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// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
// Check that DestinationPropagation does not propagate an assignment to a function argument
// (doing so can break usages of the original argument value)
//@ test-mir-pass: DestinationPropagation
fn dummy(x: u8) -> u8 {
x
}
// EMIT_MIR copy_propagation_arg.foo.DestinationPropagation.diff
fn foo(mut x: u8) {
// CHECK-LABEL: fn foo(
// CHECK: debug x => [[x:_.*]];
// CHECK: dummy(move [[x]])
// CHECK: [[x]] = move {{_.*}};
// calling `dummy` to make a use of `x` that copyprop cannot eliminate
x = dummy(x); // this will assign a local to `x`
}
// EMIT_MIR copy_propagation_arg.bar.DestinationPropagation.diff
fn bar(mut x: u8) {
// CHECK-LABEL: fn bar(
// CHECK: debug x => [[x:_.*]];
// CHECK: dummy(move [[x]])
// CHECK: [[x]] = const 5_u8;
dummy(x);
x = 5;
}
// EMIT_MIR copy_propagation_arg.baz.DestinationPropagation.diff
fn baz(mut x: i32) -> i32 {
// CHECK-LABEL: fn baz(
// CHECK: debug x => [[x:_.*]];
// CHECK-NOT: [[x]] =
// self-assignment to a function argument should be eliminated
x = x;
x
}
// EMIT_MIR copy_propagation_arg.arg_src.DestinationPropagation.diff
fn arg_src(mut x: i32) -> i32 {
// CHECK-LABEL: fn arg_src(
// CHECK: debug x => [[x:_.*]];
// CHECK: debug y => [[y:_.*]];
// CHECK: [[y]] = copy [[x]]
// CHECK: [[x]] = const 123_i32;
// CHECK-NOT: {{_.*}} = copy [[y]];
let y = x;
x = 123; // Don't propagate this assignment to `y`
y
}
fn main() {
// Make sure the function actually gets instantiated.
foo(0);
bar(0);
baz(0);
arg_src(0);
}
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