[ValueTracking] Test for ephemeral issues llvm#128152. (NFC)

Author: andjo403

llvm/test/Transforms/InstSimplify/ctpop-pow2.ll

@@ -148,6 +148,19 @@ define <2 x i32> @ctpop_lshr_intmin_vec(<2 x i32> %x) {
   ret <2 x i32> %cnt
 }
 
+; todo do not remove the assume
+define i1 @issue128152(i32 %x) {
+; CHECK-LABEL: @issue128152(
+; CHECK-NEXT:    [[RES:%.*]] = icmp eq i32 [[X:%.*]], 0
+; CHECK-NEXT:    ret i1 [[RES]]
+;
+  %ctpop = call i32 @llvm.ctpop.i32(i32 %x)
+  %cond = icmp eq i32 %ctpop, 1
+  %ext = zext i1 %cond to i8
+  call void @llvm.assume(i1 %cond)
+  %res = icmp eq i32 %x, 0
+  ret i1 %res
+}
 
 define <2 x i32> @ctpop_lshr_intmin_intmin_plus1_vec(<2 x i32> %x) {
 ; CHECK-LABEL: @ctpop_lshr_intmin_intmin_plus1_vec(