[sledge] Memoize reg to var translation
[sledge] Memoize reg to var translation

Summary:
Memoize the translation from program registers to logical
variables. Currently this is not significant, but is semantically
necessary for the concurrency analysis.

Differential Revision: D29441162

fbshipit-source-id: ff674c4c3

facebook/infer,jvillard/infer,jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer