1 files changed, 90 insertions, 0 deletions
diff --git a/tests/codegen-llvm/slice-ref-equality.rs b/tests/codegen-llvm/slice-ref-equality.rs
new file mode 100644
index 00000000000..2940378da3c
--- /dev/null
+++ b/tests/codegen-llvm/slice-ref-equality.rs
@@ -0,0 +1,90 @@
+//@ compile-flags: -Copt-level=3 -Zmerge-functions=disabled
+#![crate_type = "lib"]
+
+use std::num::NonZero;
+
+// #71602 reported a simple array comparison just generating a loop.
+// This was originally fixed by ensuring it generates a single bcmp,
+// but we now generate it as a load+icmp instead. `is_zero_slice` was
+// tweaked to still test the case of comparison against a slice,
+// and `is_zero_array` tests the new array-specific behaviour.
+// The optimization was then extended to short slice-to-array comparisons,
+// so the first test here now has a long slice to still get the bcmp.
+
+// CHECK-LABEL: @is_zero_slice_long
+#[no_mangle]
+pub fn is_zero_slice_long(data: &[u8; 456]) -> bool {
+    // CHECK: %[[BCMP:.+]] = tail call i32 @{{bcmp|memcmp}}({{.+}})
+    // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[BCMP]], 0
+    // CHECK-NEXT: ret i1 %[[EQ]]
+    &data[..] == [0; 456]
+}
+
+// CHECK-LABEL: @is_zero_slice_short
+#[no_mangle]
+pub fn is_zero_slice_short(data: &[u8; 4]) -> bool {
+    // CHECK: %[[LOAD:.+]] = load i32, ptr %{{.+}}, align 1
+    // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[LOAD]], 0
+    // CHECK-NEXT: ret i1 %[[EQ]]
+    &data[..] == [0; 4]
+}
+
+// CHECK-LABEL: @is_zero_array
+#[no_mangle]
+pub fn is_zero_array(data: &[u8; 4]) -> bool {
+    // CHECK: %[[LOAD:.+]] = load i32, ptr %{{.+}}, align 1
+    // CHECK-NEXT: %[[EQ:.+]] = icmp eq i32 %[[LOAD]], 0
+    // CHECK-NEXT: ret i1 %[[EQ]]
+    *data == [0; 4]
+}
+
+// The following test the extra specializations to make sure that slice
+// equality for non-byte types also just emit a `bcmp`, not a loop.
+
+// CHECK-LABEL: @eq_slice_of_nested_u8(
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
+#[no_mangle]
+fn eq_slice_of_nested_u8(x: &[[u8; 3]], y: &[[u8; 3]]) -> bool {
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = mul nuw nsw [[USIZE]] {{%x.1|%y.1}}, 3
+    // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
+    // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
+    x == y
+}
+
+// CHECK-LABEL: @eq_slice_of_i32(
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
+#[no_mangle]
+fn eq_slice_of_i32(x: &[i32], y: &[i32]) -> bool {
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = shl nuw nsw [[USIZE]] {{%x.1|%y.1}}, 2
+    // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
+    // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
+    x == y
+}
+
+// CHECK-LABEL: @eq_slice_of_nonzero(
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
+#[no_mangle]
+fn eq_slice_of_nonzero(x: &[NonZero<i32>], y: &[NonZero<i32>]) -> bool {
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = shl nuw nsw [[USIZE]] {{%x.1|%y.1}}, 2
+    // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
+    // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
+    x == y
+}
+
+// CHECK-LABEL: @eq_slice_of_option_of_nonzero(
+// CHECK-SAME: [[USIZE:i16|i32|i64]] noundef %x.1
+// CHECK-SAME: [[USIZE]] noundef %y.1
+#[no_mangle]
+fn eq_slice_of_option_of_nonzero(x: &[Option<NonZero<i16>>], y: &[Option<NonZero<i16>>]) -> bool {
+    // CHECK: icmp eq [[USIZE]] %x.1, %y.1
+    // CHECK: %[[BYTES:.+]] = shl nuw nsw [[USIZE]] {{%x.1|%y.1}}, 1
+    // CHECK: tail call{{( noundef)?}} i32 @{{bcmp|memcmp}}(ptr
+    // CHECK-SAME: , [[USIZE]]{{( noundef)?}} %[[BYTES]])
+    x == y
+}