This optimization reduces solve time (typically >90% of the
total) by about 78% when analysing real programs. It also
makes the solver 100% deterministic since all iterations are
ordered.
Also:
- remove unnecessary nodeid parameter to solve() method.
- don't add a fieldInfo for singleton tuples (cosmetic fix).
- inline+simplify "worklist" type.
- replace "constraintset" type by a slice.
LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://golang.org/cl/95240043
Alan Donovan