1 // Copyright 2014 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
9 // The constant is known to the compiler.
10 // There is no fundamental theory behind this number.
11 const tmpStringBufSize = 32
13 type tmpBuf [tmpStringBufSize]byte
15 // concatstrings implements a Go string concatenation x+y+z+...
16 // The operands are passed in the slice a.
17 // If buf != nil, the compiler has determined that the result does not
18 // escape the calling function, so the string data can be stored in buf
20 func concatstrings(buf *tmpBuf, a []string) string {
30 throw("string concatenation too long")
40 // If there is just one string and either it is not on the stack
41 // or our result does not escape the calling frame (buf != nil),
42 // then we can return that string directly.
43 if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) {
46 s, b := rawstringtmp(buf, l)
54 func concatstring2(buf *tmpBuf, a [2]string) string {
55 return concatstrings(buf, a[:])
58 func concatstring3(buf *tmpBuf, a [3]string) string {
59 return concatstrings(buf, a[:])
62 func concatstring4(buf *tmpBuf, a [4]string) string {
63 return concatstrings(buf, a[:])
66 func concatstring5(buf *tmpBuf, a [5]string) string {
67 return concatstrings(buf, a[:])
70 // Buf is a fixed-size buffer for the result,
71 // it is not nil if the result does not escape.
72 func slicebytetostring(buf *tmpBuf, b []byte) (str string) {
75 // Turns out to be a relatively common case.
76 // Consider that you want to parse out data between parens in "foo()bar",
77 // you find the indices and convert the subslice to string.
81 racereadrangepc(unsafe.Pointer(&b[0]),
84 funcPC(slicebytetostring))
87 msanread(unsafe.Pointer(&b[0]), uintptr(l))
91 if buf != nil && len(b) <= len(buf) {
92 p = unsafe.Pointer(buf)
94 p = mallocgc(uintptr(len(b)), nil, false)
96 stringStructOf(&str).str = p
97 stringStructOf(&str).len = len(b)
98 memmove(p, (*(*slice)(unsafe.Pointer(&b))).array, uintptr(len(b)))
102 // stringDataOnStack reports whether the string's data is
103 // stored on the current goroutine's stack.
104 func stringDataOnStack(s string) bool {
105 ptr := uintptr(stringStructOf(&s).str)
107 return stk.lo <= ptr && ptr < stk.hi
110 func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
111 if buf != nil && l <= len(buf) {
113 s = slicebytetostringtmp(b)
120 // slicebytetostringtmp returns a "string" referring to the actual []byte bytes.
122 // Callers need to ensure that the returned string will not be used after
123 // the calling goroutine modifies the original slice or synchronizes with
124 // another goroutine.
126 // The function is only called when instrumenting
127 // and otherwise intrinsified by the compiler.
129 // Some internal compiler optimizations use this function.
130 // - Used for m[string(k)] lookup where m is a string-keyed map and k is a []byte.
131 // - Used for "<"+string(b)+">" concatenation where b is []byte.
132 // - Used for string(b)=="foo" comparison where b is []byte.
133 func slicebytetostringtmp(b []byte) string {
134 if raceenabled && len(b) > 0 {
135 racereadrangepc(unsafe.Pointer(&b[0]),
138 funcPC(slicebytetostringtmp))
140 if msanenabled && len(b) > 0 {
141 msanread(unsafe.Pointer(&b[0]), uintptr(len(b)))
143 return *(*string)(unsafe.Pointer(&b))
146 func stringtoslicebyte(buf *tmpBuf, s string) []byte {
148 if buf != nil && len(s) <= len(buf) {
152 b = rawbyteslice(len(s))
158 func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
160 // unlike slicerunetostring, no race because strings are immutable.
