Source file src/runtime/runtime1.go

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package runtime
     6  
     7  import (
     8  	"internal/bytealg"
     9  	"internal/goarch"
    10  	"internal/runtime/atomic"
    11  	"unsafe"
    12  )
    13  
    14  // Keep a cached value to make gotraceback fast,
    15  // since we call it on every call to gentraceback.
    16  // The cached value is a uint32 in which the low bits
    17  // are the "crash" and "all" settings and the remaining
    18  // bits are the traceback value (0 off, 1 on, 2 include system).
    19  const (
    20  	tracebackCrash = 1 << iota
    21  	tracebackAll
    22  	tracebackShift = iota
    23  )
    24  
    25  var traceback_cache uint32 = 2 << tracebackShift
    26  var traceback_env uint32
    27  
    28  // gotraceback returns the current traceback settings.
    29  //
    30  // If level is 0, suppress all tracebacks.
    31  // If level is 1, show tracebacks, but exclude runtime frames.
    32  // If level is 2, show tracebacks including runtime frames.
    33  // If all is set, print all goroutine stacks. Otherwise, print just the current goroutine.
    34  // If crash is set, crash (core dump, etc) after tracebacking.
    35  //
    36  //go:nosplit
    37  func gotraceback() (level int32, all, crash bool) {
    38  	gp := getg()
    39  	t := atomic.Load(&traceback_cache)
    40  	crash = t&tracebackCrash != 0
    41  	all = gp.m.throwing >= throwTypeUser || t&tracebackAll != 0
    42  	if gp.m.traceback != 0 {
    43  		level = int32(gp.m.traceback)
    44  	} else if gp.m.throwing >= throwTypeRuntime {
    45  		// Always include runtime frames in runtime throws unless
    46  		// otherwise overridden by m.traceback.
    47  		level = 2
    48  	} else {
    49  		level = int32(t >> tracebackShift)
    50  	}
    51  	return
    52  }
    53  
    54  var (
    55  	argc int32
    56  	argv **byte
    57  )
    58  
    59  // nosplit for use in linux startup sysargs.
    60  //
    61  //go:nosplit
    62  func argv_index(argv **byte, i int32) *byte {
    63  	return *(**byte)(add(unsafe.Pointer(argv), uintptr(i)*goarch.PtrSize))
    64  }
    65  
    66  func args(c int32, v **byte) {
    67  	argc = c
    68  	argv = v
    69  	sysargs(c, v)
    70  }
    71  
    72  func goargs() {
    73  	if GOOS == "windows" {
    74  		return
    75  	}
    76  	argslice = make([]string, argc)
    77  	for i := int32(0); i < argc; i++ {
    78  		argslice[i] = gostringnocopy(argv_index(argv, i))
    79  	}
    80  }
    81  
    82  func goenvs_unix() {
    83  	// TODO(austin): ppc64 in dynamic linking mode doesn't
    84  	// guarantee env[] will immediately follow argv. Might cause
    85  	// problems.
    86  	n := int32(0)
    87  	for argv_index(argv, argc+1+n) != nil {
    88  		n++
    89  	}
    90  
    91  	envs = make([]string, n)
    92  	for i := int32(0); i < n; i++ {
    93  		envs[i] = gostring(argv_index(argv, argc+1+i))
    94  	}
    95  }
    96  
    97  func environ() []string {
    98  	return envs
    99  }
   100  
   101  // TODO: These should be locals in testAtomic64, but we don't 8-byte
   102  // align stack variables on 386.
