compiler: import inlinable functions from package data

    
    Start reading the export data generated by the last change in this
    series.  At this point we will inline direct calls to empty functions
    and methods defined in different packages.
    
    Reviewed-on: https://go-review.googlesource.com/c/150062

From-SVN: r266517

gcc/go/ChangeLog

+2018-11-27  Ian Lance Taylor  <iant@golang.org>
+
+	* go-gcc.cc (Gcc_backend::function): Handle function_only_inline
+	flag.
+
 2018-11-13  David Malcolm  <dmalcolm@redhat.com>
 
 	* go-gcc-diagnostics.cc: Replace "source_location" with "location_t".

gcc/go/go-gcc.cc

@@ -3086,6 +3086,11 @@ Gcc_backend::function(Btype* fntype, const std::string& name,
     TREE_THIS_VOLATILE(decl) = 1;
   if ((flags & function_in_unique_section) != 0)
     resolve_unique_section(decl, 0, 1);
+  if ((flags & function_only_inline) != 0)
+    {
+      DECL_EXTERNAL(decl) = 1;
+      DECL_DECLARED_INLINE_P(decl) = 1;
+    }
 
   go_preserve_from_gc(decl);
   return new Bfunction(decl);

gcc/go/gofrontend/MERGE

-3ecc845c337c15d9a19ed8d277e5ee9eaf49c3ad
+f551ab95f46c3d7bb7c032711e10b03bfa995ee2
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/backend.h

@@ -726,6 +726,13 @@ class Backend
   // possible.  This is used for field tracking.
   static const unsigned int function_in_unique_section = 1 << 5;
 
+  // Set if the function should be available for inlining in the
+  // backend, but should not be emitted as a standalone function.  Any
+  // call to the function that is not inlined should be treated as a
+  // call to a function defined in a different compilation unit.  This
+  // is like a C99 function marked inline but not extern.
+  static const unsigned int function_only_inline = 1 << 6;
+
   // Declare or define a function of FNTYPE.
   // NAME is the Go name of the function.  ASM_NAME, if not the empty
   // string, is the name that should be used in the symbol table; this

gcc/go/gofrontend/expressions.cc

@@ -9785,6 +9785,15 @@ Call_expression::do_lower(Gogo* gogo, Named_object* function,
 	}
     }
 
+  // If this is a call to an imported function for which we have an
+  // inlinable function body, add it to the list of functions to give
+  // to the backend as inlining opportunities.
+  Func_expression* fe = this->fn_->func_expression();
+  if (fe != NULL
+      && fe->named_object()->is_function_declaration()
+      && fe->named_object()->func_declaration_value()->has_imported_body())
+    gogo->add_imported_inlinable_function(fe->named_object());
+
   return this;
 }
 

gcc/go/gofrontend/go.cc

@@ -97,8 +97,6 @@ go_parse_input_files(const char** filenames, unsigned int filename_count,
 	}
     }
 
-  ::gogo->linemap()->stop();
-
   ::gogo->clear_file_scope();
 
   // If the global predeclared names are referenced but not defined,
@@ -122,6 +120,10 @@ go_parse_input_files(const char** filenames, unsigned int filename_count,
   // form which is easier to use.
   ::gogo->lower_parse_tree();
 
+  // At this point we have handled all inline functions, so we no
+  // longer need the linemap.
+  ::gogo->linemap()->stop();
+
   // Create function descriptors as needed.
   ::gogo->create_function_descriptors();
 

gcc/go/gofrontend/gogo.h

@@ -43,6 +43,7 @@ class Backend;
 class Export;
 class Export_function_body;
 class Import;
+class Import_function_body;
 class Bexpression;
 class Btype;
 class Bstatement;
@@ -420,6 +421,17 @@ class Gogo
   Named_object*
   declare_package_function(const std::string&, Function_type*, Location);
 
+  // Add a function declaration to the list of functions we may want
+  // to inline.
+  void
+  add_imported_inlinable_function(Named_object*);
+
+  // Add a function to the list of functions that we do want to
+  // inline.
+  void
+  add_imported_inline_function(Named_object* no)
+  { this->imported_inline_functions_.push_back(no); }
+
   // Add a label.
   Label*
   add_label_definition(const std::string&, Location);
@@ -661,7 +673,7 @@ class Gogo
   propagate_escape(Escape_context*, Node*);
 
   // Add notes about the escape level of a function's input and output
-  // parameters for exporting and importing top level functions. 
+  // parameters for exporting and importing top level functions.
   void
   tag_function(Escape_context*, Named_object*);
 
@@ -726,7 +738,7 @@ class Gogo
   void
   simplify_thunk_statements();
 
-  // Dump AST if -fgo-dump-ast is set 
+  // Dump AST if -fgo-dump-ast is set.
   void
   dump_ast(const char* basename);
 
