This patch to the Go frontend by Than McIntosh removes the LHS/RHS
context determination for variable references. It used to be needed
for a different backend but it's no longer necessary. Bootstrapped
and ran Go testsuite on x86_64-pc-linux-gnu. Committed to mainline.
Ian
2017-11-14 Than McIntosh <th...@google.com>
* go-gcc.cc (var_expression): Remove Varexpr_context parameter.
Index: gcc/go/go-gcc.cc
===================================================================
--- gcc/go/go-gcc.cc (revision 254090)
+++ gcc/go/go-gcc.cc (working copy)
@@ -276,7 +276,7 @@ class Gcc_backend : public Backend
{ return this->make_expression(null_pointer_node); }
Bexpression*
- var_expression(Bvariable* var, Varexpr_context, Location);
+ var_expression(Bvariable* var, Location);
Bexpression*
indirect_expression(Btype*, Bexpression* expr, bool known_valid, Location);
@@ -1256,7 +1256,7 @@ Gcc_backend::zero_expression(Btype* btyp
// An expression that references a variable.
Bexpression*
-Gcc_backend::var_expression(Bvariable* var, Varexpr_context, Location location)
+Gcc_backend::var_expression(Bvariable* var, Location location)
{
tree ret = var->get_tree(location);
if (ret == error_mark_node)
Index: gcc/go/gofrontend/MERGE
===================================================================
--- gcc/go/gofrontend/MERGE (revision 254729)
+++ gcc/go/gofrontend/MERGE (working copy)
@@ -1,4 +1,4 @@
-d028451131e92bab5379defb04ead87ca978ed25
+cb5dc1ce98857884a2215c461dd1d7de530f9f5e
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.
Index: gcc/go/gofrontend/backend.h
===================================================================
--- gcc/go/gofrontend/backend.h (revision 254090)
+++ gcc/go/gofrontend/backend.h (working copy)
@@ -254,7 +254,7 @@ class Backend
// Create a reference to a variable.
virtual Bexpression*
- var_expression(Bvariable* var, Varexpr_context in_lvalue_pos, Location) = 0;
+ var_expression(Bvariable* var, Location) = 0;
// Create an expression that indirects through the pointer expression EXPR
// (i.e., return the expression for *EXPR). KNOWN_VALID is true if the
pointer
Index: gcc/go/gofrontend/expressions.cc
===================================================================
--- gcc/go/gofrontend/expressions.cc (revision 254126)
+++ gcc/go/gofrontend/expressions.cc (working copy)
@@ -771,7 +771,7 @@ Var_expression::do_get_backend(Translate
go_unreachable();
Bexpression* ret =
- context->backend()->var_expression(bvar, this->in_lvalue_pos_, loc);
+ context->backend()->var_expression(bvar, loc);
if (is_in_heap)
ret = context->backend()->indirect_expression(btype, ret, true, loc);
return ret;
@@ -898,10 +898,7 @@ Temporary_reference_expression::do_get_b
{
Gogo* gogo = context->gogo();
Bvariable* bvar = this->statement_->get_backend_variable(context);
- Varexpr_context ve_ctxt = (this->is_lvalue_ ? VE_lvalue : VE_rvalue);
-
- Bexpression* ret = gogo->backend()->var_expression(bvar, ve_ctxt,
- this->location());
+ Bexpression* ret = gogo->backend()->var_expression(bvar, this->location());
// The backend can't always represent the same set of recursive types
// that the Go frontend can. In some cases this means that a
@@ -972,7 +969,7 @@ Set_and_use_temporary_expression::do_get
Location loc = this->location();
Gogo* gogo = context->gogo();
Bvariable* bvar = this->statement_->get_backend_variable(context);
- Bexpression* lvar_ref = gogo->backend()->var_expression(bvar, VE_lvalue,
loc);
+ Bexpression* lvar_ref = gogo->backend()->var_expression(bvar, loc);
Named_object* fn = context->function();
go_assert(fn != NULL);
@@ -980,7 +977,7 @@ Set_and_use_temporary_expression::do_get
Bexpression* bexpr = this->expr_->get_backend(context);
Bstatement* set = gogo->backend()->assignment_statement(bfn, lvar_ref,
bexpr, loc);
- Bexpression* var_ref = gogo->backend()->var_expression(bvar, VE_rvalue, loc);
+ Bexpression* var_ref = gogo->backend()->var_expression(bvar, loc);
Bexpression* ret = gogo->backend()->compound_expression(set, var_ref, loc);
return ret;
}
@@ -1084,11 +1081,11 @@ Sink_expression::do_get_backend(Translat
gogo->backend()->temporary_variable(fn_ctx, context->bblock(), bt, NULL,
false, loc, &decl);
Bexpression* var_ref =
- gogo->backend()->var_expression(this->bvar_, VE_lvalue, loc);
+ gogo->backend()->var_expression(this->bvar_, loc);
var_ref = gogo->backend()->compound_expression(decl, var_ref, loc);
return var_ref;
}
- return gogo->backend()->var_expression(this->bvar_, VE_lvalue, loc);
+ return gogo->backend()->var_expression(this->bvar_, loc);
}
// Ast dump for sink expression.
