Add emscripten_builtin_realloc

Also improve testing for allocator wrapping.

Fixes: #23080

Author: sbc100

system/include/emscripten/heap.h

@@ -46,6 +46,7 @@ size_t emscripten_get_heap_max(void);
 // dlmalloc and emmalloc.
 void *emscripten_builtin_memalign(size_t alignment, size_t size);
 void *emscripten_builtin_malloc(size_t size);
+void *emscripten_builtin_realloc(void *ptr, size_t size);
 void *emscripten_builtin_calloc(size_t nmemb, size_t size);
 void emscripten_builtin_free(void *ptr);
 

system/lib/dlmalloc.c

@@ -6082,6 +6082,7 @@ int mspace_mallopt(int param_number, int value) {
 // This allows an easy mechanism for hooking into memory allocation.
 #if defined(__EMSCRIPTEN__) && !ONLY_MSPACES
 extern __typeof(malloc) emscripten_builtin_malloc __attribute__((alias("dlmalloc")));
+extern __typeof(realloc) emscripten_builtin_realloc __attribute__((alias("dlrealloc")));
 extern __typeof(calloc) emscripten_builtin_calloc __attribute__((alias("dlcalloc")));
 extern __typeof(free) emscripten_builtin_free __attribute__((alias("dlfree")));
 extern __typeof(memalign) emscripten_builtin_memalign __attribute__((alias("dlmemalign")));

system/lib/emmalloc.c

@@ -1113,6 +1113,7 @@ void *emmalloc_aligned_realloc_uninitialized(void *ptr, size_t alignment, size_t
 void *emmalloc_realloc(void *ptr, size_t size) {
   return emmalloc_aligned_realloc(ptr, MALLOC_ALIGNMENT, size);
 }
+EMMALLOC_ALIAS(emscripten_builtin_realloc, emmalloc_realloc);
 EMMALLOC_ALIAS(__libc_realloc, emmalloc_realloc);
 EMMALLOC_ALIAS(realloc,        emmalloc_realloc);
 

system/lib/mimalloc/src/alloc-override.c

@@ -298,6 +298,7 @@ mi_decl_weak int reallocarr(void* p, size_t count, size_t size)    { return mi_r
 
 #ifdef __EMSCRIPTEN__ // emscripten adds some more on top of WASI
   void* emscripten_builtin_malloc(size_t size)                      MI_FORWARD1(mi_malloc, size)
+  void* emscripten_builtin_realloc(void* p, size_t size)            MI_FORWARD2(mi_realloc, p, size)
   void* emscripten_builtin_free(void* p)                            MI_FORWARD0(mi_free, p)
   void* emscripten_builtin_memalign(size_t alignment, size_t size)  { return mi_memalign(alignment, size); }
   void* emscripten_builtin_calloc(size_t nmemb, size_t size)        MI_FORWARD2(mi_calloc, nmemb, size)

test/core/test_wrap_malloc.c

@@ -11,6 +11,7 @@
 
 static int totalAllocs;
 static int totalFrees;
+static int totalReallocs;
 
 void *malloc(size_t size) {
   ++totalAllocs;
@@ -19,6 +20,13 @@ void *malloc(size_t size) {
   return ptr;
 }
 
+void *realloc(void* ptr, size_t size) {
+  ++totalReallocs;
+  ptr = emscripten_builtin_realloc(ptr, size);
+  emscripten_console_logf("Reallocated %zu bytes, got %p. %d pointers re-allocated total.", size, ptr, totalReallocs);
+  return ptr;
+}
+
 void free(void *ptr) {
   ++totalFrees;
   emscripten_builtin_free(ptr);
@@ -39,9 +47,14 @@ int main() {
     free(ptr);
   }
 
+  void* ptr = malloc(50);
+  ptr = realloc(ptr, 50);
+
   emscripten_console_logf("totalAllocs: %d", totalAllocs);
   emscripten_console_logf("totalFrees: %d", totalFrees);
-  assert(totalAllocs == 20);
+  emscripten_console_logf("totalReallocs: %d", totalReallocs);
+  assert(totalAllocs == 21);
+  assert(totalReallocs == 1);
   assert(totalFrees == 20);
   emscripten_console_logf("OK.");
   return 0;

test/test_core.py

@@ -8594,8 +8594,14 @@ def test_mallinfo(self):
 
   @no_asan('cannot replace malloc/free with ASan')
   @no_lsan('cannot replace malloc/free with LSan')
-  def test_wrap_malloc(self):
-    self.do_runf('core/test_wrap_malloc.c', 'OK.')
+  @parameterized({
+    '': ([],),
+    'emmalloc': (['-sMALLOC=emmalloc'],),
+    # FIXME(https://github.com/emscripten-core/emscripten/issues/23090)
+    # 'mimalloc': (['-sMALLOC=mimalloc'],),
+  })
+  def test_wrap_malloc(self, args):
+    self.do_runf('core/test_wrap_malloc.c', 'OK.', emcc_args=args)
 
   def test_environment(self):
     self.set_setting('ASSERTIONS')

tools/system_libs.py

@@ -1721,7 +1721,7 @@ class libmalloc(MTLibrary):
   def __init__(self, **kwargs):
     self.malloc = kwargs.pop('malloc')
     if self.malloc not in ('dlmalloc', 'emmalloc', 'emmalloc-debug', 'emmalloc-memvalidate', 'emmalloc-verbose', 'emmalloc-memvalidate-verbose', 'mimalloc', 'none'):
-      raise Exception('malloc must be one of "emmalloc[-debug|-memvalidate][-verbose]", "dlmalloc" or "none", see settings.js')
+      raise Exception('malloc must be one of "emmalloc[-debug|-memvalidate][-verbose]", "mimalloc", "dlmalloc" or "none", see settings.js')
 
     self.is_tracing = kwargs.pop('is_tracing')
     self.memvalidate = kwargs.pop('memvalidate')