[dev.cc] runtime: convert memory allocator and garbage collector to Go

The conversion was done with an automated tool and then
modified only as necessary to make it compile and run.

[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]

LGTM=r
R=r
CC=austin, dvyukov, golang-codereviews, iant, khr
https://golang.org/cl/167540043

1 files changed, 58 insertions, 0 deletions

diff --git a/src/runtime/mem_darwin.go b/src/runtime/mem_darwin.go
new file mode 100644
index 0000000000..1bee933d07
--- /dev/null
+++ b/src/runtime/mem_darwin.go
@@ -0,0 +1,58 @@
+// Copyright 2010 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 runtime
+
+import "unsafe"
+
+//go:nosplit
+func sysAlloc(n uintptr, stat *uint64) unsafe.Pointer {
+	v := (unsafe.Pointer)(mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0))
+	if uintptr(v) < 4096 {
+		return nil
+	}
+	xadd64(stat, int64(n))
+	return v
+}
+
+func sysUnused(v unsafe.Pointer, n uintptr) {
+	// Linux's MADV_DONTNEED is like BSD's MADV_FREE.
+	madvise(v, n, _MADV_FREE)
+}
+
+func sysUsed(v unsafe.Pointer, n uintptr) {
+}
+
+func sysFree(v unsafe.Pointer, n uintptr, stat *uint64) {
+	xadd64(stat, -int64(n))
+	munmap(v, n)
+}
+
+func sysFault(v unsafe.Pointer, n uintptr) {
+	mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
+}
+
+func sysReserve(v unsafe.Pointer, n uintptr, reserved *bool) unsafe.Pointer {
+	*reserved = true
+	p := (unsafe.Pointer)(mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0))
+	if uintptr(p) < 4096 {
+		return nil
+	}
+	return p
+}
+
+const (
+	_ENOMEM = 12
+)
+
+func sysMap(v unsafe.Pointer, n uintptr, reserved bool, stat *uint64) {
+	xadd64(stat, int64(n))
+	p := (unsafe.Pointer)(mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0))
+	if uintptr(p) == _ENOMEM {
+		gothrow("runtime: out of memory")
+	}
+	if p != v {
+		gothrow("runtime: cannot map pages in arena address space")
+	}
+}