Only add feature flags on functions

Author: antoyo

src/attributes.rs

@@ -94,14 +94,18 @@ pub fn from_fn_attrs<'gcc, 'tcx>(
         }))
         .collect::<Vec<_>>();
 
-    // TODO(antoyo): cg_llvm add global features to each function so that LTO keep them.
+    // TODO(antoyo): cg_llvm adds global features to each function so that LTO keep them.
     // Check if GCC requires the same.
     let mut global_features = cx.tcx.global_backend_features(()).iter().map(|s| s.as_str());
     function_features.extend(&mut global_features);
     let target_features = function_features
         .iter()
         .filter_map(|feature| {
-            if feature.contains("soft-float") || feature.contains("retpoline-external-thunk") {
+            // FIXME(antoyo): for some reasons, disabling SSE results in the following error when
+            // compiling Rust for Linux:
+            // SSE register return with SSE disabled
+            // TODO(antoyo): support soft-float and retpoline-external-thunk.
+            if feature.contains("soft-float") || feature.contains("retpoline-external-thunk") || *feature == "-sse" {
                 return None;
             }
 
@@ -118,7 +122,6 @@ pub fn from_fn_attrs<'gcc, 'tcx>(
         .collect::<Vec<_>>()
         .join(",");
     if !target_features.is_empty() {
-        println!("Function {:?}", function_features);
         #[cfg(feature="master")]
         func.add_attribute(FnAttribute::Target(&target_features));
     }

src/base.rs

@@ -98,32 +98,10 @@ pub fn compile_codegen_unit(tcx: TyCtxt<'_>, cgu_name: Symbol, target_info: Lock
             .map(|string| &string[1..])
             .collect();
 
-        let add_cpu_feature_flag = |feature: &str| {
-            if target_info.cpu_supports(feature) && !disabled_features.contains(feature) {
-                context.add_command_line_option(&format!("-m{}", feature));
-            }
-        };
-
-        let disable_cpu_feature = |feature: &str| {
-            if disabled_features.contains(feature) {
-                context.add_command_line_option(&format!("-mno-{}", feature));
-            }
-        };
-
         // TODO(antoyo): only set on x86 platforms.
         context.add_command_line_option("-masm=intel");
 
-        // TODO: instead of setting the features manually, set the correct -march flag.
-        let features = ["64", "avxvnni", "bmi", "sse2", "avx2", "sha", "fma", "fma4", "gfni", "f16c", "aes", "bmi2", "pclmul", "rtm",
-            "vaes", "vpclmulqdq", "xsavec",
-        ];
-
-
-        for feature in &features {
-            disable_cpu_feature(feature);
-
-            //add_cpu_feature_flag(feature);
-        }
+        // TODO(antoyo): set the correct -march flag.
 
         if !disabled_features.contains("avx") {
             // NOTE: we always enable AVX because the equivalent of llvm.x86.sse2.cmp.pd in GCC for

src/gcc_util.rs

@@ -100,7 +100,14 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
             Some(to_gcc_features(sess, feature)
                 .iter()
                 .flat_map(|feat| to_gcc_features(sess, feat).into_iter())
-                .map(String::from)
+                .map(|feature| {
+                    if enable_disable == '-' {
+                        format!("-{}", feature)
+                    }
+                    else {
+                        feature.to_string()
+                    }
+                })
                 .collect::<Vec<_>>(),
             )
         })