mirror of
https://github.com/golang/go
synced 2024-10-02 20:41:21 -06:00
bd70bd9cb2
They do the same thing, except memequal also has the short-circuit check if the two pointers are equal. A) We might as well always do the short-circuit check, it is only 2 instructions. B) The extra function call (memequal->memeq) is expensive. benchmark old ns/op new ns/op delta BenchmarkArrayEqual-8 8.56 5.31 -37.97% No noticeable affect on the former memeq user (maps). Fixes #14302 Change-Id: I85d1ada59ed11e64dd6c54667f79d32cc5f81948 Reviewed-on: https://go-review.googlesource.com/19843 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
276 lines
10 KiB
Go
276 lines
10 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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// Should be a built-in for unsafe.Pointer?
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//go:nosplit
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func add(p unsafe.Pointer, x uintptr) unsafe.Pointer {
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return unsafe.Pointer(uintptr(p) + x)
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}
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// getg returns the pointer to the current g.
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// The compiler rewrites calls to this function into instructions
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// that fetch the g directly (from TLS or from the dedicated register).
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func getg() *g
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// mcall switches from the g to the g0 stack and invokes fn(g),
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// where g is the goroutine that made the call.
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// mcall saves g's current PC/SP in g->sched so that it can be restored later.
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// It is up to fn to arrange for that later execution, typically by recording
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// g in a data structure, causing something to call ready(g) later.
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// mcall returns to the original goroutine g later, when g has been rescheduled.
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// fn must not return at all; typically it ends by calling schedule, to let the m
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// run other goroutines.
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//
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// mcall can only be called from g stacks (not g0, not gsignal).
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//
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// This must NOT be go:noescape: if fn is a stack-allocated closure,
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// fn puts g on a run queue, and g executes before fn returns, the
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// closure will be invalidated while it is still executing.
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func mcall(fn func(*g))
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// systemstack runs fn on a system stack.
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// If systemstack is called from the per-OS-thread (g0) stack, or
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// if systemstack is called from the signal handling (gsignal) stack,
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// systemstack calls fn directly and returns.
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// Otherwise, systemstack is being called from the limited stack
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// of an ordinary goroutine. In this case, systemstack switches
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// to the per-OS-thread stack, calls fn, and switches back.
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// It is common to use a func literal as the argument, in order
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// to share inputs and outputs with the code around the call
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// to system stack:
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//
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// ... set up y ...
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// systemstack(func() {
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// x = bigcall(y)
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// })
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// ... use x ...
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//
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//go:noescape
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func systemstack(fn func())
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func badsystemstack() {
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throw("systemstack called from unexpected goroutine")
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}
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// memclr clears n bytes starting at ptr.
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// in memclr_*.s
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//go:noescape
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func memclr(ptr unsafe.Pointer, n uintptr)
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//go:linkname reflect_memclr reflect.memclr
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func reflect_memclr(ptr unsafe.Pointer, n uintptr) {
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memclr(ptr, n)
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}
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// memmove copies n bytes from "from" to "to".
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// in memmove_*.s
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//go:noescape
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func memmove(to, from unsafe.Pointer, n uintptr)
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//go:linkname reflect_memmove reflect.memmove
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func reflect_memmove(to, from unsafe.Pointer, n uintptr) {
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memmove(to, from, n)
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}
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// exported value for testing
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var hashLoad = loadFactor
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// in asm_*.s
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func fastrand1() uint32
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// in asm_*.s
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//go:noescape
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func memequal(a, b unsafe.Pointer, size uintptr) bool
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// noescape hides a pointer from escape analysis. noescape is
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// the identity function but escape analysis doesn't think the
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// output depends on the input. noescape is inlined and currently
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// compiles down to a single xor instruction.
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// USE CAREFULLY!
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//go:nosplit
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func noescape(p unsafe.Pointer) unsafe.Pointer {
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x := uintptr(p)
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return unsafe.Pointer(x ^ 0)
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}
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func cgocallback(fn, frame unsafe.Pointer, framesize uintptr)
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func gogo(buf *gobuf)
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func gosave(buf *gobuf)
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func mincore(addr unsafe.Pointer, n uintptr, dst *byte) int32
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//go:noescape
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func jmpdefer(fv *funcval, argp uintptr)
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func exit1(code int32)
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func asminit()
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func setg(gg *g)
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func breakpoint()
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// reflectcall calls fn with a copy of the n argument bytes pointed at by arg.
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// After fn returns, reflectcall copies n-retoffset result bytes
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// back into arg+retoffset before returning. If copying result bytes back,
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// the caller should pass the argument frame type as argtype, so that
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// call can execute appropriate write barriers during the copy.
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// Package reflect passes a frame type. In package runtime, there is only
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// one call that copies results back, in cgocallbackg1, and it does NOT pass a
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// frame type, meaning there are no write barriers invoked. See that call
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// site for justification.
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func reflectcall(argtype *_type, fn, arg unsafe.Pointer, argsize uint32, retoffset uint32)
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func procyield(cycles uint32)
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type neverCallThisFunction struct{}
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// goexit is the return stub at the top of every goroutine call stack.
