mirror of git://gcc.gnu.org/git/gcc.git
464 lines
10 KiB
Go
464 lines
10 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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// For gccgo, use go:linkname to rename compiler-called functions to
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// themselves, so that the compiler will export them.
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//
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//go:linkname concatstrings runtime.concatstrings
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//go:linkname concatstring2 runtime.concatstring2
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//go:linkname concatstring3 runtime.concatstring3
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//go:linkname concatstring4 runtime.concatstring4
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//go:linkname concatstring5 runtime.concatstring5
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//go:linkname slicebytetostring runtime.slicebytetostring
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//go:linkname slicebytetostringtmp runtime.slicebytetostringtmp
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//go:linkname stringtoslicebyte runtime.stringtoslicebyte
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//go:linkname stringtoslicerune runtime.stringtoslicerune
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//go:linkname slicerunetostring runtime.slicerunetostring
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//go:linkname intstring runtime.intstring
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// Temporary for C code to call:
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//go:linkname gostringnocopy runtime.gostringnocopy
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//go:linkname findnull runtime.findnull
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// The constant is known to the compiler.
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// There is no fundamental theory behind this number.
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const tmpStringBufSize = 32
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type tmpBuf [tmpStringBufSize]byte
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// concatstrings implements a Go string concatenation x+y+z+...
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// The operands are passed in the slice a.
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// If buf != nil, the compiler has determined that the result does not
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// escape the calling function, so the string data can be stored in buf
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// if small enough.
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func concatstrings(buf *tmpBuf, a []string) string {
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// idx := 0
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l := 0
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count := 0
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for _, x := range a {
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n := len(x)
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if n == 0 {
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continue
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}
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if l+n < l {
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throw("string concatenation too long")
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}
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l += n
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count++
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// idx = i
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}
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if count == 0 {
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return ""
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}
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// If there is just one string and either it is not on the stack
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// or our result does not escape the calling frame (buf != nil),
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// then we can return that string directly.
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// Commented out for gccgo--no implementation of stringDataOnStack.
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// if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) {
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// return a[idx]
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// }
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s, b := rawstringtmp(buf, l)
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for _, x := range a {
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copy(b, x)
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b = b[len(x):]
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}
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return s
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}
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func concatstring2(buf *tmpBuf, a [2]string) string {
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return concatstrings(buf, a[:])
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}
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func concatstring3(buf *tmpBuf, a [3]string) string {
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return concatstrings(buf, a[:])
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}
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func concatstring4(buf *tmpBuf, a [4]string) string {
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return concatstrings(buf, a[:])
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}
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func concatstring5(buf *tmpBuf, a [5]string) string {
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return concatstrings(buf, a[:])
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}
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// Buf is a fixed-size buffer for the result,
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// it is not nil if the result does not escape.
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func slicebytetostring(buf *tmpBuf, b []byte) string {
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l := len(b)
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if l == 0 {
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// Turns out to be a relatively common case.
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// Consider that you want to parse out data between parens in "foo()bar",
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// you find the indices and convert the subslice to string.
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return ""
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}
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if raceenabled && l > 0 {
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racereadrangepc(unsafe.Pointer(&b[0]),
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uintptr(l),
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getcallerpc(unsafe.Pointer(&buf)),
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funcPC(slicebytetostring))
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}
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if msanenabled && l > 0 {
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msanread(unsafe.Pointer(&b[0]), uintptr(l))
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}
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s, c := rawstringtmp(buf, l)
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copy(c, b)
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return s
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}
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func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
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if buf != nil && l <= len(buf) {
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b = buf[:l]
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s = slicebytetostringtmp(b)
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} else {
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s, b = rawstring(l)
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}
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return
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}
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// slicebytetostringtmp returns a "string" referring to the actual []byte bytes.
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//
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// Callers need to ensure that the returned string will not be used after
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// the calling goroutine modifies the original slice or synchronizes with
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// another goroutine.
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//
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// The function is only called when instrumenting
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// and otherwise intrinsified by the compiler.
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//
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// Some internal compiler optimizations use this function.
