033425d0ed
PR go/91781
reflect: promote integer closure return to full word
The libffi library expects an integer return type to be promoted to a
full word. Implement that when returning from a closure written in Go.
This only matters on big-endian systems when returning an integer smaller
than the pointer size, which is why we didn't notice it until now.
Fixes https://gcc.gnu.org/PR91781.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/195858
From-SVN: r275813
94 lines
2.6 KiB
Go
94 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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"unsafe"
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)
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// The makeFuncFFI function, written in C, fills in an FFI closure.
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// It arranges for ffiCall to be invoked directly from FFI.
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func makeFuncFFI(cif unsafe.Pointer, impl unsafe.Pointer)
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// The makeCIF function, implemented in the runtime package, allocates a CIF.
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func makeCIF(ft *funcType) unsafe.Pointer
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// Export ffiCallbackGo so that C code in makefunc_ffi_c.c can call it.
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//go:linkname ffiCallbackGo
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// ffiCallbackGo implements the Go side of the libffi callback.
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//
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// The call chain arriving here looks like
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// some_go_caller
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// ->some_ffi_internals
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// ->ffi_callback (in C)
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// ->ffiCallbackGo
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//
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// The ffi_callback handles __go_makefunc_can_recover, and
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// then passes off the data as received from ffi here.
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func ffiCallbackGo(results unsafe.Pointer, params unsafe.Pointer, impl *makeFuncImpl, wordsize int32, bigEndian bool) {
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ftyp := impl.typ
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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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typedmemmove(rt, p, *(*unsafe.Pointer)(ap))
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v := Value{rt, p, flag(rt.Kind()) | 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 := impl.call(in)
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checkValue := func(v Value, typ *rtype, addr unsafe.Pointer) {
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if v.flag&flagRO != 0 {
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panic("reflect: function created by MakeFunc using " + funcName(impl.fn) +
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" returned value obtained from unexported field")
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}
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// Convert v to type typ if v is assignable to a variable
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// of type t in the language spec.
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// See issue 28761.
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v = v.assignTo("reflect.MakeFunc", typ, addr)
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}
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// In libffi a single integer return value is always promoted
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// to a full word. This only matters for integers whose size
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// is less than the size of a full word. There is similar code
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// in libgo/runtime/go-reflect-call.c.
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if len(ftyp.out) == 1 {
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typ := ftyp.out[0]
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switch typ.Kind() {
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case Bool, Int8, Int16, Int32, Uint8, Uint16, Uint32:
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v := out[0]
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checkValue(v, typ, nil)
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if bigEndian {
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results = unsafe.Pointer(uintptr(results) + uintptr(wordsize) - typ.size)
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}
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memmove(results, v.ptr, typ.size)
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return
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}
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}
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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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off = align(off, uintptr(typ.fieldAlign))
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addr := unsafe.Pointer(uintptr(results) + off)
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checkValue(v, typ, addr)
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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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typedmemmove(typ, addr, v.ptr)
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}
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off += typ.size
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}
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}
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