mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-23 18:52:11 +00:00
461 lines
15 KiB
Go
461 lines
15 KiB
Go
//go:build !go1.16
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// +build !go1.16
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/*
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* Copyright 2021 ByteDance Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package loader
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import (
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`os`
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`unsafe`
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`sort`
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`github.com/bytedance/sonic/internal/rt`
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)
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const (
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_Magic uint32 = 0xfffffffa
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)
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type pcHeader struct {
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magic uint32 // 0xFFFFFFF0
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pad1, pad2 uint8 // 0,0
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minLC uint8 // min instruction size
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ptrSize uint8 // size of a ptr in bytes
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nfunc int // number of functions in the module
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nfiles uint // number of entries in the file tab
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funcnameOffset uintptr // offset to the funcnametab variable from pcHeader
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cuOffset uintptr // offset to the cutab variable from pcHeader
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filetabOffset uintptr // offset to the filetab variable from pcHeader
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pctabOffset uintptr // offset to the pctab variable from pcHeader
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pclnOffset uintptr // offset to the pclntab variable from pcHeader
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}
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type moduledata struct {
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pcHeader *pcHeader
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funcnametab []byte
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cutab []uint32
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filetab []byte
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pctab []byte
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pclntable []byte
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ftab []funcTab
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findfunctab uintptr
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minpc, maxpc uintptr // first func address, last func address + last func size
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text, etext uintptr // start/end of text, (etext-text) must be greater than MIN_FUNC
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noptrdata, enoptrdata uintptr
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data, edata uintptr
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bss, ebss uintptr
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noptrbss, enoptrbss uintptr
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end, gcdata, gcbss uintptr
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types, etypes uintptr
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textsectmap []textSection // see runtime/symtab.go: textAddr()
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typelinks []int32 // offsets from types
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itablinks []*rt.GoItab
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ptab []ptabEntry
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pluginpath string
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pkghashes []modulehash
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modulename string
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modulehashes []modulehash
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hasmain uint8 // 1 if module contains the main function, 0 otherwise
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gcdatamask, gcbssmask bitVector
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typemap map[int32]*rt.GoType // offset to *_rtype in previous module
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bad bool // module failed to load and should be ignored
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next *moduledata
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}
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type _func struct {
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entry uintptr // start pc, as offset from moduledata.text/pcHeader.textStart
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nameOff int32 // function name, as index into moduledata.funcnametab.
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args int32 // in/out args size
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deferreturn uint32 // offset of start of a deferreturn call instruction from entry, if any.
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pcsp uint32
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pcfile uint32
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pcln uint32
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npcdata uint32
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cuOffset uint32 // runtime.cutab offset of this function's CU
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funcID uint8 // set for certain special runtime functions
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_ [2]byte // pad
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nfuncdata uint8 //
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// The end of the struct is followed immediately by two variable-length
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// arrays that reference the pcdata and funcdata locations for this
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// function.
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// pcdata contains the offset into moduledata.pctab for the start of
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// that index's table. e.g.,
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// &moduledata.pctab[_func.pcdata[_PCDATA_UnsafePoint]] is the start of
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// the unsafe point table.
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//
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// An offset of 0 indicates that there is no table.
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//
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// pcdata [npcdata]uint32
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// funcdata contains the offset past moduledata.gofunc which contains a
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// pointer to that index's funcdata. e.g.,
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// *(moduledata.gofunc + _func.funcdata[_FUNCDATA_ArgsPointerMaps]) is
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// the argument pointer map.
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//
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// An offset of ^uint32(0) indicates that there is no entry.
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//
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// funcdata [nfuncdata]uint32
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}
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type funcTab struct {
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entry uintptr
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funcoff uintptr
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}
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type bitVector struct {
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n int32 // # of bits
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bytedata *uint8
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}
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type ptabEntry struct {
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name int32
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typ int32
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}
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type textSection struct {
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vaddr uintptr // prelinked section vaddr
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end uintptr // vaddr + section length
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baseaddr uintptr // relocated section address
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}
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type modulehash struct {
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modulename string
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linktimehash string
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runtimehash *string
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}
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// findfuncbucket is an array of these structures.
