add -m64 to gcc args if appropriate

src/comp/back/link.rs

@@ -516,7 +516,9 @@ fn link_binary(sess: session::session,
     let prog: str = "gcc";
     // The invocations of gcc share some flags across platforms
 
-    let gcc_args = [stage, "-m32", "-o", out_filename, obj_filename];
+    let gcc_args =
+        [stage] + sess.get_targ_cfg().target_strs.gcc_args +
+        ["-o", out_filename, obj_filename];
     let lib_cmd;
 
     let os = sess.get_targ_cfg().os;

src/comp/back/target_strs.rs

@@ -4,5 +4,6 @@ type t = {
     module_asm: str,
     meta_sect_name: str,
     data_layout: str,
-    target_triple: str
+    target_triple: str,
+    gcc_args: [str]
 };

src/comp/back/x86.rs

@@ -33,7 +33,9 @@ fn get_target_strs(target_os: session::os) -> target_strs::t {
           session::os_macos. { "i686-apple-darwin" }
           session::os_win32. { "i686-pc-mingw32" }
           session::os_linux. { "i686-unknown-linux-gnu" }
-        }
+        },
+
+        gcc_args: ["-m32"]
     };
 }
 

src/comp/back/x86_64.rs

@@ -33,7 +33,9 @@ fn get_target_strs(target_os: session::os) -> target_strs::t {
           session::os_macos. { "x86_64-apple-darwin" }
           session::os_win32. { "x86_64-pc-mingw32" }
           session::os_linux. { "x86_64-unknown-linux-gnu" }
-        }
+        },
+
+        gcc_args: ["-m64"]
     };
 }
 

src/comp/middle/trans.rs

@@ -6063,11 +6063,13 @@ fn trans_crate(sess: session::session, crate: @ast::crate, tcx: ty::ctxt,
         llvm::LLVMModuleCreateWithNameInContext
             (buf, llvm::LLVMGetGlobalContext())
     });
+    let data_layout = sess.get_targ_cfg().target_strs.data_layout;
+    let targ_triple = sess.get_targ_cfg().target_strs.target_triple;
     let _: () =
-        str::as_buf(sess.get_targ_cfg().target_strs.data_layout,
+        str::as_buf(data_layout,
                     {|buf| llvm::LLVMSetDataLayout(llmod, buf) });
     let _: () =
-        str::as_buf(sess.get_targ_cfg().target_strs.target_triple,
+        str::as_buf(targ_triple,
                     {|buf| llvm::LLVMSetTarget(llmod, buf) });
     let targ_cfg = sess.get_targ_cfg();
     let td = mk_target_data(sess.get_targ_cfg().target_strs.data_layout);