compiler, runtime: open code select

    
    This is the gofrontend version of https://golang.org/cl/37933,
    https://golang.org/cl/37934, and https://golang.org/cl/37935.
    Open code the initialization of select cases.
    
    This is a step toward updating libgo to the 1.11 release.
    
    Reviewed-on: https://go-review.googlesource.com/135000

From-SVN: r264290

gcc/go/gofrontend/MERGE

-f68c03e509b26e7f483f2800eb70a5fbf3f74d0b
+f2cd046a4e0d681c3d21ee547b437d3eab8af268
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/escape.cc

@@ -1361,7 +1361,13 @@ Escape_analysis_assign::statement(Block*, size_t*, Statement* s)
       {
         Expression* init = s->temporary_statement()->init();
         if (init != NULL)
-          this->assign(Node::make_node(s), Node::make_node(init));
+	  {
+	    Node* n = Node::make_node(init);
+	    if (s->temporary_statement()->value_escapes())
+	      this->assign(this->context_->sink(), n);
+	    else
+	      this->assign(Node::make_node(s), n);
+	  }
       }
       break;
 
@@ -1616,15 +1622,6 @@ Escape_analysis_assign::expression(Expression** pexpr)
                 }
                 break;
 
-              case Runtime::SELECTSEND:
-                {
-                  // Send to a channel, lose track. The last argument is
-                  // the address of the value to send.
-                  Node* arg_node = Node::make_node(call->args()->back());
-                  this->assign_deref(this->context_->sink(), arg_node);
-                }
-                break;
-
               case Runtime::IFACEE2T2:
               case Runtime::IFACEI2T2:
                 {
@@ -2228,8 +2225,12 @@ Escape_analysis_assign::assign(Node* dst, Node* src)
         case Expression::EXPRESSION_TEMPORARY_REFERENCE:
           {
             // Temporary is tracked through the underlying Temporary_statement.
-            Statement* t = dst->expr()->temporary_reference_expression()->statement();
-            dst = Node::make_node(t);
+            Temporary_statement* t =
+	      dst->expr()->temporary_reference_expression()->statement();
+	    if (t->value_escapes())
+	      dst = this->context_->sink();
+	    else
+	      dst = Node::make_node(t);
           }
           break;
 

gcc/go/gofrontend/runtime.def

@@ -152,22 +152,10 @@ DEF_GO_RUNTIME(CHANRECV1, "runtime.chanrecv1", P2(CHAN, POINTER), R0())
 DEF_GO_RUNTIME(CHANRECV2, "runtime.chanrecv2", P2(CHAN, POINTER), R1(BOOL))
 
 
-// Start building a select statement.
-DEF_GO_RUNTIME(NEWSELECT, "runtime.newselect", P3(POINTER, INT64, INT32), R0())
-
-// Add a default clause to a select statement.
-DEF_GO_RUNTIME(SELECTDEFAULT, "runtime.selectdefault", P1(POINTER), R0())
-
-// Add a send clause to a select statement.
-DEF_GO_RUNTIME(SELECTSEND, "runtime.selectsend", P3(POINTER, CHAN, POINTER),
-	       R0())
-
-// Add a receive clause to a select statement.
-DEF_GO_RUNTIME(SELECTRECV, "runtime.selectrecv",
-	       P4(POINTER, CHAN, POINTER, BOOLPTR), R0())
-
-// Run a select, returning the index of the selected clause.
-DEF_GO_RUNTIME(SELECTGO, "runtime.selectgo", P1(POINTER), R1(INT))
+// Run a select, returning the index of the selected clause and
+// whether that channel received a value.
+DEF_GO_RUNTIME(SELECTGO, "runtime.selectgo", P3(POINTER, POINTER, INT),
+	       R2(INT, BOOL))
 
 
 // Panic.

gcc/go/gofrontend/statements.h

@@ -622,7 +622,8 @@ class Temporary_statement : public Statement
  public:
   Temporary_statement(Type* type, Expression* init, Location location)
     : Statement(STATEMENT_TEMPORARY, location),
-      type_(type), init_(init), bvariable_(NULL), is_address_taken_(false)
+      type_(type), init_(init), bvariable_(NULL), is_address_taken_(false),
+      value_escapes_(false)
   { }
 
   // Return the type of the temporary variable.
@@ -640,6 +641,16 @@ class Temporary_statement : public Statement
   set_is_address_taken()
   { this->is_address_taken_ = true; }
 
+  // Whether the value escapes.
+  bool
+  value_escapes() const
+  { return this->value_escapes_; }
+
+  // Record that the value escapes.
+  void
+  set_value_escapes()
+  { this->value_escapes_ = true; }
+
   // Return the temporary variable.  This should not be called until
   // after the statement itself has been converted.
   Bvariable*
@@ -676,6 +687,9 @@ class Temporary_statement : public Statement
   Bvariable* bvariable_;
   // True if something takes the address of this temporary variable.
   bool is_address_taken_;
+  // True if the value assigned to this temporary variable escapes.
+  // This is used for select statements.
+  bool value_escapes_;
 };
 
 // A variable declaration.  This marks the point in the code where a
@@ -851,7 +865,7 @@ class Send_statement : public Statement
 
   Expression*
   channel()
-  { return this->channel_; }  
+  { return this->channel_; }
 
   Expression*
   val()
@@ -924,7 +938,8 @@ class Select_clauses
 
   // Lower statements.
   void
-  lower(Gogo*, Named_object*, Block*, Temporary_statement*);
+  lower(Gogo*, Named_object*, Block*, Temporary_statement*,
+	Temporary_statement*);
 
