From 49f3c0b73689eed49df9ef822f9fd437db93ce9e Mon Sep 17 00:00:00 2001
From: Jacob Bramley <jacob.bramley@arm.com>
Date: Mon, 21 Nov 2022 16:05:51 +0000
Subject: Check AArch64 branch-protection earlier in the pipeline.

As suggested in #93516.
---
 compiler/rustc_codegen_llvm/src/context.rs | 8 +++-----
 compiler/rustc_codegen_llvm/src/errors.rs  | 4 ----
 2 files changed, 3 insertions(+), 9 deletions(-)

(limited to 'compiler/rustc_codegen_llvm/src')

diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index 4dcc7cd5447..a22a67ad7d3 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -3,7 +3,6 @@ use crate::back::write::to_llvm_code_model;
 use crate::callee::get_fn;
 use crate::coverageinfo;
 use crate::debuginfo;
-use crate::errors::BranchProtectionRequiresAArch64;
 use crate::llvm;
 use crate::llvm_util;
 use crate::type_::Type;
@@ -275,10 +274,9 @@ pub unsafe fn create_module<'ll>(
         }
     }
 
-    if let Some(BranchProtection { bti, pac_ret }) = sess.opts.unstable_opts.branch_protection {
-        if sess.target.arch != "aarch64" {
-            sess.emit_err(BranchProtectionRequiresAArch64);
-        } else {
+    // AArch64-only options (checked in rustc_session).
+    if sess.target.arch == "aarch64" {
+        if let Some(BranchProtection { bti, pac_ret }) = sess.opts.unstable_opts.branch_protection {
             llvm::LLVMRustAddModuleFlag(
                 llmod,
                 llvm::LLVMModFlagBehavior::Error,
diff --git a/compiler/rustc_codegen_llvm/src/errors.rs b/compiler/rustc_codegen_llvm/src/errors.rs
index fddfbb23c67..de508f917f3 100644
--- a/compiler/rustc_codegen_llvm/src/errors.rs
+++ b/compiler/rustc_codegen_llvm/src/errors.rs
@@ -51,10 +51,6 @@ pub(crate) struct SymbolAlreadyDefined<'a> {
     pub symbol_name: &'a str,
 }
 
-#[derive(Diagnostic)]
-#[diag(codegen_llvm_branch_protection_requires_aarch64)]
-pub(crate) struct BranchProtectionRequiresAArch64;
-
 #[derive(Diagnostic)]
 #[diag(codegen_llvm_invalid_minimum_alignment)]
 pub(crate) struct InvalidMinimumAlignment {
-- 
cgit 1.4.1-3-g733a5


From 73d374f3e7d5fe9635a23937cdc2f7e1d1c29224 Mon Sep 17 00:00:00 2001
From: Jacob Bramley <jacob.bramley@arm.com>
Date: Tue, 13 Dec 2022 17:04:02 +0000
Subject: bug! if branch-protection makes it to non-AArch64 codegen.

---
 compiler/rustc_codegen_llvm/src/context.rs | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

(limited to 'compiler/rustc_codegen_llvm/src')

diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index a22a67ad7d3..f6fcdc90cb6 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -274,9 +274,8 @@ pub unsafe fn create_module<'ll>(
         }
     }
 
-    // AArch64-only options (checked in rustc_session).
-    if sess.target.arch == "aarch64" {
-        if let Some(BranchProtection { bti, pac_ret }) = sess.opts.unstable_opts.branch_protection {
+    if let Some(BranchProtection { bti, pac_ret }) = sess.opts.unstable_opts.branch_protection {
+        if sess.target.arch == "aarch64" {
             llvm::LLVMRustAddModuleFlag(
                 llmod,
                 llvm::LLVMModFlagBehavior::Error,
@@ -302,6 +301,11 @@ pub unsafe fn create_module<'ll>(
                 "sign-return-address-with-bkey\0".as_ptr().cast(),
                 u32::from(pac_opts.key == PAuthKey::B),
             );
+        } else {
+            bug!(
+                "branch-protection used on non-AArch64 target; \
+                  this should be checked in rustc_session."
+            );
         }
     }
 
-- 
cgit 1.4.1-3-g733a5