A significant issue is that compiler "optimizations" aren't gaining a lot of general benefit anymore, and yet they are imposing a very significant cost on many people.
Lots of people still are working on C/C++ compiler optimizations, but nobody is asking if that is worthwhile to end users anymore.
Data suggests that it is not.
Compiler writers measure an "optimization" as successful if they can find any example where the "optimization" saves time. Does this matter for the overall user experience? The typical debate runs as follows:
In 2000, Todd A. Proebsting introduced "Proebsting's Law: Compiler Advances Double Computing Power Every 18 Years" (emphasis in original) and concluded that "compiler optimization work makes only marginal contributions". Proebsting commented later that "The law probably would have gone unnoticed had it not been for the protests by those receiving funds to do compiler optimization research."
Arseny Kapoulkine ran various benchmarks in 2022 and concluded that the gains were even smaller: "LLVM 11 tends to take 2x longer to compile code with optimizations, and as a result produces code that runs 10-20% faster (with occasional outliers in either direction), compared to LLVM 2.7 which is more than 10 years old."
Compiler writers typically respond with arguments like this: "10-20% is gazillions of dollars of computer time saved! What a triumph from a decade of work!"
I suspect most programmers would happily give up 10% performance on their final program if they could halve their compile times.
> I suspect most programmers would happily give up 10% performance on their final program if they could halve their compile times.
10% at FAANG scale is around a billion dollars per year. There's a reason why FAANG continues to be the largest contributor by far to LLVM and GCC, and it's not because they're full of compiler engineers implementing optimizations for the fun of it.
And, yet, Google uses Go which is glop for performance (Google even withdrew a bunch of people from the C/C++ working groups). Apple funded Clang so they could get around the GPL with GCC and mostly care about LLVM rather than Clang. Amazon doesn't care much as their customers pay for CPU.
So, yeah, Facebook cares about performance and ... that's about it. Dunno about Netflix who are probably more concerned about bandwidth.
-O0 gives you what you are after.