[Go] Use the static chain as closure parameter from Go

[Richard Henderson]

This is the non-gofrontend patch corresponding to

  https://codereview.appspot.com/180890043/

Ian, I thought I'd sent it out at the same time as
the codereview, but I guess it never went.


r~

commit 5a78f18cf8cd2160c62472693222cc72bd4379b6
Author: Richard Henderson <r...@redhat.com>
Date:   Tue Oct 7 12:28:55 2014 -0700

    Use the static chain as the closure parameter from Go
    
    This is not a standalone patch; it only touches the Go front end.
    Further changes are required for the Go runtime.

diff --git a/gcc/go/go-gcc.cc b/gcc/go/go-gcc.cc
index 9aad6b0..74be2d6 100644
--- a/gcc/go/go-gcc.cc
+++ b/gcc/go/go-gcc.cc
@@ -315,7 +315,7 @@ class Gcc_backend : public Backend
 
   Bexpression*
   call_expression(Bexpression* fn, const std::vector<Bexpression*>& args,
-                  Location);
+                  Bexpression* static_chain, Location);
 
   // Statements.
 
@@ -396,6 +396,9 @@ class Gcc_backend : public Backend
                     Location);
 
   Bvariable*
+  static_chain_variable(Bfunction*, const std::string&, Btype*, Location);
+
+  Bvariable*
   temporary_variable(Bfunction*, Bblock*, Btype*, Bexpression*, bool,
                     Location, Bstatement**);
 
@@ -1770,7 +1773,7 @@ Gcc_backend::array_index_expression(Bexpression* array, 
Bexpression* index,
 Bexpression*
 Gcc_backend::call_expression(Bexpression* fn_expr,
                              const std::vector<Bexpression*>& fn_args,
-                             Location location)
+                             Bexpression* chain_expr, Location location)
 {
   tree fn = fn_expr->get_tree();
   if (fn == error_mark_node || TREE_TYPE(fn) == error_mark_node)
@@ -1830,6 +1833,9 @@ Gcc_backend::call_expression(Bexpression* fn_expr,
                            excess_type != NULL_TREE ? excess_type : rettype,
                            fn, nargs, args);
 
+  if (chain_expr)
+    CALL_EXPR_STATIC_CHAIN (ret) = chain_expr->get_tree();
+
   if (excess_type != NULL_TREE)
     {
       // Calling convert here can undo our excess precision change.
@@ -2451,6 +2457,40 @@ Gcc_backend::parameter_variable(Bfunction* function, 
const std::string& name,
   return new Bvariable(decl);
 }
 
+// Make a static chain variable.
+
+Bvariable*
+Gcc_backend::static_chain_variable(Bfunction* function, const std::string& 
name,
+                                  Btype* btype, Location location)
+{
+  tree type_tree = btype->get_tree();
+  if (type_tree == error_mark_node)
+    return this->error_variable();
+  tree decl = build_decl(location.gcc_location(), PARM_DECL,
+                        get_identifier_from_string(name), type_tree);
+  tree fndecl = function->get_tree();
+  DECL_CONTEXT(decl) = fndecl;
+  DECL_ARG_TYPE(decl) = type_tree;
+  TREE_USED(decl) = 1;
+  DECL_ARTIFICIAL(decl) = 1;
+  DECL_IGNORED_P(decl) = 1;
+  TREE_READONLY(decl) = 1;
+
+  struct function *f = DECL_STRUCT_FUNCTION(fndecl);
+  if (f == NULL)
+    {
+      push_struct_function(fndecl);
+      pop_cfun();
+      f = DECL_STRUCT_FUNCTION(fndecl);
+    }
+  gcc_assert(f->static_chain_decl == NULL);
+  f->static_chain_decl = decl;
+  DECL_STATIC_CHAIN(fndecl) = 1;
+
+  go_preserve_from_gc(decl);
+  return new Bvariable(decl);
+}
+
 // Make a temporary variable.
 
 Bvariable*