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 // Should be a built-in for unsafe.Pointer?
11 func add(p unsafe.Pointer, x uintptr) unsafe.Pointer {
12 return unsafe.Pointer(uintptr(p) + x)
15 // getg returns the pointer to the current g.
16 // The compiler rewrites calls to this function into instructions
17 // that fetch the g directly (from TLS or from the dedicated register).
20 // mcall switches from the g to the g0 stack and invokes fn(g),
21 // where g is the goroutine that made the call.
22 // mcall saves g's current PC/SP in g->sched so that it can be restored later.
23 // It is up to fn to arrange for that later execution, typically by recording
24 // g in a data structure, causing something to call ready(g) later.
25 // mcall returns to the original goroutine g later, when g has been rescheduled.
26 // fn must not return at all; typically it ends by calling schedule, to let the m
27 // run other goroutines.
29 // mcall can only be called from g stacks (not g0, not gsignal).
31 // This must NOT be go:noescape: if fn is a stack-allocated closure,
32 // fn puts g on a run queue, and g executes before fn returns, the
33 // closure will be invalidated while it is still executing.
34 func mcall(fn func(*g))
36 // systemstack runs fn on a system stack.
37 // If systemstack is called from the per-OS-thread (g0) stack, or
38 // if systemstack is called from the signal handling (gsignal) stack,
39 // systemstack calls fn directly and returns.
40 // Otherwise, systemstack is being called from the limited stack
41 // of an ordinary goroutine. In this case, systemstack switches
42 // to the per-OS-thread stack, calls fn, and switches back.
43 // It is common to use a func literal as the argument, in order
44 // to share inputs and outputs with the code around the call
48 // systemstack(func() {
54 func systemstack(fn func())
56 var badsystemstackMsg = "fatal: systemstack called from unexpected goroutine"
59 //go:nowritebarrierrec
60 func badsystemstack() {
61 sp := stringStructOf(&badsystemstackMsg)
62 write(2, sp.str, int32(sp.len))
65 // memclrNoHeapPointers clears n bytes starting at ptr.
67 // Usually you should use typedmemclr. memclrNoHeapPointers should be
68 // used only when the caller knows that *ptr contains no heap pointers
71 // *ptr is initialized memory and its type is pointer-free, or
73 // *ptr is uninitialized memory (e.g., memory that's being reused
74 // for a new allocation) and hence contains only "junk".
76 // memclrNoHeapPointers ensures that if ptr is pointer-aligned, and n
77 // is a multiple of the pointer size, then any pointer-aligned,
78 // pointer-sized portion is cleared atomically. Despite the function
79 // name, this is necessary because this function is the underlying
80 // implementation of typedmemclr and memclrHasPointers. See the doc of
81 // memmove for more details.
83 // The (CPU-specific) implementations of this function are in memclr_*.s.
86 func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
88 //go:linkname reflect_memclrNoHeapPointers reflect.memclrNoHeapPointers
89 func reflect_memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr) {
90 memclrNoHeapPointers(ptr, n)
93 // memmove copies n bytes from "from" to "to".
95 // memmove ensures that any pointer in "from" is written to "to" with
96 // an indivisible write, so that racy reads cannot observe a
97 // half-written pointer. This is necessary to prevent the garbage
98 // collector from observing invalid pointers, and differs from memmove
99 // in unmanaged languages. However, memmove is only required to do
100 // this if "from" and "to" may contain pointers, which can only be the
101 // case if "from", "to", and "n" are all be word-aligned.
103 // Implementations are in memmove_*.s.
106 func memmove(to, from unsafe.Pointer, n uintptr)
108 //go:linkname reflect_memmove reflect.memmove
109 func reflect_memmove(to, from unsafe.Pointer, n uintptr) {
113 // exported value for testing
114 var hashLoad = float32(loadFactorNum) / float32(loadFactorDen)
117 func fastrand() uint32 {
119 // Implement xorshift64+: 2 32-bit xorshift sequences added together.
