[dev.garbage] all: merge dev.cc into dev.garbage

The garbage collector is now written in Go.
There is plenty to clean up (just like on dev.cc).

all.bash passes on darwin/amd64, darwin/386, linux/amd64, linux/386.

TBR=rlh
R=austin, rlh, bradfitz
CC=golang-codereviews
https://golang.org/cl/173250043

1 files changed, 108 insertions, 0 deletions

diff --git a/src/runtime/string1.go b/src/runtime/string1.go
new file mode 100644
index 0000000000..35cde43be0
--- /dev/null
+++ b/src/runtime/string1.go
@@ -0,0 +1,108 @@
+// Copyright 2009 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 findnull(s *byte) int {
+	if s == nil {
+		return 0
+	}
+	p := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s))
+	l := 0
+	for p[l] != 0 {
+		l++
+	}
+	return l
+}
+
+func findnullw(s *uint16) int {
+	if s == nil {
+		return 0
+	}
+	p := (*[_MaxMem/2/2 - 1]uint16)(unsafe.Pointer(s))
+	l := 0
+	for p[l] != 0 {
+		l++
+	}
+	return l
+}
+
+var maxstring uintptr = 256 // a hint for print
+
+//go:nosplit
+func gostringnocopy(str *byte) string {
+	var s string
+	sp := (*stringStruct)(unsafe.Pointer(&s))
+	sp.str = unsafe.Pointer(str)
+	sp.len = findnull(str)
+	for {
+		ms := maxstring
+		if uintptr(len(s)) <= ms || casuintptr(&maxstring, ms, uintptr(len(s))) {
+			break
+		}
+	}
+	return s
+}
+
+func gostringw(strw *uint16) string {
+	var buf [8]byte
+	str := (*[_MaxMem/2/2 - 1]uint16)(unsafe.Pointer(strw))
+	n1 := 0
+	for i := 0; str[i] != 0; i++ {
+		n1 += runetochar(buf[:], rune(str[i]))
+	}
+	s, b := rawstring(n1 + 4)
+	n2 := 0
+	for i := 0; str[i] != 0; i++ {
+		// check for race
+		if n2 >= n1 {
+			break
+		}
+		n2 += runetochar(b[n2:], rune(str[i]))
+	}
+	b[n2] = 0 // for luck
+	return s[:n2]
+}
+
+func strcmp(s1, s2 *byte) int32 {
+	p1 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s1))
+	p2 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s2))
+
+	for i := uintptr(0); ; i++ {
+		c1 := p1[i]
+		c2 := p2[i]
+		if c1 < c2 {
+			return -1
+		}
+		if c1 > c2 {
+			return +1
+		}
+		if c1 == 0 {
+			return 0
+		}
+	}
+}
+
+func strncmp(s1, s2 *byte, n uintptr) int32 {
+	p1 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s1))
+	p2 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s2))
+
+	for i := uintptr(0); i < n; i++ {
+		c1 := p1[i]
+		c2 := p2[i]
+		if c1 < c2 {
+			return -1
+		}
+		if c1 > c2 {
+			return +1
+		}
+		if c1 == 0 {
+			break
+		}
+	}
+	return 0
+}