   103  var test_z64, test_x64 uint64
   104  
   105  func testAtomic64() {
   106  	test_z64 = 42
   107  	test_x64 = 0
   108  	if atomic.Cas64(&test_z64, test_x64, 1) {
   109  		throw("cas64 failed")
   110  	}
   111  	if test_x64 != 0 {
   112  		throw("cas64 failed")
   113  	}
   114  	test_x64 = 42
   115  	if !atomic.Cas64(&test_z64, test_x64, 1) {
   116  		throw("cas64 failed")
   117  	}
   118  	if test_x64 != 42 || test_z64 != 1 {
   119  		throw("cas64 failed")
   120  	}
   121  	if atomic.Load64(&test_z64) != 1 {
   122  		throw("load64 failed")
   123  	}
   124  	atomic.Store64(&test_z64, (1<<40)+1)
   125  	if atomic.Load64(&test_z64) != (1<<40)+1 {
   126  		throw("store64 failed")
   127  	}
   128  	if atomic.Xadd64(&test_z64, (1<<40)+1) != (2<<40)+2 {
   129  		throw("xadd64 failed")
   130  	}
   131  	if atomic.Load64(&test_z64) != (2<<40)+2 {
   132  		throw("xadd64 failed")
   133  	}
   134  	if atomic.Xchg64(&test_z64, (3<<40)+3) != (2<<40)+2 {
   135  		throw("xchg64 failed")
   136  	}
   137  	if atomic.Load64(&test_z64) != (3<<40)+3 {
   138  		throw("xchg64 failed")
   139  	}
   140  }
   141  
   142  func check() {
   143  	var (
   144  		a     int8
   145  		b     uint8
   146  		c     int16
   147  		d     uint16
   148  		e     int32
   149  		f     uint32
   150  		g     int64
   151  		h     uint64
   152  		i, i1 float32
   153  		j, j1 float64
   154  		k     unsafe.Pointer
   155  		l     *uint16
   156  		m     [4]byte
   157  	)
   158  	type x1t struct {
   159  		x uint8
   160  	}
   161  	type y1t struct {
   162  		x1 x1t
   163  		y  uint8
   164  	}
   165  	var x1 x1t
   166  	var y1 y1t
   167  
   168  	if unsafe.Sizeof(a) != 1 {
   169  		throw("bad a")
   170  	}
   171  	if unsafe.Sizeof(b) != 1 {
   172  		throw("bad b")
   173  	}
   174  	if unsafe.Sizeof(c) != 2 {
   175  		throw("bad c")
   176  	}
   177  	if unsafe.Sizeof(d) != 2 {
   178  		throw("bad d")
   179  	}
   180  	if unsafe.Sizeof(e) != 4 {
   181  		throw("bad e")
   182  	}
   183  	if unsafe.Sizeof(f) != 4 {
   184  		throw("bad f")
   185  	}
   186  	if unsafe.Sizeof(g) != 8 {
   187  		throw("bad g")
   188  	}
   189  	if unsafe.Sizeof(h) != 8 {
   190  		throw("bad h")
   191  	}
   192  	if unsafe.Sizeof(i) != 4 {
   193  		throw("bad i")
   194  	}
   195  	if unsafe.Sizeof(j) != 8 {
   196  		throw("bad j")
   197  	}
   198  	if unsafe.Sizeof(k) != goarch.PtrSize {
   199  		throw("bad k")
   200  	}
   201  	if unsafe.Sizeof(l) != goarch.PtrSize {
   202  		throw("bad l")
   203  	}
   204  	if unsafe.Sizeof(x1) != 1 {
   205  		throw("bad unsafe.Sizeof x1")
   206  	}
   207  	if unsafe.Offsetof(y1.y) != 1 {
   208  		throw("bad offsetof y1.y")
   209  	}
   210  	if unsafe.Sizeof(y1) != 2 {
   211  		throw("bad unsafe.Sizeof y1")
   212  	}
   213  
   214  	if timediv(12345*1000000000+54321, 1000000000, &e) != 12345 || e != 54321 {
   215  		throw("bad timediv")
   216  	}
   217  
   218  	var z uint32
   219  	z = 1
   220  	if !atomic.Cas(&z, 1, 2) {
   221  		throw("cas1")
   222  	}
   223  	if z != 2 {
   224  		throw("cas2")
   225  	}
   226  
   227  	z = 4
   228  	if atomic.Cas(&z, 5, 6) {
   229  		throw("cas3")
   230  	}
   231  	if z != 4 {
   232  		throw("cas4")
   233  	}
   234  
   235  	z = 0xffffffff
   236  	if !atomic.Cas(&z, 0xffffffff, 0xfffffffe) {
   237  		throw("cas5")
   238  	}
   239  	if z != 0xfffffffe {
   240  		throw("cas6")
   241  	}
   242  
   243  	m = [4]byte{1, 1, 1, 1}
   244  	atomic.Or8(&m[1], 0xf0)
   245  	if m[0] != 1 || m[1] != 0xf1 || m[2] != 1 || m[3] != 1 {
