[debug] local variable is <optimized out>

[OccupyMars2025]

rust-lang/rust#46698

rust-lang/rust#53036

rust-lang/rust#70542

[OccupyMars2025]

rustc --help | less

    -g                  Equivalent to -C debuginfo=2
    -O                  Equivalent to -C opt-level=2

I use dev cargo profile, but the local variable is still optimized out

[profile.dev]
opt-level = 0
debug = true

// os/src/trap/context.rs
    pub fn app_init_context(entry: usize, sp: usize) -> Self {
        let mut sstatus_reg = sstatus::read(); // CSR sstatus
        sstatus_reg.set_spp(SPP::User); //previous privilege mode: user mode
        let mut cx = Self {
            x: [0; 32],
            sstatus: sstatus_reg,
            sepc: entry, // entry point of app
        };
        cx.set_sp(sp); // app's user stack pointer
        cx // return initial Trap Context of app
    }