2 files changed, 164 insertions, 0 deletions
diff --git a/library/stdarch/crates/simd-test-macro/Cargo.toml b/library/stdarch/crates/simd-test-macro/Cargo.toml
new file mode 100644
index 000000000..c3ecf981e
--- /dev/null
+++ b/library/stdarch/crates/simd-test-macro/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "simd-test-macro"
+version = "0.1.0"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
+
+[lib]
+proc-macro = true
+test = false
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
diff --git a/library/stdarch/crates/simd-test-macro/src/lib.rs b/library/stdarch/crates/simd-test-macro/src/lib.rs
new file mode 100644
index 000000000..9d81a4c5e
--- /dev/null
+++ b/library/stdarch/crates/simd-test-macro/src/lib.rs
@@ -0,0 +1,151 @@
+//! Implementation of the `#[simd_test]` macro
+//!
+//! This macro expands to a `#[test]` function which tests the local machine
+//! for the appropriate cfg before calling the inner test function.
+#![deny(rust_2018_idioms)]
+
+#[macro_use]
+extern crate quote;
+
+use proc_macro2::{Delimiter, Ident, Literal, Span, TokenStream, TokenTree};
+use quote::ToTokens;
+use std::env;
+
+fn string(s: &str) -> TokenTree {
+    Literal::string(s).into()
+}
+
+#[proc_macro_attribute]
+pub fn simd_test(
+    attr: proc_macro::TokenStream,
+    item: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+    let tokens = TokenStream::from(attr).into_iter().collect::<Vec<_>>();
+    if tokens.len() != 3 {
+        panic!("expected #[simd_test(enable = \"feature\")]");
+    }
+    match &tokens[0] {
+        TokenTree::Ident(tt) if *tt == "enable" => {}
+        _ => panic!("expected #[simd_test(enable = \"feature\")]"),
+    }
+    match &tokens[1] {
+        TokenTree::Punct(tt) if tt.as_char() == '=' => {}
+        _ => panic!("expected #[simd_test(enable = \"feature\")]"),
+    }
+    let enable_feature = match &tokens[2] {
+        TokenTree::Literal(tt) => tt.to_string(),
+        _ => panic!("expected #[simd_test(enable = \"feature\")]"),
+    };
+    let enable_feature = enable_feature.trim_start_matches('"').trim_end_matches('"');
+    let target_features: Vec<String> = enable_feature
+        .replace('+', "")
+        .split(',')
+        .map(String::from)
+        .collect();
+
+    let enable_feature = string(enable_feature);
+    let item = TokenStream::from(item);
+    let name = find_name(item.clone());
+
+    let name: TokenStream = name
+        .to_string()
+        .parse()
+        .unwrap_or_else(|_| panic!("failed to parse name: {}", name.to_string()));
+
+    let target = env::var("TARGET").expect(
+        "TARGET environment variable should be set for rustc (e.g. TARGET=x86_64-apple-darwin cargo test)"
+    );
+    let mut force_test = false;
+    let macro_test = match target
+        .split('-')
+        .next()
+        .unwrap_or_else(|| panic!("target triple contained no \"-\": {}", target))
+    {
+        "i686" | "x86_64" | "i586" => "is_x86_feature_detected",
+        "arm" | "armv7" => "is_arm_feature_detected",
+        "aarch64" => "is_aarch64_feature_detected",
+        maybe_riscv if maybe_riscv.starts_with("riscv") => "is_riscv_feature_detected",
+        "powerpc" | "powerpcle" => "is_powerpc_feature_detected",
+        "powerpc64" | "powerpc64le" => "is_powerpc64_feature_detected",
+        "mips" | "mipsel" | "mipsisa32r6" | "mipsisa32r6el" => {
+            // FIXME:
+            // On MIPS CI run-time feature detection always returns false due
+            // to this qemu bug: https://bugs.launchpad.net/qemu/+bug/1754372
+            //
+            // This is a workaround to force the MIPS tests to always run on
+            // CI.
+            force_test = true;
+            "is_mips_feature_detected"
+        }
+        "mips64" | "mips64el" | "mipsisa64r6" | "mipsisa64r6el" => {
+            // FIXME: see above
+            force_test = true;
+            "is_mips64_feature_detected"
+        }
+        t => panic!("unknown target: {}", t),
+    };
+    let macro_test = Ident::new(macro_test, Span::call_site());
+
+    let mut cfg_target_features = TokenStream::new();
+    for feature in target_features {
+        let q = quote_spanned! {
+            proc_macro2::Span::call_site() =>
+            #macro_test!(#feature) &&
+        };
+        q.to_tokens(&mut cfg_target_features);
+    }
+    let q = quote! { true };
+    q.to_tokens(&mut cfg_target_features);
+
+    let test_norun = std::env::var("STDSIMD_TEST_NORUN").is_ok();
+    let maybe_ignore = if test_norun {
+        quote! { #[ignore] }
+    } else {
+        TokenStream::new()
+    };
+
+    let ret: TokenStream = quote_spanned! {
+        proc_macro2::Span::call_site() =>
+        #[allow(non_snake_case)]
+        #[test]
+        #maybe_ignore
+        fn #name() {
+            if #force_test | (#cfg_target_features) {
+                let v = unsafe { #name() };
+                return v;
+            } else {
+                ::stdarch_test::assert_skip_test_ok(stringify!(#name));
+            }
+
+            #[target_feature(enable = #enable_feature)]
+            #item
+        }
+    };
+    ret.into()
+}
+
+fn find_name(item: TokenStream) -> Ident {
+    let mut tokens = item.into_iter();
+    while let Some(tok) = tokens.next() {
+        if let TokenTree::Ident(word) = tok {
+            if word == "fn" {
+                break;
+            }
+        }
+    }
+
+    fn get_ident(tt: TokenTree) -> Option<Ident> {
+        match tt {
+            TokenTree::Ident(i) => Some(i),
+            TokenTree::Group(g) if g.delimiter() == Delimiter::None => {
+                get_ident(g.stream().into_iter().next()?)
+            }
+            _ => None,
+        }
+    }
+
+    tokens
+        .next()
+        .and_then(get_ident)
+        .expect("failed to find function name")
+}