Send -march to gcc

src/base.rs

@@ -19,7 +19,7 @@ use rustc_codegen_ssa::traits::DebugInfoMethods;
 use rustc_session::config::DebugInfo;
 use rustc_span::Symbol;
 
-use crate::LockedTargetInfo;
+use crate::{LockedTargetInfo, gcc_util};
 use crate::GccContext;
 use crate::builder::Builder;
 use crate::context::CodegenCx;
@@ -101,8 +101,6 @@ pub fn compile_codegen_unit(tcx: TyCtxt<'_>, cgu_name: Symbol, target_info: Lock
         // TODO(antoyo): only set on x86 platforms.
         context.add_command_line_option("-masm=intel");
 
-        // 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
             // SSE2 is multiple builtins, so we use the AVX __builtin_ia32_cmppd instead.
@@ -127,6 +125,11 @@ pub fn compile_codegen_unit(tcx: TyCtxt<'_>, cgu_name: Symbol, target_info: Lock
             context.add_command_line_option("-fno-pie");
         }
 
+        let target_cpu = gcc_util::target_cpu(tcx.sess);
+        if target_cpu != "generic" {
+            context.add_command_line_option(&format!("-march={}", target_cpu));
+        }
+
         if tcx.sess.opts.unstable_opts.function_sections.unwrap_or(tcx.sess.target.function_sections) {
             context.add_command_line_option("-ffunction-sections");
             context.add_command_line_option("-fdata-sections");

src/gcc_util.rs

@@ -198,3 +198,18 @@ pub fn check_tied_features(sess: &Session, features: &FxHashMap<&str, bool>) ->
     }
     None
 }
+
+fn handle_native(name: &str) -> &str {
+    if name != "native" {
+        return name;
+    }
+
+    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()),
+    }
+}

src/lib.rs

@@ -107,6 +107,7 @@ use rustc_span::fatal_error::FatalError;
 use tempfile::TempDir;
 
 use crate::back::lto::ModuleBuffer;
+use crate::gcc_util::target_cpu;
 
 fluent_messages! { "../messages.ftl" }
 
@@ -366,21 +367,6 @@ fn to_gcc_opt_level(optlevel: Option<OptLevel>) -> OptimizationLevel {
     }
 }
 
-fn handle_native(name: &str) -> &str {
-    if name != "native" {
-        return name;
-    }
-
-    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()),
-    }
-}
-
 pub fn target_features(sess: &Session, allow_unstable: bool, target_info: &LockedTargetInfo) -> Vec<Symbol> {
     supported_target_features(sess)
         .iter()