[interop] Optimized unmanaged memory alloc/free

kotlin-native/Interop/Runtime/src/jvm/kotlin/kotlinx/cinterop/JvmNativeMem.kt

@@ -16,6 +16,7 @@
 
 package kotlinx.cinterop
 
+import org.jetbrains.kotlin.konan.util.nativeMemoryAllocator
 import sun.misc.Unsafe
 
 private val NativePointed.address: Long
@@ -95,19 +96,20 @@ internal object nativeMemUtils {
         return unsafe.allocateInstance(T::class.java) as T
     }
 
-    fun alloc(size: Long, align: Int): NativePointed {
-        val address = unsafe.allocateMemory(
-                if (size == 0L) 1L else size // It is a hack: `sun.misc.Unsafe` can't allocate zero bytes
-        )
-
+    internal fun allocRaw(size: Long, align: Int): NativePtr {
+        val address = unsafe.allocateMemory(size)
         if (address % align != 0L) TODO(align.toString())
-        return interpretOpaquePointed(address)
+        return address
     }
 
-    fun free(mem: NativePtr) {
+    internal fun freeRaw(mem: NativePtr) {
         unsafe.freeMemory(mem)
     }
 
+    fun alloc(size: Long, align: Int) = interpretOpaquePointed(nativeMemoryAllocator.alloc(size, align))
+
+    fun free(mem: NativePtr) = nativeMemoryAllocator.free(mem)
+
     private val unsafe = with(Unsafe::class.java.getDeclaredField("theUnsafe")) {
         isAccessible = true
         return@with this.get(null) as Unsafe

kotlin-native/Interop/Runtime/src/main/kotlin/kotlinx/cinterop/Utils.kt

@@ -395,7 +395,7 @@ private object EmptyCString: CValues<ByteVar>() {
     override val align get() = 1
 
     private val placement =
-            interpretCPointer<ByteVar>(nativeMemUtils.alloc(1, 1).rawPtr)!!.also {
+            interpretCPointer<ByteVar>(nativeMemUtils.allocRaw(1, 1))!!.also {
                 it[0] = 0.toByte()
             }
 

kotlin-native/Interop/Runtime/src/native/kotlin/kotlinx/cinterop/NativeMem.kt

@@ -118,14 +118,22 @@ internal object nativeMemUtils {
     }
 
     fun alloc(size: Long, align: Int): NativePointed {
+        return interpretOpaquePointed(allocRaw(size, align))
+    }
+
+    fun free(mem: NativePtr) {
+        freeRaw(mem)
+    }
+
+    internal fun allocRaw(size: Long, align: Int): NativePtr {
         val ptr = malloc(size, align)
         if (ptr == nativeNullPtr) {
             throw OutOfMemoryError("unable to allocate native memory")
         }
-        return interpretOpaquePointed(ptr)
+        return ptr
     }
 
-    fun free(mem: NativePtr) {
+    internal fun freeRaw(mem: NativePtr) {
         cfree(mem)
     }
 }