Teach ScalarEvolution to recognize x^-1 in the case where non-demanded

bits have been stripped out by instcombine.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72010 91177308-0d34-0410-b5e6-96231b3b80d8

test/Analysis/ScalarEvolution/and-xor.ll

@@ -0,0 +1,8 @@
+; RUN: llvm-as < %s | opt -scalar-evolution -analyze -disable-output \
+; RUN:   | grep {\\-->  (zext} | count 2
+
+define i32 @foo(i32 %x) {
+  %n = and i32 %x, 255
+  %y = xor i32 %n, 255
+  ret i32 %y
+}