tests/mir-opt/dest-prop/dead_stores_better.rs

// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
// This is a copy of the `dead_stores_79191` test, except that we turn on DSE. This demonstrates
// that that pass enables this one to do more optimizations.

//@ test-mir-pass: DestinationPropagation
//@ compile-flags: -Zmir-enable-passes=+DeadStoreElimination

fn id<T>(x: T) -> T {
    x
}

// EMIT_MIR dead_stores_better.f.DestinationPropagation.after.mir
pub fn f(mut a: usize) -> usize {
    // CHECK-LABEL: fn f(
    // CHECK: debug a => [[a:_.*]];
    // CHECK: debug b => [[b:_.*]];
    // CHECK: [[b]] = copy [[a]];
    // CHECK: [[a]] = const 5_usize;
    // CHECK: [[a]] = move [[b]];
    // CHECK: id::<usize>(move [[a]])
    let b = a;
    a = 5;
    a = b;
    id(a)
}

fn main() {
    f(0);
}