   246  		throw("atomicor8")
   247  	}
   248  
   249  	m = [4]byte{0xff, 0xff, 0xff, 0xff}
   250  	atomic.And8(&m[1], 0x1)
   251  	if m[0] != 0xff || m[1] != 0x1 || m[2] != 0xff || m[3] != 0xff {
   252  		throw("atomicand8")
   253  	}
   254  
   255  	*(*uint64)(unsafe.Pointer(&j)) = ^uint64(0)
   256  	if j == j {
   257  		throw("float64nan")
   258  	}
   259  	if !(j != j) {
   260  		throw("float64nan1")
   261  	}
   262  
   263  	*(*uint64)(unsafe.Pointer(&j1)) = ^uint64(1)
   264  	if j == j1 {
   265  		throw("float64nan2")
   266  	}
   267  	if !(j != j1) {
   268  		throw("float64nan3")
   269  	}
   270  
   271  	*(*uint32)(unsafe.Pointer(&i)) = ^uint32(0)
   272  	if i == i {
   273  		throw("float32nan")
   274  	}
   275  	if i == i {
   276  		throw("float32nan1")
   277  	}
   278  
   279  	*(*uint32)(unsafe.Pointer(&i1)) = ^uint32(1)
   280  	if i == i1 {
   281  		throw("float32nan2")
   282  	}
   283  	if i == i1 {
   284  		throw("float32nan3")
   285  	}
   286  
   287  	testAtomic64()
   288  
   289  	if fixedStack != round2(fixedStack) {
   290  		throw("FixedStack is not power-of-2")
   291  	}
   292  
   293  	if !checkASM() {
   294  		throw("assembly checks failed")
   295  	}
   296  }
   297  
   298  type dbgVar struct {
   299  	name   string
   300  	value  *int32        // for variables that can only be set at startup
   301  	atomic *atomic.Int32 // for variables that can be changed during execution
   302  	def    int32         // default value (ideally zero)
   303  }
   304  
   305  // Holds variables parsed from GODEBUG env var,
   306  // except for "memprofilerate" since there is an
   307  // existing int var for that value, which may
   308  // already have an initial value.
   309  var debug struct {
   310  	cgocheck                 int32
   311  	clobberfree              int32
   312  	disablethp               int32
   313  	dontfreezetheworld       int32
   314  	efence                   int32
   315  	gccheckmark              int32
   316  	gcpacertrace             int32
   317  	gcshrinkstackoff         int32
   318  	gcstoptheworld           int32
   319  	gctrace                  int32
   320  	invalidptr               int32
   321  	madvdontneed             int32 // for Linux; issue 28466
   322  	runtimeContentionStacks  atomic.Int32
   323  	scavtrace                int32
   324  	scheddetail              int32
   325  	schedtrace               int32
   326  	tracebackancestors       int32
   327  	asyncpreemptoff          int32
   328  	harddecommit             int32
   329  	adaptivestackstart       int32
   330  	tracefpunwindoff         int32
   331  	traceadvanceperiod       int32
   332  	traceCheckStackOwnership int32
   333  	profstackdepth           int32
   334  
   335  	// debug.malloc is used as a combined debug check
   336  	// in the malloc function and should be set
   337  	// if any of the below debug options is != 0.
   338  	malloc    bool
   339  	inittrace int32
   340  	sbrk      int32
   341  	// traceallocfree controls whether execution traces contain
   342  	// detailed trace data about memory allocation. This value
   343  	// affects debug.malloc only if it is != 0 and the execution
   344  	// tracer is enabled, in which case debug.malloc will be
   345  	// set to "true" if it isn't already while tracing is enabled.
   346  	// It will be set while the world is stopped, so it's safe.
   347  	// The value of traceallocfree can be changed any time in response
   348  	// to os.Setenv("GODEBUG").
