From dffa7328356257772dc7c00fe73aeb315229b373 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Sat, 19 Jul 2014 21:36:26 +0000
Subject: 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
---
 libgo/go/reflect/all_test.go      |  24 -------
 libgo/go/reflect/makefunc.go      |  95 +++++++++++++++++----------
 libgo/go/reflect/makefunc_dummy.c |  11 ++--
 libgo/go/reflect/makefunc_ffi.go  |  88 +++++++++++++++++++++++++
 libgo/go/reflect/makefunc_ffi_c.c | 135 ++++++++++++++++++++++++++++++++++++++
 5 files changed, 290 insertions(+), 63 deletions(-)
 create mode 100644 libgo/go/reflect/makefunc_ffi.go
 create mode 100644 libgo/go/reflect/makefunc_ffi_c.c

(limited to 'libgo/go')

diff --git a/libgo/go/reflect/all_test.go b/libgo/go/reflect/all_test.go
index 799bbea..f888d64 100644
--- a/libgo/go/reflect/all_test.go
+++ b/libgo/go/reflect/all_test.go
@@ -1502,12 +1502,6 @@ func TestCallWithStruct(t *testing.T) {
 }
 
 func TestMakeFunc(t *testing.T) {
-	switch runtime.GOARCH {
-	case "amd64", "386":
-	default:
-		t.Skip("MakeFunc not implemented for " + runtime.GOARCH)
-	}
-
 	f := dummy
 	fv := MakeFunc(TypeOf(f), func(in []Value) []Value { return in })
 	ValueOf(&f).Elem().Set(fv)
@@ -1526,12 +1520,6 @@ func TestMakeFunc(t *testing.T) {
 }
 
 func TestMakeFuncInterface(t *testing.T) {
-	switch runtime.GOARCH {
-	case "amd64", "386":
-	default:
-		t.Skip("MakeFunc not implemented for " + runtime.GOARCH)
-	}
-
 	fn := func(i int) int { return i }
 	incr := func(in []Value) []Value {
 		return []Value{ValueOf(int(in[0].Int() + 1))}
@@ -1676,12 +1664,6 @@ func TestMethod(t *testing.T) {
 }
 
 func TestMethodValue(t *testing.T) {
-	switch runtime.GOARCH {
-	case "amd64", "386":
-	default:
-		t.Skip("reflect method values not implemented for " + runtime.GOARCH)
-	}
-
 	p := Point{3, 4}
 	var i int64
 
@@ -1853,12 +1835,6 @@ type Tm4 struct {
 func (t4 Tm4) M(x int, b byte) (byte, int) { return b, x + 40 }
 
 func TestMethod5(t *testing.T) {
-	switch runtime.GOARCH {
-	case "amd64", "386":
-	default:
-		t.Skip("reflect method values not implemented for " + runtime.GOARCH)
-	}
-
 	CheckF := func(name string, f func(int, byte) (byte, int), inc int) {
 		b, x := f(1000, 99)
 		if b != 99 || x != 1000+inc {
diff --git a/libgo/go/reflect/makefunc.go b/libgo/go/reflect/makefunc.go
index a46e1d8..736ac36 100644
--- a/libgo/go/reflect/makefunc.go
+++ b/libgo/go/reflect/makefunc.go
@@ -22,6 +22,10 @@ type makeFuncImpl struct {
 	// method values.
 	method int
 	rcvr   Value
+
+	// When using FFI, hold onto the FFI closure for the garbage
+	// collector.
+	ffi *ffiData
 }
 
 // MakeFunc returns a new function of the given Type
@@ -51,22 +55,29 @@ func MakeFunc(typ Type, fn func(args []Value) (results []Value)) Value {
 		panic("reflect: call of MakeFunc with non-Func type")
 	}
 
+	t := typ.common()
+	ftyp := (*funcType)(unsafe.Pointer(t))
+
+	var code uintptr
+	var ffi *ffiData
 	switch runtime.GOARCH {
 	case "amd64", "386":
+		// Indirect Go func value (dummy) to obtain actual
+		// code address. (A Go func value is a pointer to a C
+		// function pointer. http://golang.org/s/go11func.)
+		dummy := makeFuncStub
+		code = **(**uintptr)(unsafe.Pointer(&dummy))
 	default:
-		panic("reflect.MakeFunc not implemented for " + runtime.GOARCH)
+		code, ffi = makeFuncFFI(ftyp, fn)
 	}
 
