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add test for noop drop in landing pad

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This commit is contained in:
Erik Desjardins 2021-12-30 01:03:17 -05:00
parent e4463b2453
commit 64da730a41
1 changed files with 19 additions and 4 deletions
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23
src/test/codegen/unwind-landingpad-inline.rs
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@ -3,11 +3,12 @@
#![crate_type = "lib"]
// This test checks that we can inline drop_in_place in
// unwind landing pads. Without this, the box pointers escape,
// and LLVM will not optimize out the pointer comparison.
// See https://github.com/rust-lang/rust/issues/46515
// unwind landing pads.
// Everything should be optimized out.
// Without inlining, the box pointers escape via the call to drop_in_place,
// and LLVM will not optimize out the pointer comparison.
// With inlining, everything should be optimized out.
// See https://github.com/rust-lang/rust/issues/46515
// CHECK-LABEL: @check_no_escape_in_landingpad
// CHECK: start:
// CHECK-NEXT: ret void
@ -20,3 +21,17 @@ pub fn check_no_escape_in_landingpad(f: fn()) {
f();
}
}
// Without inlining, the compiler can't tell that
// dropping an empty string (in a landing pad) does nothing.
// With inlining, the landing pad should be optimized out.
// See https://github.com/rust-lang/rust/issues/87055
// CHECK-LABEL: @check_eliminate_noop_drop
// CHECK: start:
// CHECK-NEXT: call void %g()
// CHECK-NEXT: ret void
#[no_mangle]
pub fn check_eliminate_noop_drop(g: fn()) {
let _var = String::new();
g();
}