[llvm-dev] anyone want to help tune up computeKnownBits()?

[John Regehr via llvm-dev]

I've posted a new version of these results:

   http://www.cs.utah.edu/~regehr/souper-known-bits-sep-2015-2.txt

relative to the previous version this one:

- doesn't exploit undefined behaviors

- has known bit constraints on the expressions' inputs, when available

- uses r246940

This is one of my favorites:

%0:i32 = var (xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx0)
%1:i64 = zext %0
%2:i64 = shl 1:i64, %1
infer %2

known from Souper: 
0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x0x
known from compiler: 
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

John