1 files changed, 63 insertions, 0 deletions

diff --git a/tests/codegen-llvm/issues/issue-86106.rs b/tests/codegen-llvm/issues/issue-86106.rs
new file mode 100644
index 00000000000..8d1ce116d26
--- /dev/null
+++ b/tests/codegen-llvm/issues/issue-86106.rs
@@ -0,0 +1,63 @@
+//@ only-64bit llvm appears to use stores instead of memset on 32bit
+//@ compile-flags: -C opt-level=3 -Z merge-functions=disabled
+//@ needs-deterministic-layouts
+
+// The below two functions ensure that both `String::new()` and `"".to_string()`
+// produce the identical code.
+
+#![crate_type = "lib"]
+
+// CHECK-LABEL: define {{(dso_local )?}}void @string_new
+#[no_mangle]
+pub fn string_new() -> String {
+    // CHECK-NOT: load i8
+    // CHECK: store i{{32|64}}
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store ptr
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store i{{32|64}}
+    // CHECK-NEXT: ret void
+    String::new()
+}
+
+// CHECK-LABEL: define {{(dso_local )?}}void @empty_to_string
+#[no_mangle]
+pub fn empty_to_string() -> String {
+    // CHECK-NOT: load i8
+    // CHECK: store i{{32|64}}
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store ptr
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store i{{32|64}}
+    // CHECK-NEXT: ret void
+    "".to_string()
+}
+
+// The below two functions ensure that both `vec![]` and `vec![].clone()`
+// produce the identical code.
+
+// CHECK-LABEL: @empty_vec
+#[no_mangle]
+pub fn empty_vec() -> Vec<u8> {
+    // CHECK: store i{{32|64}}
+    // CHECK-NOT: load i8
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store ptr
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store i{{32|64}}
+    // CHECK-NEXT: ret void
+    vec![]
+}
+
+// CHECK-LABEL: @empty_vec_clone
+#[no_mangle]
+pub fn empty_vec_clone() -> Vec<u8> {
+    // CHECK: store i{{32|64}}
+    // CHECK-NOT: load i8
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store ptr
+    // CHECK-NEXT: getelementptr
+    // CHECK-NEXT: store i{{32|64}}
+    // CHECK-NEXT: ret void
+    vec![].clone()
+}