Alive is a tool that can prove the correctness of InstCombine optimizations specified in a high-level language.
Alive requires Python 2.7.x and Z3 4.3.2 (or later), which can be obtained from https://github.com/Z3Prover/z3 (use the unstable branch)
./alive.py file.opt
The 'tests' directory has multiple examples of optimizations.
Please see this paper for more details about Alive:
http://www.cs.utah.edu/~regehr/papers/pldi15.pdf
Alive is also available online at: http://rise4fun.com/Alive
Alive will automatically generate benchmarks in SMT-LIB 2 format when the 'bench' directory exists and when python is run in non-optimized mode (the default). These benchmarks are over the bit-vector theory and may or may not have quantifiers.