@@ -1302,7 +1299,7 @@ Func_descriptor_expression::do_get_backe
Named_object* no = this->fn_;
Location loc = no->location();
if (this->dvar_ != NULL)
- return context->backend()->var_expression(this->dvar_, VE_rvalue, loc);
+ return context->backend()->var_expression(this->dvar_, loc);
Gogo* gogo = context->gogo();
std::string var_name(gogo->function_descriptor_name(no));
@@ -1340,7 +1337,7 @@ Func_descriptor_expression::do_get_backe
}
this->dvar_ = bvar;
- return gogo->backend()->var_expression(bvar, VE_rvalue, loc);
+ return gogo->backend()->var_expression(bvar, loc);
}
// Print a function descriptor expression.
@@ -4286,7 +4283,7 @@ Unary_expression::do_get_backend(Transla
Temporary_statement* temp = sut->temporary();
Bvariable* bvar = temp->get_backend_variable(context);
Bexpression* bvar_expr =
- gogo->backend()->var_expression(bvar, VE_lvalue, loc);
+ gogo->backend()->var_expression(bvar, loc);
Bexpression* bval = sut->expression()->get_backend(context);
Named_object* fn = context->function();
@@ -4373,7 +4370,7 @@ Unary_expression::do_get_backend(Transla
gogo->backend()->implicit_variable_set_init(implicit, var_name, btype,
true, copy_to_heap, false,
bexpr);
- bexpr = gogo->backend()->var_expression(implicit, VE_rvalue, loc);
+ bexpr = gogo->backend()->var_expression(implicit, loc);
// If we are not copying a slice initializer to the heap,
// then it can be changed by the program, so if it can
@@ -4383,7 +4380,7 @@ Unary_expression::do_get_backend(Transla
&& this->expr_->type()->has_pointer())
{
Bexpression* root =
- gogo->backend()->var_expression(implicit, VE_rvalue, loc);
+ gogo->backend()->var_expression(implicit, loc);
root = gogo->backend()->address_expression(root, loc);
Type* type = Type::make_pointer_type(this->expr_->type());
gogo->add_gc_root(Expression::make_backend(root, type, loc));
@@ -4400,7 +4397,7 @@ Unary_expression::do_get_backend(Transla
true, false, btype, loc);
gogo->backend()->immutable_struct_set_init(decl, var_name, true,
false, btype, loc, bexpr);
- bexpr = gogo->backend()->var_expression(decl, VE_rvalue, loc);
+ bexpr = gogo->backend()->var_expression(decl, loc);
}
go_assert(!this->create_temp_ || this->expr_->is_variable());
@@ -14309,7 +14306,7 @@ Heap_expression::do_get_backend(Translat
Bstatement* assn;
if (!etype->has_pointer())
{
- space = gogo->backend()->var_expression(space_temp, VE_lvalue, loc);
+ space = gogo->backend()->var_expression(space_temp, loc);
Bexpression* ref =
gogo->backend()->indirect_expression(expr_btype, space, true, loc);
assn = gogo->backend()->assignment_statement(fndecl, ref, bexpr, loc);
@@ -14322,12 +14319,12 @@ Heap_expression::do_get_backend(Translat
expr_btype, bexpr, true, loc,
&edecl);
Bexpression* btempref = gogo->backend()->var_expression(btemp,
- VE_lvalue, loc);
+ loc);
Bexpression* addr = gogo->backend()->address_expression(btempref, loc);
Expression* td = Expression::make_type_descriptor(etype, loc);
Type* etype_ptr = Type::make_pointer_type(etype);
- space = gogo->backend()->var_expression(space_temp, VE_rvalue, loc);
