a7fc76a3ab
Stop pessimizing the use of local variables in core by skipping debug info for MIR temporaries in tiny (single-BB) functions. For functions as simple as this -- `Pin::new`, etc -- nobody every actually wants debuginfo for them in the first place. They're more like intrinsics than real functions, and stepping over them is good.
36 lines
1.5 KiB
Rust
36 lines
1.5 KiB
Rust
// 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-std-debug-assertions
|
|
// Reason: precondition checks in ptr::read make them a bad candidate for MIR inlining
|
|
//@ needs-deterministic-layouts
|
|
|
|
#![crate_type = "lib"]
|
|
|
|
#[repr(C, align(8))]
|
|
pub struct Big([u64; 7]);
|
|
pub fn replace_big(dst: &mut Big, src: Big) -> Big {
|
|
// Back in 1.68, this emitted six `memcpy`s.
|
|
// `read_via_copy` in 1.69 got that down to three.
|
|
// `write_via_move` and nvro get this down to the essential two.
|
|
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{{.+}}(ptr
|
|
// CHECK-SAME: sret([56 x i8]){{.+}}[[RESULT:%.+]], ptr{{.+}}%dest, ptr{{.+}}%src)
|
|
// CHECK-NOT: call void @llvm.memcpy
|
|
// CHECK: call void @llvm.memcpy.{{.+}}(ptr align 8 [[RESULT]], ptr align 8 %dest, i{{.*}} 56, i1 false)
|
|
// CHECK-NOT: call void @llvm.memcpy
|
|
// CHECK: call void @llvm.memcpy.{{.+}}(ptr align 8 %dest, ptr align 8 %src, i{{.*}} 56, i1 false)
|
|
// CHECK-NOT: call void @llvm.memcpy
|
|
|
|
// CHECK-NOT: call void @llvm.memcpy
|