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Diffstat (limited to '')
| -rw-r--r-- | src/runtime/stubs.go | 359 |
1 files changed, 359 insertions, 0 deletions
diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go new file mode 100644 index 0000000..2ee2c74 --- /dev/null +++ b/src/runtime/stubs.go @@ -0,0 +1,359 @@ +// 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 "unsafe" + +// Should be a built-in for unsafe.Pointer? +//go:nosplit +func add(p unsafe.Pointer, x uintptr) unsafe.Pointer { + return unsafe.Pointer(uintptr(p) + x) +} + +// getg returns the pointer to the current g. +// The compiler rewrites calls to this function into instructions +// that fetch the g directly (from TLS or from the dedicated register). +func getg() *g + +// mcall switches from the g to the g0 stack and invokes fn(g), +// where g is the goroutine that made the call. +// mcall saves g's current PC/SP in g->sched so that it can be restored later. +// It is up to fn to arrange for that later execution, typically by recording +// g in a data structure, causing something to call ready(g) later. +// mcall returns to the original goroutine g later, when g has been rescheduled. +// fn must not return at all; typically it ends by calling schedule, to let the m +// run other goroutines. +// +// mcall can only be called from g stacks (not g0, not gsignal). +// +// This must NOT be go:noescape: if fn is a stack-allocated closure, +// fn puts g on a run queue, and g executes before fn returns, the +// closure will be invalidated while it is still executing. +func mcall(fn func(*g)) + +// systemstack runs fn on a system stack. +// If systemstack is called from the per-OS-thread (g0) stack, or +// if systemstack is called from the signal handling (gsignal) stack, +// systemstack calls fn directly and returns. +// Otherwise, systemstack is being called from the limited stack +// of an ordinary goroutine. In this case, systemstack switches +// to the per-OS-thread stack, calls fn, and switches back. +// It is common to use a func literal as the argument, in order +// to share inputs and outputs with the code around the call +// to system stack: +// +// ... set up y ... +// systemstack(func() { +// x = bigcall(y) +// }) +// ... use x ... +// +//go:noescape +func systemstack(fn func()) + +var badsystemstackMsg = "fatal: systemstack called from unexpected goroutine" + +//go:nosplit +//go:nowritebarrierrec +func badsystemstack() { + sp := stringStructOf(&badsystemstackMsg) + write(2, sp.str, int32(sp.len)) +} + +// memclrNoHeapPointers clears n bytes starting at ptr. +// +// Usually you should use typedmemclr. memclrNoHeapPointers should be +// used only when the caller knows that *ptr contains no heap pointers +// because either: +// +// *ptr is initialized memory and its type is pointer-free, or +// +// *ptr is uninitialized memory (e.g., memory that's being reused +// for a new allocation) and hence contains only "junk". +// +// memclrNoHeapPointers ensures that if ptr is pointer-aligned, and n +// is a multiple of the pointer size, then any pointer-aligned, +// pointer-sized portion is cleared atomically. Despite the function +// name, this is necessary because this function is the underlying +// implementation of typedmemclr and memclrHasPointers. See the doc of +// memmove for more details. +// +// The (CPU-specific) implementations of this function are in memclr_*.s. +// +//go:noescape +func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr) + +//go:linkname reflect_memclrNoHeapPointers reflect.memclrNoHeapPointers +func reflect_memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr) { + memclrNoHeapPointers(ptr, n) +} + +// memmove copies n bytes from "from" to "to". +// +// memmove ensures that any pointer in "from" is written to "to" with +// an indivisible write, so that racy reads cannot observe a +// half-written pointer. This is necessary to prevent the garbage +// collector from observing invalid pointers, and differs from memmove +// in unmanaged languages. However, memmove is only required to do +// this if "from" and "to" may contain pointers, which can only be the +// case if "from", "to", and "n" are all be word-aligned. +// +// Implementations are in memmove_*.s. +// +//go:noescape +func memmove(to, from unsafe.Pointer, n uintptr) + +//go:linkname reflect_memmove reflect.memmove +func reflect_memmove(to, from unsafe.Pointer, n uintptr) { + memmove(to, from, n) +} + +// exported value for testing +var hashLoad = float32(loadFactorNum) / float32(loadFactorDen) + +//go:nosplit +func fastrand() uint32 { + mp := getg().m + // Implement xorshift64+: 2 32-bit xorshift sequences added together. + // Shift triplet [17,7,16] was calculated as indicated in Marsaglia's + // Xorshift paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf + // This generator passes the SmallCrush suite, part of TestU01 framework: + // http://simul.iro.umontreal.ca/testu01/tu01.html + s1, s0 := mp.fastrand[0], mp.fastrand[1] + s1 ^= s1 << 17 + s1 = s1 ^ s0 ^ s1>>7 ^ s0>>16 + mp.fastrand[0], mp.fastrand[1] = s0, s1 + return s0 + s1 +} + +//go:nosplit +func fastrandn(n uint32) uint32 { + // This is similar to fastrand() % n, but faster. + // See https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/ + return uint32(uint64(fastrand()) * uint64(n) >> 32) +} + +//go:linkname sync_fastrand sync.fastrand +func sync_fastrand() uint32 { return fastrand() } + +//go:linkname net_fastrand net.fastrand +func net_fastrand() uint32 { return fastrand() } + +//go:linkname os_fastrand os.fastrand +func os_fastrand() uint32 { return fastrand() } + +// in internal/bytealg/equal_*.s +//go:noescape +func memequal(a, b unsafe.Pointer, size uintptr) bool + +// noescape hides a pointer from escape analysis. noescape is +// the identity function but escape analysis doesn't think the +// output depends on the input. noescape is inlined and currently +// compiles down to zero instructions. +// USE CAREFULLY! +//go:nosplit +func noescape(p unsafe.Pointer) unsafe.Pointer { + x := uintptr(p) + return unsafe.Pointer(x ^ 0) +} + +// Not all cgocallback frames are actually cgocallback, +// so not all have these arguments. Mark them uintptr so that the GC +// does not misinterpret memory when the arguments are not present. +// cgocallback is not called from Go, only from crosscall2. +// This in turn calls cgocallbackg, which is where we'll find +// pointer-declared arguments. +func cgocallback(fn, frame, ctxt uintptr) +func gogo(buf *gobuf) +func gosave(buf *gobuf) + +//go:noescape +func jmpdefer(fv *funcval, argp uintptr) +func asminit() +func setg(gg *g) +func breakpoint() + +// reflectcall calls fn with a copy of the n argument bytes pointed at by arg. +// After fn returns, reflectcall copies n-retoffset result bytes +// back into arg+retoffset before returning. If copying result bytes back, +// the caller should pass the argument frame type as argtype, so that +// call can execute appropriate write barriers during the copy. +// +// Package reflect always passes a frame type. In package runtime, +// Windows callbacks are the only use of this that copies results +// back, and those cannot have pointers in their results, so runtime +// passes nil for the frame type. +// +// Package reflect accesses this symbol through a linkname. +func reflectcall(argtype *_type, fn, arg unsafe.Pointer, argsize uint32, retoffset uint32) + +func procyield(cycles uint32) + +type neverCallThisFunction struct{} + +// goexit is the return stub at the top of every goroutine call stack. +// Each goroutine stack is constructed as if goexit called the +// goroutine's entry point function, so that when the entry point +// function returns, it will return to goexit, which will call goexit1 +// to perform the actual exit. +// +// This function must never be called directly. Call goexit1 instead. +// gentraceback assumes that goexit terminates the stack. A direct +// call on the stack will cause gentraceback to stop walking the stack +// prematurely and if there is leftover state it may panic. +func goexit(neverCallThisFunction) + +// publicationBarrier performs a store/store barrier (a "publication" +// or "export" barrier). Some form of synchronization is required +// between initializing an object and making that object accessible to +// another processor. Without synchronization, the initialization +// writes and the "publication" write may be reordered, allowing the +// other processor to follow the pointer and observe an uninitialized +// object. In general, higher-level synchronization should be used, +// such as locking or an atomic pointer write. publicationBarrier is +// for when those aren't an option, such as in the implementation of +// the memory manager. +// +// There's no corresponding barrier for the read side because the read +// side naturally has a data dependency order. All architectures that +// Go supports or seems likely to ever support automatically enforce +// data dependency ordering. +func publicationBarrier() + +// getcallerpc returns the program counter (PC) of its caller's caller. +// getcallersp returns the stack pointer (SP) of its caller's caller. +// The implementation may be a compiler intrinsic; there is not +// necessarily code implementing this on every platform. +// +// For example: +// +// func f(arg1, arg2, arg3 int) { +// pc := getcallerpc() +// sp := getcallersp() +// } +// +// These two lines find the PC and SP immediately following +// the call to f (where f will return). +// +// The call to getcallerpc