   // Determine types.
   void
@@ -941,7 +956,7 @@ class Select_clauses
 
   // Convert to the backend representation.
   Bstatement*
-  get_backend(Translate_context*, Temporary_statement* sel,
+  get_backend(Translate_context*, Temporary_statement* index,
 	      Unnamed_label* break_label, Location);
 
   // Dump AST representation.
@@ -974,7 +989,8 @@ class Select_clauses
 
     // Lower statements.
     void
-    lower(Gogo*, Named_object*, Block*, Temporary_statement*);
+    lower(Gogo*, Named_object*, Block*, Temporary_statement*, size_t,
+	  Temporary_statement*);
 
     // Determine types.
     void
@@ -1027,6 +1043,14 @@ class Select_clauses
     dump_clause(Ast_dump_context*) const;
 
    private:
+    // These values must match the values in libgo/go/runtime/select.go.
+    enum
+    {
+      caseRecv = 1,
+      caseSend = 2,
+      caseDefault = 3,
+    };
+
     void
     lower_default(Block*, Expression*);
 
@@ -1034,7 +1058,11 @@ class Select_clauses
     lower_send(Block*, Expression*, Expression*);
 
     void
-    lower_recv(Gogo*, Named_object*, Block*, Expression*, Expression*);
+    lower_recv(Gogo*, Named_object*, Block*, Expression*, Expression*,
+	       Temporary_statement*);
+
+    void
+    set_case(Block*, Expression*, Expression*, Expression*, int);
 
     // The channel.
     Expression* channel_;
@@ -1072,7 +1100,7 @@ class Select_statement : public Statement
  public:
   Select_statement(Location location)
     : Statement(STATEMENT_SELECT, location),
-      clauses_(NULL), sel_(NULL), break_label_(NULL), is_lowered_(false)
+      clauses_(NULL), index_(NULL), break_label_(NULL), is_lowered_(false)
   { }
 
   // Add the clauses.
@@ -1115,8 +1143,8 @@ class Select_statement : public Statement
  private:
   // The select clauses.
   Select_clauses* clauses_;
-  // A temporary which holds the select structure we build up at runtime.
-  Temporary_statement* sel_;
+  // A temporary that holds the index value returned by selectgo.
+  Temporary_statement* index_;
   // The break label.
   Unnamed_label* break_label_;
   // Whether this statement has been lowered.
@@ -1609,7 +1637,7 @@ class Case_clauses
   // Dump the AST representation to a dump context.
   void
   dump_clauses(Ast_dump_context*) const;
-  
+
  private:
   // For a constant switch we need to keep a record of constants we
   // have already seen.
@@ -1683,7 +1711,7 @@ class Case_clauses
     // Dump the AST representation to a dump context.
     void
     dump_clause(Ast_dump_context*) const;
-  
+
    private:
     // The list of case expressions.
     Expression_list* cases_;

gcc/go/gofrontend/types.cc

@@ -8557,51 +8557,29 @@ Channel_type::do_import(Import* imp)
   return Type::make_channel_type(may_send, may_receive, element_type);
 }
 
-// Return the type to manage a select statement with ncases case
-// statements.  A value of this type is allocated on the stack.  This
-// must match the type hselect in libgo/go/runtime/select.go.
+// Return the type that the runtime package uses for one case of a
+// select statement.  An array of values of this type is allocated on
+// the stack.  This must match scase in libgo/go/runtime/select.go.
 
 Type*
-Channel_type::select_type(int ncases)
+Channel_type::select_case_type()
 {
-  Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
-  Type* uint16_type = Type::lookup_integer_type("uint16");
-
   static Struct_type* scase_type;
   if (scase_type == NULL)
     {
-      Type* uintptr_type = Type::lookup_integer_type("uintptr");
-      Type* uint64_type = Type::lookup_integer_type("uint64");
+      Type* unsafe_pointer_type =
+	Type::make_pointer_type(Type::make_void_type());
+      Type* uint16_type = Type::lookup_integer_type("uint16");
+      Type* int64_type = Type::lookup_integer_type("int64");
       scase_type =
-	Type::make_builtin_struct_type(7,
+	Type::make_builtin_struct_type(4,
+				       "c", unsafe_pointer_type,
 				       "elem", unsafe_pointer_type,
-				       "chan", unsafe_pointer_type,
-				       "pc", uintptr_type,
 				       "kind", uint16_type,
-				       "index", uint16_type,
-				       "receivedp", unsafe_pointer_type,
-				       "releasetime", uint64_type);
+				       "releasetime", int64_type);
       scase_type->set_is_struct_incomparable();
     }
-
-  Expression* ncases_expr =
-    Expression::make_integer_ul(ncases, NULL, Linemap::predeclared_location());
-  Array_type* scases = Type::make_array_type(scase_type, ncases_expr);
-  scases->set_is_array_incomparable();
-  Array_type* order = Type::make_array_type(uint16_type, ncases_expr);
-  order->set_is_array_incomparable();
-
-  Struct_type* ret =
-    Type::make_builtin_struct_type(7,
-				   "tcase", uint16_type,
-				   "ncase", uint16_type,
-				   "pollorder", unsafe_pointer_type,
-				   "lockorder", unsafe_pointer_type,
-				   "scase", scases,
-				   "lockorderarr", order,
-				   "pollorderarr", order);
-  ret->set_is_struct_incomparable();
-  return ret;
+  return scase_type;
 }
 
 // Make a new channel type.

gcc/go/gofrontend/types.h

@@ -2981,7 +2981,7 @@ class Channel_type : public Type
   make_chan_type_descriptor_type();
 
   static Type*
-  select_type(int ncases);
+  select_case_type();
 
  protected:
   int