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// 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 (
"runtime/internal/atomic"
"runtime/internal/sys"
"unsafe"
)
// Frames may be used to get function/file/line information for a
// slice of PC values returned by Callers.
type Frames struct {
// callers is a slice of PCs that have not yet been expanded.
callers []uintptr
// stackExpander expands callers into a sequence of Frames,
// tracking the necessary state across PCs.
stackExpander stackExpander
// elideWrapper indicates that, if the next frame is an
// autogenerated wrapper function, it should be elided from
// the stack.
elideWrapper bool
}
// Frame is the information returned by Frames for each call frame.
type Frame struct {
// PC is the program counter for the location in this frame.
// For a frame that calls another frame, this will be the
// program counter of a call instruction. Because of inlining,
// multiple frames may have the same PC value, but different
// symbolic information.
PC uintptr
// Func is the Func value of this call frame. This may be nil
// for non-Go code or fully inlined functions.
Func *Func
// Function is the package path-qualified function name of
// this call frame. If non-empty, this string uniquely
// identifies a single function in the program.
// This may be the empty string if not known.
// If Func is not nil then Function == Func.Name().
Function string
// File and Line are the file name and line number of the
// location in this frame. For non-leaf frames, this will be
// the location of a call. These may be the empty string and
// zero, respectively, if not known.
File string
Line int
// Entry point program counter for the function; may be zero
// if not known. If Func is not nil then Entry ==
// Func.Entry().
Entry uintptr
}
// stackExpander expands a call stack of PCs into a sequence of
// Frames. It tracks state across PCs necessary to perform this
// expansion.
//
// This is the core of the Frames implementation, but is a separate
// internal API to make it possible to use within the runtime without
// heap-allocating the PC slice. The only difference with the public
// Frames API is that the caller is responsible for threading the PC
// slice between expansion steps in this API. If escape analysis were
// smarter, we may not need this (though it may have to be a lot
// smarter).
type stackExpander struct {
// pcExpander expands the current PC into a sequence of Frames.
pcExpander pcExpander
// If previous caller in iteration was a panic, then the next
// PC in the call stack is the address of the faulting
// instruction instead of the return address of the call.
wasPanic bool
// skip > 0 indicates that skip frames in the expansion of the
// first PC should be skipped over and callers[1] should also
// be skipped.
skip int
}
// CallersFrames takes a slice of PC values returned by Callers and
// prepares to return function/file/line information.
// Do not change the slice until you are done with the Frames.
func CallersFrames(callers []uintptr) *Frames {
ci := &Frames{}
ci.callers = ci.stackExpander.init(callers)
return ci
}
func (se *stackExpander) init(callers []uintptr) []uintptr {
if len(callers) >= 1 {
pc := callers[0]
s := pc - skipPC
if s >= 0 && s < sizeofSkipFunction {
// Ignore skip frame callers[0] since this means the caller trimmed the PC slice.
return callers[1:]
}
}
if len(callers) >= 2 {
pc := callers[1]
s := pc - skipPC
if s > 0 && s < sizeofSkipFunction {
// Skip the first s inlined frames when we expand the first PC.
se.skip = int(s)
}
}
return callers
}
// Next returns frame information for the next caller.
// If more is false, there are no more callers (the Frame value is valid).
func (ci *Frames) Next() (frame Frame, more bool) {
ci.callers, frame, more = ci.stackExpander.next(ci.callers, ci.elideWrapper)
ci.elideWrapper = elideWrapperCalling(frame.Function)
return
}
func (se *stackExpander) next(callers []uintptr, elideWrapper bool) (ncallers []uintptr, frame Frame, more bool) {
ncallers = callers
again:
if !se.pcExpander.more {
// Expand the next PC.
if len(ncallers) == 0 {
se.wasPanic = false
return ncallers, Frame{}, false
}
se.pcExpander.init(ncallers[0], se.wasPanic)
ncallers = ncallers[1:]
se.wasPanic = se.pcExpander.funcInfo.valid() && se.pcExpander.funcInfo.entry == sigpanicPC
if se.skip > 0 {
for ; se.skip > 0; se.skip-- {
se.pcExpander.next()
}
se.skip = 0
// Drop skipPleaseUseCallersFrames.
ncallers = ncallers[1:]
}
if !se.pcExpander.more {
// No symbolic information for this PC.
