external gc interface

std/assembly/gc.ts

@@ -1,16 +1,48 @@
 /// <reference path="./collector/index.d.ts" />
 
+import { E_NOTIMPLEMENTED } from "./util/error";
+
+// @ts-ignore
+@lazy
+var GC_ROOT = new Set<usize>();
+
 /** Garbage collector interface. */
 export namespace gc {
 
   /** Whether the garbage collector interface is implemented. */
   // @ts-ignore: decorator
   @lazy
-  export const IMPLEMENTED: bool = isDefined(__ref_collect);
+  export const implemented: bool = isDefined(__ref_collect);
 
   /** Performs a full garbage collection cycle. */
   export function collect(): void {
     if (isDefined(__ref_collect)) __ref_collect();
-    else WARNING("missing implementation: gc.collect");
+    else throw new Error(E_NOTIMPLEMENTED);
+  }
+
+  /** Retains a reference, making sure that it doesn't become collected. */
+  export function retain(ref: usize): void {
+    var root = GC_ROOT;
+    if (!root.has(ref)) {
+      root.add(ref);
+      if (implemented) {
+        if (isDefined(__ref_link)) __ref_link(ref, changetype<usize>(root));
+        else if (isDefined(__ref_retain)) __ref_retain(ref);
+        else assert(false);
+      }
+    }
+  }
+
+  /** Releases a reference, allowing it to become collected. */
+  export function release(ref: usize): void {
+    var root = GC_ROOT;
+    if (root.has(ref)) {
+      root.delete(ref);
+      if (implemented) {
+        if (isDefined(__ref_link)) __ref_unlink(ref, changetype<usize>(root));
+        else if (isDefined(__ref_retain)) __ref_release(ref);
+        else assert(false);
+      }
+    }
   }
 }

std/assembly/index.d.ts

@@ -974,6 +974,8 @@ declare function bswap16<T = i8 | u8 | i16 | u16 | i32 | u32>(value: T): T;
 
 /** Memory operations. */
 declare namespace memory {
+  /** Whether the memory managed interface is implemented. */
+  export const implemented: bool;
   /** Returns the current memory size in units of pages. One page is 64kb. */
   export function size(): i32;
   /** Grows linear memory by a given unsigned delta of pages. One page is 64kb. Returns the previous memory size in units of pages or `-1` on failure. */
@@ -985,9 +987,9 @@ declare namespace memory {
   /** Repeats `src` of length `srcLength` `count` times at `dst`. */
   export function repeat(dst: usize, src: usize, srcLength: usize, count: usize): void;
   /** Copies elements from a passive element segment to a table. */
-  // export function init(segmentIndex: u32, srcOffset: usize, dstOffset: usize, n: usize): void;
+  export function init(segmentIndex: u32, srcOffset: usize, dstOffset: usize, n: usize): void;
   /** Prevents further use of a passive element segment. */
-  // export function drop(segmentIndex: u32): void;
+  export function drop(segmentIndex: u32): void;
   /** Copies elements from one region of a table to another region. */
   export function allocate(size: usize): usize;
   /** Disposes a chunk of memory by its pointer. */
@@ -1000,20 +1002,24 @@ declare namespace memory {
 
 /** Garbage collector operations. */
 declare namespace gc {
-  /** Allocates a managed object identified by its visitor function. */
-  export function allocate(size: usize, visitFn: (ref: usize) => void): usize;
+  /** Whether the garbage collector interface is implemented. */
+  export const implemented: bool;
   /** Performs a full garbage collection cycle. */
   export function collect(): void;
+  /** Retains a reference, making sure that it doesn't become collected. */
+  export function retain(ref: usize): void;
+  /** Releases a reference, allowing it to become collected. */
+  export function release(ref: usize): void;
 }
 
 /** Table operations. */
 declare namespace table {
   /** Copies elements from a passive element segment to a table. */
-  // export function init(elementIndex: u32, srcOffset: u32, dstOffset: u32, n: u32): void;
+  export function init(elementIndex: u32, srcOffset: u32, dstOffset: u32, n: u32): void;
   /** Prevents further use of a passive element segment. */
-  // export function drop(elementIndex: u32): void;
+  export function drop(elementIndex: u32): void;
   /** Copies elements from one region of a table to another region. */
-  // export function copy(dest: u32, src: u32, n: u32): void;
+  export function copy(dest: u32, src: u32, n: u32): void;
 }
 
 /** Class representing a generic, fixed-length raw binary data buffer. */

std/assembly/memory.ts

@@ -1,6 +1,7 @@
 /// <reference path="./allocator/index.d.ts" />
 
 import { memcmp, memmove, memset } from "./util/memory";
+import { E_NOTIMPLEMENTED } from "./util/error";
 
