Sanjay Patel
|
c0339c77ef
|
[InstCombine] Fold nuw left-shifts in `ugt`/`ule` comparisons.
This transforms
%a = shl nuw %x, c1
%b = icmp {ugt|ule} %a, c0
into
%b = icmp {ugt|ule} %x, (c0 >> c1)
z3:
(declare-const x (_ BitVec 64))
(declare-const c0 (_ BitVec 64))
(declare-const c1 (_ BitVec 64))
(push)
(assert (= x (bvlshr (bvshl x c1) c1))) ; nuw
(assert (not (= (bvugt (bvshl x c1) c0)
(bvugt x
(bvlshr c0 c1)))))
(check-sat)
(get-model)
(pop)
(push)
(assert (= x (bvlshr (bvshl x c1) c1))) ; nuw
(assert (not (= (bvule (bvshl x c1) c0)
(bvule x
(bvlshr c0 c1)))))
(check-sat)
(get-model)
(pop)
Patch by bryant!
Differential Revision: https://reviews.llvm.org/D25913
llvm-svn: 285729
|
2016-11-01 19:19:29 +00:00 |