// However, we return at least one frame for
// every PC, so return an invalid frame.
return ncallers, Frame{}, len(ncallers) > 0
}
}
frame = se.pcExpander.next()
if elideWrapper && frame.File == "<autogenerated>" {
// Ignore autogenerated functions such as pointer
// method forwarding functions. These are an
// implementation detail that doesn't reflect the
// source code.
goto again
}
return ncallers, frame, se.pcExpander.more || len(ncallers) > 0
}
// A pcExpander expands a single PC into a sequence of Frames.
type pcExpander struct {
// more indicates that the next call to next will return a
// valid frame.
more bool
// pc is the pc being expanded.
pc uintptr
// frames is a pre-expanded set of Frames to return from the
// iterator. If this is set, then this is everything that will
// be returned from the iterator.
frames []Frame
// funcInfo is the funcInfo of the function containing pc.
funcInfo funcInfo
// inlTree is the inlining tree of the function containing pc.
inlTree *[1 << 20]inlinedCall
// file and line are the file name and line number of the next
// frame.
file string
line int32
// inlIndex is the inlining index of the next frame, or -1 if
// the next frame is an outermost frame.
inlIndex int32
}
// init initializes this pcExpander to expand pc. It sets ex.more if
// pc expands to any Frames.
//
// A pcExpander can be reused by calling init again.
//
// If pc was a "call" to sigpanic, panicCall should be true. In this
// case, pc is treated as the address of a faulting instruction
// instead of the return address of a call.
func (ex *pcExpander) init(pc uintptr, panicCall bool) {
ex.more = false
ex.funcInfo = findfunc(pc)
if !ex.funcInfo.valid() {
if cgoSymbolizer != nil {
// Pre-expand cgo frames. We could do this
// incrementally, too, but there's no way to
// avoid allocation in this case anyway.
ex.frames = expandCgoFrames(pc)
ex.more = len(ex.frames) > 0
}
return
}
ex.more = true
entry := ex.funcInfo.entry
ex.pc = pc
if ex.pc > entry && !panicCall {
ex.pc--
}
// file and line are the innermost position at pc.
ex.file, ex.line = funcline1(ex.funcInfo, ex.pc, false)
// Get inlining tree at pc
inldata := funcdata(ex.funcInfo, _FUNCDATA_InlTree)
if inldata != nil {
ex.inlTree = (*[1 << 20]inlinedCall)(inldata)
ex.inlIndex = pcdatavalue(ex.funcInfo, _PCDATA_InlTreeIndex, ex.pc, nil)
} else {
ex.inlTree = nil
ex.inlIndex = -1
}
}
// next returns the next Frame in the expansion of pc and sets ex.more
// if there are more Frames to follow.
func (ex *pcExpander) next() Frame {
if !ex.more {
return Frame{}
}
if len(ex.frames) > 0 {
// Return pre-expended frame.
frame := ex.frames[0]
ex.frames = ex.frames[1:]
ex.more = len(ex.frames) > 0
return frame
}
if ex.inlIndex >= 0 {
// Return inner inlined frame.
call := ex.inlTree[ex.inlIndex]
frame := Frame{
PC: ex.pc,
Func: nil, // nil for inlined functions
Function: funcnameFromNameoff(ex.funcInfo, call.func_),
File: ex.file,
Line: int(ex.line),
Entry: ex.funcInfo.entry,
}
ex.file = funcfile(ex.funcInfo, call.file)
ex.line = call.line
ex.inlIndex = call.parent
return frame
}
// No inlining or pre-expanded frames.
