Filter for all features instead of any

Adds regression tests for feature logic
Co-authored-by: bjorn3 <bjorn3@users.noreply.github.com>
Co-authored-by: Simonas Kazlauskas <git@kazlauskas.me>

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -229,6 +229,8 @@ pub fn check_tied_features(
     None
 }
 
+// Used to generate cfg variables and apply features
+// Must express features in the way Rust understands them
 pub fn target_features(sess: &Session) -> Vec<Symbol> {
     let target_machine = create_informational_target_machine(sess);
     let mut features: Vec<Symbol> =
@@ -238,13 +240,14 @@ pub fn target_features(sess: &Session) -> Vec<Symbol> {
                 if sess.is_nightly_build() || gate.is_none() { Some(feature) } else { None }
             })
             .filter(|feature| {
+                // check that all features in a given smallvec are enabled
                 for llvm_feature in to_llvm_features(sess, feature) {
                     let cstr = SmallCStr::new(llvm_feature);
-                    if unsafe { llvm::LLVMRustHasFeature(target_machine, cstr.as_ptr()) } {
-                        return true;
+                    if !unsafe { llvm::LLVMRustHasFeature(target_machine, cstr.as_ptr()) } {
+                        return false;
                     }
                 }
-                false
+                true
             })
             .map(|feature| Symbol::intern(feature))
             .collect();

src/test/ui/target-feature/no-llvm-leaks.rs

@@ -0,0 +1,64 @@
+// revisions: aarch64 x86-64
+// [aarch64] compile-flags: -Ctarget-feature=+neon,+fp16,+fhm --target=aarch64-unknown-linux-gnu
+// [aarch64] needs-llvm-components: aarch64
+// [x86-64] compile-flags: -Ctarget-feature=+sse4.2,+rdrand --target=x86_64-unknown-linux-gnu
+// [x86-64] needs-llvm-components: x86
+// build-pass
+#![no_core]
+#![crate_type = "rlib"]
+#![feature(intrinsics, rustc_attrs, no_core, lang_items, staged_api)]
+#![stable(feature = "test", since = "1.0.0")]
+
+// Supporting minimal rust core code
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+impl Copy for bool {}
+
+extern "rust-intrinsic" {
+    #[rustc_const_stable(feature = "test", since = "1.0.0")]
+    fn unreachable() -> !;
+}
+
+#[rustc_builtin_macro]
+macro_rules! cfg {
+    ($($cfg:tt)*) => {};
+}
+
+// Test code
+const fn do_or_die(cond: bool) {
+    if cond {
+    } else {
+        unsafe { unreachable() }
+    }
+}
+
+macro_rules! assert {
+    ($x:expr $(,)?) => {
+        const _: () = do_or_die($x);
+    };
+}
+
+
+#[cfg(target_arch = "aarch64")]
+fn check_aarch64() {
+    // This checks that the rustc feature name is used, not the LLVM feature.
+    assert!(cfg!(target_feature = "neon"));
+    assert!(cfg!(not(target_feature = "fp-armv8")));
+    assert!(cfg!(target_feature = "fhm"));
+    assert!(cfg!(not(target_feature = "fp16fml")));
+    assert!(cfg!(target_feature = "fp16"));
+    assert!(cfg!(not(target_feature = "fullfp16")));
+}
+
+#[cfg(target_arch = "x86_64")]
+fn check_x86_64() {
+    // This checks that the rustc feature name is used, not the LLVM feature.
+    assert!(cfg!(target_feature = "rdrand"));
+    assert!(cfg!(not(target_feature = "rdrnd")));
+
+    // Likewise: We enable LLVM's crc32 feature with SSE4.2, but Rust says it's just SSE4.2
+    assert!(cfg!(target_feature = "sse4.2"));
+    assert!(cfg!(not(target_feature = "crc32")));
+}