Remove some //go:linkname usages (#253)

* Stop using noescape

This was just a performance improvement. Removing since we want to avoid using linkname to not hinder the Go ecosystem.

* Stop using memmove

* remove memmove linkname

commit: 8ebc748ec153c98f58511bcb274540e8b517a56b
author: TotallyGamerJet · 2y ago · 2024-06-04 02:52 UTC
committer: GitHub · 2y ago · 2024-06-04 02:52 UTC
parent: 88cc579
signature: GPG UnverifiedB5690EEEBB952194 The key is unknown

5 files · +7 -14

M func.go +1 -2


@@ -340,8 +340,7 @@ func RegisterFunc(fptr interface{}, cfn uintptr) {
340	340		// We take the address and then dereference it to trick go vet from creating a possible miss-use of unsafe.Pointer
341	341		v.SetPointer((unsafe.Pointer)(unsafe.Pointer(&syscall.a1)))
342	342		case reflect.Ptr:
343		-	// It is safe to have the address of syscall.r1 not escape because it is immediately dereferenced with .Elem()
344		-	v = reflect.NewAt(outType, runtime_noescape(unsafe.Pointer(&syscall.a1))).Elem()
	343	+	v = reflect.NewAt(outType, unsafe.Pointer(&syscall.a1)).Elem()
345	344		case reflect.Func:
346	345		// wrap this C function in a nicely typed Go function
347	346		v = reflect.New(outType)

 			// We take the address and then dereference it to trick go vet from creating a possible miss-use of unsafe.Pointer
 			v.SetPointer(*(*unsafe.Pointer)(unsafe.Pointer(&syscall.a1)))
 		case reflect.Ptr:
-			// It is safe to have the address of syscall.r1 not escape because it is immediately dereferenced with .Elem()
+			v = reflect.NewAt(outType, unsafe.Pointer(&syscall.a1)).Elem()
-			v = reflect.NewAt(outType, runtime_noescape(unsafe.Pointer(&syscall.a1))).Elem()
 		case reflect.Func:
 			// wrap this C function in a nicely typed Go function
 			v = reflect.New(outType)

M go_runtime.go +0 -4


@@ -11,7 +11,3 @@ import (
11	11
12	12		//go:linkname runtime_cgocall runtime.cgocall
13	13		func runtime_cgocall(fn uintptr, arg unsafe.Pointer) int32 // from runtime/sys_libc.go
14		-
15		-	//go:linkname runtime_noescape runtime.noescape
16		-	//go:noescape
17		-	func runtime_noescape(p unsafe.Pointer) unsafe.Pointer // from runtime/stubs.go


@@ -11,7 +11,3 @@ import (
11			11
12		//go:linkname runtime_cgocall runtime.cgocall	12	//go:linkname runtime_cgocall runtime.cgocall
13		func runtime_cgocall(fn uintptr, arg unsafe.Pointer) int32 // from runtime/sys_libc.go	13	func runtime_cgocall(fn uintptr, arg unsafe.Pointer) int32 // from runtime/sys_libc.go
14	-
15	-	//go:linkname runtime_noescape runtime.noescape
16	-	//go:noescape
17	-	func runtime_noescape(p unsafe.Pointer) unsafe.Pointer // from runtime/stubs.go

M internal/fakecgo/gen.go +0 -3


@@ -32,9 +32,6 @@ import (
32	32		// setg_trampoline calls setg with the G provided
33	33		func setg_trampoline(setg uintptr, G uintptr)
34	34
35		-	//go:linkname memmove runtime.memmove
36		-	func memmove(to, from unsafe.Pointer, n uintptr)
37		-
38	35		// call5 takes fn the C function and 5 arguments and calls the function with those arguments
39	36		func call5(fn, a1, a2, a3, a4, a5 uintptr) uintptr
40	37


@@ -32,9 +32,6 @@ import (
32		// setg_trampoline calls setg with the G provided	32	// setg_trampoline calls setg with the G provided
33		func setg_trampoline(setg uintptr, G uintptr)	33	func setg_trampoline(setg uintptr, G uintptr)
34			34
35	-	//go:linkname memmove runtime.memmove
36	-	func memmove(to, from unsafe.Pointer, n uintptr)
37	-
38		// call5 takes fn the C function and 5 arguments and calls the function with those arguments	35	// call5 takes fn the C function and 5 arguments and calls the function with those arguments
39		func call5(fn, a1, a2, a3, a4, a5 uintptr) uintptr	36	func call5(fn, a1, a2, a3, a4, a5 uintptr) uintptr
40			37

M internal/fakecgo/go_util.go +6 -2


@@ -27,7 +27,11 @@ func x_cgo_thread_start(arg *ThreadStart) {
27	27		println("fakecgo: out of memory in thread_start")
28	28		abort()
29	29		}
30		-	// ts = arg would cause a writebarrier so use memmove instead
31		-	memmove(unsafe.Pointer(ts), unsafe.Pointer(arg), unsafe.Sizeof(*ts))
	30	+	// ts = arg would cause a writebarrier so copy using slices
	31	+	s1 := unsafe.Slice((uintptr)(unsafe.Pointer(ts)), unsafe.Sizeof(ts)/8)
	32	+	s2 := unsafe.Slice((uintptr)(unsafe.Pointer(arg)), unsafe.Sizeof(arg)/8)
	33	+	for i := range s2 {
	34	+	s1[i] = s2[i]
	35	+	}
32	36		_cgo_sys_thread_start(ts) // OS-dependent half
33	37		}

 		println("fakecgo: out of memory in thread_start")
 		abort()
 	}
-	// *ts = *arg would cause a writebarrier so use memmove instead
+	// *ts = *arg would cause a writebarrier so copy using slices
-	memmove(unsafe.Pointer(ts), unsafe.Pointer(arg), unsafe.Sizeof(*ts))
+	s1 := unsafe.Slice((*uintptr)(unsafe.Pointer(ts)), unsafe.Sizeof(*ts)/8)
+	s2 := unsafe.Slice((*uintptr)(unsafe.Pointer(arg)), unsafe.Sizeof(*arg)/8)
+	for i := range s2 {
+		s1[i] = s2[i]
+	}
 	_cgo_sys_thread_start(ts) // OS-dependent half
 }

M internal/fakecgo/symbols.go +0 -3


@@ -15,9 +15,6 @@ import (
15	15		// setg_trampoline calls setg with the G provided
16	16		func setg_trampoline(setg uintptr, G uintptr)
17	17
18		-	//go:linkname memmove runtime.memmove
19		-	func memmove(to, from unsafe.Pointer, n uintptr)
20		-
21	18		// call5 takes fn the C function and 5 arguments and calls the function with those arguments
22	19		func call5(fn, a1, a2, a3, a4, a5 uintptr) uintptr
23	20


@@ -15,9 +15,6 @@ import (
15		// setg_trampoline calls setg with the G provided	15	// setg_trampoline calls setg with the G provided
16		func setg_trampoline(setg uintptr, G uintptr)	16	func setg_trampoline(setg uintptr, G uintptr)
17			17
18	-	//go:linkname memmove runtime.memmove
19	-	func memmove(to, from unsafe.Pointer, n uintptr)
20	-
21		// call5 takes fn the C function and 5 arguments and calls the function with those arguments	18	// call5 takes fn the C function and 5 arguments and calls the function with those arguments
22		func call5(fn, a1, a2, a3, a4, a5 uintptr) uintptr	19	func call5(fn, a1, a2, a3, a4, a5 uintptr) uintptr
23			20