Split PAuth target feature

Author: adamgemmell

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -322,12 +322,33 @@ pub fn from_fn_attrs<'ll, 'tcx>(
     // The target doesn't care; the subtarget reads our attribute.
     apply_tune_cpu_attr(cx, llfn);
 
-    let mut function_features = codegen_fn_attrs
-        .target_features
+    let function_features =
+        codegen_fn_attrs.target_features.iter().map(|f| f.as_str()).collect::<Vec<&str>>();
+
+    if let Some(f) = llvm_util::check_tied_features(
+        cx.tcx.sess,
+        &function_features.iter().map(|f| (*f, true)).collect(),
+    ) {
+        let span = cx
+            .tcx
+            .get_attrs(instance.def_id())
+            .iter()
+            .find(|a| a.has_name(rustc_span::sym::target_feature))
+            .map_or_else(|| cx.tcx.def_span(instance.def_id()), |a| a.span);
+        let msg = format!(
+            "the target features {} must all be either enabled or disabled together",
+            f.join(", ")
+        );
+        let mut err = cx.tcx.sess.struct_span_err(span, &msg);
+        err.help("add the missing features in a `target_feature` attribute");
+        err.emit();
+        return;
+    }
+
+    let mut function_features = function_features
         .iter()
-        .flat_map(|f| {
-            let feature = f.as_str();
-            llvm_util::to_llvm_feature(cx.tcx.sess, feature)
+        .flat_map(|feat| {
+            llvm_util::to_llvm_feature(cx.tcx.sess, feat)
                 .into_iter()
                 .map(|f| format!("+{}", f))
                 .collect::<Vec<String>>()

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -2,8 +2,8 @@ use crate::back::write::create_informational_target_machine;
 use crate::{llvm, llvm_util};
 use libc::c_int;
 use libloading::Library;
-use rustc_codegen_ssa::target_features::supported_target_features;
-use rustc_data_structures::fx::FxHashSet;
+use rustc_codegen_ssa::target_features::{supported_target_features, tied_target_features};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_fs_util::path_to_c_string;
 use rustc_middle::bug;
 use rustc_session::config::PrintRequest;
@@ -191,10 +191,30 @@ pub fn to_llvm_feature<'a>(sess: &Session, s: &'a str) -> Vec<&'a str> {
         ("aarch64", "frintts") => vec!["fptoint"],
         ("aarch64", "fcma") => vec!["complxnum"],
         ("aarch64", "pmuv3") => vec!["perfmon"],
+        ("aarch64", "paca") => vec!["pauth"],
+        ("aarch64", "pacg") => vec!["pauth"],
         (_, s) => vec![s],
     }
 }
 
+// Given a map from target_features to whether they are enabled or disabled,
+// ensure only valid combinations are allowed.
+pub fn check_tied_features(
+    sess: &Session,
+    features: &FxHashMap<&str, bool>,
+) -> Option<&'static [&'static str]> {
+    for tied in tied_target_features(sess) {
+        // Tied features must be set to the same value, or not set at all
+        let mut tied_iter = tied.iter();
+        let enabled = features.get(tied_iter.next().unwrap());
+
+        if tied_iter.any(|f| enabled != features.get(f)) {
+            return Some(tied);
+        }
+    }
+    None
+}
+
 pub fn target_features(sess: &Session) -> Vec<Symbol> {
     let target_machine = create_informational_target_machine(sess);
     supported_target_features(sess)
@@ -395,15 +415,19 @@ pub fn llvm_global_features(sess: &Session) -> Vec<String> {
         Some(_) | None => {}
     };
 
+    fn strip(s: &str) -> &str {
+        s.strip_prefix(&['+', '-']).unwrap_or(s)
+    }
+
     let filter = |s: &str| {
         if s.is_empty() {
             return vec![];
         }
-        let feature = if s.starts_with('+') || s.starts_with('-') {
-            &s[1..]
-        } else {
+        let feature = strip(s);
+        if feature == s {
             return vec![s.to_string()];
-        };
+        }
+
         // Rustc-specific feature requests like `+crt-static` or `-crt-static`
         // are not passed down to LLVM.
         if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
@@ -420,8 +444,17 @@ pub fn llvm_global_features(sess: &Session) -> Vec<String> {
     features.extend(sess.target.features.split(',').flat_map(&filter));
 
