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* [gcc r12-2715] compile, runtime: make selectnbrecv return two values
@ 2021-08-03 23:40 Ian Lance Taylor
0 siblings, 0 replies; only message in thread
From: Ian Lance Taylor @ 2021-08-03 23:40 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:e435e72ad713cadd661072427588ec1c777c04e3
commit r12-2715-ge435e72ad713cadd661072427588ec1c777c04e3
Author: Ian Lance Taylor <iant@golang.org>
Date: Tue Aug 3 11:36:24 2021 -0700
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.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/339529
Diff:
---
gcc/go/gofrontend/MERGE | 2 +-
gcc/go/gofrontend/runtime.def | 8 ++----
gcc/go/gofrontend/statements.cc | 59 ++++++++++++++++++++++-------------------
libgo/go/runtime/chan.go | 31 +++-------------------
4 files changed, 37 insertions(+), 63 deletions(-)
diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 801e039a155..5a097ffee85 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-54361805bd611d896042b879ee7f6d2d4d088537
+2031f0be9c0b5fda6421d290a0261eb6bd1c8205
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/runtime.def b/gcc/go/gofrontend/runtime.def
index fad8cebc012..87a27085d60 100644
--- a/gcc/go/gofrontend/runtime.def
+++ b/gcc/go/gofrontend/runtime.def
@@ -204,12 +204,8 @@ DEF_GO_RUNTIME(SELECTNBSEND, "runtime.selectnbsend", P2(CHAN, POINTER), R1(BOOL)
// 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/gcc/go/gofrontend/statements.cc b/gcc/go/gofrontend/statements.cc
index 9643d1b42b3..95fa3c48709 100644
--- a/gcc/go/gofrontend/statements.cc
+++ b/gcc/go/gofrontend/statements.cc
@@ -6051,7 +6051,7 @@ Select_statement::lower_two_case(Block* b)
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 @@ Select_statement::lower_two_case(Block* b)
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 @@ Select_statement::lower_two_case(Block* b)
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);
-
- 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);
- }
+
+ // selected, ok = selectnbrecv(&lhs, chan)
+ Call_expression* call = Runtime::make_call(Runtime::SELECTNBRECV, loc, 2,
+ addr, 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 @@ Select_statement::lower_two_case(Block* b)
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 @@ Select_statement::lower_two_case(Block* b)
}
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 7878a8fe012..e3d0ad5acbe 100644
--- a/libgo/go/runtime/chan.go
+++ b/libgo/go/runtime/chan.go
@@ -33,7 +33,6 @@ import (
//go:linkname closechan
//go:linkname selectnbsend
//go:linkname selectnbrecv
-//go:linkname selectnbrecv2
const (
maxAlign = 8
@@ -709,28 +708,6 @@ func selectnbsend(c *hchan, elem unsafe.Pointer) (selected bool) {
return chansend(c, elem, false, getcallerpc())
}
-// 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 {
@@ -742,16 +719,14 @@ func selectnbrecv(elem unsafe.Pointer, c *hchan) (selected bool) {
//
// 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
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