[gngeal]

One thing that for years made Fortran stand out is that the language explicitly assumes all arrays passed in to a subprogram have no overlaps.

There's a HUGE number of languages that don't allow aliasing in this way. I wasn't thinking about "how to improve C", I had APL, J, K, Q etc. in mind, as well as languages that implement mass array processing with similar semantics in terms of a more conventional syntax.

[dmlorenzetti]

Fundamentally I agree with you. In my original comment, I was just trying to give a historical view of why people took the view that "optimizing Fortran compilers are hard to beat," rather than to defend it.

Personally, I think that idea is hard to justify these days, especially when, in my experience, finding 20-30% speed differences between optimizing Fortran compilers isn't all that hard.