Review comments

- Changed the separator from '+' to ','.
- Moved the branch protection options from -C to -Z.
- Additional test for incorrect branch-protection option.
- Remove LLVM < 12 code.
- Style fixes.

Co-authored-by: James McGregor <james.mcgregor2@arm.com>

3 files changed, 20 insertions, 80 deletions

diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index 768e03b5ef3..8e6329a997f 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -9,7 +9,7 @@ use rustc_hir::def_id::DefId;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::ty::layout::HasTyCtxt;
 use rustc_middle::ty::{self, TyCtxt};
-use rustc_session::config::{BranchProtection, OptLevel, PAuthKey};
+use rustc_session::config::OptLevel;
 use rustc_session::Session;
 use rustc_target::spec::abi::Abi;
 use rustc_target::spec::{FramePointer, SanitizerSet, StackProbeType, StackProtector};
@@ -203,58 +203,6 @@ pub fn non_lazy_bind(sess: &Session, llfn: &'ll Value) {
     }
 }
 
-pub fn set_branch_protection(sess: &Session, llfn: &'ll Value) {
-    // Setting PAC/BTI function attributes is only necessary for LLVM 11 and earlier.
-    // For LLVM 12 and greater, module-level metadata attributes are set in
-    // `compiler/rustc_codegen_llvm/src/context.rs`.
-    if llvm_util::get_version() >= (12, 0, 0) {
-        return;
-    }
-
-    let BranchProtection { bti, pac_ret: pac } = sess.opts.cg.branch_protection;
-
-    if bti {
-        llvm::AddFunctionAttrString(
-            llfn,
-            llvm::AttributePlace::Function,
-            cstr!("branch-target-enforcement"),
-        );
-    }
-
-    if let Some(pac_opts) = pac {
-        if pac_opts.leaf {
-            llvm::AddFunctionAttrStringValue(
-                llfn,
-                llvm::AttributePlace::Function,
-                cstr!("sign-return-address"),
-                cstr!("non-leaf"),
-            );
-        } else {
-            llvm::AddFunctionAttrStringValue(
-                llfn,
-                llvm::AttributePlace::Function,
-                cstr!("sign-return-address"),
-                cstr!("all"),
-            );
-        }
-
-        match pac_opts.key {
-            PAuthKey::A => llvm::AddFunctionAttrStringValue(
-                llfn,
-                llvm::AttributePlace::Function,
-                cstr!("sign-return-address-key"),
-                cstr!("a_key"),
-            ),
-            PAuthKey::B => llvm::AddFunctionAttrStringValue(
-                llfn,
-                llvm::AttributePlace::Function,
-                cstr!("sign-return-address-key"),
-                cstr!("b_key"),
-            ),
-        }
-    }
-}
-
 pub(crate) fn default_optimisation_attrs(sess: &Session, llfn: &'ll Value) {
     match sess.opts.optimize {
         OptLevel::Size => {
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index da05b5c0cba..0f5487a4447 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -21,7 +21,7 @@ use rustc_middle::ty::layout::{
 };
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
-use rustc_session::config::{BranchProtection, CFGuard, CrateType, DebugInfo, PAuthKey};
+use rustc_session::config::{BranchProtection, CFGuard, CrateType, DebugInfo, PAuthKey, PacRet};
 use rustc_session::Session;
 use rustc_span::source_map::Span;
 use rustc_span::symbol::Symbol;
@@ -243,7 +243,7 @@ pub unsafe fn create_module(
     }
 
     if sess.target.arch == "aarch64" {
-        let BranchProtection { bti, pac_ret: pac } = sess.opts.cg.branch_protection;
+        let BranchProtection { bti, pac_ret: pac } = sess.opts.debugging_opts.branch_protection;
 
         llvm::LLVMRustAddModuleFlag(
             llmod,
@@ -251,27 +251,23 @@ pub unsafe fn create_module(
             bti.into(),
         );
 
-        if let Some(pac_opts) = pac {
-            llvm::LLVMRustAddModuleFlag(llmod, "sign-return-address\0".as_ptr().cast(), 1);
-            llvm::LLVMRustAddModuleFlag(
-                llmod,
-                "sign-return-address-all\0".as_ptr().cast(),
-                pac_opts.leaf.into(),
-            );
-            llvm::LLVMRustAddModuleFlag(
-                llmod,
-                "sign-return-address-with-bkey\0".as_ptr().cast(),
-                if pac_opts.key == PAuthKey::A { 0 } else { 1 },
-            );
-        } else {
-            llvm::LLVMRustAddModuleFlag(llmod, "sign-return-address\0".as_ptr().cast(), 0);
-            llvm::LLVMRustAddModuleFlag(llmod, "sign-return-address-all\0".as_ptr().cast(), 0);
-            llvm::LLVMRustAddModuleFlag(
-                llmod,
-                "sign-return-address-with-bkey\0".as_ptr().cast(),
-                0,
-            );
-        }
+        llvm::LLVMRustAddModuleFlag(
+            llmod,
+            "sign-return-address\0".as_ptr().cast(),
+            pac.is_some().into(),
+        );
+        let pac_opts = pac.unwrap_or(PacRet { leaf: false, key: PAuthKey::A });
+        llvm::LLVMRustAddModuleFlag(
+            llmod,
+            "sign-return-address-all\0".as_ptr().cast(),
+            pac_opts.leaf.into(),
+        );
+        let is_bkey = if pac_opts.key == PAuthKey::A { false } else { true };
+        llvm::LLVMRustAddModuleFlag(
+            llmod,
+            "sign-return-address-with-bkey\0".as_ptr().cast(),
+            is_bkey.into(),
+        );
     }
 
     llmod
diff --git a/compiler/rustc_codegen_llvm/src/declare.rs b/compiler/rustc_codegen_llvm/src/declare.rs
index f4e754b80c9..5db82dd7669 100644
--- a/compiler/rustc_codegen_llvm/src/declare.rs
+++ b/compiler/rustc_codegen_llvm/src/declare.rs
@@ -45,10 +45,6 @@ fn declare_raw_fn(
         llvm::Attribute::NoRedZone.apply_llfn(Function, llfn);
     }
 
-    if cx.tcx.sess.target.arch == "aarch64" {
-        attributes::set_branch_protection(cx.tcx.sess, llfn);
-    }
-
     attributes::default_optimisation_attrs(cx.tcx.sess, llfn);
     attributes::non_lazy_bind(cx.sess(), llfn);