120 // Shift triplet [17,7,16] was calculated as indicated in Marsaglia's
121 // Xorshift paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf
122 // This generator passes the SmallCrush suite, part of TestU01 framework:
123 // http://simul.iro.umontreal.ca/testu01/tu01.html
124 s1, s0 := mp.fastrand[0], mp.fastrand[1]
126 s1 = s1 ^ s0 ^ s1>>7 ^ s0>>16
127 mp.fastrand[0], mp.fastrand[1] = s0, s1
132 func fastrandn(n uint32) uint32 {
133 // This is similar to fastrand() % n, but faster.
134 // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/
135 return uint32(uint64(fastrand()) * uint64(n) >> 32)
138 //go:linkname sync_fastrand sync.fastrand
139 func sync_fastrand() uint32 { return fastrand() }
141 //go:linkname net_fastrand net.fastrand
142 func net_fastrand() uint32 { return fastrand() }
144 //go:linkname os_fastrand os.fastrand
145 func os_fastrand() uint32 { return fastrand() }
147 // in internal/bytealg/equal_*.s
149 func memequal(a, b unsafe.Pointer, size uintptr) bool
151 // noescape hides a pointer from escape analysis. noescape is
152 // the identity function but escape analysis doesn't think the
153 // output depends on the input. noescape is inlined and currently
154 // compiles down to zero instructions.
157 func noescape(p unsafe.Pointer) unsafe.Pointer {
159 return unsafe.Pointer(x ^ 0)
162 // Not all cgocallback frames are actually cgocallback,
163 // so not all have these arguments. Mark them uintptr so that the GC
164 // does not misinterpret memory when the arguments are not present.
165 // cgocallback is not called from Go, only from crosscall2.
166 // This in turn calls cgocallbackg, which is where we'll find
167 // pointer-declared arguments.
168 func cgocallback(fn, frame, ctxt uintptr)
169 func gogo(buf *gobuf)
170 func gosave(buf *gobuf)
173 func jmpdefer(fv *funcval, argp uintptr)
178 // reflectcall calls fn with a copy of the n argument bytes pointed at by arg.
179 // After fn returns, reflectcall copies n-retoffset result bytes
180 // back into arg+retoffset before returning. If copying result bytes back,
181 // the caller should pass the argument frame type as argtype, so that
182 // call can execute appropriate write barriers during the copy.
184 // Package reflect always passes a frame type. In package runtime,
185 // Windows callbacks are the only use of this that copies results
186 // back, and those cannot have pointers in their results, so runtime
187 // passes nil for the frame type.
189 // Package reflect accesses this symbol through a linkname.
190 func reflectcall(argtype *_type, fn, arg unsafe.Pointer, argsize uint32, retoffset uint32)
192 func procyield(cycles uint32)
194 type neverCallThisFunction struct{}
196 // goexit is the return stub at the top of every goroutine call stack.
197 // Each goroutine stack is constructed as if goexit called the
198 // goroutine's entry point function, so that when the entry point
199 // function returns, it will return to goexit, which will call goexit1
200 // to perform the actual exit.
202 // This function must never be called directly. Call goexit1 instead.
203 // gentraceback assumes that goexit terminates the stack. A direct
204 // call on the stack will cause gentraceback to stop walking the stack
205 // prematurely and if there is leftover state it may panic.
206 func goexit(neverCallThisFunction)
208 // publicationBarrier performs a store/store barrier (a "publication"
209 // or "export" barrier). Some form of synchronization is required
210 // between initializing an object and making that object accessible to
211 // another processor. Without synchronization, the initialization
212 // writes and the "publication" write may be reordered, allowing the
213 // other processor to follow the pointer and observe an uninitialized
214 // object. In general, higher-level synchronization should be used,
215 // such as locking or an atomic pointer write. publicationBarrier is
216 // for when those aren't an option, such as in the implementation of
217 // the memory manager.
219 // There's no corresponding barrier for the read side because the read
220 // side naturally has a data dependency order. All architectures that
221 // Go supports or seems likely to ever support automatically enforce
222 // data dependency ordering.
