dffa732835
Keep using the existing 386 and amd64 code on those archs, since it is more efficient. From-SVN: r212853
89 lines
2.6 KiB
Go
89 lines
2.6 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 reflect
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import (
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"runtime"
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"unsafe"
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)
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// The ffi function, written in C, allocates an FFI closure. It
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// returns the code and data pointers. When the code pointer is
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// called, it will call callback. CIF is an FFI data structure
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// allocated as part of the closure, and is returned to ensure that
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// the GC retains it.
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func ffi(ftyp *funcType, callback func(unsafe.Pointer, unsafe.Pointer)) (code uintptr, data uintptr, cif unsafe.Pointer)
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// The ffiFree function, written in C, releases the FFI closure.
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func ffiFree(uintptr)
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// An ffiData holds the information needed to preserve an FFI closure
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// for the garbage collector.
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type ffiData struct {
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code uintptr
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data uintptr
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cif unsafe.Pointer
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callback func(unsafe.Pointer, unsafe.Pointer)
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}
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// The makeFuncFFI function uses libffi closures to implement
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// reflect.MakeFunc. This is used for processors for which we don't
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// have more efficient support.
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func makeFuncFFI(ftyp *funcType, fn func(args []Value) (results []Value)) (uintptr, *ffiData) {
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callback := func(params, results unsafe.Pointer) {
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ffiCall(ftyp, fn, params, results)
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}
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code, data, cif := ffi(ftyp, callback)
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c := &ffiData{code: code, data: data, cif: cif, callback: callback}
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runtime.SetFinalizer(c,
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func(p *ffiData) {
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ffiFree(p.data)
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})
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return code, c
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}
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// ffiCall takes pointers to the parameters, calls the function, and
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// stores the results back into memory.
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func ffiCall(ftyp *funcType, fn func([]Value) []Value, params unsafe.Pointer, results unsafe.Pointer) {
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in := make([]Value, 0, len(ftyp.in))
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ap := params
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for _, rt := range ftyp.in {
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p := unsafe_New(rt)
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memmove(p, *(*unsafe.Pointer)(ap), rt.size)
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v := Value{rt, p, flag(rt.Kind()<<flagKindShift) | flagIndir}
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in = append(in, v)
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ap = (unsafe.Pointer)(uintptr(ap) + ptrSize)
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}
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out := fn(in)
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off := uintptr(0)
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for i, typ := range ftyp.out {
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v := out[i]
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if v.typ != typ {
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panic("reflect: function created by MakeFunc using " + funcName(fn) +
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" returned wrong type: have " +
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out[i].typ.String() + " for " + typ.String())
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}
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if v.flag&flagRO != 0 {
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panic("reflect: function created by MakeFunc using " + funcName(fn) +
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" returned value obtained from unexported field")
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}
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off = align(off, uintptr(typ.fieldAlign))
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addr := unsafe.Pointer(uintptr(results) + off)
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if v.flag&flagIndir == 0 && (v.kind() == Ptr || v.kind() == UnsafePointer) {
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*(*unsafe.Pointer)(addr) = v.ptr
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} else {
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memmove(addr, v.ptr, typ.size)
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}
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off += typ.size
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}
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}
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