From 47ab3d4a42e9ab51c465c4322d2ec233f6324e6b Mon Sep 17 00:00:00 2001 From: Daniel Baumann <daniel.baumann@progress-linux.org> Date: Sun, 28 Apr 2024 15:16:40 +0200 Subject: Adding upstream version 1.18.10. Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org> --- src/runtime/string.go | 495 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 495 insertions(+) create mode 100644 src/runtime/string.go (limited to 'src/runtime/string.go') diff --git a/src/runtime/string.go b/src/runtime/string.go new file mode 100644 index 0000000..980a986 --- /dev/null +++ b/src/runtime/string.go @@ -0,0 +1,495 @@ +// Copyright 2014 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 ( + "internal/abi" + "internal/bytealg" + "internal/goarch" + "unsafe" +) + +// The constant is known to the compiler. +// There is no fundamental theory behind this number. +const tmpStringBufSize = 32 + +type tmpBuf [tmpStringBufSize]byte + +// concatstrings implements a Go string concatenation x+y+z+... +// The operands are passed in the slice a. +// If buf != nil, the compiler has determined that the result does not +// escape the calling function, so the string data can be stored in buf +// if small enough. +func concatstrings(buf *tmpBuf, a []string) string { + idx := 0 + l := 0 + count := 0 + for i, x := range a { + n := len(x) + if n == 0 { + continue + } + if l+n < l { + throw("string concatenation too long") + } + l += n + count++ + idx = i + } + if count == 0 { + return "" + } + + // If there is just one string and either it is not on the stack + // or our result does not escape the calling frame (buf != nil), + // then we can return that string directly. + if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) { + return a[idx] + } + s, b := rawstringtmp(buf, l) + for _, x := range a { + copy(b, x) + b = b[len(x):] + } + return s +} + +func concatstring2(buf *tmpBuf, a0, a1 string) string { + return concatstrings(buf, []string{a0, a1}) +} + +func concatstring3(buf *tmpBuf, a0, a1, a2 string) string { + return concatstrings(buf, []string{a0, a1, a2}) +} + +func concatstring4(buf *tmpBuf, a0, a1, a2, a3 string) string { + return concatstrings(buf, []string{a0, a1, a2, a3}) +} + +func concatstring5(buf *tmpBuf, a0, a1, a2, a3, a4 string) string { + return concatstrings(buf, []string{a0, a1, a2, a3, a4}) +} + +// slicebytetostring converts a byte slice to a string. +// It is inserted by the compiler into generated code. +// ptr is a pointer to the first element of the slice; +// n is the length of the slice. +// Buf is a fixed-size buffer for the result, +// it is not nil if the result does not escape. +func slicebytetostring(buf *tmpBuf, ptr *byte, n int) (str string) { + if n == 0 { + // Turns out to be a relatively common case. + // Consider that you want to parse out data between parens in "foo()bar", + // you find the indices and convert the subslice to string. + return "" + } + if raceenabled { + racereadrangepc(unsafe.Pointer(ptr), + uintptr(n), + getcallerpc(), + abi.FuncPCABIInternal(slicebytetostring)) + } + if msanenabled { + msanread(unsafe.Pointer(ptr), uintptr(n)) + } + if asanenabled { + asanread(unsafe.Pointer(ptr), uintptr(n)) + } + if n == 1 { + p := unsafe.Pointer(&staticuint64s[*ptr]) + if goarch.BigEndian { + p = add(p, 7) + } + stringStructOf(&str).str = p + stringStructOf(&str).len = 1 + return + } + + var p unsafe.Pointer + if buf != nil && n <= len(buf) { + p = unsafe.Pointer(buf) + } else { + p = mallocgc(uintptr(n), nil, false) + } + stringStructOf(&str).str = p + stringStructOf(&str).len = n + memmove(p, unsafe.Pointer(ptr), uintptr(n)) + return +} + +// stringDataOnStack reports whether the string's data is +// stored on the current goroutine's stack. +func stringDataOnStack(s string) bool { + ptr := uintptr(stringStructOf(&s).str) + stk := getg().stack + return stk.lo <= ptr && ptr < stk.hi +} + +func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) { + if buf != nil && l <= len(buf) { + b = buf[:l] + s = slicebytetostringtmp(&b[0], len(b)) + } else { + s, b = rawstring(l) + } + return +} + +// slicebytetostringtmp returns a "string" referring to the actual []byte bytes. +// +// Callers need to ensure that the returned string will not be used after +// the calling goroutine modifies the original slice or synchronizes with +// another goroutine. +// +// The function is only called when instrumenting +// and otherwise intrinsified by the compiler. +// +// Some internal compiler optimizations use this function. +// - Used for m[T1{... Tn{..., string(k), ...