This function accounts for 2% of "godoc -analysis=pointer"
and this change makes it twice as fast---and simpler.
Added test and benchmark.
Change-Id: I8578fa42dce34df057d81f6c522a7b4e0506d09d
Reviewed-on: https://go-review.googlesource.com/15211
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
intsets.Sparse is a sparse bit vector. It uses space proportional
to the number of elements, not the maximum element (as is the case for a dense bit vector).
A forthcoming CL will make use of it in go/pointer, where it reduces
solve time by 78%. A similar representation is used for Andersen's
analysis in gcc and LLVM.
+ Tests.
LGTM=sameer, crawshaw, gri
R=gri
CC=crawshaw, golang-codereviews, sameer
https://golang.org/cl/10837043