Re: Popularity of compiler tools, was LRgen

On Apr 6, 8:25 am, an...@mips.complang.tuwien.ac.at (Anton Ertl)
wrote:
> - Finally, many compiler writers seem to dislike tools (or maybe none
> of the tools are good enough or something).
>
> In particular, while I know of several tools for instruction
> selection using tree parsing, none of them seems to be widely-used;
> many compilers use hand-written instruction selectors, and of those
> where I have heard that they use generated tree-parsing instruction
> selectors, the generator was developed or extended in-house.
>
> One explanation I have heard is that the compiler writers don't like
> to make themselves dependent on a tool that may go away. OTOH, gcc
> reverted from using bison-generated parsers to hand-written ones (at
> least for C++ and C), and I very much doubt that the future of bison
> was the reason for that.
>
> Maybe some other posters can provide additional insights into the use
> or non-use of compiler tools and the reasons for this.


IMO there is not enough added value. Comparing writing parsing engine
from scratch vs. using off the shelf product I always prefer the
former. When chasing bugs it is much easier to find them in your own
code than being at the mercy of the tool owner. Next I find the whole
code generation idea ridiculous. I simply refuse to believe a code
generator can output a quality product. On large size grammar it can
easily generate huge methods that could overflow JVM method size (I
experienced with ANTLR). Then there limitations on what kind of
grammar a parser engine can accept, e.g. no left recursion, no
ambiguity, etc. This is totally inacceptible: a grammar is a
declarative specification of the language. Making a particular parser
engine happy does not warrant tinkering with it.


Within a wider perspective I feel a general failure of parser
technology to deliver a user friendly product. This is why we have
horrors of XML filling the void.

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