   349  	traceallocfree atomic.Int32
   350  
   351  	panicnil atomic.Int32
   352  
   353  	// asynctimerchan controls whether timer channels
   354  	// behave asynchronously (as in Go 1.22 and earlier)
   355  	// instead of their Go 1.23+ synchronous behavior.
   356  	// The value can change at any time (in response to os.Setenv("GODEBUG"))
   357  	// and affects all extant timer channels immediately.
   358  	// Programs wouldn't normally change over an execution,
   359  	// but allowing it is convenient for testing and for programs
   360  	// that do an os.Setenv in main.init or main.main.
   361  	asynctimerchan atomic.Int32
   362  }
   363  
   364  var dbgvars = []*dbgVar{
   365  	{name: "adaptivestackstart", value: &debug.adaptivestackstart},
   366  	{name: "asyncpreemptoff", value: &debug.asyncpreemptoff},
   367  	{name: "asynctimerchan", atomic: &debug.asynctimerchan},
   368  	{name: "cgocheck", value: &debug.cgocheck},
   369  	{name: "clobberfree", value: &debug.clobberfree},
   370  	{name: "disablethp", value: &debug.disablethp},
   371  	{name: "dontfreezetheworld", value: &debug.dontfreezetheworld},
   372  	{name: "efence", value: &debug.efence},
   373  	{name: "gccheckmark", value: &debug.gccheckmark},
   374  	{name: "gcpacertrace", value: &debug.gcpacertrace},
   375  	{name: "gcshrinkstackoff", value: &debug.gcshrinkstackoff},
   376  	{name: "gcstoptheworld", value: &debug.gcstoptheworld},
   377  	{name: "gctrace", value: &debug.gctrace},
   378  	{name: "harddecommit", value: &debug.harddecommit},
   379  	{name: "inittrace", value: &debug.inittrace},
   380  	{name: "invalidptr", value: &debug.invalidptr},
   381  	{name: "madvdontneed", value: &debug.madvdontneed},
   382  	{name: "panicnil", atomic: &debug.panicnil},
   383  	{name: "profstackdepth", value: &debug.profstackdepth, def: 128},
   384  	{name: "runtimecontentionstacks", atomic: &debug.runtimeContentionStacks},
   385  	{name: "sbrk", value: &debug.sbrk},
   386  	{name: "scavtrace", value: &debug.scavtrace},
   387  	{name: "scheddetail", value: &debug.scheddetail},
   388  	{name: "schedtrace", value: &debug.schedtrace},
   389  	{name: "traceadvanceperiod", value: &debug.traceadvanceperiod},
   390  	{name: "traceallocfree", atomic: &debug.traceallocfree},
   391  	{name: "tracecheckstackownership", value: &debug.traceCheckStackOwnership},
   392  	{name: "tracebackancestors", value: &debug.tracebackancestors},
   393  	{name: "tracefpunwindoff", value: &debug.tracefpunwindoff},
   394  }
   395  
   396  func parsedebugvars() {
   397  	// defaults
   398  	debug.cgocheck = 1
   399  	debug.invalidptr = 1
   400  	debug.adaptivestackstart = 1 // set this to 0 to turn larger initial goroutine stacks off
   401  	if GOOS == "linux" {
   402  		// On Linux, MADV_FREE is faster than MADV_DONTNEED,
   403  		// but doesn't affect many of the statistics that
   404  		// MADV_DONTNEED does until the memory is actually
   405  		// reclaimed. This generally leads to poor user
   406  		// experience, like confusing stats in top and other
   407  		// monitoring tools; and bad integration with
   408  		// management systems that respond to memory usage.
   409  		// Hence, default to MADV_DONTNEED.
   410  		debug.madvdontneed = 1
   411  	}
   412  	debug.traceadvanceperiod = defaultTraceAdvancePeriod
   413  
   414  	godebug := gogetenv("GODEBUG")
   415  
   416  	p := new(string)
   417  	*p = godebug
   418  	godebugEnv.Store(p)
   419  
   420  	// apply runtime defaults, if any
   421  	for _, v := range dbgvars {
   422  		if v.def != 0 {
   423  			// Every var should have either v.value or v.atomic set.