ex.more = false
return Frame{
PC: ex.pc,
Func: ex.funcInfo._Func(),
Function: funcname(ex.funcInfo),
File: ex.file,
Line: int(ex.line),
Entry: ex.funcInfo.entry,
}
}
// expandCgoFrames expands frame information for pc, known to be
// a non-Go function, using the cgoSymbolizer hook. expandCgoFrames
// returns nil if pc could not be expanded.
func expandCgoFrames(pc uintptr) []Frame {
arg := cgoSymbolizerArg{pc: pc}
callCgoSymbolizer(&arg)
if arg.file == nil && arg.funcName == nil {
// No useful information from symbolizer.
return nil
}
var frames []Frame
for {
frames = append(frames, Frame{
PC: pc,
Func: nil,
Function: gostring(arg.funcName),
File: gostring(arg.file),
Line: int(arg.lineno),
Entry: arg.entry,
})
if arg.more == 0 {
break
}
callCgoSymbolizer(&arg)
}
// No more frames for this PC. Tell the symbolizer we are done.
// We don't try to maintain a single cgoSymbolizerArg for the
// whole use of Frames, because there would be no good way to tell
// the symbolizer when we are done.
arg.pc = 0
callCgoSymbolizer(&arg)
return frames
}
// NOTE: Func does not expose the actual unexported fields, because we return *Func
// values to users, and we want to keep them from being able to overwrite the data
// with (say) *f = Func{}.
// All code operating on a *Func must call raw() to get the *_func
// or funcInfo() to get the funcInfo instead.
// A Func represents a Go function in the running binary.
type Func struct {
opaque struct{} // unexported field to disallow conversions
}
func (f *Func) raw() *_func {
return (*_func)(unsafe.Pointer(f))
}
func (f *Func) funcInfo() funcInfo {
fn := f.raw()
return funcInfo{fn, findmoduledatap(fn.entry)}
}
// PCDATA and FUNCDATA table indexes.
//
// See funcdata.h and ../cmd/internal/obj/funcdata.go.
const (
_PCDATA_StackMapIndex = 0
_PCDATA_InlTreeIndex = 1
_FUNCDATA_ArgsPointerMaps = 0
_FUNCDATA_LocalsPointerMaps = 1
_FUNCDATA_InlTree = 2
_ArgsSizeUnknown = -0x80000000
)
// moduledata records information about the layout of the executable
// image. It is written by the linker. Any changes here must be
// matched changes to the code in cmd/internal/ld/symtab.go:symtab.
// moduledata is stored in statically allocated non-pointer memory;
// none of the pointers here are visible to the garbage collector.
type moduledata struct {
pclntable []byte
ftab []functab
filetab []uint32
findfunctab uintptr
minpc, maxpc uintptr
text, etext uintptr
noptrdata, enoptrdata uintptr
data, edata uintptr
bss, ebss uintptr
noptrbss, enoptrbss uintptr
end, gcdata, gcbss uintptr
types, etypes uintptr
textsectmap []textsect
typelinks []int32 // offsets from types
itablinks []*itab
ptab []ptabEntry
pluginpath string
pkghashes []modulehash
modulename string
modulehashes []modulehash
hasmain uint8 // 1 if module contains the main function, 0 otherwise
gcdatamask, gcbssmask bitvector
typemap map[typeOff]*_type // offset to *_rtype in previous module
bad bool // module failed to load and should be ignored
next *moduledata
}
// A modulehash is used to compare the ABI of a new module or a
// package in a new module with the loaded program.
//
// For each shared library a module links against, the linker creates an entry in the
// moduledata.modulehashes slice containing the name of the module, the abi hash seen
// at link time and a pointer to the runtime abi hash. These are checked in
// moduledataverify1 below.
//
// For each loaded plugin, the pkghashes slice has a modulehash of the
// newly loaded package that can be used to check the plugin's version of
// a package against any previously loaded version of the package.
// This is done in plugin.lastmoduleinit.
type modulehash struct {
modulename string
linktimehash string
runtimehash *string
}
// pinnedTypemaps are the map[typeOff]*_type from the moduledata objects.
