Add a test case to show isKnownNonZero() returns correctly; NFC

Summary:
Added a test case just to make sure that isKnownNonZero() returns false
when we cannot guarantee that a ConstantExpr is a non-zero constant.

Reviewers: sanjoy, majnemer, mcrosier, nlewycky

Subscribers: nlewycky, mssimpso, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D16908

llvm-svn: 260544

diff --git a/llvm/test/Transforms/InstSimplify/compare.ll b/llvm/test/Transforms/InstSimplify/compare.ll
index 356019f..8c9997f 100644 (file)
--- a/llvm/test/Transforms/InstSimplify/compare.ll
+++ b/llvm/test/Transforms/InstSimplify/compare.ll
@@ -333,6 +333,21 @@ define i1 @or(i32 %x) {
 ; CHECK: ret i1 false
 }
 
+; Do not simplify if we cannot guarantee that the ConstantExpr is a non-zero
+; constant.
+@GV = common global i32* null
+define i1 @or_constexp(i32 %x) {
+; CHECK-LABEL: @or_constexp(
+entry:
+  %0 = and i32 ptrtoint (i32** @GV to i32), 32
+  %o = or i32 %x, %0
+  %c = icmp eq i32 %o, 0
+  ret i1 %c
+; CHECK: or
+; CHECK-NEXT: icmp eq
+; CHECK-NOT: ret i1 false
+}
+
 define i1 @shl1(i32 %x) {
 ; CHECK-LABEL: @shl1(
   %s = shl i32 1, %x