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.
14 // The constant is known to the compiler.
15 // There is no fundamental theory behind this number.
16 const tmpStringBufSize = 32
18 type tmpBuf [tmpStringBufSize]byte
20 // concatstrings implements a Go string concatenation x+y+z+...
21 // The operands are passed in the slice a.
22 // If buf != nil, the compiler has determined that the result does not
23 // escape the calling function, so the string data can be stored in buf
25 func concatstrings(buf *tmpBuf, a []string) string {
35 throw("string concatenation too long")
45 // If there is just one string and either it is not on the stack
46 // or our result does not escape the calling frame (buf != nil),
47 // then we can return that string directly.
48 if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) {
51 s, b := rawstringtmp(buf, l)
59 func concatstring2(buf *tmpBuf, a0, a1 string) string {
60 return concatstrings(buf, []string{a0, a1})
63 func concatstring3(buf *tmpBuf, a0, a1, a2 string) string {
64 return concatstrings(buf, []string{a0, a1, a2})
67 func concatstring4(buf *tmpBuf, a0, a1, a2, a3 string) string {
68 return concatstrings(buf, []string{a0, a1, a2, a3})
71 func concatstring5(buf *tmpBuf, a0, a1, a2, a3, a4 string) string {
72 return concatstrings(buf, []string{a0, a1, a2, a3, a4})
75 // slicebytetostring converts a byte slice to a string.
76 // It is inserted by the compiler into generated code.
77 // ptr is a pointer to the first element of the slice;
78 // n is the length of the slice.
79 // Buf is a fixed-size buffer for the result,
80 // it is not nil if the result does not escape.
81 func slicebytetostring(buf *tmpBuf, ptr *byte, n int) string {
83 // Turns out to be a relatively common case.
84 // Consider that you want to parse out data between parens in "foo()bar",
85 // you find the indices and convert the subslice to string.
89 racereadrangepc(unsafe.Pointer(ptr),
92 abi.FuncPCABIInternal(slicebytetostring))
95 msanread(unsafe.Pointer(ptr), uintptr(n))
98 asanread(unsafe.Pointer(ptr), uintptr(n))
101 p := unsafe.Pointer(&staticuint64s[*ptr])
102 if goarch.BigEndian {
105 return unsafe.String((*byte)(p), 1)
109 if buf != nil && n <= len(buf) {
110 p = unsafe.Pointer(buf)
112 p = mallocgc(uintptr(n), nil, false)
114 memmove(p, unsafe.Pointer(ptr), uintptr(n))
115 return unsafe.String((*byte)(p), n)
118 // stringDataOnStack reports whether the string's data is
119 // stored on the current goroutine's stack.
120 func stringDataOnStack(s string) bool {
121 ptr := uintptr(unsafe.Pointer(unsafe.StringData(s)))
123 return stk.lo <= ptr && ptr < stk.hi
126 func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
127 if buf != nil && l <= len(buf) {
129 s = slicebytetostringtmp(&b[0], len(b))
136 // slicebytetostringtmp returns a "string" referring to the actual []byte bytes.
138 // Callers need to ensure that the returned string will not be used after
139 // the calling goroutine modifies the original slice or synchronizes with
140 // another goroutine.
142 // The function is only called when instrumenting
143 // and otherwise intrinsified by the compiler.
145 // Some internal compiler optimizations use this function.
146 // - Used for m[T1{... Tn{..., string(k), ...} ...}] and m[string(k)]
147 // where k is []byte, T1 to Tn is a nesting of struct and array literals.
148 // - Used for "<"+string(b)+">" concatenation where b is []byte.
149 // - Used for string(b)=="foo" comparison where b is []byte.