} ...}] and m[string(k)] +// where k is []byte, T1 to Tn is a nesting of struct and array literals. +// - Used for "<"+string(b)+">" concatenation where b is []byte. +// - Used for string(b)=="foo" comparison where b is []byte. +func slicebytetostringtmp(ptr *byte, n int) (str string) { + if raceenabled && n > 0 { + racereadrangepc(unsafe.Pointer(ptr), + uintptr(n), + getcallerpc(), + abi.FuncPCABIInternal(slicebytetostringtmp)) + } + if msanenabled && n > 0 { + msanread(unsafe.Pointer(ptr), uintptr(n)) + } + if asanenabled && n > 0 { + asanread(unsafe.Pointer(ptr), uintptr(n)) + } + stringStructOf(&str).str = unsafe.Pointer(ptr) + stringStructOf(&str).len = n + return +} + +func stringtoslicebyte(buf *tmpBuf, s string) []byte { + var b []byte + if buf != nil && len(s) <= len(buf) { + *buf = tmpBuf{} + b = buf[:len(s)] + } else { + b = rawbyteslice(len(s)) + } + copy(b, s) + return b +} + +func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune { + // two passes. + // unlike slicerunetostring, no race because strings are immutable. + n := 0 + for range s { + n++ + } + + var a []rune + if buf != nil && n <= len(buf) { + *buf = [tmpStringBufSize]rune{} + a = buf[:n] + } else { + a = rawruneslice(n) + } + + n = 0 + for _, r := range s { + a[n] = r + n++ + } + return a +} + +func slicerunetostring(buf *tmpBuf, a []rune) string { + if raceenabled && len(a) > 0 { + racereadrangepc(unsafe.Pointer(&a[0]), + uintptr(len(a))*unsafe.Sizeof(a[0]), + getcallerpc(), + abi.FuncPCABIInternal(slicerunetostring)) + } + if msanenabled && len(a) > 0 { + msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0])) + } + if asanenabled && len(a) > 0 { + asanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0])) + } + var dum [4]byte + size1 := 0 + for _, r := range a { + size1 += encoderune(dum[:], r) + } + s, b := rawstringtmp(buf, size1+3) + size2 := 0 + for _, r := range a { + // check for race + if size2 >= size1 { + break + } + size2 += encoderune(b[size2:], r) + } + return s[:size2] +} + +type stringStruct struct { + str unsafe.Pointer + len int +} + +// Variant with *byte pointer type for DWARF debugging. +type stringStructDWARF struct { + str *byte + len int +} + +func stringStructOf(sp *string) *stringStruct { + return (*stringStruct)(unsafe.Pointer(sp)) +} + +func intstring(buf *[4]byte, v int64) (s string) { + var b []byte + if buf != nil { + b = buf[:] + s = slicebytetostringtmp(&b[0], len(b)) + } else { + s, b = rawstring(4) + } + if int64(rune(v)) != v { + v = runeError + } + n := encoderune(b, rune(v)) + return s[:n] +} + +// rawstring allocates storage for a new string. The returned +// string and byte slice both refer to the same storage. +// The storage is not zeroed. Callers should use +// b to set the string contents and then drop b. +func rawstring(size int) (s string, b []byte) { + p := mallocgc(uintptr(size), nil, false) + + stringStructOf(&s).str = p + stringStructOf(&s).len = size + + *(*slice)(unsafe.Pointer(&b)) = slice{p, size, size} + + return +} + +// rawbyteslice allocates a new byte slice. The byte slice is not zeroed. +func rawbyteslice(size int) (b []byte) { + cap := roundupsize(uintptr(size)) + p := mallocgc(cap, nil, false) + if cap != uintptr(size) { + memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size)) + } + + *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)} + return +} + +// rawruneslice allocates a new rune slice. The rune slice is not zeroed. +func rawruneslice(size int) (b []rune) { + if uintptr(size) > maxAlloc/4 { + throw("out of