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.
13 // The constant is known to the compiler.
14 // There is no fundamental theory behind this number.
15 const tmpStringBufSize = 32
17 type tmpBuf [tmpStringBufSize]byte
19 // concatstrings implements a Go string concatenation x+y+z+...
20 // The operands are passed in the slice a.
21 // If buf != nil, the compiler has determined that the result does not
22 // escape the calling function, so the string data can be stored in buf
24 func concatstrings(buf *tmpBuf, a []string) string {
34 throw("string concatenation too long")
44 // If there is just one string and either it is not on the stack
45 // or our result does not escape the calling frame (buf != nil),
46 // then we can return that string directly.
47 if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) {
50 s, b := rawstringtmp(buf, l)
58 func concatstring2(buf *tmpBuf, a [2]string) string {
59 return concatstrings(buf, a[:])
62 func concatstring3(buf *tmpBuf, a [3]string) string {
63 return concatstrings(buf, a[:])
66 func concatstring4(buf *tmpBuf, a [4]string) string {
67 return concatstrings(buf, a[:])
70 func concatstring5(buf *tmpBuf, a [5]string) string {
71 return concatstrings(buf, a[:])
74 // Buf is a fixed-size buffer for the result,
75 // it is not nil if the result does not escape.
76 func slicebytetostring(buf *tmpBuf, b []byte) (str string) {
79 // Turns out to be a relatively common case.
80 // Consider that you want to parse out data between parens in "foo()bar",
81 // you find the indices and convert the subslice to string.
85 racereadrangepc(unsafe.Pointer(&b[0]),
88 funcPC(slicebytetostring))
91 msanread(unsafe.Pointer(&b[0]), uintptr(l))
94 p := unsafe.Pointer(&staticuint64s[b[0]])
98 stringStructOf(&str).str = p
99 stringStructOf(&str).len = 1
104 if buf != nil && len(b) <= len(buf) {
105 p = unsafe.Pointer(buf)
107 p = mallocgc(uintptr(len(b)), nil, false)
109 stringStructOf(&str).str = p
110 stringStructOf(&str).len = len(b)
111 memmove(p, (*(*slice)(unsafe.Pointer(&b))).array, uintptr(len(b)))
115 // stringDataOnStack reports whether the string's data is
116 // stored on the current goroutine's stack.
117 func stringDataOnStack(s string) bool {
118 ptr := uintptr(stringStructOf(&s).str)
120 return stk.lo <= ptr && ptr < stk.hi
123 func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
124 if buf != nil && l <= len(buf) {
126 s = slicebytetostringtmp(b)
133 // slicebytetostringtmp returns a "string" referring to the actual []byte bytes.
135 // Callers need to ensure that the returned string will not be used after
136 // the calling goroutine modifies the original slice or synchronizes with
137 // another goroutine.
139 // The function is only called when instrumenting
140 // and otherwise intrinsified by the compiler.
142 // Some internal compiler optimizations use this function.
143 // - Used for m[T1{... Tn{..., string(k), ...} ...}] and m[string(k)]
144 // where k is []byte, T1 to Tn is a nesting of struct and array literals.
145 // - Used for "<"+string(b)+">" concatenation where b is []byte.
146 // - Used for string(b)=="foo" comparison where b is []byte.
147 func slicebytetostringtmp(b []byte) string {
148 if raceenabled && len(b) > 0 {
149 racereadrangepc(unsafe.Pointer(&b[0]),
152 funcPC(slicebytetostringtmp))
154 if msanenabled && len(b) > 0 {
155 msanread(unsafe.Pointer(&b[0]), uintptr(len(b)))
157 return *(*string)(unsafe.Pointer(&b))
160 func stringtoslicebyte(buf *tmpBuf, s string) []byte {
162 if buf != nil && len(s) <= len(buf) {
166 b = rawbyteslice(len(s))
172 func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
174 // unlike slicerunetostring, no race because strings are immutable.
181 if buf != nil && n <= len(buf) {
182 *buf = [tmpStringBufSize]rune{}
189 for _, r := range s {
196 func slicerunetostring(buf *tmpBuf, a []rune) string {
197 if raceenabled && len(a) > 0 {
198 racereadrangepc(unsafe.Pointer(&a[0]),
199 uintptr(len(a))*unsafe.Sizeof(a[0]),
201 funcPC(slicerunetostring))
203 if msanenabled && len(a) > 0 {
204 msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
208 for _, r := range a {
209 size1 += encoderune(dum[:], r)
211 s, b := rawstringtmp(buf, size1+3)
213 for _, r := range a {
218 size2 += encoderune(b[size2:], r)
223 type stringStruct struct {
228 // Variant with *byte pointer type for DWARF debugging.
229 type stringStructDWARF struct {
234 func stringStructOf(sp *string) *stringStruct {
235 return (*stringStruct)(unsafe.Pointer(sp))
238 func intstring(buf *[4]byte, v int64) (s string) {
242 s = slicebytetostringtmp(b)
246 if int64(rune(v)) != v {
249 n := encoderune(b, rune(v))
253 // rawstring allocates storage for a new string. The returned
254 // string and byte slice both refer to the same storage.
