blob: 17e342ef699a017c2849d6b8b50a1b36222ff591 [file] [log] [blame]
// 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 to frames.
callers []uintptr
// frames is a slice of Frames that have yet to be returned.
frames []Frame
frameStore [2]Frame
}
// 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
}
// 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 {
f := &Frames{callers: callers}
f.frames = f.frameStore[:0]
return f
}
// 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) {
for len(ci.frames) < 2 {
// Find the next frame.
// We need to look for 2 frames so we know what
// to return for the "more" result.
if len(ci.callers) == 0 {
break
}
pc := ci.callers[0]
ci.callers = ci.callers[1:]
funcInfo := findfunc(pc)
if !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.
ci.frames = append(ci.frames, expandCgoFrames(pc)...)
}
continue
}
f := funcInfo._Func()
entry := f.Entry()
if pc > entry {
// We store the pc of the start of the instruction following
// the instruction in question (the call or the inline mark).
// This is done for historical reasons, and to make FuncForPC
// work correctly for entries in the result of runtime.Callers.
pc--
}
name := funcname(funcInfo)
file, line := funcline1(funcInfo, pc, false)
if inldata := funcdata(funcInfo, _FUNCDATA_InlTree); inldata != nil {
inltree := (*[1 << 20]inlinedCall)(inldata)
ix := pcdatavalue(funcInfo, _PCDATA_InlTreeIndex, pc, nil)
if ix >= 0 {
// Note: entry is not modified. It always refers to a real frame, not an inlined one.
f = nil
name = funcnameFromNameoff(funcInfo, inltree[ix].func_)
// File/line is already correct.
// TODO: remove file/line from InlinedCall?
}
}
ci.frames = append(ci.frames, Frame{
PC: pc,
Func: f,
Function: name,
File: file,
Line: int(line),
Entry: entry,
})
}
// Pop one frame from the frame list. Keep the rest.
// Avoid allocation in the common case, which is 1 or 2 frames.
switch len(ci.frames) {
case 0: // In the rare case when there are no frames at all, we return Frame{}.
case 1:
frame = ci.frames[0]
ci.frames = ci.frameStore[:0]
case 2:
frame = ci.frames[0]
ci.frameStore[0] = ci.frames[1]
ci.frames = ci.frameStore[:1]
default:
frame = ci.frames[0]
ci.frames = ci.frames[1:]
}
more = len(ci.frames) > 0
return
}
// 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/objabi/funcdata.go.
const (
_PCDATA_StackMapIndex = 0
_PCDATA_InlTreeIndex = 1
_PCDATA_RegMapIndex = 2
_FUNCDATA_ArgsPointerMaps = 0
_FUNCDATA_LocalsPointerMaps = 1
_FUNCDATA_InlTree = 2
_FUNCDATA_RegPointerMaps = 3
_FUNCDATA_StackObjects = 4
_ArgsSizeUnknown = -0x80000000
)
// A FuncID identifies particular functions that need to be treated
// specially by the runtime.
// Note that in some situations involving plugins, there may be multiple
// copies of a particular special runtime function.
// Note: this list must match the list in cmd/internal/objabi/funcid.go.
type funcID uint8
const (
funcID_normal funcID = iota // not a special function
funcID_runtime_main
funcID_goexit
funcID_jmpdefer
funcID_mcall
funcID_morestack
funcID_mstart
funcID_rt0_go
funcID_asmcgocall
funcID_sigpanic
funcID_runfinq
funcID_gcBgMarkWorker
funcID_systemstack_switch
funcID_systemstack
funcID_cgocallback_gofunc
funcID_gogo
funcID_externalthreadhandler
funcID_debugCallV1
funcID_gopanic
funcID_panicwrap
funcID_wrapper // any autogenerated code (hash/eq algorithms, method wrappers, etc.)
)
// 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 a *Func describing the innermost function, but with an entry
// of the outermost function.
func FuncForPC(pc uintptr) *Func {
f := findfunc(pc)
if !f.valid() {
return nil
}
if inldata := funcdata(f, _FUNCDATA_InlTree); inldata != nil {
// Note: strict=false so bad PCs (those between functions) don't crash the runtime.