and getcallersp must be done in the +// frame being asked about. +// +// The result of getcallersp is correct at the time of the return, +// but it may be invalidated by any subsequent call to a function +// that might relocate the stack in order to grow or shrink it. +// A general rule is that the result of getcallersp should be used +// immediately and can only be passed to nosplit functions. + +//go:noescape +func getcallerpc() uintptr + +//go:noescape +func getcallersp() uintptr // implemented as an intrinsic on all platforms + +// getclosureptr returns the pointer to the current closure. +// getclosureptr can only be used in an assignment statement +// at the entry of a function. Moreover, go:nosplit directive +// must be specified at the declaration of caller function, +// so that the function prolog does not clobber the closure register. +// for example: +// +// //go:nosplit +// func f(arg1, arg2, arg3 int) { +// dx := getclosureptr() +// } +// +// The compiler rewrites calls to this function into instructions that fetch the +// pointer from a well-known register (DX on x86 architecture, etc.) directly. +func getclosureptr() uintptr + +//go:noescape +func asmcgocall(fn, arg unsafe.Pointer) int32 + +func morestack() +func morestack_noctxt() +func rt0_go() + +// return0 is a stub used to return 0 from deferproc. +// It is called at the very end of deferproc to signal +// the calling Go function that it should not jump +// to deferreturn. +// in asm_*.s +func return0() + +// in asm_*.s +// not called directly; definitions here supply type information for traceback. +func call16(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call32(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call64(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call128(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call256(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call512(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call1024(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call2048(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call4096(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call8192(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call16384(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call32768(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call65536(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call131072(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call262144(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call524288(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call1048576(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call2097152(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call4194304(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call8388608(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call16777216(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call33554432(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call67108864(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call134217728(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call268435456(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call536870912(typ, fn, arg unsafe.Pointer, n, retoffset uint32) +func call1073741824(typ, fn, arg unsafe.Pointer, n, retoffset uint32) + +func systemstack_switch() + +// alignUp rounds n up to a multiple of a. a must be a power of 2. +func alignUp(n, a uintptr) uintptr { + return (n + a - 1) &^ (a - 1) +} + +// alignDown rounds n down to a multiple of a. a must be a power of 2. +func alignDown(n, a uintptr) uintptr { + return n &^ (a - 1) +} + +// divRoundUp returns ceil(n / a). +func divRoundUp(n, a uintptr) uintptr { + // a is generally a power of two. This will get inlined and + // the compiler will optimize the division. + return (n + a - 1) / a +} + +// checkASM reports whether assembly runtime checks have passed. +func checkASM() bool + +func memequal_varlen(a, b unsafe.Pointer) bool + +// bool2int returns 0 if x is false or 1 if x is true. +func bool2int(x bool) int { + // Avoid branches. In the SSA compiler, this compiles to + // exactly what you would want it to. + return int(uint8(*(*uint8)(unsafe.Pointer(&x)))) +} + +// abort crashes the runtime in situations where even throw might not +// work. In general it should do something a debugger will recognize +// (e.g., an INT3 on x86). A crash in abort is recognized by the +// signal handler, which will attempt to tear down the runtime +// immediately. +func abort() + +// Called from compiled code; declared for vet; do NOT call from Go. +func gcWriteBarrier() +func duffzero() +func duffcopy() + +// Called from linker-generated .initarray; declared for go vet; do NOT call from Go. +func addmoduledata() |