Move warning reporting from flag_to_backend_features to cfg_target_feature

compiler/rustc_codegen_gcc/src/gcc_util.rs

@@ -11,7 +11,7 @@ fn gcc_features_by_flags(sess: &Session, features: &mut Vec<String>) {
 
 /// 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> {
+pub(crate) fn global_gcc_features(sess: &Session) -> 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:
     //
@@ -36,27 +36,18 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
     features.extend(sess.target.features.split(',').filter(|v| !v.is_empty()).map(String::from));
 
     // -Ctarget-features
-    target_features::flag_to_backend_features(
-        sess,
-        diagnostics,
-        |feature| to_gcc_features(sess, feature),
-        |feature, enable| {
-            // 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.
-            features.extend(
-                to_gcc_features(sess, feature)
-                    .iter()
-                    .flat_map(|feat| to_gcc_features(sess, feat).into_iter())
-                    .map(
-                        |feature| {
-                            if !enable { format!("-{}", feature) } else { feature.to_string() }
-                        },
-                    ),
-            );
-        },
-    );
+    target_features::flag_to_backend_features(sess, |feature, enable| {
+        // 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.
+        features.extend(
+            to_gcc_features(sess, feature)
+                .iter()
+                .flat_map(|feat| to_gcc_features(sess, feat).into_iter())
+                .map(|feature| if !enable { format!("-{}", feature) } else { feature.to_string() }),
+        );
+    });
 
     gcc_features_by_flags(sess, &mut features);
 

compiler/rustc_codegen_gcc/src/lib.rs

@@ -107,7 +107,7 @@ use rustc_target::spec::RelocModel;
 use tempfile::TempDir;
 
 use crate::back::lto::ModuleBuffer;
-use crate::gcc_util::target_cpu;
+use crate::gcc_util::{target_cpu, to_gcc_features};
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
@@ -220,7 +220,7 @@ impl CodegenBackend for GccCodegenBackend {
     }
 
     fn provide(&self, providers: &mut Providers) {
-        providers.global_backend_features = |tcx, ()| gcc_util::global_gcc_features(tcx.sess, true)
+        providers.global_backend_features = |tcx, ()| gcc_util::global_gcc_features(tcx.sess)
     }
 
     fn codegen_crate(&self, tcx: TyCtxt<'_>) -> Box<dyn Any> {
@@ -446,21 +446,25 @@ fn to_gcc_opt_level(optlevel: Option<OptLevel>) -> OptimizationLevel {
 
 /// Returns the features that should be set in `cfg(target_feature)`.
 fn target_config(sess: &Session, target_info: &LockedTargetInfo) -> TargetConfig {
-    let (unstable_target_features, target_features) = cfg_target_feature(sess, |feature| {
-        // TODO: we disable Neon for now since we don't support the LLVM intrinsics for it.
-        if feature == "neon" {
-            return false;
-        }
-        target_info.cpu_supports(feature)
-        // cSpell:disable
-        /*
-          adx, aes, avx, avx2, avx512bf16, avx512bitalg, avx512bw, avx512cd, avx512dq, avx512er, avx512f, avx512fp16, avx512ifma,
-          avx512pf, avx512vbmi, avx512vbmi2, avx512vl, avx512vnni, avx512vp2intersect, avx512vpopcntdq,
-          bmi1, bmi2, cmpxchg16b, ermsb, f16c, fma, fxsr, gfni, lzcnt, movbe, pclmulqdq, popcnt, rdrand, rdseed, rtm,
-          sha, sse, sse2, sse3, sse4.1, sse4.2, sse4a, ssse3, tbm, vaes, vpclmulqdq, xsave, xsavec, xsaveopt, xsaves
-        */
-        // cSpell:enable
-    });
+    let (unstable_target_features, target_features) = cfg_target_feature(
+        sess,
+        |feature| to_gcc_features(sess, feature),
+        |feature| {
+            // TODO: we disable Neon for now since we don't support the LLVM intrinsics for it.
+            if feature == "neon" {
+                return false;
+            }
+            target_info.cpu_supports(feature)
+            // cSpell:disable
+            /*
+              adx, aes, avx, avx2, avx512bf16, avx512bitalg, avx512bw, avx512cd, avx512dq, avx512er, avx512f, avx512fp16, avx512ifma,
+              avx512pf, avx512vbmi, avx512vbmi2, avx512vl, avx512vnni, avx512vp2intersect, avx512vpopcntdq,
+              bmi1, bmi2, cmpxchg16b, ermsb, f16c, fma, fxsr, gfni, lzcnt, movbe, pclmulqdq, popcnt, rdrand, rdseed, rtm,
+              sha, sse, sse2, sse3, sse4.1, sse4.2, sse4a, ssse3, tbm, vaes, vpclmulqdq, xsave, xsavec, xsaveopt, xsaves
+            */
+            // cSpell:enable
+        },
+    );
 
     let has_reliable_f16 = target_info.supports_target_dependent_type(CType::Float16);
     let has_reliable_f128 = target_info.supports_target_dependent_type(CType::Float128);

