Merging upstream version 1.75.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 230 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_gcc/src/gcc_util.rs b/compiler/rustc_codegen_gcc/src/gcc_util.rs
new file mode 100644
index 000000000..1248fdcd2
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/gcc_util.rs
@@ -0,0 +1,230 @@
+#[cfg(feature="master")]
+use gccjit::Context;
+use smallvec::{smallvec, SmallVec};
+
+use rustc_codegen_ssa::target_features::{
+    supported_target_features, tied_target_features, RUSTC_SPECIFIC_FEATURES,
+};
+use rustc_data_structures::fx::FxHashMap;
+use rustc_middle::bug;
+use rustc_session::Session;
+
+use crate::errors::{PossibleFeature, TargetFeatureDisableOrEnable, UnknownCTargetFeature, UnknownCTargetFeaturePrefix};
+
+/// The list of GCC features computed from CLI flags (`-Ctarget-cpu`, `-Ctarget-feature`,
+/// `--target` and similar).
+pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<String> {
+    // Features that come earlier are overridden by conflicting features later in the string.
+    // Typically we'll want more explicit settings to override the implicit ones, so:
+    //
+    // * Features from -Ctarget-cpu=*; are overridden by [^1]
+    // * Features implied by --target; are overridden by
+    // * Features from -Ctarget-feature; are overridden by
+    // * function specific features.
+    //
+    // [^1]: target-cpu=native is handled here, other target-cpu values are handled implicitly
+    // through GCC march implementation.
+    //
+    // FIXME(nagisa): it isn't clear what's the best interaction between features implied by
+    // `-Ctarget-cpu` and `--target` are. On one hand, you'd expect CLI arguments to always
+    // override anything that's implicit, so e.g. when there's no `--target` flag, features implied
+    // the host target are overridden by `-Ctarget-cpu=*`. On the other hand, what about when both
+    // `--target` and `-Ctarget-cpu=*` are specified? Both then imply some target features and both
+    // flags are specified by the user on the CLI. It isn't as clear-cut which order of precedence
+    // should be taken in cases like these.
+    let mut features = vec![];
+
+    // Features implied by an implicit or explicit `--target`.
+    features.extend(
+        sess.target
+            .features
+            .split(',')
+            .filter(|v| !v.is_empty() && backend_feature_name(v).is_some())
+            .map(String::from),
+    );
+
+    // -Ctarget-features
+    let supported_features = supported_target_features(sess);
+    let mut featsmap = FxHashMap::default();
+    let feats = sess.opts.cg.target_feature
+        .split(',')
+        .filter_map(|s| {
+            let enable_disable = match s.chars().next() {
+                None => return None,
+                Some(c @ ('+' | '-')) => c,
+                Some(_) => {
+                    if diagnostics {
+                        sess.emit_warning(UnknownCTargetFeaturePrefix { feature: s });
+                    }
+                    return None;
+                }
+            };
+
+            let feature = backend_feature_name(s)?;
+            // Warn against use of GCC specific feature names on the CLI.
+            if diagnostics && !supported_features.iter().any(|&(v, _)| v == feature) {
+                let rust_feature = supported_features.iter().find_map(|&(rust_feature, _)| {
+                    let gcc_features = to_gcc_features(sess, rust_feature);
+                    if gcc_features.contains(&feature) && !gcc_features.contains(&rust_feature) {
+                        Some(rust_feature)
+                    } else {
+                        None
+                    }
+                });
+                let unknown_feature =
+                    if let Some(rust_feature) = rust_feature {
+                        UnknownCTargetFeature {
+                            feature,
+                            rust_feature: PossibleFeature::Some { rust_feature },
+                        }
+                    }
+                    else {
+                        UnknownCTargetFeature { feature, rust_feature: PossibleFeature::None }
+                    };
+                sess.emit_warning(unknown_feature);
+            }
+
+            if diagnostics {
+                // FIXME(nagisa): figure out how to not allocate a full hashset here.
+                featsmap.insert(feature, enable_disable == '+');
+            }
+
+            // rustc-specific features do not get passed down to GCC…
+            if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
+                return None;
+            }
+            // ... otherwise though we run through `to_gcc_features` when
+            // passing requests down to GCC. This means that all in-language
+            // features also work on the command line instead of having two
+            // different names when the GCC name and the Rust name differ.
+            Some(to_gcc_features(sess, feature)
+                .iter()
+                .flat_map(|feat| to_gcc_features(sess, feat).into_iter())
+                .map(|feature| {
+                    if enable_disable == '-' {
+                        format!("-{}", feature)
+                    }
+                    else {
+                        feature.to_string()
+                    }
+                })
+                .collect::<Vec<_>>(),
+            )
+        })
+        .flatten();
+    features.extend(feats);
+
+    if diagnostics {
+        if let Some(f) = check_tied_features(sess, &featsmap) {
+            sess.emit_err(TargetFeatureDisableOrEnable {
+                features: f,
+                span: None,
+                missing_features: None,
+            });
+        }
+    }
+
+    features
+}
+
+/// Returns a feature name for the given `+feature` or `-feature` string.
