Add compiler tests for xray

Author: quininer

tests/assembly/x86_64-xray.rs

@@ -0,0 +1,15 @@
+//@ assembly-output: emit-asm
+//@ compile-flags: --crate-type lib -Zinstrument-xray=always -C llvm-args=-x86-asm-syntax=intel
+//@ only-x86_64
+//@ ignore-sgx
+
+// CHECK-LABEL: xray_func:
+#[no_mangle]
+pub fn xray_func() {
+    // CHECK: nop word ptr [rax + rax + 512]
+
+    std::hint::black_box(());
+
+    // CHECK: ret
+    // CHECK-NEXT: nop word ptr cs:[rax + rax + 512]
+}

tests/ui/instrument-xray/target-supported-but-unstable.rs

@@ -0,0 +1,9 @@
+// Verify that this is still an unstable flag on supported targets
+//
+//@ needs-llvm-components: x86
+//@ rustc-env:RUSTC_BOOTSTRAP=-1
+//@ compile-flags: -Z instrument-xray --target x86_64-unknown-linux-gnu
+
+#![feature(no_core)]
+#![no_core]
+#![no_main]

tests/ui/instrument-xray/target-supported-but-unstable.stderr

@@ -0,0 +1,10 @@
+error: the option `Z` is only accepted on the nightly compiler
+
+help: consider switching to a nightly toolchain: `rustup default nightly`
+
+note: selecting a toolchain with `+toolchain` arguments require a rustup proxy; see <https://rust-lang.github.io/rustup/concepts/index.html>
+
+note: for more information about Rust's stability policy, see <https://doc.rust-lang.org/book/appendix-07-nightly-rust.html#unstable-features>
+
+error: 1 nightly option were parsed
+