memory") + } + mem := roundupsize(uintptr(size) * 4) + p := mallocgc(mem, nil, false) + if mem != uintptr(size)*4 { + memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4) + } + + *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)} + return +} + +// used by cmd/cgo +func gobytes(p *byte, n int) (b []byte) { + if n == 0 { + return make([]byte, 0) + } + + if n < 0 || uintptr(n) > maxAlloc { + panic(errorString("gobytes: length out of range")) + } + + bp := mallocgc(uintptr(n), nil, false) + memmove(bp, unsafe.Pointer(p), uintptr(n)) + + *(*slice)(unsafe.Pointer(&b)) = slice{bp, n, n} + return +} + +// This is exported via linkname to assembly in syscall (for Plan9). +//go:linkname gostring +func gostring(p *byte) string { + l := findnull(p) + if l == 0 { + return "" + } + s, b := rawstring(l) + memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l)) + return s +} + +func gostringn(p *byte, l int) string { + if l == 0 { + return "" + } + s, b := rawstring(l) + memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l)) + return s +} + +func hasPrefix(s, prefix string) bool { + return len(s) >= len(prefix) && s[:len(prefix)] == prefix +} + +const ( + maxUint = ^uint(0) + maxInt = int(maxUint >> 1) +) + +// atoi parses an int from a string s. +// The bool result reports whether s is a number +// representable by a value of type int. +func atoi(s string) (int, bool) { + if s == "" { + return 0, false + } + + neg := false + if s[0] == '-' { + neg = true + s = s[1:] + } + + un := uint(0) + for i := 0; i < len(s); i++ { + c := s[i] + if c < '0' || c > '9' { + return 0, false + } + if un > maxUint/10 { + // overflow + return 0, false + } + un *= 10 + un1 := un + uint(c) - '0' + if un1 < un { + // overflow + return 0, false + } + un = un1 + } + + if !neg && un > uint(maxInt) { + return 0, false + } + if neg && un > uint(maxInt)+1 { + return 0, false + } + + n := int(un) + if neg { + n = -n + } + + return n, true +} + +// atoi32 is like atoi but for integers +// that fit into an int32. +func atoi32(s string) (int32, bool) { + if n, ok := atoi(s); n == int(int32(n)) { + return int32(n), ok + } + return 0, false +} + +//go:nosplit +func findnull(s *byte) int { + if s == nil { + return 0 + } + + // Avoid IndexByteString on Plan 9 because it uses SSE instructions + // on x86 machines, and those are classified as floating point instructions, + // which are illegal in a note handler. + if GOOS == "plan9" { + p := (*[maxAlloc/2 - 1]byte)(unsafe.Pointer(s)) + l := 0 + for p[l] != 0 { + l++ + } + return l + } + + // pageSize is the unit we scan at a time looking for NULL. + // It must be the minimum page size for any architecture Go + // runs on. It's okay (just a minor performance loss) if the + // actual system page size is larger than this value. + const pageSize = 4096 + + offset := 0 + ptr := unsafe.Pointer(s) + // IndexByteString uses wide reads, so we need to be careful + // with page boundaries. Call IndexByteString on + // [ptr, endOfPage) interval. + safeLen := int(pageSize - uintptr(ptr)%pageSize) + + for { + t := *(*string)(unsafe.Pointer(&stringStruct{ptr, safeLen})) + // Check one page at a time. + if i := bytealg.IndexByteString(t, 0); i != -1 { + return offset + i + } + // Move to next page + ptr = unsafe.Pointer(uintptr(ptr) + uintptr(safeLen)) + offset += safeLen + safeLen = pageSize + } +} + +func findnullw(s *uint16) int { + if s == nil { + return 0 + } + p := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(s)) + l := 0 + for p[l] != 0 { + l++ + } + return l +} + +//go:nosplit +func gostringnocopy(str *byte) string { + ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)} + s := *(*string)(unsafe.Pointer(&ss)) + return s +} + +func gostringw(strw *uint16) string { + var buf [8]byte + str := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(strw)) + n1 := 0 + for i := 0; str[i] != 0; i++ { + n1 += encoderune(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 += encoderune(b[n2:], rune(str[i])) + } + b[n2] = 0 // for luck + return s[:n2] +} -- cgit v1.2.3