//
// These typemap objects are allocated at run time on the heap, but the
// only direct reference to them is in the moduledata, created by the
// linker and marked SNOPTRDATA so it is ignored by the GC.
//
// To make sure the map isn't collected, we keep a second reference here.
var pinnedTypemaps []map[typeOff]*_type
var firstmoduledata moduledata // linker symbol
var lastmoduledatap *moduledata // linker symbol
var modulesSlice *[]*moduledata // see activeModules
// activeModules returns a slice of active modules.
//
// A module is active once its gcdatamask and gcbssmask have been
// assembled and it is usable by the GC.
//
// This is nosplit/nowritebarrier because it is called by the
// cgo pointer checking code.
//go:nosplit
//go:nowritebarrier
func activeModules() []*moduledata {
p := (*[]*moduledata)(atomic.Loadp(unsafe.Pointer(&modulesSlice)))
if p == nil {
return nil
}
return *p
}
// modulesinit creates the active modules slice out of all loaded modules.
//
// When a module is first loaded by the dynamic linker, an .init_array
// function (written by cmd/link) is invoked to call addmoduledata,
// appending to the module to the linked list that starts with
// firstmoduledata.
//
// There are two times this can happen in the lifecycle of a Go
// program. First, if compiled with -linkshared, a number of modules
// built with -buildmode=shared can be loaded at program initialization.
// Second, a Go program can load a module while running that was built
// with -buildmode=plugin.
//
// After loading, this function is called which initializes the
// moduledata so it is usable by the GC and creates a new activeModules
// list.
//
// Only one goroutine may call modulesinit at a time.
func modulesinit() {
modules := new([]*moduledata)
for md := &firstmoduledata; md != nil; md = md.next {
if md.bad {
continue
}
*modules = append(*modules, md)
if md.gcdatamask == (bitvector{}) {
md.gcdatamask = progToPointerMask((*byte)(unsafe.Pointer(md.gcdata)), md.edata-md.data)
md.gcbssmask = progToPointerMask((*byte)(unsafe.Pointer(md.gcbss)), md.ebss-md.bss)
}
}
// Modules appear in the moduledata linked list in the order they are
// loaded by the dynamic loader, with one exception: the
// firstmoduledata itself the module that contains the runtime. This
// is not always the first module (when using -buildmode=shared, it
// is typically libstd.so, the second module). The order matters for
// typelinksinit, so we swap the first module with whatever module
// contains the main function.
//
// See Issue #18729.
for i, md := range *modules {
if md.hasmain != 0 {
(*modules)[0] = md
(*modules)[i] = &firstmoduledata
break
}
}
atomicstorep(unsafe.Pointer(&modulesSlice), unsafe.Pointer(modules))
}
type functab struct {
entry uintptr
funcoff uintptr
}
// Mapping information for secondary text sections
type textsect struct {
vaddr uintptr // prelinked section vaddr
length uintptr // section length
baseaddr uintptr // relocated section address
}
const minfunc = 16 // minimum function size
const pcbucketsize = 256 * minfunc // size of bucket in the pc->func lookup table
// findfunctab is an array of these structures.
// Each bucket represents 4096 bytes of the text segment.
// Each subbucket represents 256 bytes of the text segment.
// To find a function given a pc, locate the bucket and subbucket for
// that pc. Add together the idx and subbucket value to obtain a
// function index. Then scan the functab array starting at that
// index to find the target function.
