minor change

Signed-off-by: Miguel Ángel Ortuño <[email protected]>

monotonic_arena.go

@@ -37,12 +37,12 @@ func (s *monotonicBuffer) alloc(size, alignment uintptr) (unsafe.Pointer, bool)
 	ptr := unsafe.Pointer(uintptr(s.ptr) + s.offset + alignOffset)
 	s.offset += allocSize
 
-	b := unsafe.Slice((*byte)(ptr), size)
-
 	// This piece of code will be translated into a runtime.memclrNoHeapPointers
 	// invocation by the compiler, which is an assembler optimized implementation.
 	// Architecture specific code can be found at src/runtime/memclr_$GOARCH.s
 	// in Go source (since https://codereview.appspot.com/137880043).
+	b := unsafe.Slice((*byte)(ptr), size)
+
 	for i := range b {
 		b[i] = 0
 	}