bjoernager/rust
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Use collect to initialize features.

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This commit is contained in:
Nicholas Nethercote 2025-02-25 16:27:09 +11:00
parent 936a8232df
commit 35b7994ea8
1 changed files with 25 additions and 28 deletions
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53
compiler/rustc_codegen_llvm/src/llvm_util.rs
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@ -307,8 +307,6 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
/// ///
/// We do not have to worry about RUSTC_SPECIFIC_FEATURES here, those are handled outside codegen. /// We do not have to worry about RUSTC_SPECIFIC_FEATURES here, those are handled outside codegen.
pub(crate) fn target_features_cfg(sess: &Session) -> (Vec<Symbol>, Vec<Symbol>) { pub(crate) fn target_features_cfg(sess: &Session) -> (Vec<Symbol>, Vec<Symbol>) {
let mut features: FxHashSet<Symbol> = Default::default();
// Add base features for the target. // Add base features for the target.
// We do *not* add the -Ctarget-features there, and instead duplicate the logic for that below. // We do *not* add the -Ctarget-features there, and instead duplicate the logic for that below.
// The reason is that if LLVM considers a feature implied but we do not, we don't want that to // The reason is that if LLVM considers a feature implied but we do not, we don't want that to
@ -318,34 +316,33 @@ pub(crate) fn target_features_cfg(sess: &Session) -> (Vec<Symbol>, Vec<Symbol>)
let target_machine = create_informational_target_machine(sess, true); let target_machine = create_informational_target_machine(sess, true);
// Compute which of the known target features are enabled in the 'base' target machine. We only // Compute which of the known target features are enabled in the 'base' target machine. We only
// consider "supported" features; "forbidden" features are not reflected in `cfg` as of now. // consider "supported" features; "forbidden" features are not reflected in `cfg` as of now.
features.extend( let mut features: FxHashSet<Symbol> = sess
sess.target .target
.rust_target_features() .rust_target_features()
.iter() .iter()
.filter(|(feature, _, _)| { .filter(|(feature, _, _)| {
// skip checking special features, as LLVM may not understand them // skip checking special features, as LLVM may not understand them
if RUSTC_SPECIAL_FEATURES.contains(feature) { if RUSTC_SPECIAL_FEATURES.contains(feature) {
return true; return true;
} }
// check that all features in a given smallvec are enabled // check that all features in a given smallvec are enabled
if let Some(feat) = to_llvm_features(sess, feature) { if let Some(feat) = to_llvm_features(sess, feature) {
for llvm_feature in feat { for llvm_feature in feat {
let cstr = SmallCStr::new(llvm_feature); let cstr = SmallCStr::new(llvm_feature);
// `LLVMRustHasFeature` is moderately expensive. On targets with many // `LLVMRustHasFeature` is moderately expensive. On targets with many
// features (e.g. x86) these calls take a non-trivial fraction of runtime // features (e.g. x86) these calls take a non-trivial fraction of runtime
// when compiling very small programs. // when compiling very small programs.
if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } {
{ return false;
return false;
}
} }
true
} else {
false
} }
}) true
.map(|(feature, _, _)| Symbol::intern(feature)), } else {
); false
}
})
.map(|(feature, _, _)| Symbol::intern(feature))
.collect();
// Add enabled and remove disabled features. // Add enabled and remove disabled features.
for (enabled, feature) in for (enabled, feature) in