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// Each goroutine stack is constructed as if goexit called the
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// goroutine's entry point function, so that when the entry point
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// function returns, it will return to goexit, which will call goexit1
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// to perform the actual exit.
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//
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// This function must never be called directly. Call goexit1 instead.
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// gentraceback assumes that goexit terminates the stack. A direct
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// call on the stack will cause gentraceback to stop walking the stack
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// prematurely and if there are leftover stack barriers it may panic.
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func goexit(neverCallThisFunction)
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// Not all cgocallback_gofunc frames are actually cgocallback_gofunc,
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// so not all have these arguments. Mark them uintptr so that the GC
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// does not misinterpret memory when the arguments are not present.
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// cgocallback_gofunc is not called from go, only from cgocallback,
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// so the arguments will be found via cgocallback's pointer-declared arguments.
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// See the assembly implementations for more details.
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func cgocallback_gofunc(fv uintptr, frame uintptr, framesize uintptr)
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// publicationBarrier performs a store/store barrier (a "publication"
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// or "export" barrier). Some form of synchronization is required
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// between initializing an object and making that object accessible to
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// another processor. Without synchronization, the initialization
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// writes and the "publication" write may be reordered, allowing the
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// other processor to follow the pointer and observe an uninitialized
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// object. In general, higher-level synchronization should be used,
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// such as locking or an atomic pointer write. publicationBarrier is
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// for when those aren't an option, such as in the implementation of
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// the memory manager.
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//
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// There's no corresponding barrier for the read side because the read
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// side naturally has a data dependency order. All architectures that
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// Go supports or seems likely to ever support automatically enforce
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// data dependency ordering.
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func publicationBarrier()
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//go:noescape
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func setcallerpc(argp unsafe.Pointer, pc uintptr)
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// getcallerpc returns the program counter (PC) of its caller's caller.
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// getcallersp returns the stack pointer (SP) of its caller's caller.
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// For both, the argp must be a pointer to the caller's first function argument.
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// The implementation may or may not use argp, depending on
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// the architecture.
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//
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// For example:
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//
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// func f(arg1, arg2, arg3 int) {
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// pc := getcallerpc(unsafe.Pointer(&arg1))
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// sp := getcallersp(unsafe.Pointer(&arg1))
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// }
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//
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// These two lines find the PC and SP immediately following
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// the call to f (where f will return).
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//
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// The call to getcallerpc and getcallersp must be done in the
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// frame being asked about. It would not be correct for f to pass &arg1
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// to another function g and let g call getcallerpc/getcallersp.
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// The call inside g might return information about g's caller or
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// information about f's caller or complete garbage.
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//
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// The result of getcallersp is correct at the time of the return,
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// but it may be invalidated by any subsequent call to a function
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// that might relocate the stack in order to grow or shrink it.
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// A general rule is that the result of getcallersp should be used
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// immediately and can only be passed to nosplit functions.
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//go:noescape
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func getcallerpc(argp unsafe.Pointer) uintptr
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//go:noescape
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func getcallersp(argp unsafe.Pointer) uintptr
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//go:noescape
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func asmcgocall(fn, arg unsafe.Pointer) int32
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// argp used in Defer structs when there is no argp.
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const _NoArgs = ^uintptr(0)
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func morestack()
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func rt0_go()
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// stackBarrier records that the stack has been unwound past a certain
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// point. It is installed over a return PC on the stack. It must
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// retrieve the original return PC from g.stkbuf, increment
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// g.stkbufPos to record that the barrier was hit, and jump to the
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// original return PC.
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func stackBarrier()
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// return0 is a stub used to return 0 from deferproc.
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// It is called at the very end of deferproc to signal
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// the calling Go function that it should not jump
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// to deferreturn.
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// in asm_*.s
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func return0()
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//go:linkname time_now time.now
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func time_now() (sec int64, nsec int32)
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// in asm_*.s
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// not called directly; definitions here supply type information for traceback.
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func call32(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call64(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call128(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call256(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call512(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call1024(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call2048(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call4096(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call8192(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call16384(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call32768(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call65536(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call131072(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call262144(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call524288(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call1048576(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call2097152(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call4194304(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call8388608(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call16777216(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call33554432(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call67108864(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call134217728(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call268435456(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call536870912(fn, arg unsafe.Pointer, n, retoffset uint32)
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func call1073741824(fn, arg unsafe.Pointer, n, retoffset uint32)
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func systemstack_switch()
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func prefetcht0(addr uintptr)
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func prefetcht1(addr uintptr)
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func prefetcht2(addr uintptr)
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func prefetchnta(addr uintptr)
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func unixnanotime() int64 {
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sec, nsec := time_now()
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return sec*1e9 + int64(nsec)
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}
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// round n up to a multiple of a. a must be a power of 2.
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func round(n, a uintptr) uintptr {
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return (n + a - 1) &^ (a - 1)
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}
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// checkASM returns whether assembly runtime checks have passed.
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func checkASM() bool
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