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// Each bucket represents 4096 bytes of the text segment.
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// Each subbucket represents 256 bytes of the text segment.
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// To find a function given a pc, locate the bucket and subbucket for
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// that pc. Add together the idx and subbucket value to obtain a
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// function index. Then scan the functab array starting at that
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// index to find the target function.
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// This table uses 20 bytes for every 4096 bytes of code, or ~0.5% overhead.
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type findfuncbucket struct {
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idx uint32
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_SUBBUCKETS [16]byte
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}
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type compilationUnit struct {
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fileNames []string
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}
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func makeFtab(funcs []_func, maxpc uintptr) (ftab []funcTab, pclntabSize int64, startLocations []uint32) {
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// Allocate space for the pc->func table. This structure consists of a pc offset
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// and an offset to the func structure. After that, we have a single pc
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// value that marks the end of the last function in the binary.
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pclntabSize = int64(len(funcs)*2*int(_PtrSize) + int(_PtrSize))
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startLocations = make([]uint32, len(funcs))
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for i, f := range funcs {
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pclntabSize = rnd(pclntabSize, int64(_PtrSize))
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//writePCToFunc
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startLocations[i] = uint32(pclntabSize)
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pclntabSize += int64(uint8(_FUNC_SIZE) + f.nfuncdata*_PtrSize + uint8(f.npcdata)*4)
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}
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ftab = make([]funcTab, 0, len(funcs)+1)
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// write a map of pc->func info offsets
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for i, f := range funcs {
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ftab = append(ftab, funcTab{uintptr(f.entry), uintptr(startLocations[i])})
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}
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// Final entry of table is just end pc offset.
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ftab = append(ftab, funcTab{maxpc, 0})
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return
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}
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// Pcln table format: [...]funcTab + [...]_Func
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func makePclntable(size int64, startLocations []uint32, funcs []_func, maxpc uintptr, pcdataOffs [][]uint32, funcdataAddr uintptr, funcdataOffs [][]uint32) (pclntab []byte) {
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pclntab = make([]byte, size, size)
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// write a map of pc->func info offsets
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offs := 0
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for i, f := range funcs {
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byteOrder.PutUint64(pclntab[offs:offs+8], uint64(f.entry))
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byteOrder.PutUint64(pclntab[offs+8:offs+16], uint64(startLocations[i]))
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offs += 16
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}
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// Final entry of table is just end pc offset.
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byteOrder.PutUint64(pclntab[offs:offs+8], uint64(maxpc))
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offs += 8
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// write func info table
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for i, f := range funcs {
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off := startLocations[i]
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// write _func structure to pclntab
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byteOrder.PutUint64(pclntab[off:off+8], uint64(f.entry))
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off += 8
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.nameOff))
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off += 4
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.args))
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off += 4
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.deferreturn))
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off += 4
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.pcsp))
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off += 4
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.pcfile))
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off += 4
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.pcln))
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off += 4
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.npcdata))
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off += 4
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byteOrder.PutUint32(pclntab[off:off+4], uint32(f.cuOffset))
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off += 4
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pclntab[off] = f.funcID
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// NOTICE: _[2]byte alignment
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off += 3
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pclntab[off] = f.nfuncdata
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off += 1
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// NOTICE: _func.pcdata always starts from PcUnsafePoint, which is index 3
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for j := 3; j < len(pcdataOffs[i]); j++ {
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byteOrder.PutUint32(pclntab[off:off+4], uint32(pcdataOffs[i][j]))
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off += 4
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}
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off = uint32(rnd(int64(off), int64(_PtrSize)))
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// funcdata refs as offsets from gofunc
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for _, funcdata := range funcdataOffs[i] {
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if funcdata == _INVALID_FUNCDATA_OFFSET {
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byteOrder.PutUint64(pclntab[off:off+8], 0)
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} else {
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byteOrder.PutUint64(pclntab[off:off+8], uint64(funcdataAddr)+uint64(funcdata))
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}
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off += 8
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}
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}
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return
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}
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// findfunc table used to map pc to belonging func,
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// returns the index in the func table.
