More asm tests

tests/asm/asm/comments.rs

@@ -0,0 +1,12 @@
+//@ assembly-output: emit-asm
+//@ only-x86_64
+// Check that comments in assembly get passed
+
+#![crate_type = "lib"]
+
+// CHECK-LABEL: "test_comments":
+#[no_mangle]
+pub fn test_comments() {
+    // CHECK: example comment
+    unsafe { core::arch::asm!("nop // example comment") };
+}

tests/asm/naked-functions/x86_64-naked-fn-no-cet-prolog.rs

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+//@ compile-flags: -C no-prepopulate-passes -Zcf-protection=full
+//@ assembly-output: emit-asm
+//@ needs-asm-support
+//@ only-x86_64
+
+#![crate_type = "lib"]
+
+use std::arch::naked_asm;
+
+// The problem at hand: Rust has adopted a fairly strict meaning for "naked functions",
+// meaning "no prologue whatsoever, no, really, not one instruction."
+// Unfortunately, x86's control-flow enforcement, specifically indirect branch protection,
+// works by using an instruction for each possible landing site,
+// and LLVM implements this via making sure of that.
+#[no_mangle]
+#[unsafe(naked)]
+pub extern "sysv64" fn will_halt() -> ! {
+    // CHECK-NOT: endbr{{32|64}}
+    // CHECK: hlt
+    naked_asm!("hlt")
+}
+
+// what about aarch64?
+// "branch-protection"=false

tests/asm/x86_64-sse_crc.rs

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+//@ only-x86_64
+//@ assembly-output: emit-asm
+//@ compile-flags: --crate-type staticlib -Ctarget-feature=+sse4.2
+
+// CHECK-LABEL: banana
+// CHECK: crc32
+#[no_mangle]
+pub unsafe fn banana(v: u8) -> u32 {
+    use std::arch::x86_64::*;
+    let out = !0u32;
+    _mm_crc32_u8(out, v)
+}