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by astrange 1467 days ago
You can read GCC Summit presentations for things like that. The register allocator is called IRA/LRA. It used to have a ball of mud called reload that isn’t worth understanding because it doesn’t make much sense.

GCC’s code style is strange because the original authors wanted to make it look like Lisp for some reason.
2 comments
touisteur 1467 days ago
Err I always thought it looked strange because it was in C with classes before or after some holy war.

While gcc (and in general compiler) plugins are some of the most interesting tech enablers (be it for fuzzing,, static analysis, or runtime checks injection) 'People competently maintaining gcc plugins' (a sect I'm not a part anymore, thank dog) are amongst the most patient, devoted, unsung angels of this world.

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astrange 1467 days ago
It’s in C++ now. The weird spacing and functions ending in _p are Lispisms.

It’s also garbage collected so it’s still not “normal” C++ but neither is LLVM.

Not sure about the plugin API, but C++ is basically impossible to use with plugins because it’s so hard to keep ABI contracts, so it might not have changed.

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touisteur 1467 days ago
Well you basically have to compile the plugins against your gcc's headers anyway, and they're gpl by default (same as wireshark dissectors iirc). No the pain is all the churn on gcc internals and in plugin APIs over the years. You basically become an ifdef monkey and end up testing myriads of gcc versions...
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UncleEntity 1467 days ago
Isn’t the compiler the one who makes the ABI contract?

And I’ve seen _p and friends all over the place usually to differentiate between a pointer and, umm, not pointer. I thought it was a C++ism to be honest.

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astrange 1467 days ago
C++ has things like the fragile base class problem meaning you can accidentally break it easily. There's issues with throwing exceptions across different libraries on some platforms (maybe just Windows?) but I forget the reason why.

p is short for predicate.

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pjmlp 1467 days ago
Fragile base class problem affects all languages that offer some kind of inheritance, not only C++.
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valleyer 1467 days ago
You are of course correct in a broad sense.

However, when the discussion already mentions "ABI contracts", they're probably referring specifically to the "fragile binary interface problem" (especially regarding member field access), which does not affect all languages that offer inheritance.

As the Wikipedia article mentions, this more specific problem is (confusingly) often referred to just as the "fragile base class problem".

https://en.wikipedia.org/wiki/Fragile_binary_interface_probl...

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iib 1467 days ago
Maybe the lispism are Stallman's legacy. He is a great lisp proponent after all.
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