150 func slicebytetostringtmp(ptr *byte, n int) string {
151 if raceenabled && n > 0 {
152 racereadrangepc(unsafe.Pointer(ptr),
155 abi.FuncPCABIInternal(slicebytetostringtmp))
157 if msanenabled && n > 0 {
158 msanread(unsafe.Pointer(ptr), uintptr(n))
160 if asanenabled && n > 0 {
161 asanread(unsafe.Pointer(ptr), uintptr(n))
163 return unsafe.String(ptr, n)
166 func stringtoslicebyte(buf *tmpBuf, s string) []byte {
168 if buf != nil && len(s) <= len(buf) {
172 b = rawbyteslice(len(s))
178 func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
180 // unlike slicerunetostring, no race because strings are immutable.
187 if buf != nil && n <= len(buf) {
188 *buf = [tmpStringBufSize]rune{}
195 for _, r := range s {
202 func slicerunetostring(buf *tmpBuf, a []rune) string {
203 if raceenabled && len(a) > 0 {
204 racereadrangepc(unsafe.Pointer(&a[0]),
205 uintptr(len(a))*unsafe.Sizeof(a[0]),
207 abi.FuncPCABIInternal(slicerunetostring))
209 if msanenabled && len(a) > 0 {
210 msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
212 if asanenabled && len(a) > 0 {
213 asanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
217 for _, r := range a {
218 size1 += encoderune(dum[:], r)
220 s, b := rawstringtmp(buf, size1+3)
222 for _, r := range a {
227 size2 += encoderune(b[size2:], r)
232 type stringStruct struct {
237 // Variant with *byte pointer type for DWARF debugging.
238 type stringStructDWARF struct {
243 func stringStructOf(sp *string) *stringStruct {
244 return (*stringStruct)(unsafe.Pointer(sp))
247 func intstring(buf *[4]byte, v int64) (s string) {
251 s = slicebytetostringtmp(&b[0], len(b))
255 if int64(rune(v)) != v {
258 n := encoderune(b, rune(v))
262 // rawstring allocates storage for a new string. The returned
263 // string and byte slice both refer to the same storage.
264 // The storage is not zeroed. Callers should use
265 // b to set the string contents and then drop b.
266 func rawstring(size int) (s string, b []byte) {
267 p := mallocgc(uintptr(size), nil, false)
268 return unsafe.String((*byte)(p), size), unsafe.Slice((*byte)(p), size)
271 // rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
272 func rawbyteslice(size int) (b []byte) {
273 cap := roundupsize(uintptr(size))
274 p := mallocgc(cap, nil, false)
275 if cap != uintptr(size) {
276 memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size))
279 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)}
283 // rawruneslice allocates a new rune slice. The rune slice is not zeroed.
284 func rawruneslice(size int) (b []rune) {
285 if uintptr(size) > maxAlloc/4 {
286 throw("out of memory")
288 mem := roundupsize(uintptr(size) * 4)
289 p := mallocgc(mem, nil, false)
290 if mem != uintptr(size)*4 {
291 memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4)
294 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)}
299 func gobytes(p *byte, n int) (b []byte) {
301 return make([]byte, 0)
304 if n < 0 || uintptr(n) > maxAlloc {
305 panic(errorString("gobytes: length out of range"))
308 bp := mallocgc(uintptr(n), nil, false)
309 memmove(bp, unsafe.Pointer(p), uintptr(n))
311 *(*slice)(unsafe.Pointer(&b)) = slice{bp, n, n}
315 // This is exported via linkname to assembly in syscall (for Plan9).
317 //go:linkname gostring
318 func gostring(p *byte) string {
324 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
328 // internal_syscall_gostring is a version of gostring for internal/syscall/unix.
330 //go:linkname internal_syscall_gostring internal/syscall/unix.gostring
331 func internal_syscall_gostring(p *byte) string {
335 func gostringn(p *byte, l int) string {
340 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
344 func hasPrefix(s, prefix string) bool {
345 return len(s) >= len(prefix) && s[:len(prefix)] == prefix
348 func hasSuffix(s, suffix string) bool {
349 return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix
353 maxUint64 = ^uint64(0)
354 maxInt64 = int64(maxUint64 >> 1)
357 // atoi64 parses an int64 from a string s.
