compiler, runtime: support and use single argument go:linkname

    
    The gc compiler has started permitting go:linkname comments with a
    single argument to mean that a function should be externally visible
    outside the package.  Implement this in the Go frontend.
    
    Change the libgo runtime package to use it, rather than repeating the
    name just to export a function.
    
    Remove a couple of unnecessary go:linkname comments on declarations.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/192197

From-SVN: r275239

1 files changed, 11 insertions, 1 deletions

diff --git a/gcc/go/gofrontend/gogo.h b/gcc/go/gofrontend/gogo.h
index 087e890..e742b6e 100644
--- a/gcc/go/gofrontend/gogo.h
+++ b/gcc/go/gofrontend/gogo.h
@@ -547,7 +547,9 @@ class Gogo
   { this->file_block_names_[name] = location; }
 
   // Add a linkname, from the go:linkname compiler directive.  This
-  // changes the externally visible name of go_name to be ext_name.
+  // changes the externally visible name of GO_NAME to be EXT_NAME.
+  // If EXT_NAME is the empty string, GO_NAME is unchanged, but the
+  // symbol is made publicly visible.
   void
   add_linkname(const std::string& go_name, bool is_exported,
 	       const std::string& ext_name, Location location);
@@ -1359,6 +1361,11 @@ class Function
   set_asm_name(const std::string& asm_name)
   { this->asm_name_ = asm_name; }
 
+  // Mark this symbol as exported by a linkname directive.
+  void
+  set_is_exported_by_linkname()
+  { this->is_exported_by_linkname_ = true; }
+
   // Return the pragmas for this function.
   unsigned int
   pragmas() const
@@ -1706,6 +1713,9 @@ class Function
   // True if this function is referenced from an inlined body that
   // will be put into the export data.
   bool is_referenced_by_inline_ : 1;
+  // True if we should make this function visible to other packages
+  // because of a go:linkname directive.
+  bool is_exported_by_linkname_ : 1;
 };
 
 // A snapshot of the current binding state.