@@ -1062,6 +1074,12 @@ class Gogo
   std::vector<Analysis_set> analysis_sets_;
   // A list of objects to add to the GC roots.
   std::vector<Expression*> gc_roots_;
+  // A list of function declarations with imported bodies that we may
+  // want to inline.
+  std::vector<Named_object*> imported_inlinable_functions_;
+  // A list of functions that we want to inline.  These will be sent
+  // to the backend.
+  std::vector<Named_object*> imported_inline_functions_;
 };
 
 // A block of statements.
@@ -1144,6 +1162,10 @@ class Block
   void
   export_block(Export_function_body*);
 
+  // Turn exported block data into a block.
+  static bool
+  import_block(Block*, Import_function_body*, Location);
+
   // Convert the block to the backend representation.
   Bblock*
   get_backend(Translate_context*);
@@ -1419,6 +1441,17 @@ class Function
   set_export_for_inlining()
   { this->export_for_inlining_ = true; }
 
+  // Return whether this function is inline only.
+  bool
+  is_inline_only() const
+  { return this->is_inline_only_; }
+
+  // Mark the function as inline only: the body should not be emitted
+  // if it is not inlined.
+  void
+  set_is_inline_only()
+  { this->is_inline_only_ = true; }
+
   // Swap with another function.  Used only for the thunk which calls
   // recover.
   void
@@ -1476,14 +1509,15 @@ class Function
   // Export a function with a type.
   static void
   export_func_with_type(Export*, const std::string& name,
-			const Function_type*, bool nointerface, Block* block);
+			const Function_type*, bool nointerface, Block* block,
+			Location);
 
   // Import a function.
   static void
   import_func(Import*, std::string* pname, Typed_identifier** receiver,
 	      Typed_identifier_list** pparameters,
 	      Typed_identifier_list** presults, bool* is_varargs,
-	      bool* nointerface);
+	      bool* nointerface, std::string* body);
 
  private:
   // Type for mapping from label names to Label objects.
@@ -1557,6 +1591,9 @@ class Function
   // True if we should export the body of this function for
   // cross-package inlining.
   bool export_for_inlining_ : 1;
+  // True if this function is inline only: if it should not be emitted
+  // if it is not inlined.
+  bool is_inline_only_ : 1;
 };
 
 // A snapshot of the current binding state.
@@ -1600,7 +1637,8 @@ class Function_declaration
  public:
   Function_declaration(Function_type* fntype, Location location)
     : fntype_(fntype), location_(location), asm_name_(), descriptor_(NULL),
-      fndecl_(NULL), pragmas_(0)
+      fndecl_(NULL), pragmas_(0), imported_body_(),
+      is_on_inlinable_list_(false)
   { }
 
   Function_type*
@@ -1646,6 +1684,30 @@ class Function_declaration
   void
   set_nointerface();
 
+  // Whether we have an imported function body.
+  bool
+  has_imported_body() const
+  { return !this->imported_body_.empty(); }
+
+  // Record the imported body of this function.
+  void
+  set_imported_body(const std::string& imported_body)
+  { this->imported_body_ = imported_body; }
+
+  // Whether this declaration is on the list of inlinable functions.
+  bool
+  is_on_inlinable_list() const
+  { return this->is_on_inlinable_list_; }
+
+  // Set that this function is on the list of inlinable functions.
+  void
+  set_is_on_inlinable_list()
+  { this->is_on_inlinable_list_ = true; }
+
+  // Import the function body, creating a function.
+  void
+  import_function_body(Gogo*, Named_object*);
+
   // Return an expression for the function descriptor, given the named
   // object for this function.  This may only be called for functions
   // without a closure.  This will be an immutable struct with one
@@ -1673,7 +1735,7 @@ class Function_declaration
   {
     Function::export_func_with_type(exp, name, this->fntype_,
 				    this->is_method() && this->nointerface(),
-				    NULL);
+				    NULL, this->location_);
   }
 
   // Check that the types used in this declaration's signature are defined.
@@ -1694,6 +1756,10 @@ class Function_declaration
   Bfunction* fndecl_;
   // Pragmas for this function.  This is a set of GOPRAGMA bits.
   unsigned int pragmas_;
+  // Export data for function body if imported from a different package.
+  std::string imported_body_;
+  // Whether this declaration is already on the list of inlinable functions.
+  bool is_on_inlinable_list_;
 };
 
 // A variable.
@@ -1789,7 +1855,7 @@ class Variable
   bool
   is_in_heap() const
   {
-    return this->is_address_taken_ 
+    return this->is_address_taken_
       && this->escapes_
       && !this->is_global_;
   }
@@ -2103,7 +2169,7 @@ class Result_variable
   void
   set_non_escaping_address_taken()
   { this->is_non_escaping_address_taken_ = true; }
-  
+
   // Return whether this variable escapes the function it is declared in.
   bool
   escapes()
@@ -3200,7 +3266,7 @@ class Package
 
