internal/runtime/maps: initial swiss table map implementation

Add a new package that will contain a new "Swiss Table"
(https://abseil.io/about/design/swisstables) map implementation, which
is intended to eventually replace the existing runtime map
implementation.

This implementation is based on the fabulous
github.com/cockroachdb/swiss package contributed by Peter Mattis.

This CL adds an hash map implementation. It supports all the core
operations, but does not have incremental growth.

For #54766.

Change-Id: I52cf371448c3817d471ddb1f5a78f3513565db41
Reviewed-on: https://go-review.googlesource.com/c/go/+/582415
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/internal/runtime/maps/runtime.go b/src/internal/runtime/maps/runtime.go
new file mode 100644
index 0000000000..9ebfb34b28
--- /dev/null
+++ b/src/internal/runtime/maps/runtime.go
@@ -0,0 +1,24 @@
+// Copyright 2024 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.
+
+package maps
+
+import (
+	"internal/abi"
+	"unsafe"
+)
+
+// Functions below pushed from runtime.
+
+//go:linkname rand
+func rand() uint64
+
+//go:linkname typedmemmove
+func typedmemmove(typ *abi.Type, dst, src unsafe.Pointer)
+
+//go:linkname typedmemclr
+func typedmemclr(typ *abi.Type, ptr unsafe.Pointer)
+
+//go:linkname newarray
+func newarray(typ *abi.Type, n int) unsafe.Pointer