Rename tests/codegen into tests/codegen-llvm

tests/codegen-llvm/step_by-overflow-checks.rs

@@ -0,0 +1,26 @@
+//@ compile-flags: -Copt-level=3
+
+#![crate_type = "lib"]
+
+use std::iter::StepBy;
+use std::slice::Iter;
+
+// The constructor for `StepBy` ensures we can never end up needing to do zero
+// checks on denominators, so check that the code isn't emitting panic paths.
+
+// CHECK-LABEL: @step_by_len_std
+#[no_mangle]
+pub fn step_by_len_std(x: &StepBy<Iter<i32>>) -> usize {
+    // CHECK-NOT: div_by_zero
+    // CHECK: udiv
+    // CHECK-NOT: div_by_zero
+    x.len()
+}
+
+// CHECK-LABEL: @step_by_len_naive
+#[no_mangle]
+pub fn step_by_len_naive(x: Iter<i32>, step_minus_one: usize) -> usize {
+    // CHECK: udiv
+    // CHECK: call{{.+}}div_by_zero
+    x.len() / (step_minus_one + 1)
+}