sync dlmalloc from wasi-libc

packages/emnapi/src/malloc/dlmalloc/malloc.c

@@ -4619,14 +4619,14 @@ void* dlmalloc(size_t bytes) {
  ensure_initialization(); /* initialize in sys_alloc if not using locks */
 #endif
 
+ if (!PREACTION(gm)) {
 #if __wasilibc_unmodified_upstream // Try to initialize the allocator.
 #else
- if (!is_initialized(gm)) {
- try_init_allocator();
- }
+  if (!is_initialized(gm)) {
+  try_init_allocator();
+  }
 #endif
 
- if (!PREACTION(gm)) {
  void* mem;
  size_t nb;
  if (bytes <= MAX_SMALL_REQUEST) {
@@ -5241,7 +5241,7 @@ static void internal_inspect_all(mstate m,
 
 /* Symbol marking the end of data, bss and explicit stack, provided by wasm-ld. */
 extern char __heap_base;
-extern char __heap_end __attribute__((__weak__));
+extern char __heap_end;
 
 /* Initialize the initial state of dlmalloc to be able to use free memory between __heap_base and initial. */
 static void try_init_allocator(void) {
@@ -5253,23 +5253,18 @@ static void try_init_allocator(void) {
 
  char *base = &__heap_base;
  // Try to use the linker pseudo-symbol `__heap_end` for the initial size of
- // the heap, but if that's not defined due to LLVM being too old perhaps then
- // round up `base` to the nearest `PAGESIZE`. The initial size of linear
- // memory will be at least the heap base to this page boundary, and it's then
- // assumed that the initial linear memory image was truncated at that point.
- // While this reflects the default behavior of `wasm-ld` it is also possible
- // for users to craft larger linear memories by passing options to extend
- // beyond this threshold. In this situation the memory will not be used for
- // dlmalloc.
- //
- // Note that `sbrk(0)`, or in dlmalloc-ese `CALL_MORECORE(0)`, is specifically
- // not used here. That captures the current size of the heap but is only
- // correct if the we're the first to try to grow the heap. If the heap has
- // grown elsewhere, such as a different allocator in place, then this would
- // incorrectly claim such memroy as our own.
+ // the heap.
  char *end = &__heap_end;
- if (end == NULL)
- end = (char*) page_align((size_t) base);
+ if (end < base) {
+ // "end" can be NULL when 1. you are using an old wasm-ld which doesn't
+ // provide `__heap_end` (< 15.0.7) and 2. something (other libraries
+ // or maybe your app?) includes a weak reference to `__heap_end` and
+ // 3. the weak reference is found by the linker before this strong
+ // reference.
+ //
+ // Note: This is a linker bug: https://github.com/llvm/llvm-project/issues/60829
+ __builtin_trap();
+ }
  size_t initial_heap_size = end - base;
 
  /* Check that initial heap is long enough to serve a minimal allocation request. */