There are some "shoulds" related to aliasing I believe. Things the compiler can assume when compiling a rust program that it can't when compiling C, which should in theory let it generate more efficient code.
But last I heard Rust wasn't taking advantage of this due to issues with LLVM. The same benefits should also be achievable in C with pragmas.
> The same benefits should also be achievable in C with pragmas.
I don't know that any compiler provides a noalias-all pragma. I don't know that it would be very sane either since C very much defines pointers as aliasing by default. Plus you wouldn't have any way to revert this behaviour and mark pointers as aliasing.
> C very much defines pointers as aliasing by default.
This is actually a huge issue for the CRuby JIT which generates C from the VM bytecode. Alias analysis on the generated C code, which is full of indirection, is basically useless and severely restricts the possible optimizations.
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> Has anyone demonstrated that well-written Rust code should run faster than C
Should? No. Can? Yes. See Brian Cantrill’s http://dtrace.org/blogs/bmc/2018/09/28/the-relative-performa... or Cliff Biffle’s http://cliffle.com/p/dangerust/