+ space = gogo->backend()->var_expression(space_temp, loc);
Expression* elhs = Expression::make_backend(space, etype_ptr, loc);
Expression* erhs = Expression::make_backend(addr, etype_ptr, loc);
Expression* call = Runtime::make_call(Runtime::TYPEDMEMMOVE, loc, 3,
@@ -14337,7 +14334,7 @@ Heap_expression::do_get_backend(Translat
assn = gogo->backend()->compound_statement(edecl, s);
}
decl = gogo->backend()->compound_statement(decl, assn);
- space = gogo->backend()->var_expression(space_temp, VE_rvalue, loc);
+ space = gogo->backend()->var_expression(space_temp, loc);
return gogo->backend()->compound_expression(decl, space, loc);
}
@@ -14661,7 +14658,7 @@ Ptrmask_symbol_expression::do_get_backen
Bvariable* bvar = this->type_->gc_ptrmask_var(gogo, ptrsize, ptrdata);
Location bloc = Linemap::predeclared_location();
- Bexpression* bref = gogo->backend()->var_expression(bvar, VE_rvalue, bloc);
+ Bexpression* bref = gogo->backend()->var_expression(bvar, bloc);
Bexpression* baddr = gogo->backend()->address_expression(bref, bloc);
Type* uint8_type = Type::lookup_integer_type("uint8");
@@ -15380,8 +15377,7 @@ Interface_mtable_expression::do_get_back
Gogo* gogo = context->gogo();
Location loc = Linemap::predeclared_location();
if (this->bvar_ != NULL)
- return gogo->backend()->var_expression(this->bvar_, VE_rvalue,
- this->location());
+ return gogo->backend()->var_expression(this->bvar_, this->location());
const Typed_identifier_list* interface_methods = this->itype_->methods();
go_assert(!interface_methods->empty());
@@ -15421,8 +15417,7 @@ Interface_mtable_expression::do_get_back
this->bvar_ =
gogo->backend()->immutable_struct_reference(mangled_name, asm_name,
btype, loc);
- return gogo->backend()->var_expression(this->bvar_, VE_rvalue,
- this->location());
+ return gogo->backend()->var_expression(this->bvar_, this->location());
}
// The first element is the type descriptor.
@@ -15487,7 +15482,7 @@ Interface_mtable_expression::do_get_back
!is_public, btype, loc);
gogo->backend()->immutable_struct_set_init(this->bvar_, mangled_name, false,
!is_public, btype, loc, ctor);
- return gogo->backend()->var_expression(this->bvar_, VE_lvalue, loc);
+ return gogo->backend()->var_expression(this->bvar_, loc);
}
void
Index: gcc/go/gofrontend/expressions.h
===================================================================
--- gcc/go/gofrontend/expressions.h (revision 254090)
+++ gcc/go/gofrontend/expressions.h (working copy)
@@ -1298,7 +1298,7 @@ class Var_expression : public Expression
public:
Var_expression(Named_object* variable, Location location)
: Expression(EXPRESSION_VAR_REFERENCE, location),
- variable_(variable), in_lvalue_pos_(VE_rvalue)
+ variable_(variable)
{ }
// Return the variable.
@@ -1306,16 +1306,6 @@ class Var_expression : public Expression
named_object() const
{ return this->variable_; }
- // Does this var expression appear in an lvalue (assigned-to) context?
- bool
- in_lvalue_pos() const
- { return this->in_lvalue_pos_ == VE_lvalue; }
-
- // Mark a var_expression as appearing in an lvalue context.
- void
- set_in_lvalue_pos()
- { this->in_lvalue_pos_ = VE_lvalue; }
-
protected:
Expression*
do_lower(Gogo*, Named_object*, Statement_inserter*, int);
@@ -1346,8 +1336,6 @@ class Var_expression : public Expression
private:
// The variable we are referencing.
Named_object* variable_;
- // Set to TRUE if var expression appears in lvalue context
- Varexpr_context in_lvalue_pos_;
};
// A reference to a variable within an enclosing function.
Index: gcc/go/gofrontend/gogo.cc
===================================================================
--- gcc/go/gofrontend/gogo.cc (revision 254090)
+++ gcc/go/gofrontend/gogo.cc (working copy)
@@ -1394,7 +1394,7 @@ Gogo::write_globals()
{
Location loc = var->location();
Bexpression* var_expr =
- this->backend()->var_expression(bvar, VE_lvalue, loc);
+ this->backend()->var_expression(bvar, loc);
var_init_stmt =
this->backend()->assignment_statement(init_bfn, var_expr,
var_binit, loc);
@@ -5798,8 +5798,7 @@ Function::return_value(Gogo* gogo, Named
{
Named_object* no = (*this->results_)[i];
Bvariable* bvar = no->get_backend_variable(gogo, named_function);
- Bexpression* val = gogo->backend()->var_expression(bvar, VE_rvalue,
- location);
+ Bexpression* val = gogo->backend()->var_expression(bvar, location);
if (no->result_var_value()->is_in_heap())
{
Btype* bt = no->result_var_value()->type()->get_backend(gogo);
@@ -6632,7 +6631,7 @@ Variable::get_init_block(Gogo* gogo, Nam
Expression::make_cast(this->type(), this->init_, loc);
Bexpression* val = val_expr->get_backend(&context);
Bexpression* var_ref =
- gogo->backend()->var_expression(var_decl, VE_lvalue, loc);
+ gogo->backend()->var_expression(var_decl, loc);
decl_init = gogo->backend()->assignment_statement(bfunction, var_ref,
val, loc);
}
Index: gcc/go/gofrontend/operator.h
===================================================================
--- gcc/go/gofrontend/operator.h (revision 254090)
+++ gcc/go/gofrontend/operator.h (working copy)
@@ -63,10 +63,4 @@ enum Operator
OPERATOR_RSQUARE // ]
};
-// Whether a variable expression appears in lvalue (assignment) context.
-enum Varexpr_context {
- VE_rvalue,
- VE_lvalue
-};
-
#endif // !defined(GO_OPERATOR_H)
Index: gcc/go/gofrontend/statements.cc
===================================================================
--- gcc/go/gofrontend/statements.cc (revision 254090)
+++ gcc/go/gofrontend/statements.cc (working copy)
@@ -836,100 +836,6 @@ Assignment_statement::do_flatten(Gogo*,
return this;
}
-
-// Helper class to locate a root Var_expression within an expression
-// tree and mark it as being in an "lvalue" or assignment
-// context. Examples:
-//
-// x, y = 40, foo(w)
-// x[2] = bar(v)
-// x.z.w[blah(v + u)], y.another = 2, 3
-//
-// In the code above, vars "x" and "y" appear in lvalue / assignment
-// context, whereas the other vars "v", "u", etc are in rvalue context.
-//
-// Note: at the moment the Var_expression version of "do_copy()"
-// defaults to returning the original object, not a new object,
-// meaning that a given Var_expression can be referenced from more
-// than one place in the tree. This means that when we want to mark a
-// Var_expression as having lvalue semantics, we need to make a copy
-// of it. Example:
-//
-// mystruct.myfield += 42
-//
-// When this is lowered to eliminate the += operator, we get a tree
-//
-// mystruct.myfield = mystruct.field + 42
-//
-// in which the "mystruct" same Var_expression is referenced on both
-// LHS and RHS subtrees. This in turn means that if we try to mark the
-// LHS Var_expression the RHS Var_expression will also be marked. To
-// address this issue, the code below clones any var_expression before
-// applying an lvalue marking.
-//
-
-class Mark_lvalue_varexprs : public Traverse
-{
- public:
- Mark_lvalue_varexprs()
- : Traverse(traverse_expressions)
- { }
-
- protected:
- int
- expression(Expression**);
-
- private:
-};
-
-int Mark_lvalue_varexprs::expression(Expression** ppexpr)
-{
- Expression* e = *ppexpr;
-
- Var_expression* ve = e->var_expression();
- if (ve)
- {
- ve = new Var_expression(ve->named_object(), ve->location());
- ve->set_in_lvalue_pos();
- *ppexpr = ve;
- return TRAVERSE_EXIT;
- }
-
- Field_reference_expression* fre = e->field_reference_expression();
- if (fre != NULL)
- return TRAVERSE_CONTINUE;
-
- Array_index_expression* aie = e->array_index_expression();
- if (aie != NULL)
- {
- Mark_lvalue_varexprs mlve;
- aie->set_is_lvalue();
- aie->array()->traverse_subexpressions(&mlve);
- return TRAVERSE_EXIT;
- }
-
- Unary_expression* ue = e->unary_expression();
- if (ue && ue->op() == OPERATOR_MULT)
- return TRAVERSE_CONTINUE;
-
- Type_conversion_expression* ce = e->conversion_expression();
- if (ce)
- return TRAVERSE_CONTINUE;
-
- Temporary_reference_expression* tre =
- e->temporary_reference_expression();
- if (tre)
- {
- tre = new Temporary_reference_expression(tre->statement(),
- tre->location());
- *ppexpr = tre;
- tre->set_is_lvalue();
- return TRAVERSE_EXIT;
- }
-
- return TRAVERSE_EXIT;
-}
-
// Convert an assignment statement to the backend representation.
Bstatement*
@@ -942,9 +848,6 @@ Assignment_statement::do_get_backend(Tra
return context->backend()->expression_statement(bfunction, rhs);
}
- Mark_lvalue_varexprs mlve;
- Expression::traverse(&this->lhs_, &mlve);
-
Bexpression* lhs = this->lhs_->get_backend(context);
Expression* conv =
Expression::convert_for_assignment(context->gogo(), this->lhs_->type(),
Index: gcc/go/gofrontend/types.cc
===================================================================
--- gcc/go/gofrontend/types.cc (revision 254090)
+++ gcc/go/gofrontend/types.cc (working copy)
@@ -1206,8 +1206,7 @@ Type::type_descriptor_pointer(Gogo* gogo
go_assert(t->type_descriptor_var_ != NULL);
}
Bexpression* var_expr =
- gogo->backend()->var_expression(t->type_descriptor_var_,
- VE_rvalue, location);
+ gogo->backend()->var_expression(t->type_descriptor_var_, location);
Bexpression* var_addr =
gogo->backend()->address_expression(var_expr, location);
Type* td_type = Type::make_type_descriptor_type();
@@ -2385,7 +2384,7 @@ Type::gc_symbol_pointer(Gogo* gogo)
}
Location bloc = Linemap::predeclared_location();
Bexpression* var_expr =
- gogo->backend()->var_expression(t->gc_symbol_var_, VE_rvalue, bloc);
+ gogo->backend()->var_expression(t->gc_symbol_var_, bloc);
Bexpression* addr_expr =
gogo->backend()->address_expression(var_expr, bloc);
@@ -7395,7 +7394,6 @@ Array_type::get_value_pointer(Gogo*, Exp
else if (ve != NULL)
{
ve = new Var_expression(ve->named_object(), ve->location());
- ve->set_in_lvalue_pos();
array = ve;
}
}
Index: gcc/go/gofrontend/wb.cc
===================================================================
--- gcc/go/gofrontend/wb.cc (revision 254090)
+++ gcc/go/gofrontend/wb.cc (working copy)
@@ -175,7 +175,6 @@ Write_barriers::variable(Named_object* n
// Replace the initializer.
Location loc = init->location();
Expression* ref = Expression::make_var_reference(no, loc);
- ref->var_expression()->set_in_lvalue_pos();
Statement_inserter inserter(this->gogo_, var);
Statement* s = this->gogo_->assign_with_write_barrier(NULL, NULL, &inserter,
