all: merge dev.cc (81884b89bd88) into default

With this change, default now contains Go 1.5 work.
Any future bug fixes for Go 1.4 in the compilers or
the runtime will have to be made directly to the
release branch.

1 files changed, 119 insertions, 0 deletions

diff --git a/src/runtime/mem_windows.go b/src/runtime/mem_windows.go
new file mode 100644
index 000000000..a1dcad013
--- /dev/null
+++ b/src/runtime/mem_windows.go
@@ -0,0 +1,119 @@
+// 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"
+)
+
+const (
+	_MEM_COMMIT   = 0x1000
+	_MEM_RESERVE  = 0x2000
+	_MEM_DECOMMIT = 0x4000
+	_MEM_RELEASE  = 0x8000
+
+	_PAGE_READWRITE = 0x0004
+	_PAGE_NOACCESS  = 0x0001
+)
+
+//go:cgo_import_dynamic runtime._VirtualAlloc VirtualAlloc "kernel32.dll"
+//go:cgo_import_dynamic runtime._VirtualFree VirtualFree "kernel32.dll"
+//go:cgo_import_dynamic runtime._VirtualProtect VirtualProtect "kernel32.dll"
+
+var (
+	_VirtualAlloc,
+	_VirtualFree,
+	_VirtualProtect stdFunction
+)
+
+//go:nosplit
+func sysAlloc(n uintptr, stat *uint64) unsafe.Pointer {
+	xadd64(stat, int64(n))
+	return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_COMMIT|_MEM_RESERVE, _PAGE_READWRITE))
+}
+
+func sysUnused(v unsafe.Pointer, n uintptr) {
+	r := stdcall3(_VirtualFree, uintptr(v), n, _MEM_DECOMMIT)
+	if r != 0 {
+		return
+	}
+
+	// Decommit failed. Usual reason is that we've merged memory from two different
+	// VirtualAlloc calls, and Windows will only let each VirtualFree handle pages from
+	// a single VirtualAlloc. It is okay to specify a subset of the pages from a single alloc,
+	// just not pages from multiple allocs. This is a rare case, arising only when we're
+	// trying to give memory back to the operating system, which happens on a time
+	// scale of minutes. It doesn't have to be terribly fast. Instead of extra bookkeeping
+	// on all our VirtualAlloc calls, try freeing successively smaller pieces until
+	// we manage to free something, and then repeat. This ends up being O(n log n)
+	// in the worst case, but that's fast enough.
+	for n > 0 {
+		small := n
+		for small >= 4096 && stdcall3(_VirtualFree, uintptr(v), small, _MEM_DECOMMIT) == 0 {
+			small /= 2
+			small &^= 4096 - 1
+		}
+		if small < 4096 {
+			gothrow("runtime: failed to decommit pages")
+		}
+		v = add(v, small)
+		n -= small
+	}
+}
+
+func sysUsed(v unsafe.Pointer, n uintptr) {
+	r := stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_COMMIT, _PAGE_READWRITE)
+	if r != uintptr(v) {
+		gothrow("runtime: failed to commit pages")
+	}
+
+	// Commit failed. See SysUnused.
+	for n > 0 {
+		small := n
+		for small >= 4096 && stdcall4(_VirtualAlloc, uintptr(v), small, _MEM_COMMIT, _PAGE_READWRITE) == 0 {
+			small /= 2
+			small &^= 4096 - 1
+		}
+		if small < 4096 {
+			gothrow("runtime: failed to decommit pages")
+		}
+		v = add(v, small)
+		n -= small
+	}
+}
+
+func sysFree(v unsafe.Pointer, n uintptr, stat *uint64) {
+	xadd64(stat, -int64(n))
+	r := stdcall3(_VirtualFree, uintptr(v), 0, _MEM_RELEASE)
+	if r == 0 {
+		gothrow("runtime: failed to release pages")
+	}
+}
+
+func sysFault(v unsafe.Pointer, n uintptr) {
+	// SysUnused makes the memory inaccessible and prevents its reuse
+	sysUnused(v, n)
+}
+
+func sysReserve(v unsafe.Pointer, n uintptr, reserved *bool) unsafe.Pointer {
+	*reserved = true
+	// v is just a hint.
+	// First try at v.
+	v = unsafe.Pointer(stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_RESERVE, _PAGE_READWRITE))
+	if v != nil {
+		return v
+	}
+
+	// Next let the kernel choose the address.
+	return unsafe.Pointer(stdcall4(_VirtualAlloc, 0, n, _MEM_RESERVE, _PAGE_READWRITE))
+}
+
+func sysMap(v unsafe.Pointer, n uintptr, reserved bool, stat *uint64) {
+	xadd64(stat, int64(n))
+	p := stdcall4(_VirtualAlloc, uintptr(v), n, _MEM_COMMIT, _PAGE_READWRITE)
+	if p != uintptr(v) {
+		gothrow("runtime: cannot map pages in arena address space")
+	}
+}