compile, runtime: make selectnbrecv return two values
The only different between selectnbrecv and selectnbrecv2 is the later
set the input pointer value by second return value from chanrecv.
So by making selectnbrecv return two values from chanrecv, we can get
rid of selectnbrecv2, the compiler can now call only selectnbrecv and
generate simpler code.
This is the gofrontend version of https://golang.org/cl/292890.
Change-Id: Ied87c4ab6c36e48669aeba22cbbb80a34d99d3d7
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/339529
Trust: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
diff --git a/go/runtime.def b/go/runtime.def
index fad8ceb..87a2708 100644
--- a/go/runtime.def
+++ b/go/runtime.def
@@ -204,12 +204,8 @@
// Non-blocking receive a value from a channel, used for two-case select
// statement with a default case.
-DEF_GO_RUNTIME(SELECTNBRECV, "runtime.selectnbrecv", P2(POINTER, CHAN), R1(BOOL))
-
-// Non-blocking tuple receive from a channel, used for two-case select
-// statement with a default case.
-DEF_GO_RUNTIME(SELECTNBRECV2, "runtime.selectnbrecv2", P3(POINTER, POINTER, CHAN),
- R1(BOOL))
+DEF_GO_RUNTIME(SELECTNBRECV, "runtime.selectnbrecv", P2(POINTER, CHAN),
+ R2(BOOL, BOOL))
// Block execution. Used for zero-case select.
DEF_GO_RUNTIME(BLOCK, "runtime.block", P0(), R0())
diff --git a/go/statements.cc b/go/statements.cc
index 9643d1b..95fa3c4 100644
--- a/go/statements.cc
+++ b/go/statements.cc
@@ -6051,7 +6051,7 @@
Expression* chanref = Expression::make_temporary_reference(chantmp, loc);
Block* bchan;
- Expression* call;
+ Expression* cond;
if (chancase.is_send())
{
// if selectnbsend(chan, &val) { body } else { default body }
@@ -6065,7 +6065,7 @@
Expression* ref = Expression::make_temporary_reference(ts, loc);
Expression* addr = Expression::make_unary(OPERATOR_AND, ref, loc);
- call = Runtime::make_call(Runtime::SELECTNBSEND, loc, 2, chanref, addr);
+ cond = Runtime::make_call(Runtime::SELECTNBSEND, loc, 2, chanref, addr);
bchan = chancase.statements();
}
else
@@ -6075,34 +6075,31 @@
Expression* ref = Expression::make_temporary_reference(ts, loc);
Expression* addr = Expression::make_unary(OPERATOR_AND, ref, loc);
- Expression* okref = NULL;
- if (chancase.closed() == NULL && chancase.closedvar() == NULL)
- {
- // Simple receive.
- // if selectnbrecv(&lhs, chan) { body } else { default body }
- call = Runtime::make_call(Runtime::SELECTNBRECV, loc, 2, addr, chanref);
- }
- else
- {
- // Tuple receive.
- // if selectnbrecv2(&lhs, &ok, chan) { body } else { default body }
- Type* booltype = Type::make_boolean_type();
- Temporary_statement* okts = Statement::make_temporary(booltype, NULL,
- loc);
- b->add_statement(okts);
+ // selected, ok = selectnbrecv(&lhs, chan)
+ Call_expression* call = Runtime::make_call(Runtime::SELECTNBRECV, loc, 2,
+ addr, chanref);
- okref = Expression::make_temporary_reference(okts, loc);
- Expression* okaddr = Expression::make_unary(OPERATOR_AND, okref, loc);
- call = Runtime::make_call(Runtime::SELECTNBRECV2, loc, 3, addr, okaddr,
- chanref);
- }
+ Temporary_statement* selected_temp =
+ Statement::make_temporary(Type::make_boolean_type(),
+ Expression::make_call_result(call, 0),
+ loc);
+ b->add_statement(selected_temp);
+
+ Temporary_statement* ok_temp =
+ Statement::make_temporary(Type::make_boolean_type(),
+ Expression::make_call_result(call, 1),
+ loc);
+ b->add_statement(ok_temp);
+
+ cond = Expression::make_temporary_reference(selected_temp, loc);
Location cloc = chancase.location();
bchan = new Block(b, loc);
if (chancase.val() != NULL && !chancase.val()->is_sink_expression())
{
- Statement* as = Statement::make_assignment(chancase.val(), ref->copy(),
+ Statement* as = Statement::make_assignment(chancase.val(),
+ ref->copy(),
cloc);
bchan->add_statement(as);
}
@@ -6114,12 +6111,18 @@
if (chancase.closed() != NULL && !chancase.closed()->is_sink_expression())
{
+ Expression* okref = Expression::make_temporary_reference(ok_temp,
+ cloc);
Statement* as = Statement::make_assignment(chancase.closed(),
- okref->copy(), cloc);
+ okref, cloc);
bchan->add_statement(as);
}
else if (chancase.closedvar() != NULL)
- chancase.closedvar()->var_value()->set_init(okref->copy());
+ {
+ Expression* okref = Expression::make_temporary_reference(ok_temp,
+ cloc);
+ chancase.closedvar()->var_value()->set_init(okref);
+ }
Statement* bs = Statement::make_block_statement(chancase.statements(),
cloc);
@@ -6127,7 +6130,7 @@
}
Statement* ifs =
- Statement::make_if_statement(call, bchan, defcase.statements(), loc);
+ Statement::make_if_statement(cond, bchan, defcase.statements(), loc);
b->add_statement(ifs);
Statement* label =
diff --git a/libgo/go/runtime/chan.go b/libgo/go/runtime/chan.go
index 7878a8f..e3d0ad5 100644
--- a/libgo/go/runtime/chan.go
+++ b/libgo/go/runtime/chan.go
@@ -33,7 +33,6 @@
//go:linkname closechan
//go:linkname selectnbsend
//go:linkname selectnbrecv
-//go:linkname selectnbrecv2
const (
maxAlign = 8
@@ -712,28 +711,6 @@
// compiler implements
//
// select {
-// case v = <-c:
-// ... foo
-// default:
-// ... bar
-// }
-//
-// as
-//
-// if selectnbrecv(&v, c) {
-// ... foo
-// } else {
-// ... bar
-// }
-//
-func selectnbrecv(elem unsafe.Pointer, c *hchan) (selected bool) {
- selected, _ = chanrecv(c, elem, false)
- return
-}
-
-// compiler implements
-//
-// select {
// case v, ok = <-c:
// ... foo
// default:
@@ -742,16 +719,14 @@
//
// as
//
-// if c != nil && selectnbrecv2(&v, &ok, c) {
+// if selected, ok = selectnbrecv(&v, c); selected {
// ... foo
// } else {
// ... bar
// }
//
-func selectnbrecv2(elem unsafe.Pointer, received *bool, c *hchan) (selected bool) {
- // TODO(khr): just return 2 values from this function, now that it is in Go.
- selected, *received = chanrecv(c, elem, false)
- return
+func selectnbrecv(elem unsafe.Pointer, c *hchan) (selected, received bool) {
+ return chanrecv(c, elem, false)
}
//go:linkname reflect_chansend reflect.chansend