     // -Ctarget-features
-    features.extend(sess.opts.cg.target_feature.split(',').flat_map(&filter));
-
+    let feats: Vec<&str> = sess.opts.cg.target_feature.split(',').collect();
+    // LLVM enables based on the last occurence of a feature
+    if let Some(f) =
+        check_tied_features(sess, &feats.iter().map(|f| (strip(f), !f.starts_with("-"))).collect())
+    {
+        sess.err(&format!(
+            "Target features {} must all be enabled or disabled together",
+            f.join(", ")
+        ));
+    }
+    features.extend(feats.iter().flat_map(|&f| filter(f)));
     features
 }
 

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -74,8 +74,10 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("ssbs", Some(sym::aarch64_target_feature)),
     // FEAT_SB
     ("sb", Some(sym::aarch64_target_feature)),
-    // FEAT_PAUTH
-    ("pauth", Some(sym::aarch64_target_feature)),
+    // FEAT_PAUTH (address authentication)
+    ("paca", Some(sym::aarch64_target_feature)),
+    // FEAT_PAUTH (generic authentication)
+    ("pacg", Some(sym::aarch64_target_feature)),
     // FEAT_DPB
     ("dpb", Some(sym::aarch64_target_feature)),
     // FEAT_DPB2
@@ -137,6 +139,8 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("v8.7a", Some(sym::aarch64_target_feature)),
 ];
 
+const AARCH64_TIED_FEATURES: &[&[&str]] = &[&["paca", "pacg"]];
+
 const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("adx", Some(sym::adx_target_feature)),
     ("aes", None),
@@ -256,6 +260,13 @@ pub fn supported_target_features(sess: &Session) -> &'static [(&'static str, Opt
     }
 }
 
+pub fn tied_target_features(sess: &Session) -> &'static [&'static [&'static str]] {
+    match &*sess.target.arch {
+        "aarch64" => AARCH64_TIED_FEATURES,
+        _ => &[],
+    }
+}
+
 pub(crate) fn provide(providers: &mut Providers) {
     providers.supported_target_features = |tcx, cnum| {
         assert_eq!(cnum, LOCAL_CRATE);

src/test/ui/target-feature/tied-features-cli.one.stderr

@@ -0,0 +1,4 @@
+error: Target features paca, pacg must all be enabled or disabled together
+
+error: aborting due to previous error
+

src/test/ui/target-feature/tied-features-cli.rs

@@ -0,0 +1,9 @@
+// only-aarch64
+// revisions: one two three four
+//[one] compile-flags: -C target-feature=+paca
+//[two] compile-flags: -C target-feature=-pacg,+pacg
+//[three] compile-flags: -C target-feature=+paca,+pacg,-paca
+//[four] check-pass
+//[four] compile-flags: -C target-feature=-paca,+pacg -C target-feature=+paca
+
+fn main() {}

src/test/ui/target-feature/tied-features-cli.three.stderr

@@ -0,0 +1,4 @@
+error: Target features paca, pacg must all be enabled or disabled together
+
+error: aborting due to previous error
+

src/test/ui/target-feature/tied-features-cli.two.stderr

@@ -0,0 +1,4 @@
+error: Target features paca, pacg must all be enabled or disabled together
+
+error: aborting due to previous error
+

src/test/ui/target-feature/tied-features.rs

@@ -0,0 +1,29 @@
+// only-aarch64
+// build-fail
+
+#![feature(aarch64_target_feature, target_feature_11)]
+
+fn main() {
+    #[target_feature(enable = "pacg")]
+    //~^ ERROR must all be either enabled or disabled together
+    unsafe fn inner() {}
+
+    unsafe {
+        foo();
+        bar();
+        baz();
+        inner();
+    }
+}
+
+#[target_feature(enable = "paca")]
+//~^ ERROR must all be either enabled or disabled together
+unsafe fn foo() {}
+
+
+#[target_feature(enable = "paca,pacg")]
+unsafe fn bar() {}
+
+#[target_feature(enable = "paca")]
+#[target_feature(enable = "pacg")]
+unsafe fn baz() {}

src/test/ui/target-feature/tied-features.stderr

@@ -0,0 +1,18 @@
+error: the target features paca, pacg must all be either enabled or disabled together
+  --> $DIR/tied-features.rs:7:5
+   |
+LL |     #[target_feature(enable = "pacg")]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add the missing features in a `target_feature` attribute
+
+error: the target features paca, pacg must all be either enabled or disabled together
+  --> $DIR/tied-features.rs:19:1
+   |
+LL | #[target_feature(enable = "paca")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add the missing features in a `target_feature` attribute
+
+error: aborting due to 2 previous errors
+