that strict aliasing rules in C are more trouble than they're worth, I find his arguments compelling. Here's one of many examples: https://lore.kernel.org/all/CAHk-=wgq1DvgNVoodk7JKc6BuU1m9Un... (the entire thread worth reading if you find this sort of thing interesting)

Is Rust somehow fundamentally different? Based on limited experience, it seems not (at least, when unsafe is involved...).

Personally, I would like compilers to better exploit vectorization, which can get you 2x to 10x faster on random things within typical workloads, rather than worry about dubious optimizations that have performance improvements that may or may not be caused by changing the alignment of code and data blocks.

I would like to see more effort dedicated to basic one liners that show up in real code like counting how many of a given character are in a string. E.g. `for (str) |e| count += e == '%'`. For this, LLVM spits out a loop that wants to do horizontal addition every iteration on x86-64 targets with vectors, at least. Let's focus on issues that can easily net a 2x performance gain before going after that 1-2% that people think pointer aliasing gets you.