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -107,7 +107,7 @@ pub(crate) fn create_informational_target_machine(
     let config = TargetMachineFactoryConfig { split_dwarf_file: None, output_obj_file: None };
     // Can't use query system here quite yet because this function is invoked before the query
     // system/tcx is set up.
-    let features = llvm_util::global_llvm_features(sess, false, only_base_features);
+    let features = llvm_util::global_llvm_features(sess, only_base_features);
     target_machine_factory(sess, config::OptLevel::No, &features)(config)
         .unwrap_or_else(|err| llvm_err(sess.dcx(), err))
 }

compiler/rustc_codegen_llvm/src/lib.rs

@@ -247,7 +247,7 @@ impl CodegenBackend for LlvmCodegenBackend {
 
     fn provide(&self, providers: &mut Providers) {
         providers.global_backend_features =
-            |tcx, ()| llvm_util::global_llvm_features(tcx.sess, true, false)
+            |tcx, ()| llvm_util::global_llvm_features(tcx.sess, false)
     }
 
     fn print(&self, req: &PrintRequest, out: &mut String, sess: &Session) {

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -291,26 +291,34 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
 pub(crate) fn target_config(sess: &Session) -> TargetConfig {
     let target_machine = create_informational_target_machine(sess, true);
 
-    let (unstable_target_features, target_features) = cfg_target_feature(sess, |feature| {
-        // This closure determines whether the target CPU has the feature according to LLVM. We do
-        // *not* consider the `-Ctarget-feature`s here, as that will be handled later in
-        // `cfg_target_feature`.
-        if let Some(feat) = to_llvm_features(sess, feature) {
-            // All the LLVM features this expands to must be enabled.
-            for llvm_feature in feat {
-                let cstr = SmallCStr::new(llvm_feature);
-                // `LLVMRustHasFeature` is moderately expensive. On targets with many
-                // features (e.g. x86) these calls take a non-trivial fraction of runtime
-                // when compiling very small programs.
-                if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } {
-                    return false;
+    let (unstable_target_features, target_features) = cfg_target_feature(
+        sess,
+        |feature| {
+            to_llvm_features(sess, feature)
+                .map(|f| SmallVec::<[&str; 2]>::from_iter(f.into_iter()))
+                .unwrap_or_default()
+        },
+        |feature| {
+            // This closure determines whether the target CPU has the feature according to LLVM. We do
+            // *not* consider the `-Ctarget-feature`s here, as that will be handled later in
+            // `cfg_target_feature`.
+            if let Some(feat) = to_llvm_features(sess, feature) {
+                // All the LLVM features this expands to must be enabled.
+                for llvm_feature in feat {
+                    let cstr = SmallCStr::new(llvm_feature);
+                    // `LLVMRustHasFeature` is moderately expensive. On targets with many
+                    // features (e.g. x86) these calls take a non-trivial fraction of runtime
+                    // when compiling very small programs.
+                    if !unsafe { llvm::LLVMRustHasFeature(target_machine.raw(), cstr.as_ptr()) } {
+                        return false;
+                    }
                 }
+                true
+            } else {
+                false
             }
-            true
-        } else {
-            false
-        }
-    });
+        },
+    );
 
     let mut cfg = TargetConfig {
         target_features,
@@ -615,11 +623,7 @@ fn llvm_features_by_flags(sess: &Session, features: &mut Vec<String>) {
 
 /// The list of LLVM features computed from CLI flags (`-Ctarget-cpu`, `-Ctarget-feature`,
 /// `--target` and similar).
-pub(crate) fn global_llvm_features(
-    sess: &Session,
-    diagnostics: bool,
-    only_base_features: bool,
-) -> Vec<String> {
+pub(crate) fn global_llvm_features(sess: &Session, only_base_features: 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:
     //
@@ -679,39 +683,27 @@ pub(crate) fn global_llvm_features(
 
     // -Ctarget-features
     if !only_base_features {
-        target_features::flag_to_backend_features(
-            sess,
-            diagnostics,
-            |feature| {
-                to_llvm_features(sess, feature)
-                    .map(|f| SmallVec::<[&str; 2]>::from_iter(f.into_iter()))
-                    .unwrap_or_default()
-            },
-            |feature, enable| {
-                let enable_disable = if enable { '+' } else { '-' };
-                // We run through `to_llvm_features` when
-                // passing requests down to LLVM. This means that all in-language
-                // features also work on the command line instead of having two
-                // different names when the LLVM name and the Rust name differ.
-                let Some(llvm_feature) = to_llvm_features(sess, feature) else { return };
-
-                features.extend(
-                    std::iter::once(format!(
-                        "{}{}",
-                        enable_disable, llvm_feature.llvm_feature_name
-                    ))
-                    .chain(llvm_feature.dependencies.into_iter().filter_map(
-                        move |feat| match (enable, feat) {
+        target_features::flag_to_backend_features(sess, |feature, enable| {
+            let enable_disable = if enable { '+' } else { '-' };
+            // We run through `to_llvm_features` when
+            // passing requests down to LLVM. This means that all in-language
+            // features also work on the command line instead of having two
+            // different names when the LLVM name and the Rust name differ.
+            let Some(llvm_feature) = to_llvm_features(sess, feature) else { return };
+
+            features.extend(
+                std::iter::once(format!("{}{}", enable_disable, llvm_feature.llvm_feature_name))
+                    .chain(llvm_feature.dependencies.into_iter().filter_map(move |feat| {
+                        match (enable, feat) {
                             (_, TargetFeatureFoldStrength::Both(f))
                             | (true, TargetFeatureFoldStrength::EnableOnly(f)) => {
                                 Some(format!("{enable_disable}{f}"))
                             }
                             _ => None,
-                        },
-                    )),
-                )
-            },
-        );
+                        }
+                    })),
+            )
+        });
     }
 
     // We add this in the "base target" so that these show up in `sess.unstable_target_features`.