167 if buf != nil && n <= len(buf) {
168 *buf = [tmpStringBufSize]rune{}
175 for _, r := range s {
182 func slicerunetostring(buf *tmpBuf, a []rune) string {
183 if raceenabled && len(a) > 0 {
184 racereadrangepc(unsafe.Pointer(&a[0]),
185 uintptr(len(a))*unsafe.Sizeof(a[0]),
187 funcPC(slicerunetostring))
189 if msanenabled && len(a) > 0 {
190 msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
194 for _, r := range a {
195 size1 += encoderune(dum[:], r)
197 s, b := rawstringtmp(buf, size1+3)
199 for _, r := range a {
204 size2 += encoderune(b[size2:], r)
209 type stringStruct struct {
214 // Variant with *byte pointer type for DWARF debugging.
215 type stringStructDWARF struct {
220 func stringStructOf(sp *string) *stringStruct {
221 return (*stringStruct)(unsafe.Pointer(sp))
224 func intstring(buf *[4]byte, v int64) string {
229 s = slicebytetostringtmp(b)
233 if int64(rune(v)) != v {
236 n := encoderune(b, rune(v))
240 // rawstring allocates storage for a new string. The returned
241 // string and byte slice both refer to the same storage.
242 // The storage is not zeroed. Callers should use
243 // b to set the string contents and then drop b.
244 func rawstring(size int) (s string, b []byte) {
245 p := mallocgc(uintptr(size), nil, false)
247 stringStructOf(&s).str = p
248 stringStructOf(&s).len = size
250 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, size}
255 // rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
256 func rawbyteslice(size int) (b []byte) {
257 cap := roundupsize(uintptr(size))
258 p := mallocgc(cap, nil, false)
259 if cap != uintptr(size) {
260 memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size))
263 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)}
267 // rawruneslice allocates a new rune slice. The rune slice is not zeroed.
268 func rawruneslice(size int) (b []rune) {
269 if uintptr(size) > maxAlloc/4 {
270 throw("out of memory")
272 mem := roundupsize(uintptr(size) * 4)
273 p := mallocgc(mem, nil, false)
274 if mem != uintptr(size)*4 {
275 memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4)
278 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)}
283 func gobytes(p *byte, n int) []byte {
285 return make([]byte, 0)
288 memmove(unsafe.Pointer(&x[0]), unsafe.Pointer(p), uintptr(n))
292 func gostring(p *byte) string {
298 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
302 func gostringn(p *byte, l int) string {
307 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
311 func index(s, t string) int {
315 for i := 0; i < len(s); i++ {
316 if s[i] == t[0] && hasprefix(s[i:], t) {
323 func contains(s, t string) bool {
324 return index(s, t) >= 0
327 func hasprefix(s, t string) bool {
328 return len(s) >= len(t) && s[:len(t)] == t
333 maxInt = int(maxUint >> 1)
336 // atoi parses an int from a string s.
337 // The bool result reports whether s is a number
338 // representable by a value of type int.
339 func atoi(s string) (int, bool) {
351 for i := 0; i < len(s); i++ {
353 if c < '0' || c > '9' {
361 un1 := un + uint(c) - '0'
369 if !neg && un > uint(maxInt) {
372 if neg && un > uint(maxInt)+1 {
384 // atoi32 is like atoi but for integers
385 // that fit into an int32.
386 func atoi32(s string) (int32, bool) {
387 if n, ok := atoi(s); n == int(int32(n)) {
394 func findnull(s *byte) int {
398 p := (*[maxAlloc/2 - 1]byte)(unsafe.Pointer(s))
406 func findnullw(s *uint16) int {
410 p := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(s))
419 func gostringnocopy(str *byte) string {
420 ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)}
421 s := *(*string)(unsafe.Pointer(&ss))
425 func gostringw(strw *uint16) string {
427 str := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(strw))
429 for i := 0; str[i] != 0; i++ {
430 n1 += encoderune(buf[:], rune(str[i]))
432 s, b := rawstring(n1 + 4)
434 for i := 0; str[i] != 0; i++ {
439 n2 += encoderune(b[n2:], rune(str[i]))
441 b[n2] = 0 // for luck