Missing tests for intrinsics.

[lcnr]

There are a few intrinsics which are not tested.

We also don't test the emitted IR for most intrinsics, e.g. ctlz_nonzero could use ctlz without being noticed.

• pref_align_of: never used
• volatile_copy_nonoverlapping_memory: used in a test for write_volatile causes ICE with zero-sized types. #39827 without checking its output or IR
• volatile_copy_memory: ^
• volatile_set_memory: ^^
• unaligned_volatile_load: both IR and use with unaligned addr never checked
• unaligned_volatile_store: ^
• nearbyintf32: never used
• nearbyintf64: ^

[lcnr]

If someone wants to work on this feel free to ask here or on zulip.

See

rust/src/test/codegen/intrinsics/unchecked_math.rs

Lines 1 to 11 in 5db778a

	#![crate_type = "lib"]
	#![feature(core_intrinsics)]
	use std::intrinsics::*;
	// CHECK-LABEL: @unchecked_add_signed
	#[no_mangle]
	pub unsafe fn unchecked_add_signed(a: i32, b: i32) -> i32 {
	// CHECK: add nsw
	unchecked_add(a, b)
	}

for how to test an intrinsic.

[theo-lw]

I'd like to take a stab at this (if no one else is working on this issue yet).

[lcnr]

Doesn't seem like someone else is already looking at this.