   424  			if v.value != nil {
   425  				*v.value = v.def
   426  			} else if v.atomic != nil {
   427  				v.atomic.Store(v.def)
   428  			}
   429  		}
   430  	}
   431  
   432  	// apply compile-time GODEBUG settings
   433  	parsegodebug(godebugDefault, nil)
   434  
   435  	// apply environment settings
   436  	parsegodebug(godebug, nil)
   437  
   438  	debug.malloc = (debug.inittrace | debug.sbrk) != 0
   439  	debug.profstackdepth = min(debug.profstackdepth, maxProfStackDepth)
   440  
   441  	setTraceback(gogetenv("GOTRACEBACK"))
   442  	traceback_env = traceback_cache
   443  }
   444  
   445  // reparsedebugvars reparses the runtime's debug variables
   446  // because the environment variable has been changed to env.
   447  func reparsedebugvars(env string) {
   448  	seen := make(map[string]bool)
   449  	// apply environment settings
   450  	parsegodebug(env, seen)
   451  	// apply compile-time GODEBUG settings for as-yet-unseen variables
   452  	parsegodebug(godebugDefault, seen)
   453  	// apply defaults for as-yet-unseen variables
   454  	for _, v := range dbgvars {
   455  		if v.atomic != nil && !seen[v.name] {
   456  			v.atomic.Store(0)
   457  		}
   458  	}
   459  }
   460  
   461  // parsegodebug parses the godebug string, updating variables listed in dbgvars.
   462  // If seen == nil, this is startup time and we process the string left to right
   463  // overwriting older settings with newer ones.
   464  // If seen != nil, $GODEBUG has changed and we are doing an
   465  // incremental update. To avoid flapping in the case where a value is
   466  // set multiple times (perhaps in the default and the environment,
   467  // or perhaps twice in the environment), we process the string right-to-left
   468  // and only change values not already seen. After doing this for both
   469  // the environment and the default settings, the caller must also call
   470  // cleargodebug(seen) to reset any now-unset values back to their defaults.
   471  func parsegodebug(godebug string, seen map[string]bool) {
   472  	for p := godebug; p != ""; {
   473  		var field string
   474  		if seen == nil {
   475  			// startup: process left to right, overwriting older settings with newer
   476  			i := bytealg.IndexByteString(p, ',')
   477  			if i < 0 {
   478  				field, p = p, ""
   479  			} else {
   480  				field, p = p[:i], p[i+1:]
   481  			}
   482  		} else {
   483  			// incremental update: process right to left, updating and skipping seen
   484  			i := len(p) - 1
   485  			for i >= 0 && p[i] != ',' {
   486  				i--
   487  			}
   488  			if i < 0 {
   489  				p, field = "", p
   490  			} else {
   491  				p, field = p[:i], p[i+1:]
   492  			}
   493  		}
   494  		i := bytealg.IndexByteString(field, '=')
   495  		if i < 0 {
   496  			continue
   497  		}
   498  		key, value := field[:i], field[i+1:]
   499  		if seen[key] {
   500  			continue
   501  		}
   502  		if seen != nil {
   503  			seen[key] = true
   504  		}
   505  
   506  		// Update MemProfileRate directly here since it
   507  		// is int, not int32, and should only be updated
   508  		// if specified in GODEBUG.
   509  		if seen == nil && key == "memprofilerate" {
   510  			if n, ok := atoi(value); ok {
   511  				MemProfileRate = n
   512  			}
   513  		} else {
   514  			for _, v := range dbgvars {
   515  				if v.name == key {
   516  					if n, ok := atoi32(value); ok {
   517  						if seen == nil && v.value != nil {
   518  							*v.value = n
   519  						} else if v.atomic != nil {
   520  							v.atomic.Store(n)
   521  						}
   522  					}
   523  				}
   524  			}
   525  		}
   526  	}
   527  
   528  	if debug.cgocheck > 1 {
   529  		throw("cgocheck > 1 mode is no longer supported at runtime. Use GOEXPERIMENT=cgocheck2 at build time instead.")
