1 // Copyright 2014 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.
9 "internal/goexperiment"
13 // Should be a built-in for unsafe.Pointer?
15 func add(p unsafe.Pointer, x uintptr) unsafe.Pointer {
16 return unsafe.Pointer(uintptr(p) + x)
19 // getg returns the pointer to the current g.
20 // The compiler rewrites calls to this function into instructions
21 // that fetch the g directly (from TLS or from the dedicated register).
24 // mcall switches from the g to the g0 stack and invokes fn(g),
25 // where g is the goroutine that made the call.
26 // mcall saves g's current PC/SP in g->sched so that it can be restored later.
27 // It is up to fn to arrange for that later execution, typically by recording
28 // g in a data structure, causing something to call ready(g) later.
29 // mcall returns to the original goroutine g later, when g has been rescheduled.
30 // fn must not return at all; typically it ends by calling schedule, to let the m
31 // run other goroutines.
33 // mcall can only be called from g stacks (not g0, not gsignal).
35 // This must NOT be go:noescape: if fn is a stack-allocated closure,
36 // fn puts g on a run queue, and g executes before fn returns, the
37 // closure will be invalidated while it is still executing.
38 func mcall(fn func(*g))
40 // systemstack runs fn on a system stack.
41 // If systemstack is called from the per-OS-thread (g0) stack, or
42 // if systemstack is called from the signal handling (gsignal) stack,
43 // systemstack calls fn directly and returns.
44 // Otherwise, systemstack is being called from the limited stack
45 // of an ordinary goroutine. In this case, systemstack switches
46 // to the per-OS-thread stack, calls fn, and switches back.
47 // It is common to use a func literal as the argument, in order
48 // to share inputs and outputs with the code around the call
52 // systemstack(func() {
58 func systemstack(fn func())
60 var badsystemstackMsg = "fatal: systemstack called from unexpected goroutine"
63 //go:nowritebarrierrec
64 func badsystemstack() {
65 sp := stringStructOf(&badsystemstackMsg)
66 write(2, sp.str, int32(sp.len))
69 // memclrNoHeapPointers clears n bytes starting at ptr.
71 // Usually you should use typedmemclr. memclrNoHeapPointers should be
72 // used only when the caller knows that *ptr contains no heap pointers
75 // *ptr is initialized memory and its type is pointer-free, or
77 // *ptr is uninitialized memory (e.g., memory that's being reused
78 // for a new allocation) and hence contains only "junk".
80 // memclrNoHeapPointers ensures that if ptr is pointer-aligned, and n
81 // is a multiple of the pointer size, then any pointer-aligned,
82 // pointer-sized portion is cleared atomically. Despite the function
83 // name, this is necessary because this function is the underlying
84 // implementation of typedmemclr and memclrHasPointers. See the doc of
85 // memmove for more details.
87 // The (CPU-specific) implementations of this function are in memclr_*.s.
90 func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
92 //go:linkname reflect_memclrNoHeapPointers reflect.memclrNoHeapPointers
93 func reflect_memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr) {
94 memclrNoHeapPointers(ptr, n)
97 // memmove copies n bytes from "from" to "to".
99 // memmove ensures that any pointer in "from" is written to "to" with
100 // an indivisible write, so that racy reads cannot observe a
101 // half-written pointer. This is necessary to prevent the garbage
102 // collector from observing invalid pointers, and differs from memmove
103 // in unmanaged languages. However, memmove is only required to do
104 // this if "from" and "to" may contain pointers, which can only be the
105 // case if "from", "to", and "n" are all be word-aligned.
107 // Implementations are in memmove_*.s.
110 func memmove(to, from unsafe.Pointer, n uintptr)
112 // Outside assembly calls memmove. Make sure it has ABI wrappers.
113 //go:linkname memmove
115 //go:linkname reflect_memmove reflect.memmove
116 func reflect_memmove(to, from unsafe.Pointer, n uintptr) {
120 // exported value for testing
121 var hashLoad = float32(loadFactorNum) / float32(loadFactorDen)
124 func fastrand() uint32 {
126 // Implement xorshift64+: 2 32-bit xorshift sequences added together.
127 // Shift triplet [17,7,16] was calculated as indicated in Marsaglia's
128 // Xorshift paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf
129 // This generator passes the SmallCrush suite, part of TestU01 framework:
130 // http://simul.iro.umontreal.ca/testu01/tu01.html
131 s1, s0 := mp.fastrand[0], mp.fastrand[1]
133 s1 = s1 ^ s0 ^ s1>>7 ^ s0>>16
134 mp.fastrand[0], mp.fastrand[1] = s0, s1
139 func fastrandn(n uint32) uint32 {
140 // This is similar to fastrand() % n, but faster.
