reflect, runtime: Use libffi closures to implement reflect.MakeFunc.

Keep using the existing 386 and amd64 code on those archs,
since it is more efficient.

From-SVN: r212853

1 files changed, 88 insertions, 0 deletions

diff --git a/libgo/go/reflect/makefunc_ffi.go b/libgo/go/reflect/makefunc_ffi.go
new file mode 100644
index 0000000..a13ef17
--- /dev/null
+++ b/libgo/go/reflect/makefunc_ffi.go
@@ -0,0 +1,88 @@
+// 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 reflect
+
+import (
+	"runtime"
+	"unsafe"
+)
+
+// The ffi function, written in C, allocates an FFI closure.  It
+// returns the code and data pointers.  When the code pointer is
+// called, it will call callback.  CIF is an FFI data structure
+// allocated as part of the closure, and is returned to ensure that
+// the GC retains it.
+func ffi(ftyp *funcType, callback func(unsafe.Pointer, unsafe.Pointer)) (code uintptr, data uintptr, cif unsafe.Pointer)
+
+// The ffiFree function, written in C, releases the FFI closure.
+func ffiFree(uintptr)
+
+// An ffiData holds the information needed to preserve an FFI closure
+// for the garbage collector.
+type ffiData struct {
+	code     uintptr
+	data     uintptr
+	cif      unsafe.Pointer
+	callback func(unsafe.Pointer, unsafe.Pointer)
+}
+
+// The makeFuncFFI function uses libffi closures to implement
+// reflect.MakeFunc.  This is used for processors for which we don't
+// have more efficient support.
+func makeFuncFFI(ftyp *funcType, fn func(args []Value) (results []Value)) (uintptr, *ffiData) {
+	callback := func(params, results unsafe.Pointer) {
+		ffiCall(ftyp, fn, params, results)
+	}
+
+	code, data, cif := ffi(ftyp, callback)
+
+	c := &ffiData{code: code, data: data, cif: cif, callback: callback}
+
+	runtime.SetFinalizer(c,
+		func(p *ffiData) {
+			ffiFree(p.data)
+		})
+
+	return code, c
+}
+
+// ffiCall takes pointers to the parameters, calls the function, and
+// stores the results back into memory.
+func ffiCall(ftyp *funcType, fn func([]Value) []Value, params unsafe.Pointer, results unsafe.Pointer) {
+	in := make([]Value, 0, len(ftyp.in))
+	ap := params
+	for _, rt := range ftyp.in {
+		p := unsafe_New(rt)
+		memmove(p, *(*unsafe.Pointer)(ap), rt.size)
+		v := Value{rt, p, flag(rt.Kind()<<flagKindShift) | flagIndir}
+		in = append(in, v)
+		ap = (unsafe.Pointer)(uintptr(ap) + ptrSize)
+	}
+
+	out := fn(in)
+
+	off := uintptr(0)
+	for i, typ := range ftyp.out {
+		v := out[i]
+		if v.typ != typ {
+			panic("reflect: function created by MakeFunc using " + funcName(fn) +
+				" returned wrong type: have " +
+				out[i].typ.String() + " for " + typ.String())
+		}
+		if v.flag&flagRO != 0 {
+			panic("reflect: function created by MakeFunc using " + funcName(fn) +
+				" returned value obtained from unexported field")
+		}
+
+		off = align(off, uintptr(typ.fieldAlign))
+		addr := unsafe.Pointer(uintptr(results) + off)
+		if v.flag&flagIndir == 0 && (v.kind() == Ptr || v.kind() == UnsafePointer) {
+			*(*unsafe.Pointer)(addr) = v.ptr
+		} else {
+			memmove(addr, v.ptr, typ.size)
+		}
+		off += typ.size
+	}
+}