 // @ts-ignore: decorator
 @builtin
@@ -9,6 +10,11 @@ export declare const HEAP_BASE: usize;
 /** Memory manager interface. */
 export namespace memory {
 
+  /** Whether the memory managed interface is implemented. */
+  // @ts-ignore: decorator
+  @lazy
+  export const implemented: bool = isDefined(__mem_allocate);
+
   /** Gets the size of the memory in pages. */
   // @ts-ignore: decorator
   @builtin
@@ -37,14 +43,14 @@ export namespace memory {
   // @ts-ignore: decorator
   @unsafe
   export function init(segmentIndex: u32, srcOffset: usize, dstOffset: usize, n: usize): void {
-    unreachable(); // not yet implemented
+    throw new Error(E_NOTIMPLEMENTED);
   }
 
   /** Drops a memory segment. */
   // @ts-ignore: decorator
   @unsafe
   export function drop(segmentIndex: u32): void {
-    unreachable(); // not yet implemented
+    throw new Error(E_NOTIMPLEMENTED);
   }
 
   /** Dynamically allocates a section of memory and returns its address. */
@@ -52,7 +58,7 @@ export namespace memory {
   @unsafe
   export function allocate(size: usize): usize {
     if (isDefined(__mem_allocate)) return __mem_allocate(size);
-    else return <usize>unreachable();
+    else throw new Error(E_NOTIMPLEMENTED);
   }
 
   /** Dynamically frees a section of memory by the previously allocated address. */
@@ -60,7 +66,7 @@ export namespace memory {
   @unsafe
   export function free(ptr: usize): void {
     if (isDefined(__mem_free)) __mem_free(ptr);
-    else unreachable();
+    else throw new Error(E_NOTIMPLEMENTED);
   }
 
   /** Resets the memory to its initial state. Arena allocator only. */
@@ -68,7 +74,7 @@ export namespace memory {
   @unsafe
   export function reset(): void {
     if (isDefined(__mem_reset)) __mem_reset();
-    else unreachable();
+    else throw new Error(E_NOTIMPLEMENTED);
   }
 
   /** Repeats a section of memory at a specific address. */

std/assembly/table.ts

@@ -1,14 +1,16 @@
+import { E_NOTIMPLEMENTED } from "./util/error";
+
 export namespace table {
 
   export function copy(dst: u32, src: u32, n: u32): void {
-    ERROR("not implemented: table.copy");
+    throw new Error(E_NOTIMPLEMENTED);
   }
 
   export function init(elementIndex: u32, srcOffset: u32, dstOffset: u32, n: u32): void {
-    ERROR("not implemented: table.init");
+    throw new Error(E_NOTIMPLEMENTED);
   }
 
   export function drop(elementIndex: u32): void {
-    ERROR("not implemented: table.drop");
+    throw new Error(E_NOTIMPLEMENTED);
   }
 }

std/assembly/util/error.ts

@@ -16,3 +16,7 @@ export const E_EMPTYARRAY: string = "Array is empty";
 // @ts-ignore: decorator
 @lazy @inline
 export const E_HOLEYARRAY: string = "Element type must be nullable if array is holey";
+
+// @ts-ignore: decorator
+@lazy @inline
+export const E_NOTIMPLEMENTED: string = "Not implemented";

tests/compiler/gc.ts

@@ -0,0 +1,39 @@
+import "allocator/arena";
+import { link_count, unlink_count, collect_count } from "./gc/_dummy";
+export { gc };
+
+class Ref {}
+
+@start export function main(): void {
+  var ref = new Ref();
+
+  assert(gc.implemented);
+
+  var previous_link_count = link_count;
+  var previous_unlink_count = unlink_count;
+  var previous_collect_count = collect_count;
+
+  gc.retain(changetype<usize>(ref));
+
+  assert(link_count == previous_link_count + 1);
+  assert(unlink_count == previous_unlink_count);
+  assert(collect_count == previous_collect_count);
+  previous_link_count = link_count;
+  previous_unlink_count = unlink_count;
+  previous_collect_count = collect_count;
+
+  gc.release(changetype<usize>(ref));
+
+  assert(link_count == previous_link_count);
+  assert(unlink_count == previous_unlink_count + 1);
+  assert(collect_count == previous_collect_count);
+  previous_link_count = link_count;
+  previous_unlink_count = unlink_count;
+  previous_collect_count = collect_count;
+
+  gc.collect();
+
+  assert(link_count == previous_link_count);
+  assert(unlink_count == previous_unlink_count);
+  assert(collect_count == previous_collect_count + 1);
+}