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//
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// All text section are divided into buckets sized _BUCKETSIZE(4K):
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// every bucket is divided into _SUBBUCKETS sized _SUB_BUCKETSIZE(64),
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// and it has a base idx to plus the offset stored in jth subbucket.
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// see findfunc() in runtime/symtab.go
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func writeFindfunctab(out *[]byte, ftab []funcTab) (start int) {
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start = len(*out)
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max := ftab[len(ftab)-1].entry
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min := ftab[0].entry
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nbuckets := (max - min + _BUCKETSIZE - 1) / _BUCKETSIZE
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n := (max - min + _SUB_BUCKETSIZE - 1) / _SUB_BUCKETSIZE
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tab := make([]findfuncbucket, 0, nbuckets)
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var s, e = 0, 0
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for i := 0; i<int(nbuckets); i++ {
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// store the start func of the bucket
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var fb = findfuncbucket{idx: uint32(s)}
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// find the last e-th func of the bucket
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var pc = min + uintptr((i+1)*_BUCKETSIZE)
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for ; e < len(ftab)-1 && ftab[e+1].entry <= pc; e++ {}
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for j := 0; j<_SUBBUCKETS && (i*_SUBBUCKETS+j)<int(n); j++ {
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// store the start func of the subbucket
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fb._SUBBUCKETS[j] = byte(uint32(s) - fb.idx)
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// find the s-th end func of the subbucket
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pc = min + uintptr(i*_BUCKETSIZE) + uintptr((j+1)*_SUB_BUCKETSIZE)
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for ; s < len(ftab)-1 && ftab[s+1].entry <= pc; s++ {}
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}
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s = e
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tab = append(tab, fb)
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}
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// write findfuncbucket
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if len(tab) > 0 {
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size := int(unsafe.Sizeof(findfuncbucket{}))*len(tab)
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*out = append(*out, rt.BytesFrom(unsafe.Pointer(&tab[0]), size, size)...)
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}
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return
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}
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func makeModuledata(name string, filenames []string, funcsp *[]Func, text []byte) (mod *moduledata) {
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mod = new(moduledata)
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mod.modulename = name
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// sort funcs by entry
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funcs := *funcsp
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sort.Slice(funcs, func(i, j int) bool {
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return funcs[i].EntryOff < funcs[j].EntryOff
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})
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*funcsp = funcs
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// make filename table
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cu := make([]string, 0, len(filenames))
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cu = append(cu, filenames...)
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cutab, filetab, cuOffs := makeFilenametab([]compilationUnit{{cu}})
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mod.cutab = cutab
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mod.filetab = filetab
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// make funcname table
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funcnametab, nameOffs := makeFuncnameTab(funcs)
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mod.funcnametab = funcnametab
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// mmap() text and funcdata segements
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p := os.Getpagesize()
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size := int(rnd(int64(len(text)), int64(p)))
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addr := mmap(size)
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// copy the machine code
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s := rt.BytesFrom(unsafe.Pointer(addr), len(text), size)
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copy(s, text)
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// make it executable
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mprotect(addr, size)
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// assign addresses
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mod.text = addr
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mod.etext = addr + uintptr(size)
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mod.minpc = addr
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mod.maxpc = addr + uintptr(len(text))
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// make pcdata table
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// NOTICE: _func only use offset to index pcdata, thus no need mmap() pcdata
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cuOff := cuOffs[0]
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pctab, pcdataOffs, _funcs := makePctab(funcs, addr, cuOff, nameOffs)
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mod.pctab = pctab
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// write func data
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// NOTICE: _func use mod.gofunc+offset to directly point funcdata, thus need cache funcdata
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// TODO: estimate accurate capacity
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cache := make([]byte, 0, len(funcs)*int(_PtrSize))
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fstart, funcdataOffs := writeFuncdata(&cache, funcs)
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// make pc->func (binary search) func table
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ftab, pclntSize, startLocations := makeFtab(_funcs, mod.maxpc)
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mod.ftab = ftab