// This table uses 20 bytes for every 4096 bytes of code, or ~0.5% overhead.
type findfuncbucket struct {
idx uint32
subbuckets [16]byte
}
func moduledataverify() {
for datap := &firstmoduledata; datap != nil; datap = datap.next {
moduledataverify1(datap)
}
}
const debugPcln = false
func moduledataverify1(datap *moduledata) {
// See golang.org/s/go12symtab for header: 0xfffffffb,
// two zero bytes, a byte giving the PC quantum,
// and a byte giving the pointer width in bytes.
pcln := *(**[8]byte)(unsafe.Pointer(&datap.pclntable))
pcln32 := *(**[2]uint32)(unsafe.Pointer(&datap.pclntable))
if pcln32[0] != 0xfffffffb || pcln[4] != 0 || pcln[5] != 0 || pcln[6] != sys.PCQuantum || pcln[7] != sys.PtrSize {
println("runtime: function symbol table header:", hex(pcln32[0]), hex(pcln[4]), hex(pcln[5]), hex(pcln[6]), hex(pcln[7]))
throw("invalid function symbol table\n")
}
// ftab is lookup table for function by program counter.
nftab := len(datap.ftab) - 1
for i := 0; i < nftab; i++ {
// NOTE: ftab[nftab].entry is legal; it is the address beyond the final function.
if datap.ftab[i].entry > datap.ftab[i+1].entry {
f1 := funcInfo{(*_func)(unsafe.Pointer(&datap.pclntable[datap.ftab[i].funcoff])), datap}
f2 := funcInfo{(*_func)(unsafe.Pointer(&datap.pclntable[datap.ftab[i+1].funcoff])), datap}
f2name := "end"
if i+1 < nftab {
f2name = funcname(f2)
}
println("function symbol table not sorted by program counter:", hex(datap.ftab[i].entry), funcname(f1), ">", hex(datap.ftab[i+1].entry), f2name)
for j := 0; j <= i; j++ {
print("\t", hex(datap.ftab[j].entry), " ", funcname(funcInfo{(*_func)(unsafe.Pointer(&datap.pclntable[datap.ftab[j].funcoff])), datap}), "\n")
}
throw("invalid runtime symbol table")
}
}
if datap.minpc != datap.ftab[0].entry ||
datap.maxpc != datap.ftab[nftab].entry {
throw("minpc or maxpc invalid")
}
for _, modulehash := range datap.modulehashes {
if modulehash.linktimehash != *modulehash.runtimehash {
println("abi mismatch detected between", datap.modulename, "and", modulehash.modulename)
throw("abi mismatch")
}
}
}
// FuncForPC returns a *Func describing the function that contains the
// given program counter address, or else nil.
//
// If pc represents multiple functions because of inlining, it returns
// the *Func describing the outermost function.
func FuncForPC(pc uintptr) *Func {
return findfunc(pc)._Func()
}
// Name returns the name of the function.
func (f *Func) Name() string {
if f == nil {
return ""
}
return funcname(f.funcInfo())
}
// Entry returns the entry address of the function.
func (f *Func) Entry() uintptr {
return f.raw().entry
}
// FileLine returns the file name and line number of the
// source code corresponding to the program counter pc.
// The result will not be accurate if pc is not a program
// counter within f.
func (f *Func) FileLine(pc uintptr) (file string, line int) {
// Pass strict=false here, because anyone can call this function,
// and they might just be wrong about targetpc belonging to f.
file, line32 := funcline1(f.funcInfo(), pc, false)
return file, int(line32)
}
func findmoduledatap(pc uintptr) *moduledata {
for datap := &firstmoduledata; datap != nil; datap = datap.next {
if datap.minpc <= pc && pc < datap.maxpc {
return datap
}
}
return nil
}
type funcInfo struct {
*_func
datap *moduledata
}
func (f funcInfo) valid() bool {
return f._func != nil
}
func (f funcInfo) _Func() *Func {
return (*Func)(unsafe.Pointer(f._func))
}
func findfunc(pc uintptr) funcInfo {
datap := findmoduledatap(pc)
if datap == nil {
return funcInfo{}
}
const nsub = uintptr(len(findfuncbucket{}.subbuckets))
x := pc - datap.minpc
b := x / pcbucketsize
i := x % pcbucketsize / (pcbucketsize / nsub)
ffb := (*findfuncbucket)(add(unsafe.Pointer(datap.findfunctab), b*unsafe.Sizeof(findfuncbucket{})))
idx := ffb.idx + uint32(ffb.subbuckets[i])
// If the idx is beyond the end of the ftab, set it to the end of the table and search backward.