   // Return the bindings.
   Bindings*
-  bindings()
+  bindings() const
   { return this->bindings_; }
 
   // Type used to map import names to package aliases.

gcc/go/gofrontend/import.cc

@@ -744,8 +744,9 @@ Import::import_func(Package* package)
   Typed_identifier_list* results;
   bool is_varargs;
   bool nointerface;
-  Function::import_func(this, &name, &receiver,
-			&parameters, &results, &is_varargs, &nointerface);
+  std::string body;
+  Function::import_func(this, &name, &receiver, &parameters, &results,
+			&is_varargs, &nointerface, &body);
   Function_type *fntype = Type::make_function_type(receiver, parameters,
 						   results, this->location_);
   if (is_varargs)
@@ -788,6 +789,8 @@ Import::import_func(Package* package)
 
   if (nointerface)
     no->func_declaration_value()->set_nointerface();
+  if (!body.empty() && !no->func_declaration_value()->has_imported_body())
+    no->func_declaration_value()->set_imported_body(body);
 
   return no;
 }
@@ -1395,3 +1398,13 @@ Stream_from_file::do_advance(size_t skip)
 	this->data_.clear();
     }
 }
+
+// Class Import_function_body.
+
+// The name of the function we are parsing.
+
+const std::string&
+Import_function_body::name() const
+{
+  return this->named_object_->name();
+}

gcc/go/gofrontend/import.h

@@ -11,6 +11,7 @@
 #include "go-linemap.h"
 
 class Gogo;
+class Block;
 class Package;
 class Type;
 class Named_object;
@@ -464,4 +465,74 @@ class Stream_from_string_ref : public Import::Stream
   size_t end_;
 };
 
+// Class to manage importing a function body.  This is passed around
+// to Statements and Expressions.  It parses the function into the IR.
+
+class Import_function_body
+{
+ public:
+  Import_function_body(Gogo* gogo, Location loc, Named_object* named_object,
+		       const std::string& body, size_t off, Block* block,
+		       int indent)
+    : gogo_(gogo), loc_(loc), named_object_(named_object), body_(body),
+      off_(off), block_(block), indent_(indent)
+  { }
+
+  // The IR.
+  Gogo*
+  gogo()
+  { return this->gogo_; }
+
+  // The location to report in an error message.
+  Location
+  location() const
+  { return this->loc_; }
+
+  // A reference to the body we are reading.
+  const std::string&
+  body() const
+  { return this->body_; }
+
+  // The current offset into the body.
+  size_t
+  off()
+  { return this->off_; }
+
+  // Update the offset into the body.
+  void
+  set_off(size_t off)
+  { this->off_ = off; }
+
+  // The current block.
+  Block*
+  block()
+  { return this->block_; }
+
+  // The current indentation.
+  int
+  indent() const
+  { return this->indent_; }
+
+  // The name of the function we are parsing.
+  const std::string&
+  name() const;
+
+ private:
+  // The IR.
+  Gogo* gogo_;
+  // The location to report in an error message.
+  Location loc_;
+  // The function we are parsing.
+  Named_object* named_object_;
+  // The exported data we are parsing.  Note that this is a reference;
+  // the body string must laster longer than this object.
+  const std::string& body_;
+  // The current offset into body_.
+  size_t off_;
+  // Current block.
+  Block* block_;
+  // Current expected indentation level.
+  int indent_;
+};
+
 #endif // !defined(GO_IMPORT_H)

gcc/go/gofrontend/statements.cc

@@ -121,6 +121,14 @@ Statement::determine_types()
   this->do_determine_types();
 }
 
+// Read a statement from export data.
+
+Statement*
+Statement::import_statement(Import_function_body*, Location)
+{
+  go_unreachable();
+}
+
 // If this is a thunk statement, return it.
 
 Thunk_statement*

gcc/go/gofrontend/statements.h

@@ -338,6 +338,10 @@ class Statement
   export_statement(Export_function_body* efb)
   { this->do_export_statement(efb); }
 
+  // Read a statement from export data.
+  static Statement*
+  import_statement(Import_function_body*, Location);
+
   // Return whether this is a block statement.
   bool
   is_block_statement() const

gcc/go/gofrontend/types.cc

@@ -9865,7 +9865,9 @@ Named_type::add_method(const std::string& name, Function* function)
   go_assert(!this->is_alias_);
   if (this->local_methods_ == NULL)
     this->local_methods_ = new Bindings(NULL);
-  return this->local_methods_->add_function(name, NULL, function);
+  return this->local_methods_->add_function(name,
+					    this->named_object_->package(),
+					    function);
 }
 
 // Add a method declaration to this type.