// We just report the preceeding function in that situation. See issue 29735.
// TODO: Perhaps we should report no function at all in that case.
// The runtime currently doesn't have function end info, alas.
if ix := pcdatavalue1(f, _PCDATA_InlTreeIndex, pc, nil, false); ix >= 0 {
inltree := (*[1 << 20]inlinedCall)(inldata)
name := funcnameFromNameoff(f, inltree[ix].func_)
file, line := funcline(f, pc)
fi := &funcinl{
entry: f.entry, // entry of the real (the outermost) function.
name: name,
file: file,
line: int(line),
}
return (*Func)(unsafe.Pointer(fi))
}
}
return f._Func()
}
// Name returns the name of the function.
func (f *Func) Name() string {
if f == nil {
return ""
}
fn := f.raw()
if fn.entry == 0 { // inlined version
fi := (*funcinl)(unsafe.Pointer(fn))
return fi.name
}
return funcname(f.funcInfo())
}
// Entry returns the entry address of the function.
func (f *Func) Entry() uintptr {
fn := f.raw()
if fn.entry == 0 { // inlined version
fi := (*funcinl)(unsafe.Pointer(fn))
return fi.entry
}
return fn.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) {
fn := f.raw()
if fn.entry == 0 { // inlined version
fi := (*funcinl)(unsafe.Pointer(fn))
return fi.file, fi.line
}
// 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 [2][8]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
}
// pcvalueCacheKey returns the outermost index in a pcvalueCache to use for targetpc.
// It must be very cheap to calculate.
// For now, align to sys.PtrSize and reduce mod the number of entries.
// In practice, this appears to be fairly randomly and evenly distributed.
func pcvalueCacheKey(targetpc uintptr) uintptr {
return (targetpc / sys.PtrSize) % uintptr(len(pcvalueCache{}.entries))
}
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 {
x := pcvalueCacheKey(targetpc)
for i := range cache.entries[x] {
// 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[x][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.
// Put the new element at the beginning,
// since it is the most likely to be newly used.
if cache != nil {
x := pcvalueCacheKey(targetpc)
e := &cache.entries[x]
ci := fastrand() % uint32(len(cache.entries[x]))
e[ci] = e[0]
e[0] = 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 pcdatastart(f funcInfo, table int32) int32 {
return *(*int32)(add(unsafe.Pointer(&f.nfuncdata), unsafe.Sizeof(f.nfuncdata)+uintptr(table)*4))
}
func pcdatavalue(f funcInfo, table int32, targetpc uintptr, cache *pcvalueCache) int32 {
if table < 0 || table >= f.npcdata {
return -1
}
return pcvalue(f, pcdatastart(f, table), targetpc, cache, true)
}
func pcdatavalue1(f funcInfo, table int32, targetpc uintptr, cache *pcvalueCache, strict bool) int32 {
if table < 0 || table >= f.npcdata {
return -1
}
return pcvalue(f, pcdatastart(f, table), targetpc, cache, strict)
}
func funcdata(f funcInfo, i uint8) 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)
}
*val += int32(-(uvdelta & 1) ^ (uvdelta >> 1))
p = p[n:]
pcdelta := uint32(p[0])
n = 1
if pcdelta&0x80 != 0 {
n, pcdelta = readvarint(p)
}
p = p[n:]
*pc += uintptr(pcdelta * sys.PCQuantum)
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 {
// Check this invariant only when stackDebug is on at all.
// The invariant is already checked by many of stackmapdata's callers,
// and disabling it by default allows stackmapdata to be inlined.
if stackDebug > 0 && (n < 0 || n >= stkmap.n) {
throw("stackmapdata: index out of range")
}
return bitvector{stkmap.nbit, addb(&stkmap.bytedata[0], uintptr(n*((stkmap.nbit+7)>>3)))}
}
// inlinedCall is the encoding of entries in the FUNCDATA_InlTree table.
type inlinedCall struct {
parent int16 // index of parent in the inltree, or < 0
funcID funcID // type of the called function
_ byte
file int32 // fileno index into filetab
line int32 // line number of the call site
func_ int32 // offset into pclntab for name of called function
parentPc int32 // position of an instruction whose source position is the call site (offset from entry)
}