From 936a8232df56cf6fbf41beb3b2329a99498d2167 Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Tue, 25 Feb 2025 15:25:54 +1100 Subject: Change signature of `target_features_cfg`. Currently it is called twice, once with `allow_unstable` set to true and once with it set to false. This results in some duplicated work. Most notably, for the LLVM backend, `LLVMRustHasFeature` is called twice for every feature, and it's moderately slow. For very short running compilations on platforms with many features (e.g. a `check` build of hello-world on x86) this is a significant fraction of runtime. This commit changes `target_features_cfg` so it is only called once, and it now returns a pair of feature sets. This halves the number of `LLVMRustHasFeature` calls. --- compiler/rustc_interface/src/util.rs | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'compiler/rustc_interface/src/util.rs') diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs index bc2aae7cd87..5cccab893bb 100644 --- a/compiler/rustc_interface/src/util.rs +++ b/compiler/rustc_interface/src/util.rs @@ -39,11 +39,11 @@ pub(crate) fn add_configuration( ) { let tf = sym::target_feature; - let unstable_target_features = codegen_backend.target_features_cfg(sess, true); - sess.unstable_target_features.extend(unstable_target_features.iter().cloned()); + let (target_features, unstable_target_features) = codegen_backend.target_features_cfg(sess); - let target_features = codegen_backend.target_features_cfg(sess, false); - sess.target_features.extend(target_features.iter().cloned()); + sess.unstable_target_features.extend(unstable_target_features.iter().copied()); + + sess.target_features.extend(target_features.iter().copied()); cfg.extend(target_features.into_iter().map(|feat| (tf, Some(feat)))); -- cgit 1.4.1-3-g733a5