141 // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/
142 return uint32(uint64(fastrand()) * uint64(n) >> 32)
145 //go:linkname sync_fastrand sync.fastrand
146 func sync_fastrand() uint32 { return fastrand() }
148 //go:linkname net_fastrand net.fastrand
149 func net_fastrand() uint32 { return fastrand() }
151 //go:linkname os_fastrand os.fastrand
152 func os_fastrand() uint32 { return fastrand() }
154 // in internal/bytealg/equal_*.s
156 func memequal(a, b unsafe.Pointer, size uintptr) bool
158 // noescape hides a pointer from escape analysis. noescape is
159 // the identity function but escape analysis doesn't think the
160 // output depends on the input. noescape is inlined and currently
161 // compiles down to zero instructions.
164 func noescape(p unsafe.Pointer) unsafe.Pointer {
166 return unsafe.Pointer(x ^ 0)
169 // Not all cgocallback frames are actually cgocallback,
170 // so not all have these arguments. Mark them uintptr so that the GC
171 // does not misinterpret memory when the arguments are not present.
172 // cgocallback is not called from Go, only from crosscall2.
173 // This in turn calls cgocallbackg, which is where we'll find
174 // pointer-declared arguments.
175 func cgocallback(fn, frame, ctxt uintptr)
177 func gogo(buf *gobuf)
180 func jmpdefer(fv func(), argp uintptr)
185 // reflectcall calls fn with arguments described by stackArgs, stackArgsSize,
186 // frameSize, and regArgs.
188 // Arguments passed on the stack and space for return values passed on the stack
189 // must be laid out at the space pointed to by stackArgs (with total length
190 // stackArgsSize) according to the ABI.
192 // stackRetOffset must be some value <= stackArgsSize that indicates the
193 // offset within stackArgs where the return value space begins.
195 // frameSize is the total size of the argument frame at stackArgs and must
196 // therefore be >= stackArgsSize. It must include additional space for spilling
197 // register arguments for stack growth and preemption.
199 // TODO(mknyszek): Once we don't need the additional spill space, remove frameSize,
200 // since frameSize will be redundant with stackArgsSize.
202 // Arguments passed in registers must be laid out in regArgs according to the ABI.
203 // regArgs will hold any return values passed in registers after the call.
205 // reflectcall copies stack arguments from stackArgs to the goroutine stack, and
206 // then copies back stackArgsSize-stackRetOffset bytes back to the return space
207 // in stackArgs once fn has completed. It also "unspills" argument registers from
208 // regArgs before calling fn, and spills them back into regArgs immediately
209 // following the call to fn. If there are results being returned on the stack,
210 // the caller should pass the argument frame type as stackArgsType so that
211 // reflectcall can execute appropriate write barriers during the copy.
213 // reflectcall expects regArgs.ReturnIsPtr to be populated indicating which
214 // registers on the return path will contain Go pointers. It will then store
215 // these pointers in regArgs.Ptrs such that they are visible to the GC.
217 // Package reflect passes a frame type. In package runtime, there is only
218 // one call that copies results back, in callbackWrap in syscall_windows.go, and it
219 // does NOT pass a frame type, meaning there are no write barriers invoked. See that
220 // call site for justification.
222 // Package reflect accesses this symbol through a linkname.
224 // Arguments passed through to reflectcall do not escape. The type is used
225 // only in a very limited callee of reflectcall, the stackArgs are copied, and
226 // regArgs is only used in the reflectcall frame.
228 func reflectcall(stackArgsType *_type, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
230 func procyield(cycles uint32)
232 type neverCallThisFunction struct{}
234 // goexit is the return stub at the top of every goroutine call stack.
235 // Each goroutine stack is constructed as if goexit called the
236 // goroutine's entry point function, so that when the entry point
237 // function returns, it will return to goexit, which will call goexit1
238 // to perform the actual exit.
240 // This function must never be called directly. Call goexit1 instead.
241 // gentraceback assumes that goexit terminates the stack. A direct
242 // call on the stack will cause gentraceback to stop walking the stack
243 // prematurely and if there is leftover state it may panic.
244 func goexit(neverCallThisFunction)
246 // publicationBarrier performs a store/store barrier (a "publication"
247 // or "export" barrier). Some form of synchronization is required
248 // between initializing an object and making that object accessible to
249 // another processor. Without synchronization, the initialization
250 // writes and the "publication" write may be reordered, allowing the
251 // other processor to follow the pointer and observe an uninitialized
252 // object. In general, higher-level synchronization should be used,
253 // such as locking or an atomic pointer write. publicationBarrier is
254 // for when those aren't an option, such as in the implementation of
255 // the memory manager.
257 // There's no corresponding barrier for the read side because the read
258 // side naturally has a data dependency order. All architectures that
259 // Go supports or seems likely to ever support automatically enforce
260 // data dependency ordering.
261 func publicationBarrier()
263 // getcallerpc returns the program counter (PC) of its caller's caller.
264 // getcallersp returns the stack pointer (SP) of its caller's caller.
265 // The implementation may be a compiler intrinsic; there is not
266 // necessarily code implementing this on every platform.