-	t := typ.common()
-	ftyp := (*funcType)(unsafe.Pointer(t))
-
-	// Indirect Go func value (dummy) to obtain
-	// actual code address. (A Go func value is a pointer
-	// to a C function pointer. http://golang.org/s/go11func.)
-	dummy := makeFuncStub
-	code := **(**uintptr)(unsafe.Pointer(&dummy))
-
-	impl := &makeFuncImpl{code: code, typ: ftyp, fn: fn, method: -1}
+	impl := &makeFuncImpl{
+		code:   code,
+		typ:    ftyp,
+		fn:     fn,
+		method: -1,
+		ffi:    ffi,
+	}
 
 	return Value{t, unsafe.Pointer(&impl), flag(Func<<flagKindShift) | flagIndir}
 }
@@ -90,12 +101,6 @@ func makeMethodValue(op string, v Value) Value {
 		panic("reflect: internal error: invalid use of makeMethodValue")
 	}
 
-	switch runtime.GOARCH {
-	case "amd64", "386":
-	default:
-		panic("reflect.makeMethodValue not implemented for " + runtime.GOARCH)
-	}
-
 	// Ignoring the flagMethod bit, v describes the receiver, not the method type.
 	fl := v.flag & (flagRO | flagAddr | flagIndir)
 	fl |= flag(v.typ.Kind()) << flagKindShift
@@ -104,22 +109,37 @@ func makeMethodValue(op string, v Value) Value {
 	// v.Type returns the actual type of the method value.
 	ft := v.Type().(*rtype)
 
-	// Indirect Go func value (dummy) to obtain
-	// actual code address. (A Go func value is a pointer
-	// to a C function pointer. http://golang.org/s/go11func.)
-	dummy := makeFuncStub
-	code := **(**uintptr)(unsafe.Pointer(&dummy))
-
 	// Cause panic if method is not appropriate.
 	// The panic would still happen during the call if we omit this,
 	// but we want Interface() and other operations to fail early.
 	_, t, _ := methodReceiver(op, rcvr, int(v.flag)>>flagMethodShift)
 
+	ftyp := (*funcType)(unsafe.Pointer(t))
+	method := int(v.flag) >> flagMethodShift
+
+	var code uintptr
+	var ffi *ffiData
+	switch runtime.GOARCH {
+	case "amd64", "386":
+		// Indirect Go func value (dummy) to obtain actual
+		// code address. (A Go func value is a pointer to a C
+		// function pointer. http://golang.org/s/go11func.)
+		dummy := makeFuncStub
+		code = **(**uintptr)(unsafe.Pointer(&dummy))
+	default:
+		code, ffi = makeFuncFFI(ftyp,
+			func(in []Value) []Value {
+				m := rcvr.Method(method)
+				return m.Call(in)
+			})
+	}
+
 	fv := &makeFuncImpl{
 		code:   code,
-		typ:    (*funcType)(unsafe.Pointer(t)),
-		method: int(v.flag) >> flagMethodShift,
+		typ:    ftyp,
+		method: method,
 		rcvr:   rcvr,
+		ffi:    ffi,
 	}
 
 	return Value{ft, unsafe.Pointer(&fv), v.flag&flagRO | flag(Func)<<flagKindShift | flagIndir}
@@ -137,26 +157,31 @@ func makeValueMethod(v Value) Value {
 		panic("reflect: call of makeValueMethod with non-MethodFn")
 	}
 
+	t := typ.common()
+	ftyp := (*funcType)(unsafe.Pointer(t))
+
+	var code uintptr
+	var ffi *ffiData
 	switch runtime.GOARCH {
 	case "amd64", "386":
+		// Indirect Go func value (dummy) to obtain actual
+		// code address. (A Go func value is a pointer to a C
+		// function pointer. http://golang.org/s/go11func.)
+		dummy := makeFuncStub
+		code = **(**uintptr)(unsafe.Pointer(&dummy))
 	default:
-		panic("reflect.makeValueMethod not implemented for " + runtime.GOARCH)
+		code, ffi = makeFuncFFI(ftyp,
+			func(in []Value) []Value {
+				return v.Call(in)
+			})
 	}
 
-	t := typ.common()
-	ftyp := (*funcType)(unsafe.Pointer(t))
-
-	// Indirect Go func value (dummy) to obtain
-	// actual code address. (A Go func value is a pointer
-	// to a C function pointer. http://golang.org/s/go11func.)
-	dummy := makeFuncStub
-	code := **(**uintptr)(unsafe.Pointer(&dummy))
-
 	impl := &makeFuncImpl{
 		code:   code,
 		typ:    ftyp,
 		method: -2,
 		rcvr:   v,
+		ffi:    ffi,
 	}
 
 	return Value{t, unsafe.Pointer(&impl), flag(Func<<flagKindShift) | flagIndir}
diff --git a/libgo/go/reflect/makefunc_dummy.c b/libgo/go/reflect/makefunc_dummy.c
index aba48df..8eff0c1 100644
--- a/libgo/go/reflect/makefunc_dummy.c
+++ b/libgo/go/reflect/makefunc_dummy.c
@@ -2,11 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !amd64
+#include "runtime.h"
 