255 // The storage is not zeroed. Callers should use
256 // b to set the string contents and then drop b.
257 func rawstring(size int) (s string, b []byte) {
258 p := mallocgc(uintptr(size), nil, false)
260 stringStructOf(&s).str = p
261 stringStructOf(&s).len = size
263 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, size}
268 // rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
269 func rawbyteslice(size int) (b []byte) {
270 cap := roundupsize(uintptr(size))
271 p := mallocgc(cap, nil, false)
272 if cap != uintptr(size) {
273 memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size))
276 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)}
280 // rawruneslice allocates a new rune slice. The rune slice is not zeroed.
281 func rawruneslice(size int) (b []rune) {
282 if uintptr(size) > maxAlloc/4 {
283 throw("out of memory")
285 mem := roundupsize(uintptr(size) * 4)
286 p := mallocgc(mem, nil, false)
287 if mem != uintptr(size)*4 {
288 memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4)
291 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)}
296 func gobytes(p *byte, n int) (b []byte) {
298 return make([]byte, 0)
301 if n < 0 || uintptr(n) > maxAlloc {
302 panic(errorString("gobytes: length out of range"))
305 bp := mallocgc(uintptr(n), nil, false)
306 memmove(bp, unsafe.Pointer(p), uintptr(n))
308 *(*slice)(unsafe.Pointer(&b)) = slice{bp, n, n}
312 // This is exported via linkname to assembly in syscall (for Plan9).
313 //go:linkname gostring
314 func gostring(p *byte) string {
320 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
324 func gostringn(p *byte, l int) string {
329 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
333 func index(s, t string) int {
337 for i := 0; i < len(s); i++ {
338 if s[i] == t[0] && hasPrefix(s[i:], t) {
345 func contains(s, t string) bool {
346 return index(s, t) >= 0
349 func hasPrefix(s, prefix string) bool {
350 return len(s) >= len(prefix) && s[:len(prefix)] == prefix
355 maxInt = int(maxUint >> 1)
358 // atoi parses an int from a string s.
359 // The bool result reports whether s is a number
360 // representable by a value of type int.
361 func atoi(s string) (int, bool) {
373 for i := 0; i < len(s); i++ {
375 if c < '0' || c > '9' {
383 un1 := un + uint(c) - '0'
391 if !neg && un > uint(maxInt) {
394 if neg && un > uint(maxInt)+1 {
406 // atoi32 is like atoi but for integers
407 // that fit into an int32.
408 func atoi32(s string) (int32, bool) {
409 if n, ok := atoi(s); n == int(int32(n)) {
416 func findnull(s *byte) int {
421 // Avoid IndexByteString on Plan 9 because it uses SSE instructions
422 // on x86 machines, and those are classified as floating point instructions,
423 // which are illegal in a note handler.
425 p := (*[maxAlloc/2 - 1]byte)(unsafe.Pointer(s))
433 // pageSize is the unit we scan at a time looking for NULL.
434 // It must be the minimum page size for any architecture Go
435 // runs on. It's okay (just a minor performance loss) if the
436 // actual system page size is larger than this value.
437 const pageSize = 4096
440 ptr := unsafe.Pointer(s)
441 // IndexByteString uses wide reads, so we need to be careful
442 // with page boundaries. Call IndexByteString on
443 // [ptr, endOfPage) interval.
444 safeLen := int(pageSize - uintptr(ptr)%pageSize)
447 t := *(*string)(unsafe.Pointer(&stringStruct{ptr, safeLen}))
448 // Check one page at a time.
449 if i := bytealg.IndexByteString(t, 0); i != -1 {
453 ptr = unsafe.Pointer(uintptr(ptr) + uintptr(safeLen))
459 func findnullw(s *uint16) int {
463 p := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(s))
472 func gostringnocopy(str *byte) string {
473 ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)}
474 s := *(*string)(unsafe.Pointer(&ss))
478 func gostringw(strw *uint16) string {
480 str := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(strw))
482 for i := 0; str[i] != 0; i++ {
483 n1 += encoderune(buf[:], rune(str[i]))
485 s, b := rawstring(n1 + 4)
487 for i := 0; str[i] != 0; i++ {
492 n2 += encoderune(b[n2:], rune(str[i]))
494 b[n2] = 0 // for luck
498 // parseRelease parses a dot-separated version number. It follows the
499 // semver syntax, but allows the minor and patch versions to be
501 func parseRelease(rel string) (major, minor, patch int, ok bool) {
502 // Strip anything after a dash or plus.
503 for i := 0; i < len(rel); i++ {
504 if rel[i] == '-' || rel[i] == '+' {
510 next := func() (int, bool) {
511 for i := 0; i < len(rel); i++ {
513 ver, ok := atoi(rel[:i])
522 if major, ok = next(); !ok || rel == "" {
525 if minor, ok = next(); !ok || rel == "" {