   530  	}
   531  }
   532  
   533  //go:linkname setTraceback runtime/debug.SetTraceback
   534  func setTraceback(level string) {
   535  	var t uint32
   536  	switch level {
   537  	case "none":
   538  		t = 0
   539  	case "single", "":
   540  		t = 1 << tracebackShift
   541  	case "all":
   542  		t = 1<<tracebackShift | tracebackAll
   543  	case "system":
   544  		t = 2<<tracebackShift | tracebackAll
   545  	case "crash":
   546  		t = 2<<tracebackShift | tracebackAll | tracebackCrash
   547  	case "wer":
   548  		if GOOS == "windows" {
   549  			t = 2<<tracebackShift | tracebackAll | tracebackCrash
   550  			enableWER()
   551  			break
   552  		}
   553  		fallthrough
   554  	default:
   555  		t = tracebackAll
   556  		if n, ok := atoi(level); ok && n == int(uint32(n)) {
   557  			t |= uint32(n) << tracebackShift
   558  		}
   559  	}
   560  	// when C owns the process, simply exit'ing the process on fatal errors
   561  	// and panics is surprising. Be louder and abort instead.
   562  	if islibrary || isarchive {
   563  		t |= tracebackCrash
   564  	}
   565  
   566  	t |= traceback_env
   567  
   568  	atomic.Store(&traceback_cache, t)
   569  }
   570  
   571  // Poor mans 64-bit division.
   572  // This is a very special function, do not use it if you are not sure what you are doing.
   573  // int64 division is lowered into _divv() call on 386, which does not fit into nosplit functions.
   574  // Handles overflow in a time-specific manner.
   575  // This keeps us within no-split stack limits on 32-bit processors.
   576  //
   577  //go:nosplit
   578  func timediv(v int64, div int32, rem *int32) int32 {
   579  	res := int32(0)
   580  	for bit := 30; bit >= 0; bit-- {
   581  		if v >= int64(div)<<uint(bit) {
   582  			v = v - (int64(div) << uint(bit))
   583  			// Before this for loop, res was 0, thus all these
   584  			// power of 2 increments are now just bitsets.
   585  			res |= 1 << uint(bit)
   586  		}
   587  	}
   588  	if v >= int64(div) {
   589  		if rem != nil {
   590  			*rem = 0
   591  		}
   592  		return 0x7fffffff
   593  	}
   594  	if rem != nil {
   595  		*rem = int32(v)
   596  	}
   597  	return res
   598  }
   599  
   600  // Helpers for Go. Must be NOSPLIT, must only call NOSPLIT functions, and must not block.
   601  
   602  //go:nosplit
   603  func acquirem() *m {
   604  	gp := getg()
   605  	gp.m.locks++
   606  	return gp.m
   607  }
   608  
   609  //go:nosplit
   610  func releasem(mp *m) {
   611  	gp := getg()
   612  	mp.locks--
   613  	if mp.locks == 0 && gp.preempt {
   614  		// restore the preemption request in case we've cleared it in newstack
   615  		gp.stackguard0 = stackPreempt
   616  	}
   617  }
   618  
   619  // reflect_typelinks is meant for package reflect,
   620  // but widely used packages access it using linkname.
   621  // Notable members of the hall of shame include:
   622  //   - gitee.com/quant1x/gox
   623  //   - github.com/goccy/json
   624  //   - github.com/modern-go/reflect2
   625  //   - github.com/vmware/govmomi
   626  //   - github.com/pinpoint-apm/pinpoint-go-agent
   627  //   - github.com/timandy/routine
   628  //   - github.com/v2pro/plz
   629  //
   630  // Do not remove or change the type signature.
   631  // See go.dev/issue/67401.
   632  //
   633  //go:linkname reflect_typelinks reflect.typelinks
   634  func reflect_typelinks() ([]unsafe.Pointer, [][]int32) {
   635  	modules := activeModules()
   636  	sections := []unsafe.Pointer{unsafe.Pointer(modules[0].types)}
   637  	ret := [][]int32{modules[0].typelinks}
   638  	for _, md := range modules[1:] {
   639  		sections = append(sections, unsafe.Pointer(md.types))
   640  		ret = append(ret, md.typelinks)
   641  	}
   642  	return sections, ret
   643  }
   644  
   645  // reflect_resolveNameOff resolves a name offset from a base pointer.