358 // The bool result reports whether s is a number
359 // representable by a value of type int64.
360 func atoi64(s string) (int64, bool) {
372 for i := 0; i < len(s); i++ {
374 if c < '0' || c > '9' {
377 if un > maxUint64/10 {
382 un1 := un + uint64(c) - '0'
390 if !neg && un > uint64(maxInt64) {
393 if neg && un > uint64(maxInt64)+1 {
405 // atoi is like atoi64 but for integers
406 // that fit into an int.
407 func atoi(s string) (int, bool) {
408 if n, ok := atoi64(s); n == int64(int(n)) {
414 // atoi32 is like atoi but for integers
415 // that fit into an int32.
416 func atoi32(s string) (int32, bool) {
417 if n, ok := atoi64(s); n == int64(int32(n)) {
423 // parseByteCount parses a string that represents a count of bytes.
425 // s must match the following regular expression:
427 // ^[0-9]+(([KMGT]i)?B)?$
429 // In other words, an integer byte count with an optional unit
430 // suffix. Acceptable suffixes include one of
431 // - KiB, MiB, GiB, TiB which represent binary IEC/ISO 80000 units, or
432 // - B, which just represents bytes.
434 // Returns an int64 because that's what its callers want and receive,
435 // but the result is always non-negative.
436 func parseByteCount(s string) (int64, bool) {
437 // The empty string is not valid.
441 // Handle the easy non-suffix case.
443 if last >= '0' && last <= '9' {
450 // Failing a trailing digit, this must always end in 'B'.
451 // Also at this point there must be at least one digit before
453 if last != 'B' || len(s) < 2 {
456 // The one before that must always be a digit or 'i'.
457 if c := s[len(s)-2]; c >= '0' && c <= '9' {
458 // Trivial 'B' suffix.
459 n, ok := atoi64(s[:len(s)-1])
467 // Finally, we need at least 4 characters now, for the unit
468 // prefix and at least one digit.
487 for i := 0; i < power; i++ {
490 n, ok := atoi64(s[:len(s)-3])
495 if un > maxUint64/m {
500 if un > uint64(maxInt64) {
504 return int64(un), true
508 func findnull(s *byte) int {
513 // Avoid IndexByteString on Plan 9 because it uses SSE instructions
514 // on x86 machines, and those are classified as floating point instructions,
515 // which are illegal in a note handler.
517 p := (*[maxAlloc/2 - 1]byte)(unsafe.Pointer(s))
525 // pageSize is the unit we scan at a time looking for NULL.
526 // It must be the minimum page size for any architecture Go
527 // runs on. It's okay (just a minor performance loss) if the
528 // actual system page size is larger than this value.
529 const pageSize = 4096
532 ptr := unsafe.Pointer(s)
533 // IndexByteString uses wide reads, so we need to be careful
534 // with page boundaries. Call IndexByteString on
535 // [ptr, endOfPage) interval.
536 safeLen := int(pageSize - uintptr(ptr)%pageSize)
539 t := *(*string)(unsafe.Pointer(&stringStruct{ptr, safeLen}))
540 // Check one page at a time.
541 if i := bytealg.IndexByteString(t, 0); i != -1 {
545 ptr = unsafe.Pointer(uintptr(ptr) + uintptr(safeLen))
551 func findnullw(s *uint16) int {
555 p := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(s))
564 func gostringnocopy(str *byte) string {
565 ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)}
566 s := *(*string)(unsafe.Pointer(&ss))
570 func gostringw(strw *uint16) string {
572 str := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(strw))
574 for i := 0; str[i] != 0; i++ {
575 n1 += encoderune(buf[:], rune(str[i]))
577 s, b := rawstring(n1 + 4)
579 for i := 0; str[i] != 0; i++ {
584 n2 += encoderune(b[n2:], rune(str[i]))
586 b[n2] = 0 // for luck