Fold aarch64 feature +fp into +neon

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -187,7 +187,6 @@ pub fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> SmallVec<[&'a str; 2]
         ("x86", "avx512vaes") => smallvec!["vaes"],
         ("x86", "avx512gfni") => smallvec!["gfni"],
         ("x86", "avx512vpclmulqdq") => smallvec!["vpclmulqdq"],
-        ("aarch64", "fp") => smallvec!["fp-armv8"],
         ("aarch64", "rcpc2") => smallvec!["rcpc-immo"],
         ("aarch64", "dpb") => smallvec!["ccpp"],
         ("aarch64", "dpb2") => smallvec!["ccdp"],
@@ -230,6 +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> =
@@ -239,13 +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();

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -43,10 +43,8 @@ const ARM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
 ];
 
 const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
-    // FEAT_AdvSimd
+    // FEAT_AdvSimd & FEAT_FP
     ("neon", None),
-    // FEAT_FP
-    ("fp", None),
     // FEAT_FP16
     ("fp16", None),
     // FEAT_SVE
@@ -143,7 +141,6 @@ const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
 ];
 
 const AARCH64_TIED_FEATURES: &[&[&str]] = &[
-    &["fp", "neon"],   // Silicon always has both, so avoid needless complications
     &["paca", "pacg"], // Together these represent `pauth` in LLVM
 ];
 

compiler/rustc_target/src/asm/aarch64.rs

@@ -64,7 +64,7 @@ impl AArch64InlineAsmRegClass {
         match self {
             Self::reg => types! { _: I8, I16, I32, I64, F32, F64; },
             Self::vreg | Self::vreg_low16 => types! {
-                fp: I8, I16, I32, I64, F32, F64,
+                neon: I8, I16, I32, I64, F32, F64,
                     VecI8(8), VecI16(4), VecI32(2), VecI64(1), VecF32(2), VecF64(1),
                     VecI8(16), VecI16(8), VecI32(4), VecI64(2), VecF32(4), VecF64(2);
             },

library/std/tests/run-time-detect.rs

@@ -29,7 +29,6 @@ fn aarch64_linux() {
     println!("neon: {}", is_aarch64_feature_detected!("neon"));
     println!("asimd: {}", is_aarch64_feature_detected!("asimd"));
     println!("pmull: {}", is_aarch64_feature_detected!("pmull"));
-    println!("fp: {}", is_aarch64_feature_detected!("fp"));
     println!("fp16: {}", is_aarch64_feature_detected!("fp16"));
     println!("sve: {}", is_aarch64_feature_detected!("sve"));
     println!("crc: {}", is_aarch64_feature_detected!("crc"));

src/test/run-make-fulldeps/simd-ffi/Makefile

@@ -41,7 +41,7 @@ define MK_TARGETS
 # now.
 $(1): simd.rs
 	$$(RUSTC) --target=$(1) --emit=llvm-ir,asm simd.rs \
-                -C target-feature='+fp,+neon,+sse2' -C extra-filename=-$(1)
+                -C target-feature='+neon,+sse2' -C extra-filename=-$(1)
 endef
 
 $(foreach targetxxx,$(TARGETS),$(eval $(call MK_TARGETS,$(targetxxx))))

src/test/ui/asm/aarch64/bad-reg.rs

@@ -1,5 +1,5 @@
 // only-aarch64
-// compile-flags: -C target-feature=+fp
+// compile-flags: -C target-feature=+neon
 
 #![feature(asm_const, asm_sym)]
 

src/test/ui/target-feature/aarch64-neon-works.rs

@@ -0,0 +1,23 @@
+// only-aarch64
+// run-pass
+#![allow(dead_code)]
+use std::arch::*;
+use std::arch::aarch64::*;
+
+// Smoke test to verify aarch64 code that enables NEON compiles.
+fn main() {
+    let _zero = if is_aarch64_feature_detected!("neon") {
+        unsafe {
+            let zeros = zero_vector();
+            vgetq_lane_u8::<1>(zeros)
+        }
+    } else {
+        0
+    };
+}
+
+
+#[target_feature(enable = "neon")]
+unsafe fn zero_vector() -> uint8x16_t {
+    vmovq_n_u8(0)
+}

src/test/ui/target-feature/feature-hierarchy.rs

@@ -0,0 +1,58 @@
+// revisions: aarch64-neon aarch64-sve2
+// [aarch64-neon] compile-flags: -Ctarget-feature=+neon --target=aarch64-unknown-linux-gnu
+// [aarch64-neon] needs-llvm-components: aarch64
+// [aarch64-sve2] compile-flags: -Ctarget-feature=-neon,+sve2 --target=aarch64-unknown-linux-gnu
+// [aarch64-sve2] needs-llvm-components: aarch64
+// build-pass
+#![no_core]
+#![crate_type = "rlib"]
+#![feature(intrinsics, rustc_attrs, no_core, lang_items, staged_api)]
+#![stable(feature = "test", since = "1.0.0")]
+
+// Tests vetting "feature hierarchies" in the cases where we impose them.
+
+// 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(aarch64_neon)]
+fn check_neon_not_sve2() {
+    // This checks that a normal aarch64 target doesn't suddenly jump up the feature hierarchy.
+    assert!(cfg!(target_feature = "neon"));
+    assert!(cfg!(not(target_feature = "sve2")));
+}
+
+#[cfg(aarch64_sve2)]
+fn check_sve2_includes_neon() {
+    // This checks that aarch64's sve2 includes neon
+    assert!(cfg!(target_feature = "neon"));
+    assert!(cfg!(target_feature = "sve2"));
+}

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")));
+}