223 func publicationBarrier()
225 // getcallerpc returns the program counter (PC) of its caller's caller.
226 // getcallersp returns the stack pointer (SP) of its caller's caller.
227 // The implementation may be a compiler intrinsic; there is not
228 // necessarily code implementing this on every platform.
232 // func f(arg1, arg2, arg3 int) {
233 // pc := getcallerpc()
234 // sp := getcallersp()
237 // These two lines find the PC and SP immediately following
238 // the call to f (where f will return).
240 // The call to getcallerpc and getcallersp must be done in the
241 // frame being asked about.
243 // The result of getcallersp is correct at the time of the return,
244 // but it may be invalidated by any subsequent call to a function
245 // that might relocate the stack in order to grow or shrink it.
246 // A general rule is that the result of getcallersp should be used
247 // immediately and can only be passed to nosplit functions.
250 func getcallerpc() uintptr
253 func getcallersp() uintptr // implemented as an intrinsic on all platforms
255 // getclosureptr returns the pointer to the current closure.
256 // getclosureptr can only be used in an assignment statement
257 // at the entry of a function. Moreover, go:nosplit directive
258 // must be specified at the declaration of caller function,
259 // so that the function prolog does not clobber the closure register.
263 // func f(arg1, arg2, arg3 int) {
264 // dx := getclosureptr()
267 // The compiler rewrites calls to this function into instructions that fetch the
268 // pointer from a well-known register (DX on x86 architecture, etc.) directly.
269 func getclosureptr() uintptr
272 func asmcgocall(fn, arg unsafe.Pointer) int32
275 func morestack_noctxt()
278 // return0 is a stub used to return 0 from deferproc.
279 // It is called at the very end of deferproc to signal
280 // the calling Go function that it should not jump
286 // not called directly; definitions here supply type information for traceback.
287 func call16(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
288 func call32(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
289 func call64(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
290 func call128(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
291 func call256(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
292 func call512(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
293 func call1024(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
294 func call2048(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
295 func call4096(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
296 func call8192(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
297 func call16384(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
298 func call32768(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
299 func call65536(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
300 func call131072(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
301 func call262144(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
302 func call524288(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
303 func call1048576(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
304 func call2097152(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
305 func call4194304(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
306 func call8388608(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
307 func call16777216(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
308 func call33554432(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
309 func call67108864(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
310 func call134217728(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
311 func call268435456(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
312 func call536870912(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
313 func call1073741824(typ, fn, arg unsafe.Pointer, n, retoffset uint32)
315 func systemstack_switch()
317 // alignUp rounds n up to a multiple of a. a must be a power of 2.
318 func alignUp(n, a uintptr) uintptr {
319 return (n + a - 1) &^ (a - 1)
322 // alignDown rounds n down to a multiple of a. a must be a power of 2.
323 func alignDown(n, a uintptr) uintptr {
327 // divRoundUp returns ceil(n / a).
328 func divRoundUp(n, a uintptr) uintptr {
329 // a is generally a power of two. This will get inlined and
330 // the compiler will optimize the division.
331 return (n + a - 1) / a
334 // checkASM reports whether assembly runtime checks have passed.
337 func memequal_varlen(a, b unsafe.Pointer) bool
339 // bool2int returns 0 if x is false or 1 if x is true.
340 func bool2int(x bool) int {
341 // Avoid branches. In the SSA compiler, this compiles to
342 // exactly what you would want it to.
343 return int(uint8(*(*uint8)(unsafe.Pointer(&x))))
346 // abort crashes the runtime in situations where even throw might not
347 // work. In general it should do something a debugger will recognize
348 // (e.g., an INT3 on x86). A crash in abort is recognized by the
349 // signal handler, which will attempt to tear down the runtime
353 // Called from compiled code; declared for vet; do NOT call from Go.
354 func gcWriteBarrier()
358 // Called from linker-generated .initarray; declared for go vet; do NOT call from Go.