Revert r153423 as this is causing failures on our internal nightly testers.

Original commit message:
Use the new range metadata in computeMaskedBits and add a new optimization to
instruction simplify that lets us remove an and when loading a boolean value.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153452 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstSimplify/pr12251.ll

@@ -1,15 +0,0 @@
-; RUN: opt < %s -instsimplify -S | FileCheck %s
-
-define zeroext i1 @_Z3fooPb(i8* nocapture %x) {
-entry:
-  %a = load i8* %x, align 1, !range !0
-  %b = and i8 %a, 1
-  %tobool = icmp ne i8 %b, 0
-  ret i1 %tobool
-}
-
-; CHECK: %a = load i8* %x, align 1, !range !0
-; CHECK-NEXT: %tobool = icmp ne i8 %a, 0
-; CHECK-NEXT: ret i1 %tobool
-
-!0 = metadata !{i8 0, i8 2}