diff options
Diffstat (limited to 'tests/codegen/mem-replace-big-type.rs')
| -rw-r--r-- | tests/codegen/mem-replace-big-type.rs | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/tests/codegen/mem-replace-big-type.rs b/tests/codegen/mem-replace-big-type.rs new file mode 100644 index 000000000..f6898e2f7 --- /dev/null +++ b/tests/codegen/mem-replace-big-type.rs @@ -0,0 +1,36 @@ +// This test ensures that `mem::replace::<T>` only ever calls `@llvm.memcpy` +// with `size_of::<T>()` as the size, and never goes through any wrapper that +// may e.g. multiply `size_of::<T>()` with a variable "count" (which is only +// known to be `1` after inlining). + +// compile-flags: -C no-prepopulate-passes -Zinline-mir=no +// ignore-debug: the debug assertions get in the way + +#![crate_type = "lib"] + +#[repr(C, align(8))] +pub struct Big([u64; 7]); +pub fn replace_big(dst: &mut Big, src: Big) -> Big { + // Before the `read_via_copy` intrinsic, this emitted six `memcpy`s. + std::mem::replace(dst, src) +} + +// NOTE(eddyb) the `CHECK-NOT`s ensure that the only calls of `@llvm.memcpy` in +// the entire output, are the direct calls we want, from `ptr::replace`. + +// CHECK-NOT: call void @llvm.memcpy + +// For a large type, we expect exactly three `memcpy`s +// CHECK-LABEL: define internal void @{{.+}}mem{{.+}}replace{{.+}}sret(%Big) + // CHECK-NOT: alloca + // CHECK: alloca %Big + // CHECK-NOT: alloca + // CHECK-NOT: call void @llvm.memcpy + // CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %{{.*}}, {{i8\*|ptr}} align 8 %{{.*}}, i{{.*}} 56, i1 false) + // CHECK-NOT: call void @llvm.memcpy + // CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %{{.*}}, {{i8\*|ptr}} align 8 %{{.*}}, i{{.*}} 56, i1 false) + // CHECK-NOT: call void @llvm.memcpy + // CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %{{.*}}, {{i8\*|ptr}} align 8 %{{.*}}, i{{.*}} 56, i1 false) + // CHECK-NOT: call void @llvm.memcpy + +// CHECK-NOT: call void @llvm.memcpy |