   646  //
   647  // reflect_resolveNameOff is for package reflect,
   648  // but widely used packages access it using linkname.
   649  // Notable members of the hall of shame include:
   650  //   - github.com/agiledragon/gomonkey/v2
   651  //
   652  // Do not remove or change the type signature.
   653  // See go.dev/issue/67401.
   654  //
   655  //go:linkname reflect_resolveNameOff reflect.resolveNameOff
   656  func reflect_resolveNameOff(ptrInModule unsafe.Pointer, off int32) unsafe.Pointer {
   657  	return unsafe.Pointer(resolveNameOff(ptrInModule, nameOff(off)).Bytes)
   658  }
   659  
   660  // reflect_resolveTypeOff resolves an *rtype offset from a base type.
   661  //
   662  // reflect_resolveTypeOff is meant for package reflect,
   663  // but widely used packages access it using linkname.
   664  // Notable members of the hall of shame include:
   665  //   - gitee.com/quant1x/gox
   666  //   - github.com/modern-go/reflect2
   667  //   - github.com/v2pro/plz
   668  //   - github.com/timandy/routine
   669  //
   670  // Do not remove or change the type signature.
   671  // See go.dev/issue/67401.
   672  //
   673  //go:linkname reflect_resolveTypeOff reflect.resolveTypeOff
   674  func reflect_resolveTypeOff(rtype unsafe.Pointer, off int32) unsafe.Pointer {
   675  	return unsafe.Pointer(toRType((*_type)(rtype)).typeOff(typeOff(off)))
   676  }
   677  
   678  // reflect_resolveTextOff resolves a function pointer offset from a base type.
   679  //
   680  // reflect_resolveTextOff is for package reflect,
   681  // but widely used packages access it using linkname.
   682  // Notable members of the hall of shame include:
   683  //   - github.com/cloudwego/frugal
   684  //   - github.com/agiledragon/gomonkey/v2
   685  //
   686  // Do not remove or change the type signature.
   687  // See go.dev/issue/67401.
   688  //
   689  //go:linkname reflect_resolveTextOff reflect.resolveTextOff
   690  func reflect_resolveTextOff(rtype unsafe.Pointer, off int32) unsafe.Pointer {
   691  	return toRType((*_type)(rtype)).textOff(textOff(off))
   692  }
   693  
   694  // reflectlite_resolveNameOff resolves a name offset from a base pointer.
   695  //
   696  //go:linkname reflectlite_resolveNameOff internal/reflectlite.resolveNameOff
   697  func reflectlite_resolveNameOff(ptrInModule unsafe.Pointer, off int32) unsafe.Pointer {
   698  	return unsafe.Pointer(resolveNameOff(ptrInModule, nameOff(off)).Bytes)
   699  }
   700  
   701  // reflectlite_resolveTypeOff resolves an *rtype offset from a base type.
   702  //
   703  //go:linkname reflectlite_resolveTypeOff internal/reflectlite.resolveTypeOff
   704  func reflectlite_resolveTypeOff(rtype unsafe.Pointer, off int32) unsafe.Pointer {
   705  	return unsafe.Pointer(toRType((*_type)(rtype)).typeOff(typeOff(off)))
   706  }
   707  
   708  // reflect_addReflectOff adds a pointer to the reflection offset lookup map.
   709  //
   710  //go:linkname reflect_addReflectOff reflect.addReflectOff
   711  func reflect_addReflectOff(ptr unsafe.Pointer) int32 {
   712  	reflectOffsLock()
   713  	if reflectOffs.m == nil {
   714  		reflectOffs.m = make(map[int32]unsafe.Pointer)
   715  		reflectOffs.minv = make(map[unsafe.Pointer]int32)
   716  		reflectOffs.next = -1
   717  	}
   718  	id, found := reflectOffs.minv[ptr]
   719  	if !found {
   720  		id = reflectOffs.next
   721  		reflectOffs.next-- // use negative offsets as IDs to aid debugging
   722  		reflectOffs.m[id] = ptr
   723  		reflectOffs.minv[ptr] = id
   724  	}
   725  	reflectOffsUnlock()
   726  	return id
   727  }
   728  

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