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// - Used for m[string(k)] lookup where m is a string-keyed map and k is a []byte.
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// - Used for "<"+string(b)+">" concatenation where b is []byte.
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// - Used for string(b)=="foo" comparison where b is []byte.
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func slicebytetostringtmp(b []byte) string {
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if raceenabled && len(b) > 0 {
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racereadrangepc(unsafe.Pointer(&b[0]),
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uintptr(len(b)),
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getcallerpc(unsafe.Pointer(&b)),
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funcPC(slicebytetostringtmp))
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}
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if msanenabled && len(b) > 0 {
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msanread(unsafe.Pointer(&b[0]), uintptr(len(b)))
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}
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return *(*string)(unsafe.Pointer(&b))
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}
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func stringtoslicebyte(buf *tmpBuf, s string) []byte {
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var b []byte
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if buf != nil && len(s) <= len(buf) {
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*buf = tmpBuf{}
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b = buf[:len(s)]
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} else {
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b = rawbyteslice(len(s))
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}
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copy(b, s)
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return b
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}
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func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
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// two passes.
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// unlike slicerunetostring, no race because strings are immutable.
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n := 0
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for range s {
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n++
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}
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var a []rune
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if buf != nil && n <= len(buf) {
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*buf = [tmpStringBufSize]rune{}
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a = buf[:n]
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} else {
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a = rawruneslice(n)
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}
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n = 0
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for _, r := range s {
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a[n] = r
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n++
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}
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return a
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}
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func slicerunetostring(buf *tmpBuf, a []rune) string {
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if raceenabled && len(a) > 0 {
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racereadrangepc(unsafe.Pointer(&a[0]),
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uintptr(len(a))*unsafe.Sizeof(a[0]),
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getcallerpc(unsafe.Pointer(&buf)),
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funcPC(slicerunetostring))
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}
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if msanenabled && len(a) > 0 {
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msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
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}
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var dum [4]byte
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size1 := 0
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for _, r := range a {
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size1 += encoderune(dum[:], r)
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}
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s, b := rawstringtmp(buf, size1+3)
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size2 := 0
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for _, r := range a {
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// check for race
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if size2 >= size1 {
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break
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}
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size2 += encoderune(b[size2:], r)
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}
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return s[:size2]
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}
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type stringStruct struct {
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str unsafe.Pointer
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len int
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}
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// Variant with *byte pointer type for DWARF debugging.
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type stringStructDWARF struct {
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str *byte
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len int
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}
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func stringStructOf(sp *string) *stringStruct {
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return (*stringStruct)(unsafe.Pointer(sp))
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}
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func intstring(buf *[4]byte, v int64) string {
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var s string
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var b []byte
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if buf != nil {
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b = buf[:]
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s = slicebytetostringtmp(b)
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} else {
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s, b = rawstring(4)
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}
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if int64(rune(v)) != v {
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v = runeError
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}
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n := encoderune(b, rune(v))
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return s[:n]
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}
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// rawstring allocates storage for a new string. The returned
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// string and byte slice both refer to the same storage.
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// The storage is not zeroed. Callers should use
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// b to set the string contents and then drop b.
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func rawstring(size int) (s string, b []byte) {
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p := mallocgc(uintptr(size), nil, false)
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stringStructOf(&s).str = p
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stringStructOf(&s).len = size
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*(*slice)(unsafe.Pointer(&b)) = slice{p, size, size}
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return
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}
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// rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
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func rawbyteslice(size int) (b []byte) {
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cap := roundupsize(uintptr(size))
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p := mallocgc(cap, nil, false)
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if cap != uintptr(size) {
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memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size))
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}
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*(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)}
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return
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}
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// rawruneslice allocates a new rune slice. The rune slice is not zeroed.
