src/test/codegen/vec-in-place.rs

   1 // min-llvm-version: 14.0
   2 // ignore-debug: the debug assertions get in the way
   3 // compile-flags: -O -Z merge-functions=disabled
   4 #![crate_type = "lib"]
   5
   6 // Ensure that trivial casts of vec elements are O(1)
   7
   8 pub struct Wrapper<T>(T);
   9
  10 #[repr(C)]
  11 pub struct Foo {
  12     a: u64,
  13     b: u64,
  14     c: u64,
  15     d: u64,
  16 }
  17
  18 // Going from an aggregate struct to another type currently requires Copy to
  19 // enable the TrustedRandomAccess specialization. Without it optimizations do not yet
  20 // reliably recognize the loops as noop for repr(C) or non-Copy structs.
  21 #[derive(Copy, Clone)]
  22 pub struct Bar {
  23     a: u64,
  24     b: u64,
  25     c: u64,
  26     d: u64,
  27 }
  28
  29 // CHECK-LABEL: @vec_iterator_cast_primitive
  30 #[no_mangle]
  31 pub fn vec_iterator_cast_primitive(vec: Vec<i8>) -> Vec<u8> {
  32     // CHECK-NOT: loop
  33     // CHECK-NOT: call
  34     vec.into_iter().map(|e| e as u8).collect()
  35 }
  36
  37 // CHECK-LABEL: @vec_iterator_cast_wrapper
  38 #[no_mangle]
  39 pub fn vec_iterator_cast_wrapper(vec: Vec<u8>) -> Vec<Wrapper<u8>> {
  40     // CHECK-NOT: loop
  41     // CHECK-NOT: call
  42     vec.into_iter().map(|e| Wrapper(e)).collect()
  43 }
  44
  45 // CHECK-LABEL: @vec_iterator_cast_unwrap
  46 #[no_mangle]
  47 pub fn vec_iterator_cast_unwrap(vec: Vec<Wrapper<u8>>) -> Vec<u8> {
  48     // CHECK-NOT: loop
  49     // CHECK-NOT: call
  50     vec.into_iter().map(|e| e.0).collect()
  51 }
  52
  53 // CHECK-LABEL: @vec_iterator_cast_aggregate
  54 #[no_mangle]
  55 pub fn vec_iterator_cast_aggregate(vec: Vec<[u64; 4]>) -> Vec<Foo> {
  56     // FIXME These checks should be the same as other functions.
  57     // CHECK-NOT: @__rust_alloc
  58     // CHECK-NOT: @__rust_alloc
  59     vec.into_iter().map(|e| unsafe { std::mem::transmute(e) }).collect()
  60 }
  61
  62 // CHECK-LABEL: @vec_iterator_cast_deaggregate
  63 #[no_mangle]
  64 pub fn vec_iterator_cast_deaggregate(vec: Vec<Bar>) -> Vec<[u64; 4]> {
  65     // FIXME These checks should be the same as other functions.
  66     // CHECK-NOT: @__rust_alloc
  67     // CHECK-NOT: @__rust_alloc
  68
  69     // Safety: For the purpose of this test we assume that Bar layout matches [u64; 4].
  70     // This currently is not guaranteed for repr(Rust) types, but it happens to work here and
  71     // the UCG may add additional guarantees for homogenous types in the future that would make this
  72     // correct.
  73     vec.into_iter().map(|e| unsafe { std::mem::transmute(e) }).collect()
  74 }