+///
+/// Only allows features that are backend specific (i.e. not [`RUSTC_SPECIFIC_FEATURES`].)
+fn backend_feature_name(s: &str) -> Option<&str> {
+    // features must start with a `+` or `-`.
+    let feature = s.strip_prefix(&['+', '-'][..]).unwrap_or_else(|| {
+        bug!("target feature `{}` must begin with a `+` or `-`", s);
+    });
+    // Rustc-specific feature requests like `+crt-static` or `-crt-static`
+    // are not passed down to GCC.
+    if RUSTC_SPECIFIC_FEATURES.contains(&feature) {
+        return None;
+    }
+    Some(feature)
+}
+
+// To find a list of GCC's names, check https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
+pub fn to_gcc_features<'a>(sess: &Session, s: &'a str) -> SmallVec<[&'a str; 2]> {
+    let arch = if sess.target.arch == "x86_64" { "x86" } else { &*sess.target.arch };
+    match (arch, s) {
+        ("x86", "sse4.2") => smallvec!["sse4.2", "crc32"],
+        ("x86", "pclmulqdq") => smallvec!["pclmul"],
+        ("x86", "rdrand") => smallvec!["rdrnd"],
+        ("x86", "bmi1") => smallvec!["bmi"],
+        ("x86", "cmpxchg16b") => smallvec!["cx16"],
+        ("x86", "avx512vaes") => smallvec!["vaes"],
+        ("x86", "avx512gfni") => smallvec!["gfni"],
+        ("x86", "avx512vpclmulqdq") => smallvec!["vpclmulqdq"],
+        // NOTE: seems like GCC requires 'avx512bw' for 'avx512vbmi2'.
+        ("x86", "avx512vbmi2") => smallvec!["avx512vbmi2", "avx512bw"],
+        // NOTE: seems like GCC requires 'avx512bw' for 'avx512bitalg'.
+        ("x86", "avx512bitalg") => smallvec!["avx512bitalg", "avx512bw"],
+        ("aarch64", "rcpc2") => smallvec!["rcpc-immo"],
+        ("aarch64", "dpb") => smallvec!["ccpp"],
+        ("aarch64", "dpb2") => smallvec!["ccdp"],
+        ("aarch64", "frintts") => smallvec!["fptoint"],
+        ("aarch64", "fcma") => smallvec!["complxnum"],
+        ("aarch64", "pmuv3") => smallvec!["perfmon"],
+        ("aarch64", "paca") => smallvec!["pauth"],
+        ("aarch64", "pacg") => smallvec!["pauth"],
+        // Rust ties fp and neon together. In GCC neon implicitly enables fp,
+        // but we manually enable neon when a feature only implicitly enables fp
+        ("aarch64", "f32mm") => smallvec!["f32mm", "neon"],
+        ("aarch64", "f64mm") => smallvec!["f64mm", "neon"],
+        ("aarch64", "fhm") => smallvec!["fp16fml", "neon"],
+        ("aarch64", "fp16") => smallvec!["fullfp16", "neon"],
+        ("aarch64", "jsconv") => smallvec!["jsconv", "neon"],
+        ("aarch64", "sve") => smallvec!["sve", "neon"],
+        ("aarch64", "sve2") => smallvec!["sve2", "neon"],
+        ("aarch64", "sve2-aes") => smallvec!["sve2-aes", "neon"],
+        ("aarch64", "sve2-sm4") => smallvec!["sve2-sm4", "neon"],
+        ("aarch64", "sve2-sha3") => smallvec!["sve2-sha3", "neon"],
+        ("aarch64", "sve2-bitperm") => smallvec!["sve2-bitperm", "neon"],
+        (_, s) => smallvec![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(|feature| enabled != features.get(feature)) {
+            return Some(tied);
+        }
+    }
+    None
+}
+
+fn arch_to_gcc(name: &str) -> &str {
+    match name {
+        "M68020" => "68020",
+         _ => name,
+    }
+}
+
+fn handle_native(name: &str) -> &str {
+    if name != "native" {
+        return arch_to_gcc(name);
+    }
+
+    #[cfg(feature="master")]
+    {
+        // Get the native arch.
+        let context = Context::default();
+        context.get_target_info().arch().unwrap()
+            .to_str()
+            .unwrap()
+    }
+    #[cfg(not(feature="master"))]
+    unimplemented!();
+}
+
+pub fn target_cpu(sess: &Session) -> &str {
+    match sess.opts.cg.target_cpu {
+        Some(ref name) => handle_native(name),
+        None => handle_native(sess.target.cpu.as_ref()),
+    }
+}