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func rawruneslice(size int) (b []rune) {
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if uintptr(size) > _MaxMem/4 {
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throw("out of memory")
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}
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mem := roundupsize(uintptr(size) * 4)
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p := mallocgc(mem, nil, false)
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if mem != uintptr(size)*4 {
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memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4)
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}
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*(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)}
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return
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}
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// used by cmd/cgo
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func gobytes(p *byte, n int) []byte {
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if n == 0 {
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return make([]byte, 0)
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}
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x := make([]byte, n)
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memmove(unsafe.Pointer(&x[0]), unsafe.Pointer(p), uintptr(n))
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return x
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}
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func gostring(p *byte) string {
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l := findnull(p)
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if l == 0 {
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return ""
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}
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s, b := rawstring(l)
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memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
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return s
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}
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func gostringn(p *byte, l int) string {
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if l == 0 {
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return ""
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}
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s, b := rawstring(l)
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memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
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return s
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}
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func index(s, t string) int {
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if len(t) == 0 {
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return 0
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}
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for i := 0; i < len(s); i++ {
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if s[i] == t[0] && hasprefix(s[i:], t) {
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return i
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}
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}
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return -1
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}
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func contains(s, t string) bool {
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return index(s, t) >= 0
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}
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func hasprefix(s, t string) bool {
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return len(s) >= len(t) && s[:len(t)] == t
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}
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const (
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maxUint = ^uint(0)
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maxInt = int(maxUint >> 1)
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)
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// atoi parses an int from a string s.
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// The bool result reports whether s is a number
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// representable by a value of type int.
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func atoi(s string) (int, bool) {
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if s == "" {
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return 0, false
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}
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neg := false
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if s[0] == '-' {
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neg = true
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s = s[1:]
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}
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un := uint(0)
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for i := 0; i < len(s); i++ {
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c := s[i]
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if c < '0' || c > '9' {
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return 0, false
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}
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if un > maxUint/10 {
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// overflow
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return 0, false
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}
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un *= 10
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un1 := un + uint(c) - '0'
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if un1 < un {
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// overflow
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return 0, false
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}
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un = un1
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}
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if !neg && un > uint(maxInt) {
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return 0, false
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}
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if neg && un > uint(maxInt)+1 {
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return 0, false
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}
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n := int(un)
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if neg {
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n = -n
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}
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return n, true
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}
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// atoi32 is like atoi but for integers
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// that fit into an int32.
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func atoi32(s string) (int32, bool) {
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if n, ok := atoi(s); n == int(int32(n)) {
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return int32(n), ok
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}
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return 0, false
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}
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//go:nosplit
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func findnull(s *byte) int {
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if s == nil {
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return 0
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}
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p := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s))
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l := 0
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for p[l] != 0 {
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l++
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}
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return l
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}
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func findnullw(s *uint16) int {
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if s == nil {
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return 0
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}
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p := (*[_MaxMem/2/2 - 1]uint16)(unsafe.Pointer(s))
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l := 0
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for p[l] != 0 {
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l++
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}
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return l
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}
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//go:nosplit
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func gostringnocopy(str *byte) string {
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ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)}
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s := *(*string)(unsafe.Pointer(&ss))
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return s
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}
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func gostringw(strw *uint16) string {
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var buf [8]byte
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str := (*[_MaxMem/2/2 - 1]uint16)(unsafe.Pointer(strw))
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n1 := 0
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for i := 0; str[i] != 0; i++ {
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n1 += encoderune(buf[:], rune(str[i]))
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}
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s, b := rawstring(n1 + 4)
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n2 := 0
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for i := 0; str[i] != 0; i++ {
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// check for race
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if n2 >= n1 {
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break
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}
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n2 += encoderune(b[n2:], rune(str[i]))
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}
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b[n2] = 0 // for luck
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return s[:n2]
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}
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// These two functions are called by code generated by cgo -gccgo.
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//go:linkname __go_byte_array_to_string __go_byte_array_to_string
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func __go_byte_array_to_string(p unsafe.Pointer, l int) string {
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if l == 0 {
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return ""
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}
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s, c := rawstringtmp(nil, l)
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memmove(unsafe.Pointer(&c[0]), p, uintptr(l))
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return s
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}
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//go:linkname __go_string_to_byte_array __go_string_to_byte_array
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func __go_string_to_byte_array(s string) []byte {
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return stringtoslicebyte(nil, s)
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}
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