src/test/codegen/drop.rs

// ignore-wasm32-bare compiled with panic=abort by default
// compile-flags: -C no-prepopulate-passes

#![crate_type = "lib"]

struct SomeUniqueName;

impl Drop for SomeUniqueName {
    fn drop(&mut self) {
    }
}

pub fn possibly_unwinding() {
}

// CHECK-LABEL: @droppy
#[no_mangle]
pub fn droppy() {
// Check that there are exactly 6 drop calls. The cleanups for the unwinding should be reused, so
// that's one new drop call per call to possibly_unwinding(), and finally 3 drop calls for the
// regular function exit. We used to have problems with quadratic growths of drop calls in such
// functions.
// FIXME(eddyb) the `void @` forces a match on the instruction, instead of the
// comment, that's `; call core::intrinsics::drop_in_place::<drop::SomeUniqueName>`
// for the `v0` mangling, should switch to matching on that once `legacy` is gone.
// CHECK-NOT: invoke void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK: call void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK: call void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK-NOT: call void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK: invoke void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK: call void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK: invoke void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK: call void @{{.*}}drop_in_place{{.*}}SomeUniqueName
// CHECK-NOT: {{(call|invoke) void @.*}}drop_in_place{{.*}}SomeUniqueName
// The next line checks for the } that ends the function definition
// CHECK-LABEL: {{^[}]}}
    let _s = SomeUniqueName;
    possibly_unwinding();
    let _s = SomeUniqueName;
    possibly_unwinding();
    let _s = SomeUniqueName;
    possibly_unwinding();
}