> ... avoid relying on a non-deterministic compiler optimization doesn't decrease readability. It is extremely naive to assume that a heuristic-guided ... This

> ... avoid relying on a non-deterministic compiler optimization doesn't decrease readability. It is extremely naive to assume that a heuristic-guided ... This is a post about crawling the compiler IR to find things the compiler missed so that the programmer can change their code to work around the compiler. Even if the crawl-the-IR is a heuristic, moving that into the compiler would mean exactly the cases that were reported are now fixed automatically. Non-deterministic compilers are broken. Arguably by definition, but also by heuristic as a non-deterministic compiler is enough of a nightmare to debug and fix that it can be expected to grow more errors over time. Heuristic compilers are very much a thing. Also sadly fragile optimisations are a thing, where minor changes to the application take it over some threshold and the change in output is larger than anticipated. However, the plan of attack of "change the program until the compiler did what you hoped for" is itself a heuristic that future changes to program and compiler may upset. An alternative is to patch the compiler to do the right thing, and add a regression test to the compiler so that it will continue to do the right thing. That has better engineering properties in the large.