1 files changed, 47 insertions, 0 deletions
diff --git a/tests/codegen/intrinsics/three_way_compare.rs b/tests/codegen/intrinsics/three_way_compare.rs
new file mode 100644
index 00000000000..f3b631abc22
--- /dev/null
+++ b/tests/codegen/intrinsics/three_way_compare.rs
@@ -0,0 +1,47 @@
+//@ revisions: DEBUG OPTIM
+//@ [DEBUG] compile-flags: -C opt-level=0
+//@ [OPTIM] compile-flags: -C opt-level=3
+//@ compile-flags: -C no-prepopulate-passes
+
+#![crate_type = "lib"]
+#![feature(core_intrinsics)]
+
+use std::intrinsics::three_way_compare;
+
+#[no_mangle]
+// CHECK-LABEL: @signed_cmp
+// DEBUG-SAME: (i16 %a, i16 %b)
+// OPTIM-SAME: (i16 noundef %a, i16 noundef %b)
+pub fn signed_cmp(a: i16, b: i16) -> std::cmp::Ordering {
+    // DEBUG: %[[GT:.+]] = icmp sgt i16 %a, %b
+    // DEBUG: %[[ZGT:.+]] = zext i1 %[[GT]] to i8
+    // DEBUG: %[[LT:.+]] = icmp slt i16 %a, %b
+    // DEBUG: %[[ZLT:.+]] = zext i1 %[[LT]] to i8
+    // DEBUG: %[[R:.+]] = sub nsw i8 %[[ZGT]], %[[ZLT]]
+
+    // OPTIM: %[[LT:.+]] = icmp slt i16 %a, %b
+    // OPTIM: %[[NE:.+]] = icmp ne i16 %a, %b
+    // OPTIM: %[[CGE:.+]] = select i1 %[[NE]], i8 1, i8 0
+    // OPTIM: %[[CGEL:.+]] = select i1 %[[LT]], i8 -1, i8 %[[CGE]]
+    // OPTIM: ret i8 %[[CGEL]]
+    three_way_compare(a, b)
+}
+
+#[no_mangle]
+// CHECK-LABEL: @unsigned_cmp
+// DEBUG-SAME: (i16 %a, i16 %b)
+// OPTIM-SAME: (i16 noundef %a, i16 noundef %b)
+pub fn unsigned_cmp(a: u16, b: u16) -> std::cmp::Ordering {
+    // DEBUG: %[[GT:.+]] = icmp ugt i16 %a, %b
+    // DEBUG: %[[ZGT:.+]] = zext i1 %[[GT]] to i8
+    // DEBUG: %[[LT:.+]] = icmp ult i16 %a, %b
+    // DEBUG: %[[ZLT:.+]] = zext i1 %[[LT]] to i8
+    // DEBUG: %[[R:.+]] = sub nsw i8 %[[ZGT]], %[[ZLT]]
+
+    // OPTIM: %[[LT:.+]] = icmp ult i16 %a, %b
+    // OPTIM: %[[NE:.+]] = icmp ne i16 %a, %b
+    // OPTIM: %[[CGE:.+]] = select i1 %[[NE]], i8 1, i8 0
+    // OPTIM: %[[CGEL:.+]] = select i1 %[[LT]], i8 -1, i8 %[[CGE]]
+    // OPTIM: ret i8 %[[CGEL]]
+    three_way_compare(a, b)
+}