code review 14346043: compiler: Use backend interface for temporary reference...

compiler: Use backend interface for temporary reference expressions.

[cmang, 2013-10-03 17:20:51]

Hello iant@golang.org (cc: gofrontend-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/gofrontend

[cmang, 2013-10-03 17:21:30]

On 2013/10/03 17:20:51, cmang wrote:
> Hello mailto:iant@golang.org (cc: mailto:gofrontend-dev@googlegroups.com),
> 
> I'd like you to review this change to
> https://code.google.com/p/gofrontend

And the patch to gcc/go/go-gcc.cc:

Index: gcc/go/go-gcc.cc
===================================================================
--- gcc/go/go-gcc.cc	(revision 203131)
+++ gcc/go/go-gcc.cc	(working copy)
@@ -229,6 +229,9 @@
   Bexpression*
   complex_constant_expression(Btype* btype, mpfr_t real, mpfr_t imag);
 
+  Bexpression*
+  temporary_reference_expression(Btype* type, Bvariable* var, Location);
+
   // Statements.
 
   Bstatement*
@@ -949,6 +952,21 @@
   return tree_to_expr(ret);
 }
 
+// An expression that references a temporary variable.
+
+Bexpression*
+Gcc_backend::temporary_reference_expression(Btype* type, Bvariable* var,
+                                            Location loc)
+{
+  tree type_tree = type->get_tree();
+  tree var_tree = var->get_tree();
+  if (type_tree == error_mark_node || var_tree == error_mark_node)
+    return this->error_expression();
+
+  tree ret = fold_convert_loc(loc.gcc_location(), type_tree, var_tree);
+  return tree_to_expr(ret);
+}
+
 // An expression as a statement.
 
 Bstatement*

[iant, 2013-10-04 05:23:48]

Sorry to keep doing this to you, but I think this one ought to be different too.
 We're going to need a backend type conversion in a few other places, e.g., in
Type_conversion_expression::do_get_tree.  So I think you should introduce a
backend method to do a simple type conversion--not a conversion that involves
changing the value, just expressing the value as a different type.  And then
this code should call the existing var_expression and then if necessary the new
convert_expression.

[cmang, 2013-10-04 17:11:14]

On 2013/10/04 05:23:48, iant wrote:
> Sorry to keep doing this to you, but I think this one ought to be different
too.
>  We're going to need a backend type conversion in a few other places, e.g., in
> Type_conversion_expression::do_get_tree.  So I think you should introduce a
> backend method to do a simple type conversion--not a conversion that involves
> changing the value, just expressing the value as a different type.  And then
> this code should call the existing var_expression and then if necessary the
new
> convert_expression.

Ok, I've updated the patch, PTAL. Here's the new diff from gcc/go/go-gcc.cc:

Index: gcc/go/go-gcc.cc
===================================================================
--- gcc/go/go-gcc.cc	(revision 203207)
+++ gcc/go/go-gcc.cc	(working copy)
@@ -229,6 +229,9 @@
   Bexpression*
   complex_constant_expression(Btype* btype, mpfr_t real, mpfr_t imag);
 
+  Bexpression*
+  convert_expression(Btype* type, Bexpression* expr);
+
   // Statements.
 
   Bstatement*
@@ -949,6 +952,20 @@
   return tree_to_expr(ret);
 }
 
+// An expression that converts an expression to a different type.
+
+Bexpression*
+Gcc_backend::convert_expression(Btype* type, Bexpression* expr)
+{
+  tree type_tree = type->get_tree();
+  tree expr_tree = expr->get_tree();
+  if (type_tree == error_mark_node || expr_tree == error_mark_node)
+    return this->error_expression();
+
+  tree ret = fold_convert(type_tree, expr_tree);
+  return tree_to_expr(ret);
+}
+
 // An expression as a statement.
 
 Bstatement*

[iant, 2013-10-04 17:17:00]

https://codereview.appspot.com/14346043/diff/11001/go/backend.h
File go/backend.h (right):

https://codereview.appspot.com/14346043/diff/11001/go/backend.h#newcode267
go/backend.h:267: convert_expression(Btype* type, Bexpression* expr) = 0;
This should take a Location argument.

[cmang, 2013-10-04 17:29:09]

And the updated diff to gcc/go/go-gcc:

Index: gcc/go/go-gcc.cc
===================================================================
--- gcc/go/go-gcc.cc	(revision 203207)
+++ gcc/go/go-gcc.cc	(working copy)
@@ -229,6 +229,9 @@
   Bexpression*
   complex_constant_expression(Btype* btype, mpfr_t real, mpfr_t imag);
 
+  Bexpression*
+  convert_expression(Btype* type, Bexpression* expr, Location);
+
   // Statements.
 
   Bstatement*
@@ -949,6 +952,20 @@
   return tree_to_expr(ret);
 }
 
+// An expression that converts an expression to a different type.
+
+Bexpression*
+Gcc_backend::convert_expression(Btype* type, Bexpression* expr, Location)
+{
+  tree type_tree = type->get_tree();
+  tree expr_tree = expr->get_tree();
+  if (type_tree == error_mark_node || expr_tree == error_mark_node)
+    return this->error_expression();
+
+  tree ret = fold_convert(type_tree, expr_tree);
+  return tree_to_expr(ret);
+}
+
 // An expression as a statement.
 
 Bstatement*

https://codereview.appspot.com/14346043/diff/11001/go/backend.h
File go/backend.h (right):

https://codereview.appspot.com/14346043/diff/11001/go/backend.h#newcode267
go/backend.h:267: convert_expression(Btype* type, Bexpression* expr) = 0;
On 2013/10/04 17:17:00, iant wrote:
> This should take a Location argument.

Done.

[iant, 2013-10-04 17:54:40]

LGTM

Thanks.

[iant, 2013-10-04 18:00:43]

*** Submitted as
https://code.google.com/p/gofrontend/source/detail?r=52c01e7b81fe ***

compiler: Use backend interface for temporary reference expressions.

R=iant
CC=gofrontend-dev
https://codereview.appspot.com/14346043

Committer: Ian Lance Taylor <iant@golang.org>