diff options
Diffstat (limited to 'compiler/rustc_codegen_gcc/src/gcc_util.rs')
| -rw-r--r-- | compiler/rustc_codegen_gcc/src/gcc_util.rs | 223 |
1 files changed, 223 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 00000000000..0514c9988e0 --- /dev/null +++ b/compiler/rustc_codegen_gcc/src/gcc_util.rs @@ -0,0 +1,223 @@ +#[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 handle_native(name: &str) -> &str { + if name != "native" { + return 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()), + } +} |