From 2d476222e8458aa873e6760aac189b5e9d0a9930 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Wed, 18 Oct 2023 16:58:17 +0200 Subject: Add `-Zfunction-return={keep,thunk-extern}` option This is intended to be used for Linux kernel RETHUNK builds. With this commit (optionally backported to Rust 1.73.0), plus a patched Linux kernel to pass the flag, I get a RETHUNK build with Rust enabled that is `objtool`-warning-free and is able to boot in QEMU and load a sample Rust kernel module. Signed-off-by: Miguel Ojeda --- tests/codegen/function-return.rs | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 tests/codegen/function-return.rs (limited to 'tests/codegen/function-return.rs') diff --git a/tests/codegen/function-return.rs b/tests/codegen/function-return.rs new file mode 100644 index 00000000000..d832d19ac39 --- /dev/null +++ b/tests/codegen/function-return.rs @@ -0,0 +1,28 @@ +// Test that the `fn_ret_thunk_extern` function attribute is (not) emitted when +// the `-Zfunction-return={keep,thunk-extern}` flag is (not) set. + +// revisions: unset keep thunk-extern keep-thunk-extern thunk-extern-keep +// needs-llvm-components: x86 +// compile-flags: --target x86_64-unknown-linux-gnu +// [keep] compile-flags: -Zfunction-return=keep +// [thunk-extern] compile-flags: -Zfunction-return=thunk-extern +// [keep-thunk-extern] compile-flags: -Zfunction-return=keep -Zfunction-return=thunk-extern +// [thunk-extern-keep] compile-flags: -Zfunction-return=thunk-extern -Zfunction-return=keep + +#![crate_type = "lib"] +#![feature(no_core, lang_items)] +#![no_core] + +#[lang = "sized"] +trait Sized {} + +#[no_mangle] +pub fn foo() { + // CHECK: @foo() unnamed_addr #0 + + // unset-NOT: fn_ret_thunk_extern + // keep-NOT: fn_ret_thunk_extern + // thunk-extern: attributes #0 = { {{.*}}fn_ret_thunk_extern{{.*}} } + // keep-thunk-extern: attributes #0 = { {{.*}}fn_ret_thunk_extern{{.*}} } + // thunk-extern-keep-NOT: fn_ret_thunk_extern +} -- cgit 1.4.1-3-g733a5