[LLVMdev] Question about Value Range Propagation

[John Criswell]

On 2/22/11 5:19 AM, Duncan Sands wrote:
> Hi Andrey,
>
>> On 21.02.2011 20:27, Douglas do Couto Teixeira wrote:
>>> My work is not part of the LLVM mainline yet. But I would be happy to
>>> contribute with the code of my range analysis implementation if it can help
>>> you in something else.
>> We were thinking of adding VRP to LLVM too, though we were mostly
>> interested in Patterson's approach (i.e. not connected with SSI form).  It
>> would be great if you can share the code nevertheless.
> the big problem with Patterson's VRP is that it is expensive in terms of
> compile time.  LLVM used to have some passes (ABCD, predsimplify) that did
> this kind of thing, but they were removed essentially because their compile
> time was too great for the goodness they brought.

I was under the impression that ABCD was removed because no one was 
maintaining and improving it.  Is my impression incorrect?

The SAFECode compiler adds additional run-time checks for array bounds 
checking.  If the ABCD code was working but just wasn't useful for 
regular C code, I'd like to know.  It may still have value for projects 
like SAFECode.

-- John T.

> Ciao, Duncan.
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