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// write pc->func (modmap) findfunc table
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ffstart := writeFindfunctab(&cache, ftab)
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// cache funcdata and findfuncbucket
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moduleCache.Lock()
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moduleCache.m[mod] = cache
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moduleCache.Unlock()
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mod.findfunctab = uintptr(rt.IndexByte(cache, ffstart))
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funcdataAddr := uintptr(rt.IndexByte(cache, fstart))
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// make pclnt table
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pclntab := makePclntable(pclntSize, startLocations, _funcs, mod.maxpc, pcdataOffs, funcdataAddr, funcdataOffs)
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mod.pclntable = pclntab
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// make pc header
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mod.pcHeader = &pcHeader {
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magic : _Magic,
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minLC : _MinLC,
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ptrSize : _PtrSize,
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nfunc : len(funcs),
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nfiles: uint(len(cu)),
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funcnameOffset: getOffsetOf(moduledata{}, "funcnametab"),
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cuOffset: getOffsetOf(moduledata{}, "cutab"),
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filetabOffset: getOffsetOf(moduledata{}, "filetab"),
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pctabOffset: getOffsetOf(moduledata{}, "pctab"),
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pclnOffset: getOffsetOf(moduledata{}, "pclntable"),
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}
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// sepecial case: gcdata and gcbss must by non-empty
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mod.gcdata = uintptr(unsafe.Pointer(&emptyByte))
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mod.gcbss = uintptr(unsafe.Pointer(&emptyByte))
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return
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}
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// makePctab generates pcdelta->valuedelta tables for functions,
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// and returns the table and the entry offset of every kind pcdata in the table.
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func makePctab(funcs []Func, addr uintptr, cuOffset uint32, nameOffset []int32) (pctab []byte, pcdataOffs [][]uint32, _funcs []_func) {
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_funcs = make([]_func, len(funcs))
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// Pctab offsets of 0 are considered invalid in the runtime. We respect
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// that by just padding a single byte at the beginning of runtime.pctab,
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// that way no real offsets can be zero.
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pctab = make([]byte, 1, 12*len(funcs)+1)
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pcdataOffs = make([][]uint32, len(funcs))
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for i, f := range funcs {
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_f := &_funcs[i]
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var writer = func(pc *Pcdata) {
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var ab []byte
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var err error
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if pc != nil {
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ab, err = pc.MarshalBinary()
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if err != nil {
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panic(err)
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}
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pcdataOffs[i] = append(pcdataOffs[i], uint32(len(pctab)))
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} else {
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ab = []byte{0}
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pcdataOffs[i] = append(pcdataOffs[i], _PCDATA_INVALID_OFFSET)
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}
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pctab = append(pctab, ab...)
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}
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if f.Pcsp != nil {
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_f.pcsp = uint32(len(pctab))
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}
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writer(f.Pcsp)
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if f.Pcfile != nil {
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_f.pcfile = uint32(len(pctab))
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}
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writer(f.Pcfile)
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if f.Pcline != nil {
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_f.pcln = uint32(len(pctab))
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}
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writer(f.Pcline)
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writer(f.PcUnsafePoint)
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writer(f.PcStackMapIndex)
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writer(f.PcInlTreeIndex)
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writer(f.PcArgLiveIndex)
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_f.entry = addr + uintptr(f.EntryOff)
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_f.nameOff = nameOffset[i]
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_f.args = f.ArgsSize
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_f.deferreturn = f.DeferReturn
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// NOTICE: _func.pcdata is always as [PCDATA_UnsafePoint(0) : PCDATA_ArgLiveIndex(3)]
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_f.npcdata = uint32(_N_PCDATA)
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_f.cuOffset = cuOffset
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_f.funcID = f.ID
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_f.nfuncdata = uint8(_N_FUNCDATA)
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}
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return
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}
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func registerFunction(name string, pc uintptr, textSize uintptr, fp int, args int, size uintptr, argptrs uintptr, localptrs uintptr) {}
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