270 // func f(arg1, arg2, arg3 int) {
271 // pc := getcallerpc()
272 // sp := getcallersp()
275 // These two lines find the PC and SP immediately following
276 // the call to f (where f will return).
278 // The call to getcallerpc and getcallersp must be done in the
279 // frame being asked about.
281 // The result of getcallersp is correct at the time of the return,
282 // but it may be invalidated by any subsequent call to a function
283 // that might relocate the stack in order to grow or shrink it.
284 // A general rule is that the result of getcallersp should be used
285 // immediately and can only be passed to nosplit functions.
288 func getcallerpc() uintptr
291 func getcallersp() uintptr // implemented as an intrinsic on all platforms
293 // getclosureptr returns the pointer to the current closure.
294 // getclosureptr can only be used in an assignment statement
295 // at the entry of a function. Moreover, go:nosplit directive
296 // must be specified at the declaration of caller function,
297 // so that the function prolog does not clobber the closure register.
301 // func f(arg1, arg2, arg3 int) {
302 // dx := getclosureptr()
305 // The compiler rewrites calls to this function into instructions that fetch the
306 // pointer from a well-known register (DX on x86 architecture, etc.) directly.
307 func getclosureptr() uintptr
310 func asmcgocall(fn, arg unsafe.Pointer) int32
313 func morestack_noctxt()
316 // return0 is a stub used to return 0 from deferproc.
317 // It is called at the very end of deferproc to signal
318 // the calling Go function that it should not jump
324 // not called directly; definitions here supply type information for traceback.
325 // These must have the same signature (arg pointer map) as reflectcall.
326 func call16(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
327 func call32(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
328 func call64(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
329 func call128(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
330 func call256(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
331 func call512(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
332 func call1024(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
333 func call2048(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
334 func call4096(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
335 func call8192(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
336 func call16384(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
337 func call32768(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
338 func call65536(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
339 func call131072(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
340 func call262144(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
341 func call524288(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
342 func call1048576(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
343 func call2097152(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
344 func call4194304(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
345 func call8388608(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
346 func call16777216(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
347 func call33554432(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
348 func call67108864(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
349 func call134217728(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
350 func call268435456(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
351 func call536870912(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
352 func call1073741824(typ, fn, stackArgs unsafe.Pointer, stackArgsSize, stackRetOffset, frameSize uint32, regArgs *abi.RegArgs)
354 func systemstack_switch()
356 // alignUp rounds n up to a multiple of a. a must be a power of 2.
357 func alignUp(n, a uintptr) uintptr {
358 return (n + a - 1) &^ (a - 1)
361 // alignDown rounds n down to a multiple of a. a must be a power of 2.
362 func alignDown(n, a uintptr) uintptr {
366 // divRoundUp returns ceil(n / a).
367 func divRoundUp(n, a uintptr) uintptr {
368 // a is generally a power of two. This will get inlined and
369 // the compiler will optimize the division.
370 return (n + a - 1) / a
373 // checkASM reports whether assembly runtime checks have passed.
376 func memequal_varlen(a, b unsafe.Pointer) bool
378 // bool2int returns 0 if x is false or 1 if x is true.
379 func bool2int(x bool) int {
380 // Avoid branches. In the SSA compiler, this compiles to
381 // exactly what you would want it to.
382 return int(uint8(*(*uint8)(unsafe.Pointer(&x))))
385 // abort crashes the runtime in situations where even throw might not
386 // work. In general it should do something a debugger will recognize
387 // (e.g., an INT3 on x86). A crash in abort is recognized by the
388 // signal handler, which will attempt to tear down the runtime
392 // Called from compiled code; declared for vet; do NOT call from Go.
393 func gcWriteBarrier()
397 // Called from linker-generated .initarray; declared for go vet; do NOT call from Go.
400 // Injected by the signal handler for panicking signals.
401 // Initializes any registers that have fixed meaning at calls but
402 // are scratch in bodies and calls sigpanic.
403 // On many platforms it just jumps to sigpanic.
406 // intArgRegs is used by the various register assignment
407 // algorithm implementations in the runtime. These include:.
408 // - Finalizers (mfinal.go)
409 // - Windows callbacks (syscall_windows.go)
411 // Both are stripped-down versions of the algorithm since they
412 // only have to deal with a subset of cases (finalizers only
413 // take a pointer or interface argument, Go Windows callbacks
414 // don't support floating point).
416 // It should be modified with care and are generally only
417 // modified when testing this package.
419 // It should never be set higher than its internal/abi
420 // constant counterparts, because the system relies on a
421 // structure that is at least large enough to hold the
422 // registers the system supports.
424 // Currently it's set to zero because using the actual
425 // constant will break every part of the toolchain that
426 // uses finalizers or Windows callbacks to call functions
427 // The value that is currently commented out there should be
428 // the actual value once we're ready to use the register ABI
431 // Protected by finlock.
432 var intArgRegs = abi.IntArgRegs * goexperiment.RegabiArgsInt