-// Dummy function for processors without makefunc support.
+/* Dummy function for processors that implement MakeFunc using FFI
+   rather than having builtin support.  */
 
-void makeFuncStub () __asm__ ("reflect.makeFuncStub");
-void makeFuncStub ()
+void makeFuncStub (void) __asm__ ("reflect.makeFuncStub");
+
+void makeFuncStub (void)
 {
+  runtime_throw ("impossible call to makeFuncStub");
 }
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
+	}
+}
diff --git a/libgo/go/reflect/makefunc_ffi_c.c b/libgo/go/reflect/makefunc_ffi_c.c
new file mode 100644
index 0000000..fba269d
--- /dev/null
+++ b/libgo/go/reflect/makefunc_ffi_c.c
@@ -0,0 +1,135 @@
+// 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.
+
+#include "runtime.h"
+#include "go-type.h"
+#include "go-panic.h"
+
+#ifdef USE_LIBFFI
+
+#include "go-ffi.h"
+
+#if FFI_CLOSURES
+#define USE_LIBFFI_CLOSURES
+#endif
+
+#endif /* defined(USE_LIBFFI) */
+
+/* Declare C functions with the names used to call from Go.  */
+
+struct ffi_ret {
+  void *code;
+  void *data;
+  void *cif;
+};
+
+struct ffi_ret ffi(const struct __go_func_type *ftyp, FuncVal *callback)
+  __asm__ (GOSYM_PREFIX "reflect.ffi");
+
+void ffiFree(void *data)
+  __asm__ (GOSYM_PREFIX "reflect.ffiFree");
+
+#ifdef USE_LIBFFI_CLOSURES
+
+/* The function that we pass to ffi_prep_closure_loc.  This calls the
+   Go callback function (passed in user_data) with the pointer to the
+   arguments and the results area.  */
+
+static void
+ffi_callback (ffi_cif* cif __attribute__ ((unused)), void *results,
+	      void **args, void *user_data)
+{
+  Location locs[6];
+  int n;
+  int i;
+  const void *pc;
+  FuncVal *fv;
+  void (*f) (void *, void *);
+
+  /* This function is called from some series of FFI closure functions
+     called by a Go function.  We want to pass the PC of the Go
+     function to makefunc_can_recover.  Look up the stack for a
+     function that is definitely not an FFI function.  */
+  n = runtime_callers (1, &locs[0], sizeof locs / sizeof locs[0], true);
+  for (i = 0; i < n; i++)
+    {
+      const byte *name;
+
+      if (locs[i].function.len == 0)
+	continue;
+      if (locs[i].function.len < 4)
+	break;
+      name = locs[i].function.str;
+      if (*name == '_')
+	{
+	  if (locs[i].function.len < 5)
+	    break;
+	  ++name;
+	}
+      if (name[0] != 'f' || name[1] != 'f' || name[2] != 'i' || name[3] != '_')
+	break;
+    }
+  if (i < n)
+    pc = (const void *) locs[i].pc;
+  else
+    pc = __builtin_return_address (0);
+
+  __go_makefunc_can_recover (pc);
+
+  fv = (FuncVal *) user_data;
+  __go_set_closure (fv);
+  f = (void *) fv->fn;
+  f (args, results);
+
+  __go_makefunc_returning ();
+}
+
+/* Allocate an FFI closure and arrange to call ffi_callback.  */
+
+struct ffi_ret
+ffi (const struct __go_func_type *ftyp, FuncVal *callback)
+{
+  ffi_cif *cif;
+  void *code;
+  void *data;
+  struct ffi_ret ret;
+
+  cif = (ffi_cif *) __go_alloc (sizeof (ffi_cif));
+  __go_func_to_cif (ftyp, 0, 0, cif);
+  data = ffi_closure_alloc (sizeof (ffi_closure), &code);
+  if (data == NULL)
+    runtime_panicstring ("ffi_closure_alloc failed");
+  if (ffi_prep_closure_loc (data, cif, ffi_callback, callback, code)
+      != FFI_OK)
+    runtime_panicstring ("ffi_prep_closure_loc failed");
+  ret.code = code;
+  ret.data = data;
+  ret.cif = cif;
+  return ret;
+}
+
+/* Free the FFI closure.  */
+
+void
+ffiFree (void *data)
+{
+  ffi_closure_free (data);
+}
+
+#else /* !defined(USE_LIBFFI_CLOSURES) */
+
+struct ffi_ret
+ffi(const struct __go_func_type *ftyp, FuncVal *callback)
+{
+  runtime_panicstring ("libgo built without FFI does not support "
+		       "reflect.MakeFunc");
+}
+
+void ffiFree(void *data)
+{
+  runtime_panicstring ("libgo built without FFI does not support "
+		       "reflect.MakeFunc");
+}
+
+#endif
-- 
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