llvm dev - Oct 2011 - [LLVMdev] LLVM Language Reference Strictness

> For the level of specificity you're looking for, just the source code
itself. The LLVM IR language documentation is not, and isn't intended to be,
a true language standard document in the same way that the C or C++ standards
are. For any given case, check the docs first, and if your question isn't
answered there, check the source code of the target(s) you're interested in.
And once you've understood, submit a doc patch explaining it :)

Ciao, Duncan.

On 10/20/2011 07:42 AM, Duncan Sands wrote:
>> For the level of specificity you're looking for, just the source
code itself. The LLVM IR language documentation is not, and isn't intended
to be, a true language standard document in the same way that the C or C++
standards are. For any given case, check the docs first, and if your question
isn't answered there, check the source code of the target(s) you're
interested in.
> And once you've understood, submit a doc patch explaining it :)
>
> Ciao, Duncan.
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> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
I'm in the process of writing a formal spec for LLVM IR.

I have a lot of the grammar done and a tool for checking the grammar for 
completeness
and generating cross reference and such. I'm using a nice extended 
regular expression form of BNF.

My intent is to open source it at google code when it's done but if 
other people want to help me with this project I could do that now.

About 80% of it is done.

I have documented it mostly from reading the source code.

Beyond just using the grammar to document things I have some tools in 
mind later for specifying various optimizations using grammatical 
transformations that are then translated in C++ code for LLVM.

I think also that I could replace the adhoc parser in LLVM with 
something better once we have a clean grammar for it using a parser 
generator tool.

My little tool can be expanded to be a parser generator tool. I've 
written regular expression YACC type equivalents and can do any of those 
type. I probably will do a special one for this project because YACC is 
a dinosaur and some of the newer ones are not exactly what I want either.

I would like to see the many adhoc parsers in LLVM get replaced by ones 
generated from grammars.

Reed

Reed,

On Oct 20, 2011, at 9:47 AM, Reed Kotler wrote:
> I would like to see the many adhoc parsers in LLVM get replaced by ones 
> generated from grammars.

FYI, this is very unlikely to happen.  The parsers in LLVM were historically
generated from grammars (bison, as I recall), and those implementations were
removed in favor of hand-written implementations both because the latter were
significantly easier to maintain, and because they were much better suited to
offer reasonable diagnostics.  Any plan to reverse that decisions is likely to
meet a lot of resistance.

--Owen
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