Rollup merge of rust-lang#141045 - dpaoliello:noarmhazard, r=jieyouxu

[win][arm64] Remove 'Arm64 Hazard' undocumented MSVC option and instead disable problematic test

PR rust-lang#140758 added the undocumented `/arm64hazardfree` MSVC linker flag to work around a test failure where LLVM generated code that would trip a hazard in an outdated ARM processor.

Adding this flag caused issues with LLD, as it doesn't recognize it.

Rethinking the issue, using the undocumented flag seems like the incorrect solution: there's no guarantee that the flag won't be removed in the future, or change its meaning.

Instead, I've disabled the problematic test for Arm64 Windows and have filed a bug with the MSVC team to have the check removed: <https://developercommunity.microsoft.com/t/Remove-checking-for-and-fixing-Cortex-A/10905134>

This PR supersedes rust-lang#140977

r? ``@jieyouxu``

Author: fmease

compiler/rustc_target/src/spec/targets/aarch64_pc_windows_msvc.rs

@@ -1,4 +1,4 @@
-use crate::spec::{FramePointer, LinkerFlavor, Lld, Target, TargetMetadata, base};
+use crate::spec::{FramePointer, Target, TargetMetadata, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::windows_msvc::opts();
@@ -11,11 +11,6 @@ pub(crate) fn target() -> Target {
     // and other services. It must point to the previous {x29, x30} pair on the stack."
     base.frame_pointer = FramePointer::NonLeaf;
 
-    // MSVC emits a warning about code that may trip "Cortex-A53 MPCore processor bug #843419" (see
-    // https://developer.arm.com/documentation/epm048406/latest) which is sometimes emitted by LLVM.
-    // Since Arm64 Windows 10+ isn't supported on that processor, it's safe to disable the warning.
-    base.add_pre_link_args(LinkerFlavor::Msvc(Lld::No), &["/arm64hazardfree"]);
-
     Target {
         llvm_target: "aarch64-pc-windows-msvc".into(),
         metadata: TargetMetadata {

tests/run-make/llvm-location-discriminator-limit-dummy-span/rmake.rs

@@ -11,6 +11,13 @@
 //@ needs-dynamic-linking
 //@ only-nightly (requires unstable rustc flag)
 
+// This test trips a check in the MSVC linker for an outdated processor:
+// "LNK1322: cannot avoid potential ARM hazard (Cortex-A53 MPCore processor bug #843419)"
+// Until MSVC removes this check:
+// https://developercommunity.microsoft.com/t/Remove-checking-for-and-fixing-Cortex-A/10905134
+// we'll need to disable this test on Arm64 Windows.
+//@ ignore-aarch64-pc-windows-msvc
+
 #![deny(warnings)]
 
 use run_make_support::{dynamic_lib_name, rfs, rust_lib_name, rustc};