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Advanced Compilers: Self-Guided Online Course

cs.cornell.edu

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Re: Advanced Compilers: Self-Guided Online Course

#151

Post by malsirhc »

mcguire wrote: post #17

The course materials look good. But what is a "PhD level course"? All I've seen is undergrad and graduate, and the difference between masters and PhD has nothing to do with classes.

Cornell student here that's taken a bunch of classes at all of the levels - in my experience, undergraduate classes/master's classes are kind of taught with the expectation that you're taking the course as a requirement and are much more evaluation heavy, and that you're likely taking a full course load of other courses as well. PhD level courses are generally assumed to be the only course that you're taking that semester and that you're taking it more because the material will be useful for your research rather than for the credential, so there's much less emphasis on evaluation; i.e. a smaller quantity homeworks that each much harder than an undergraduate version of the same class, and final evaluations are much closer to reading recent research papers and understanding them rather than a timed exam.

Re: Advanced Compilers: Self-Guided Online Course

#152

Post by onei »

ohazi wrote: post #127
throwaway_pdp09 wrote: post #119

Earlier quoted context omitted.

Text -> parser -> AST -> job done. If it's any different in an IDE vs anything else I'd like to know how.

Your IDE parser will be unusable if it goes bananas while you're typing the characters needed to get from one fully, correctly parseable state to the next. It needs to be able to handle: printf("hello"); and also: prin and also: printf("He It also needs to be able to autocomplete function signatures that exist below the current line being edited, so the parser can't simply bail out as soon as it reaches the first inc…

Isn't that pretty standard for a parser? When was the last time a compiler bailed on the very first error it hit and refused to do anything else?

The solution is to pick synchronisation points to start parsing again, i.e. ; at the end of a statement or } at the end of a block.

Re: Advanced Compilers: Self-Guided Online Course

#153

Post by [deleted] »

ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

[deleted]

Re: Advanced Compilers: Self-Guided Online Course

#154

Post by nojvek »

I wish they’d be more courses on compilers that also serve as language servers. The current world is moving towards a phase where a language needs IDE tooling such as compilers, linters, formatters, REPL, language servers, debuggers and profilers.

Would love to see a high level course that covers how to build the tooling for a great developer experience.

Re: Advanced Compilers: Self-Guided Online Course

#155

Post by richardjennings »

mafribe wrote: post #126
ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

I understand the problem. I teach compilers at a big university. And I would love to hire graduates with compiler skills for my startup, but find it difficult. There are several structural problems that conspire to keep students from acquiring knowledge in low-level programming domain like compilation: a course needs to fit with the rest of the curriculum, and with student interest. I cannot get students interested i…

Is it at all possible that traditionally compilation is taught back to front? I am just a hobbyist, my CS degree did not include anything about compilation other than the theory of types of Grammar. I am the first to put my hand up and say I do not really know what I am talking about.

For me, compilers are interesting because of a. optimisations; at my level simple logic that is obviously advantageous to a CFG. b. interaction with the dependencies and operation of low level hardware; how does it REALLY work.

In the hobbyist pursuit of an understanding I have become belligerent to parsing. Parsing is interesting. But also not really. I would have benefited substantially from an abstract introduction via graphs, analysis and lowering. Both in terms of interest and fundamental understanding.

Re: Advanced Compilers: Self-Guided Online Course

#156

Post by fooker »

ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

> When do you use packrat parser vs LALR vs LL?

This is not something you can expects candidates to know.

Re: Advanced Compilers: Self-Guided Online Course

#157

Post by markus_zhang »

mafribe wrote: post #147
markus_zhang wrote: post #140

Earlier quoted context omitted.

Thanks. I'm actually very interested in lexing and parsing, because that's probably 99% of the stuff a layman-programmer gets to do with compiler theory in job. I mean not everyone gets chance to write the backend part, but parsing skill is almost used universally.

A fun exercise is writing a lexer generator or a parser generator. It's probably easier starting out with writing a lexer generator like Flex for your favourite language. I recommend using the Flex input format, than you can test your creation using Flex as a testing oracle! This is not something you can do in a weekend.

Thanks mafribe, looking forward to your future book (if there is one) :D

Re: Advanced Compilers: Self-Guided Online Course

#158

Post by WalterBright »

cinericius wrote: post #69
ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

Do you think it is the responsibility of academia to teach "industry relevant stuff"? I agree that courses generally don't teach judgement well, but I do think that it is the workplace/industry's responsbility to train their engineers and not expect fresh grads to be fully equipped to work on something that specific.

> Do you think it is the responsibility of academia to teach "industry relevant stuff"?

In college I learned a lot of math and how to do things like calculate stress and bending. I learned nothing about material finishes, material selection, fastener selection, tolerances, drafting, etc. But the latter was easy to pick up on the job, while learning mathematical analysis on the job just doesn't happen.

Re: Advanced Compilers: Self-Guided Online Course

#159

Post by mathattack »

bachmeier wrote: post #76
ibains wrote: post #59

I’ve worked on multiple compilers (optimizations expert) at MSFT on VS and CUDA and gave developed a DSL and worked on Database Compilers. I can’t hire compiler people with right skills. We’re building an IDE and those parsers are written differently, and we use Scala packrat parser combinators. These courses teach very little judgement or industry relevant stuff. When do you use packrat parser vs LALR vs LL? Good lu…

> I’d like to sit down all university professors who teach compiler courses and teach them a course on what’s relevant. I don't teach compiler courses, but I'm an academic, and I do keep in touch with industry people to find out what's important for my data analysis course. A couple of big problems with your proposal: 1. Time variation in "what industry wants". This year one thing's hot, the next year it's something…

My two cents - what’s useful for employers is giving students the confidence to jump into the code and figure it out. By this measure, what’s relevant for a compilers course isn’t the material itself. It’s that it’s structured to force the students to figure certain things for themselves.

There are college hires who need to be spoon fed, and college hires who just need mentorship and direction. Group two are invaluable.

Re: Advanced Compilers: Self-Guided Online Course

#160

Post by WalterBright »

Kranar wrote: post #149
WalterBright wrote: post #144

Earlier quoted context omitted.

Languages being context sensitive results from hacking in new language features. It's a constant struggle to keep D context free :-/

Strictly speaking, D is not context free nor is any statically typed programming language. That said most languages, including D, have supersets that are context free and can be used to build an AST which can then be refined further with context sensitive checks (ie. variables are used after declaration) and then even further with type checks. Many language tools don't need a full blown language parser and can get by…

I suppose we could argue about the definition of context free, but the compiler lexes it without any reference to the parser, and the parser builds the AST without any reference to symbols or semantic meaning.

> spell checking ... using context-free parsers

Only up to a point. D's spell checker uses the symbols in scope as its "dictionary". This means it is very good at guessing what you meant instead of what is typed, as the dictionary is very targeted. I.e. it uses the context, and the spell checker is part of the semantic pass.

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