// This situation can occur if multiple text sections are generated to handle large text sections
// and the linker has inserted jump tables between them.
if idx >= uint32(len(datap.ftab)) {
idx = uint32(len(datap.ftab) - 1)
}
if pc < datap.ftab[idx].entry {
// With multiple text sections, the idx might reference a function address that
// is higher than the pc being searched, so search backward until the matching address is found.
for datap.ftab[idx].entry > pc && idx > 0 {
idx--
}
if idx == 0 {
throw("findfunc: bad findfunctab entry idx")
}
} else {
// linear search to find func with pc >= entry.
for datap.ftab[idx+1].entry <= pc {
idx++
}
}
return funcInfo{(*_func)(unsafe.Pointer(&datap.pclntable[datap.ftab[idx].funcoff])), datap}
}
type pcvalueCache struct {
entries [16]pcvalueCacheEnt
}
type pcvalueCacheEnt struct {
// targetpc and off together are the key of this cache entry.
targetpc uintptr
off int32
// val is the value of this cached pcvalue entry.
val int32
}
func pcvalue(f funcInfo, off int32, targetpc uintptr, cache *pcvalueCache, strict bool) int32 {
if off == 0 {
return -1
}
// Check the cache. This speeds up walks of deep stacks, which
// tend to have the same recursive functions over and over.
//
// This cache is small enough that full associativity is
// cheaper than doing the hashing for a less associative
// cache.
if cache != nil {
for i := range cache.entries {
// We check off first because we're more
// likely to have multiple entries with
// different offsets for the same targetpc
// than the other way around, so we'll usually
// fail in the first clause.
ent := &cache.entries[i]
if ent.off == off && ent.targetpc == targetpc {
return ent.val
}
}
}
if !f.valid() {
if strict && panicking == 0 {
print("runtime: no module data for ", hex(f.entry), "\n")
throw("no module data")
}
return -1
}
datap := f.datap
p := datap.pclntable[off:]
pc := f.entry
val := int32(-1)
for {
var ok bool
p, ok = step(p, &pc, &val, pc == f.entry)
if !ok {
break
}
if targetpc < pc {
// Replace a random entry in the cache. Random
// replacement prevents a performance cliff if
// a recursive stack's cycle is slightly
// larger than the cache.
if cache != nil {
ci := fastrandn(uint32(len(cache.entries)))
cache.entries[ci] = pcvalueCacheEnt{
targetpc: targetpc,
off: off,
val: val,
}
}
return val
}
}
// If there was a table, it should have covered all program counters.
// If not, something is wrong.
if panicking != 0 || !strict {
return -1
}
print("runtime: invalid pc-encoded table f=", funcname(f), " pc=", hex(pc), " targetpc=", hex(targetpc), " tab=", p, "\n")
p = datap.pclntable[off:]
pc = f.entry
val = -1
for {
var ok bool
p, ok = step(p, &pc, &val, pc == f.entry)
if !ok {
break
}
print("\tvalue=", val, " until pc=", hex(pc), "\n")
}
throw("invalid runtime symbol table")
return -1
}
func cfuncname(f funcInfo) *byte {
if !f.valid() || f.nameoff == 0 {
return nil
}
return &f.datap.pclntable[f.nameoff]
}
func funcname(f funcInfo) string {
return gostringnocopy(cfuncname(f))
}
func funcnameFromNameoff(f funcInfo, nameoff int32) string {
datap := f.datap
if !f.valid() {
return ""
}
cstr := &datap.pclntable[nameoff]
return gostringnocopy(cstr)
}
func funcfile(f funcInfo, fileno int32) string {
datap := f.datap
if !f.valid() {
return "?"
