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statements.cc
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// statements.cc -- Go frontend statements.
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "go-system.h"
#include "go-c.h"
#include "go-diagnostics.h"
#include "types.h"
#include "expressions.h"
#include "gogo.h"
#include "export.h"
#include "import.h"
#include "runtime.h"
#include "backend.h"
#include "statements.h"
#include "ast-dump.h"
// Class Statement.
Statement::Statement(Statement_classification classification,
Location location)
: classification_(classification), location_(location)
{
}
Statement::~Statement()
{
}
// Traverse the tree. The work of walking the components is handled
// by the subclasses.
int
Statement::traverse(Block* block, size_t* pindex, Traverse* traverse)
{
if (this->classification_ == STATEMENT_ERROR)
return TRAVERSE_CONTINUE;
unsigned int traverse_mask = traverse->traverse_mask();
if ((traverse_mask & Traverse::traverse_statements) != 0)
{
int t = traverse->statement(block, pindex, this);
if (t == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
else if (t == TRAVERSE_SKIP_COMPONENTS)
return TRAVERSE_CONTINUE;
}
// No point in checking traverse_mask here--a statement may contain
// other blocks or statements, and if we got here we always want to
// walk them.
return this->do_traverse(traverse);
}
// Traverse the contents of a statement.
int
Statement::traverse_contents(Traverse* traverse)
{
return this->do_traverse(traverse);
}
// Traverse an expression in a statement. This is a helper function
// for child classes.
int
Statement::traverse_expression(Traverse* traverse, Expression** expr)
{
if ((traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) == 0)
return TRAVERSE_CONTINUE;
return Expression::traverse(expr, traverse);
}
// Traverse an expression list in a statement. This is a helper
// function for child classes.
int
Statement::traverse_expression_list(Traverse* traverse,
Expression_list* expr_list)
{
if (expr_list == NULL)
return TRAVERSE_CONTINUE;
if ((traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) == 0)
return TRAVERSE_CONTINUE;
return expr_list->traverse(traverse);
}
// Traverse a type in a statement. This is a helper function for
// child classes.
int
Statement::traverse_type(Traverse* traverse, Type* type)
{
if ((traverse->traverse_mask()
& (Traverse::traverse_types | Traverse::traverse_expressions)) == 0)
return TRAVERSE_CONTINUE;
return Type::traverse(type, traverse);
}
// Set type information for unnamed constants. This is really done by
// the child class.
void
Statement::determine_types(Gogo* gogo)
{
this->do_determine_types(gogo);
}
// Read a statement from export data.
Statement*
Statement::import_statement(Import_function_body* ifb, Location loc)
{
if (ifb->match_c_string("{"))
{
bool is_lowered_for_statement;
Block* block = Block_statement::do_import(ifb, loc,
&is_lowered_for_statement);
if (block == NULL)
return Statement::make_error_statement(loc);
Block_statement* s = Statement::make_block_statement(block, loc);
if (is_lowered_for_statement)
s->set_is_lowered_for_statement();
return s;
}
else if (ifb->match_c_string("return"))
{
// After lowering return statements have no expressions. The
// return expressions are assigned to result parameters.
ifb->advance(6);
return Statement::make_return_statement(ifb->function(), NULL, loc);
}
else if (ifb->match_c_string("var $t"))
return Temporary_statement::do_import(ifb, loc);
else if (ifb->match_c_string("var "))
return Variable_declaration_statement::do_import(ifb, loc);
else if (ifb->match_c_string("if "))
return If_statement::do_import(ifb, loc);
else if (ifb->match_c_string(":"))
return Label_statement::do_import(ifb, loc);
else if (ifb->match_c_string("goto "))
return Goto_statement::do_import(ifb, loc);
Expression* lhs = Expression::import_expression(ifb, loc);
if (ifb->match_c_string(" //"))
return Statement::make_statement(lhs, true);
ifb->require_c_string(" = ");
Expression* rhs = Expression::import_expression(ifb, loc);
return Statement::make_assignment(lhs, rhs, loc);
}
// If this is a thunk statement, return it.
Thunk_statement*
Statement::thunk_statement()
{
Thunk_statement* ret = this->convert<Thunk_statement, STATEMENT_GO>();
if (ret == NULL)
ret = this->convert<Thunk_statement, STATEMENT_DEFER>();
return ret;
}
// Convert a Statement to the backend representation. This is really
// done by the child class.
Bstatement*
Statement::get_backend(Translate_context* context)
{
if (this->classification_ == STATEMENT_ERROR)
return context->backend()->error_statement();
return this->do_get_backend(context);
}
// Dump AST representation for a statement to a dump context.
void
Statement::dump_statement(Ast_dump_context* ast_dump_context) const
{
this->do_dump_statement(ast_dump_context);
}
// Note that this statement is erroneous. This is called by children
// when they discover an error.
void
Statement::set_is_error()
{
this->classification_ = STATEMENT_ERROR;
}
// For children to call to report an error conveniently.
void
Statement::report_error(const char* msg)
{
go_error_at(this->location_, "%s", msg);
this->set_is_error();
}
// An error statement, used to avoid crashing after we report an
// error.
class Error_statement : public Statement
{
public:
Error_statement(Location location)
: Statement(STATEMENT_ERROR, location)
{ }
protected:
int
do_traverse(Traverse*)
{ return TRAVERSE_CONTINUE; }
Bstatement*
do_get_backend(Translate_context*)
{ go_unreachable(); }
void
do_dump_statement(Ast_dump_context*) const;
};
//
// Helper to tack on available source position information
// at the end of a statement.
//
static std::string
dsuffix(Location location)
{
std::string lstr = Linemap::location_to_string(location);
if (lstr == "")
return lstr;
std::string rval(" // ");
rval += lstr;
return rval;
}
// Dump the AST representation for an error statement.
void
Error_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->ostream() << "Error statement" << std::endl;
}
// Make an error statement.
Statement*
Statement::make_error_statement(Location location)
{
return new Error_statement(location);
}
// Class Variable_declaration_statement.
Variable_declaration_statement::Variable_declaration_statement(
Named_object* var)
: Statement(STATEMENT_VARIABLE_DECLARATION, var->var_value()->location()),
var_(var)
{
}
// We don't actually traverse the variable here; it was traversed
// while traversing the Block.
int
Variable_declaration_statement::do_traverse(Traverse*)
{
return TRAVERSE_CONTINUE;
}
void
Variable_declaration_statement::do_determine_types(Gogo* gogo)
{
this->var_->var_value()->determine_type(gogo);
}
// Lower the variable's initialization expression.
Statement*
Variable_declaration_statement::do_lower(Gogo* gogo, Named_object* function,
Block*, Statement_inserter* inserter)
{
this->var_->var_value()->lower_init_expression(gogo, function, inserter);
return this;
}
// Flatten the variable's initialization expression.
Statement*
Variable_declaration_statement::do_flatten(Gogo* gogo, Named_object* function,
Block*, Statement_inserter* inserter)
{
Variable* var = this->var_->var_value();
if (var->type()->is_error_type()
|| (var->init() != NULL
&& var->init()->is_error_expression()))
{
go_assert(saw_errors());
return Statement::make_error_statement(this->location());
}
this->var_->var_value()->flatten_init_expression(gogo, function, inserter);
return this;
}
// Add explicit type conversions.
void
Variable_declaration_statement::do_add_conversions()
{
Variable* var = this->var_->var_value();
Expression* init = var->init();
if (init == NULL)
return;
Type* lt = var->type();
Type* rt = init->type();
if (!Type::are_identical(lt, rt, 0, NULL)
&& lt->interface_type() != NULL)
var->set_init(Expression::make_cast(lt, init, this->location()));
}
// Convert a variable declaration to the backend representation.
Bstatement*
Variable_declaration_statement::do_get_backend(Translate_context* context)
{
if (this->var_->is_redefinition())
return context->backend()->error_statement();
Bfunction* bfunction = context->function()->func_value()->get_decl();
Variable* var = this->var_->var_value();
Bvariable* bvar = this->var_->get_backend_variable(context->gogo(),
context->function());
Bexpression* binit = var->get_init(context->gogo(), context->function());
if (!var->is_in_heap())
{
go_assert(binit != NULL);
return context->backend()->init_statement(bfunction, bvar, binit);
}
// Something takes the address of this variable, so the value is
// stored in the heap. Initialize it to newly allocated memory
// space, and assign the initial value to the new space.
Location loc = this->location();
Named_object* newfn = context->gogo()->lookup_global("new");
go_assert(newfn != NULL && newfn->is_function_declaration());
Expression* func = Expression::make_func_reference(newfn, NULL, loc);
Expression_list* params = new Expression_list();
params->push_back(Expression::make_type(var->type(), loc));
Expression* call = Expression::make_call(func, params, false, loc);
context->gogo()->lower_expression(context->function(), NULL, &call);
Temporary_statement* temp = Statement::make_temporary(NULL, call, loc);
Bstatement* btemp = temp->get_backend(context);
Bstatement* set = NULL;
if (binit != NULL)
{
Expression* e = Expression::make_temporary_reference(temp, loc);
e = Expression::make_dereference(e, Expression::NIL_CHECK_NOT_NEEDED,
loc);
Bexpression* be = e->get_backend(context);
set = context->backend()->assignment_statement(bfunction, be, binit, loc);
}
Expression* ref = Expression::make_temporary_reference(temp, loc);
Bexpression* bref = ref->get_backend(context);
Bstatement* sinit = context->backend()->init_statement(bfunction, bvar, bref);
std::vector<Bstatement*> stats;
stats.reserve(3);
stats.push_back(btemp);
if (set != NULL)
stats.push_back(set);
stats.push_back(sinit);
return context->backend()->statement_list(stats);
}
// Dump the AST representation for a variable declaration.
void
Variable_declaration_statement::do_dump_statement(
Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
go_assert(var_->is_variable());
ast_dump_context->ostream() << "var " << this->var_->name() << " ";
Variable* var = this->var_->var_value();
if (var->has_type())
{
ast_dump_context->dump_type(var->type());
ast_dump_context->ostream() << " ";
}
if (var->init() != NULL)
{
ast_dump_context->ostream() << "= ";
ast_dump_context->dump_expression(var->init());
}
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make a variable declaration.
Statement*
Statement::make_variable_declaration(Named_object* var)
{
return new Variable_declaration_statement(var);
}
// Export a variable declaration.
void
Variable_declaration_statement::do_export_statement(Export_function_body* efb)
{
efb->write_c_string("var ");
efb->write_string(Gogo::unpack_hidden_name(this->var_->name()));
efb->write_c_string(" ");
Variable* var = this->var_->var_value();
Type* type = var->type();
efb->write_type(type);
Expression* init = var->init();
if (init != NULL)
{
efb->write_c_string(" = ");
go_assert(efb->type_context() == NULL);
efb->set_type_context(type);
init->export_expression(efb);
efb->set_type_context(NULL);
}
}
// Import a variable declaration.
Statement*
Variable_declaration_statement::do_import(Import_function_body* ifb,
Location loc)
{
ifb->require_c_string("var ");
std::string id = ifb->read_identifier();
ifb->require_c_string(" ");
Type* type = ifb->read_type();
Expression* init = NULL;
if (ifb->match_c_string(" = "))
{
ifb->advance(3);
init = Expression::import_expression(ifb, loc);
}
Variable* var = new Variable(type, init, false, false, false, loc);
var->set_is_used();
// FIXME: The package we are importing does not yet exist, so we
// can't pass the correct package here. It probably doesn't matter.
Named_object* no = ifb->block()->bindings()->add_variable(id, NULL, var);
return Statement::make_variable_declaration(no);
}
// Class Temporary_statement.
// Return the type of the temporary variable.
Type*
Temporary_statement::type() const
{
Type* type = this->type_ != NULL ? this->type_ : this->init_->type();
// Temporary variables cannot have a void type.
if (type->is_void_type())
{
go_assert(saw_errors());
return Type::make_error_type();
}
return type;
}
// Traversal.
int
Temporary_statement::do_traverse(Traverse* traverse)
{
if (this->type_ != NULL
&& this->traverse_type(traverse, this->type_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
if (this->init_ == NULL)
return TRAVERSE_CONTINUE;
else
return this->traverse_expression(traverse, &this->init_);
}
// Determine types.
void
Temporary_statement::do_determine_types(Gogo* gogo)
{
if (this->type_ != NULL && this->type_->is_abstract())
this->type_ = this->type_->make_non_abstract_type();
if (this->init_ != NULL)
{
if (this->type_ == NULL)
this->init_->determine_type_no_context(gogo);
else
{
Type_context context(this->type_, false);
this->init_->determine_type(gogo, &context);
}
}
if (this->type_ == NULL)
{
this->type_ = this->init_->type();
go_assert(!this->type_->is_abstract());
}
}
// Check types.
void
Temporary_statement::do_check_types(Gogo*)
{
if (this->type_ != NULL && this->init_ != NULL)
{
std::string reason;
if (!Type::are_assignable(this->type_, this->init_->type(), &reason))
{
if (reason.empty())
go_error_at(this->location(), "incompatible types in assignment");
else
go_error_at(this->location(), "incompatible types in assignment (%s)",
reason.c_str());
this->set_is_error();
}
}
}
// Flatten a temporary statement: add another temporary when it might
// be needed for interface conversion.
Statement*
Temporary_statement::do_flatten(Gogo*, Named_object*, Block*,
Statement_inserter* inserter)
{
if (this->type()->is_error_type()
|| (this->init_ != NULL
&& this->init_->is_error_expression()))
{
go_assert(saw_errors());
return Statement::make_error_statement(this->location());
}
if (this->type_ != NULL
&& this->init_ != NULL
&& !Type::are_identical(this->type_, this->init_->type(),
Type::COMPARE_ERRORS | Type::COMPARE_TAGS,
NULL)
&& this->init_->type()->interface_type() != NULL
&& !this->init_->is_multi_eval_safe())
{
Temporary_statement *temp =
Statement::make_temporary(NULL, this->init_, this->location());
inserter->insert(temp);
this->init_ = Expression::make_temporary_reference(temp,
this->location());
}
return this;
}
// Add explicit type conversions.
void
Temporary_statement::do_add_conversions()
{
if (this->init_ == NULL)
return;
Type* lt = this->type();
Type* rt = this->init_->type();
if (!Type::are_identical(lt, rt, 0, NULL)
&& lt->interface_type() != NULL)
this->init_ = Expression::make_cast(lt, this->init_, this->location());
}
// Convert to backend representation.
Bstatement*
Temporary_statement::do_get_backend(Translate_context* context)
{
go_assert(this->bvariable_ == NULL);
Named_object* function = context->function();
go_assert(function != NULL);
Bfunction* bfunction = function->func_value()->get_decl();
Btype* btype = this->type()->get_backend(context->gogo());
Bexpression* binit;
if (this->init_ == NULL)
binit = NULL;
else if (this->type_ == NULL)
binit = this->init_->get_backend(context);
else
{
Expression* init = Expression::convert_for_assignment(context->gogo(),
this->type_,
this->init_,
this->location());
binit = init->get_backend(context);
}
if (binit != NULL)
binit = context->backend()->convert_expression(btype, binit,
this->location());
unsigned int flags = 0;
if (this->is_address_taken_)
flags |= Backend::variable_address_is_taken;
Bstatement* statement;
this->bvariable_ =
context->backend()->temporary_variable(bfunction, context->bblock(),
btype, binit, flags,
this->location(), &statement);
return statement;
}
// Return the backend variable.
Bvariable*
Temporary_statement::get_backend_variable(Translate_context* context) const
{
if (this->bvariable_ == NULL)
{
go_assert(saw_errors());
return context->backend()->error_variable();
}
return this->bvariable_;
}
// Dump the AST represemtation for a temporary statement
void
Temporary_statement::do_dump_statement(Ast_dump_context* ast_dump_context) const
{
ast_dump_context->print_indent();
ast_dump_context->dump_temp_variable_name(this);
if (this->type_ != NULL)
{
ast_dump_context->ostream() << " ";
ast_dump_context->dump_type(this->type_);
}
if (this->init_ != NULL)
{
ast_dump_context->ostream() << " = ";
ast_dump_context->dump_expression(this->init_);
}
ast_dump_context->ostream() << dsuffix(location()) << std::endl;
}
// Make and initialize a temporary variable in BLOCK.
Temporary_statement*
Statement::make_temporary(Type* type, Expression* init,
Location location)
{
return new Temporary_statement(type, init, location);
}
// Export a temporary statement.
void
Temporary_statement::do_export_statement(Export_function_body* efb)
{
unsigned int idx = efb->record_temporary(this);
char buf[100];
snprintf(buf, sizeof buf, "var $t%u", idx);
efb->write_c_string(buf);
if (this->type_ != NULL)
{
efb->write_c_string(" ");
efb->write_type(this->type_);
}
if (this->init_ != NULL)
{
efb->write_c_string(" = ");
go_assert(efb->type_context() == NULL);
efb->set_type_context(this->type_);
this->init_->export_expression(efb);
efb->set_type_context(NULL);
}
}
// Import a temporary statement.
Statement*
Temporary_statement::do_import(Import_function_body* ifb, Location loc)
{
ifb->require_c_string("var ");
std::string id = ifb->read_identifier();
go_assert(id[0] == '$' && id[1] == 't');
const char *p = id.c_str();
char *end;
long idx = strtol(p + 2, &end, 10);
if (*end != '\0' || idx > 0x7fffffff)
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"bad temporary statement index at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
Type* type = NULL;
if (!ifb->match_c_string(" = "))
{
ifb->require_c_string(" ");
type = ifb->read_type();
}
Expression* init = NULL;
if (ifb->match_c_string(" = "))
{
ifb->advance(3);
init = Expression::import_expression(ifb, loc);
}
if (type == NULL && init == NULL)
{
if (!ifb->saw_error())
go_error_at(loc,
("invalid export data for %qs: "
"temporary statement has neither type nor init at %lu"),
ifb->name().c_str(),
static_cast<unsigned long>(ifb->off()));
ifb->set_saw_error();
return Statement::make_error_statement(loc);
}
Temporary_statement* temp = Statement::make_temporary(type, init, loc);
ifb->record_temporary(temp, static_cast<unsigned int>(idx));
return temp;
}
// The Move_subexpressions class is used to move all top-level
// subexpressions of an expression. This is used for things like
// index expressions in which we must evaluate the index value before
// it can be changed by a multiple assignment.
class Move_subexpressions : public Traverse
{
public:
Move_subexpressions(int skip, Block* block)
: Traverse(traverse_expressions),
skip_(skip), block_(block)
{ }
protected:
int
expression(Expression**);
private:
// The number of subexpressions to skip moving. This is used to
// avoid moving the array itself, as we only need to move the index.
int skip_;
// The block where new temporary variables should be added.
Block* block_;
};
int
Move_subexpressions::expression(Expression** pexpr)
{
if (this->skip_ > 0)
--this->skip_;
else if ((*pexpr)->temporary_reference_expression() == NULL
&& !(*pexpr)->is_nil_expression()
&& !(*pexpr)->is_constant())
{
Location loc = (*pexpr)->location();
Temporary_statement* temp = Statement::make_temporary(NULL, *pexpr, loc);
this->block_->add_statement(temp);
*pexpr = Expression::make_temporary_reference(temp, loc);
}
// We only need to move top-level subexpressions.
return TRAVERSE_SKIP_COMPONENTS;
}
// The Move_ordered_evals class is used to find any subexpressions of
// an expression that have an evaluation order dependency. It creates
// temporary variables to hold them.
class Move_ordered_evals : public Traverse
{
public:
Move_ordered_evals(Block* block)
: Traverse(traverse_expressions),
block_(block)
{ }
protected:
int
expression(Expression**);
private:
// The block where new temporary variables should be added.
Block* block_;
};
int
Move_ordered_evals::expression(Expression** pexpr)
{
// We have to look at subexpressions first.
if ((*pexpr)->traverse_subexpressions(this) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
int i;
if ((*pexpr)->must_eval_subexpressions_in_order(&i))
{
Move_subexpressions ms(i, this->block_);
if ((*pexpr)->traverse_subexpressions(&ms) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
}
if ((*pexpr)->must_eval_in_order())
{
Call_expression* call = (*pexpr)->call_expression();
if (call != NULL && call->is_multi_value_arg())
{
// A call expression which returns multiple results as an argument
// to another call must be handled specially. We can't create a
// temporary because there is no type to give it. Instead, group
// the caller and this multi-valued call argument and use a temporary
// variable to hold them.
return TRAVERSE_SKIP_COMPONENTS;
}
Location loc = (*pexpr)->location();
Temporary_statement* temp = Statement::make_temporary(NULL, *pexpr, loc);
this->block_->add_statement(temp);
*pexpr = Expression::make_temporary_reference(temp, loc);
}
return TRAVERSE_SKIP_COMPONENTS;
}
// Class Assignment_statement.
// Traversal.
int
Assignment_statement::do_traverse(Traverse* traverse)
{
if (this->traverse_expression(traverse, &this->lhs_) == TRAVERSE_EXIT)
return TRAVERSE_EXIT;
return this->traverse_expression(traverse, &this->rhs_);
}
// Lower an assignment to a map index expression to a runtime function
// call. Mark some slice assignments as not requiring a write barrier.
Statement*
Assignment_statement::do_lower(Gogo* gogo, Named_object*, Block* enclosing,
Statement_inserter*)
{
Map_index_expression* mie = this->lhs_->map_index_expression();
if (mie != NULL)
{
Location loc = this->location();
Expression* map = mie->map();
Map_type* mt = map->type()->map_type();
if (mt == NULL)
{
go_assert(saw_errors());
return Statement::make_error_statement(loc);
}
Block* b = new Block(enclosing, loc);
// Move out any subexpressions on the left hand side to make
// sure that functions are called in the required order.
Move_ordered_evals moe(b);
mie->traverse_subexpressions(&moe);
// Copy the key into a temporary so that we can take its address
// without pushing the value onto the heap.
// var key_temp KEY_TYPE = MAP_INDEX
Temporary_statement* key_temp = Statement::make_temporary(mt->key_type(),
mie->index(),
loc);
b->add_statement(key_temp);
// Copy the value into a temporary to ensure that it is
// evaluated before we add the key to the map. This may matter
// if the value is itself a reference to the map.
// var val_temp VAL_TYPE = RHS
Temporary_statement* val_temp = Statement::make_temporary(mt->val_type(),
this->rhs_,
loc);
b->add_statement(val_temp);
// *mapassign(TYPE, MAP, &key_temp) = RHS
Expression* a1 = Expression::make_type_descriptor(mt, loc);
Expression* a2 = mie->map();
Temporary_reference_expression* ref =
Expression::make_temporary_reference(key_temp, loc);
Expression* a3 = Expression::make_unary(OPERATOR_AND, ref, loc);
Runtime::Function code;
Map_type::Map_alg alg = mt->algorithm(gogo);
switch (alg)
{
case Map_type::MAP_ALG_FAST32:
{
code = Runtime::MAPASSIGN_FAST32;
Type* uint32_type = Type::lookup_integer_type("uint32");
Type* uint32_ptr_type = Type::make_pointer_type(uint32_type);
a3 = Expression::make_unsafe_cast(uint32_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FAST64:
{
code = Runtime::MAPASSIGN_FAST64;
Type* uint64_type = Type::lookup_integer_type("uint64");
Type* uint64_ptr_type = Type::make_pointer_type(uint64_type);
a3 = Expression::make_unsafe_cast(uint64_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FAST32PTR:
case Map_type::MAP_ALG_FAST64PTR:
{
code = (alg == Map_type::MAP_ALG_FAST32PTR
? Runtime::MAPASSIGN_FAST32PTR
: Runtime::MAPASSIGN_FAST64PTR);
Type* ptr_type =
Type::make_pointer_type(Type::make_void_type());
Type* ptr_ptr_type = Type::make_pointer_type(ptr_type);
a3 = Expression::make_unsafe_cast(ptr_ptr_type, a3,
loc);
a3 = Expression::make_dereference(a3,
Expression::NIL_CHECK_NOT_NEEDED,
loc);
break;
}
case Map_type::MAP_ALG_FASTSTR:
code = Runtime::MAPASSIGN_FASTSTR;
a3 = ref;
break;
default:
code = Runtime::MAPASSIGN;
break;
}
Expression* call = Runtime::make_call(gogo, code, loc, 3,
a1, a2, a3);
Type* ptrval_type = Type::make_pointer_type(mt->val_type());
call = Expression::make_cast(ptrval_type, call, loc);
Expression* indir =
Expression::make_dereference(call, Expression::NIL_CHECK_NOT_NEEDED,
loc);
ref = Expression::make_temporary_reference(val_temp, loc);
Statement* s = Statement::make_assignment(indir, ref, loc);
s->determine_types(gogo);
b->add_statement(s);
return Statement::make_block_statement(b, loc);
}
// An assignment of the form s = s[:n] does not require a write
// barrier, because the pointer value will not change.
Array_index_expression* aie = this->rhs_->array_index_expression();
if (aie != NULL
&& aie->end() != NULL
&& Expression::is_same_variable(this->lhs_, aie->array()))
{
Numeric_constant nc;
unsigned long ival;
if (aie->start()->numeric_constant_value(&nc)
&& nc.to_unsigned_long(&ival) == Numeric_constant::NC_UL_VALID
&& ival == 0)
this->omit_write_barrier_ = true;
}