`Vec::pop` unwrap panic branch not optimized out for types with niche opts

[y21]

This code:

use std::ptr::NonNull;

// type Value = NonNull<i64>;
type Value = *const i64;

pub fn pop2(stack: &mut Vec<Value>) -> (Value, Value) {
    assert!(stack.len() >= 2);
    let b = stack.pop().unwrap();
    let a = stack.pop().unwrap();
    (a, b)
}

optimizes differently based on if Value is *const i64 or NonNull<i64> (or apparently any other type with niche optimizations, like &i64 or NonZeroI64).

Reproducer

Specifically, *const i64 has the unwrap panic checks optimized out,

        push    rax
        mov     rax, qword ptr [rdi + 16]
        cmp     rax, 1
        jbe     .LBB0_1 ; assert
        mov     rcx, qword ptr [rdi + 8]
        mov     rdx, qword ptr [rcx + 8*rax - 8]
        lea     rsi, [rax - 2]
        mov     qword ptr [rdi + 16], rsi
        mov     rax, qword ptr [rcx + 8*rax - 16]
        pop     rcx
        ret

while NonNull<i64> keeps them.

example::pop2:
        cmp     rax, 2
        jb      .LBB0_7 ; assert
        ...
        test    rdx, rdx
        je      .LBB0_2 ; unwrap 1
        ...
        test    rax, rax
        je      .LBB0_5 ; unwrap 2

Meta

rustc --version --verbose:

rustc 1.69.0-nightly (c8e6a9e8b 2023-01-23)
binary: rustc
commit-hash: c8e6a9e8b6251bbc8276cb78cabe1998deecbed7
commit-date: 2023-01-23
host: x86_64-unknown-linux-gnu
release: 1.69.0-nightly
LLVM version: 15.0.7

[Noratrieb]

Vec::pop returns Option<T>, so NonNull gets a niche opt there, which confuses LLVM.
-Copt-level=3 --emit llvm-ir -Cno-prepopulate-passes shows what I assume is the key difference:

- %_9 = load i64, ptr %self, align 8, !dbg !129, !range !119, !noundef !12
+ %_9 = select i1 %4, i64 0, i64 1, !dbg !147

For Option<*const i64> we just load the discriminant from the option.
For Option<NonNull<i64>> we need a select to compute the discriminant.

[y21]

Actually this looks like a duplicate of #71257. Closing.