}
return gostringnocopy(&datap.pclntable[datap.filetab[fileno]])
}
func funcline1(f funcInfo, targetpc uintptr, strict bool) (file string, line int32) {
datap := f.datap
if !f.valid() {
return "?", 0
}
fileno := int(pcvalue(f, f.pcfile, targetpc, nil, strict))
line = pcvalue(f, f.pcln, targetpc, nil, strict)
if fileno == -1 || line == -1 || fileno >= len(datap.filetab) {
// print("looking for ", hex(targetpc), " in ", funcname(f), " got file=", fileno, " line=", lineno, "\n")
return "?", 0
}
file = gostringnocopy(&datap.pclntable[datap.filetab[fileno]])
return
}
func funcline(f funcInfo, targetpc uintptr) (file string, line int32) {
return funcline1(f, targetpc, true)
}
func funcspdelta(f funcInfo, targetpc uintptr, cache *pcvalueCache) int32 {
x := pcvalue(f, f.pcsp, targetpc, cache, true)
if x&(sys.PtrSize-1) != 0 {
print("invalid spdelta ", funcname(f), " ", hex(f.entry), " ", hex(targetpc), " ", hex(f.pcsp), " ", x, "\n")
}
return x
}
func pcdatavalue(f funcInfo, table int32, targetpc uintptr, cache *pcvalueCache) int32 {
if table < 0 || table >= f.npcdata {
return -1
}
off := *(*int32)(add(unsafe.Pointer(&f.nfuncdata), unsafe.Sizeof(f.nfuncdata)+uintptr(table)*4))
return pcvalue(f, off, targetpc, cache, true)
}
func funcdata(f funcInfo, i int32) unsafe.Pointer {
if i < 0 || i >= f.nfuncdata {
return nil
}
p := add(unsafe.Pointer(&f.nfuncdata), unsafe.Sizeof(f.nfuncdata)+uintptr(f.npcdata)*4)
if sys.PtrSize == 8 && uintptr(p)&4 != 0 {
if uintptr(unsafe.Pointer(f._func))&4 != 0 {
println("runtime: misaligned func", f._func)
}
p = add(p, 4)
}
return *(*unsafe.Pointer)(add(p, uintptr(i)*sys.PtrSize))
}
// step advances to the next pc, value pair in the encoded table.
func step(p []byte, pc *uintptr, val *int32, first bool) (newp []byte, ok bool) {
// For both uvdelta and pcdelta, the common case (~70%)
// is that they are a single byte. If so, avoid calling readvarint.
uvdelta := uint32(p[0])
if uvdelta == 0 && !first {
return nil, false
}
n := uint32(1)
if uvdelta&0x80 != 0 {
n, uvdelta = readvarint(p)
}
p = p[n:]
if uvdelta&1 != 0 {
uvdelta = ^(uvdelta >> 1)
} else {
uvdelta >>= 1
}
vdelta := int32(uvdelta)
pcdelta := uint32(p[0])
n = 1
if pcdelta&0x80 != 0 {
n, pcdelta = readvarint(p)
}
p = p[n:]
*pc += uintptr(pcdelta * sys.PCQuantum)
*val += vdelta
return p, true
}
// readvarint reads a varint from p.
func readvarint(p []byte) (read uint32, val uint32) {
var v, shift, n uint32
for {
b := p[n]
n++
v |= uint32(b&0x7F) << (shift & 31)
if b&0x80 == 0 {
break
}
shift += 7
}
return n, v
}
type stackmap struct {
n int32 // number of bitmaps
nbit int32 // number of bits in each bitmap
bytedata [1]byte // bitmaps, each starting on a byte boundary
}
//go:nowritebarrier
func stackmapdata(stkmap *stackmap, n int32) bitvector {
if n < 0 || n >= stkmap.n {
throw("stackmapdata: index out of range")
}
return bitvector{stkmap.nbit, (*byte)(add(unsafe.Pointer(&stkmap.bytedata), uintptr(n*((stkmap.nbit+7)>>3))))}
}
// inlinedCall is the encoding of entries in the FUNCDATA_InlTree table.
type inlinedCall struct {
parent int32 // index of parent in the inltree, or < 0
file int32 // fileno index into filetab
line int32 // line number of the call site
func_ int32 // offset into pclntab for name of called function
}