Use debug version of malloc when ASSERTIONS=1. NFC (#23330)

Previously we were only using it with `ASSERTIONS=2`.  

The debug version dlmalloc has many very useful checks, including
checking for double-free. This is something that is done by glibc malloc
even in release builds. It seems reasonable that we should do this basic
checking in our debug builds at least.

Required fixing two genuine bugs: One double-free in test code and one
invalid free in embind.

Fixes: #23360

Author: sbc100

ChangeLog.md

@@ -66,6 +66,10 @@ See docs/process.md for more on how version tagging works.
   specified with `-L`) for `libfoo.js`. (#23338)
 - The `mallinfo` struct members are now defined as `size_t` which makes them
   compatible with larger memories, and is also how linux defines them. (#23368)
+- Emscripten now uses the debug version of malloc (i.e. assertions enabled)
+  when linking in debug mode (`-O0` and/or `-sASSERTIONS`).  This means that
+  things like double-free will be detected in these builds.  Previously this was
+  only true with `-sASSERTIONS=2`. (#23330)
 
 3.1.74 - 12/14/24
 -----------------

embuilder.py

@@ -54,6 +54,7 @@
     'libdlmalloc-tracing',
     'libdlmalloc-debug',
     'libdlmalloc-ww',
+    'libdlmalloc-ww-debug',
     'libembind',
     'libembind-rtti',
     'libemmalloc',
@@ -101,6 +102,7 @@
     'libc++-mt',
     'libc++-mt-noexcept',
     'libdlmalloc-mt',
+    'libdlmalloc-mt-debug',
     'libGL-emu',
     'libGL-emu-webgl2-getprocaddr',
     'libGL-mt-getprocaddr',

src/embind/embind.js

@@ -567,7 +567,7 @@ var LibraryEmbind = {
             for (var i = 0; i < length; ++i) {
               var charCode = value.charCodeAt(i);
               if (charCode > 255) {
-                _free(ptr);
+                _free(base);
                 throwBindingError('String has UTF-16 code units that do not fit in 8 bits');
               }
               HEAPU8[ptr + i] = charCode;

test/code_size/embind_hello_wasm.json

@@ -2,9 +2,9 @@
   "a.html": 552,
   "a.html.gz": 380,
   "a.js": 9879,
-  "a.js.gz": 4288,
+  "a.js.gz": 4287,
   "a.wasm": 7348,
   "a.wasm.gz": 3375,
   "total": 17779,
-  "total_gz": 8043
+  "total_gz": 8042
 }

test/code_size/embind_val_wasm.json

@@ -2,9 +2,9 @@
   "a.html": 552,
   "a.html.gz": 380,
   "a.js": 7153,
-  "a.js.gz": 3042,
+  "a.js.gz": 3041,
   "a.wasm": 9119,
   "a.wasm.gz": 4701,
   "total": 16824,
-  "total_gz": 8123
+  "total_gz": 8122
 }

test/other/test_tsearch.c

@@ -39,6 +39,10 @@ static void action(const void *nodep, VISIT which, int depth) {
     }
 }
 
+static void free_node(void* nodep) {
+    // no-op since we didn't allocate any per-node data
+}
+
 int main(void) {
     int  ptr[12];
     void *val = NULL;
@@ -51,6 +55,6 @@ int main(void) {
         assert(val);
     }
     twalk(root, action);
-    tdestroy(root, free);
+    tdestroy(root, free_node);
     return 0;
-} 
+}

test/test_other.py

@@ -8019,10 +8019,10 @@ def test_dlmalloc_modes(self):
         printf("double-freed\n");
       }
     ''')
-    self.run_process([EMCC, 'src.c'])
+    self.run_process([EMCC, 'src.c', '-O2'])
     self.assertContained('double-freed', self.run_js('a.out.js'))
     # in debug mode, the double-free is caught
-    self.run_process([EMCC, 'src.c', '-sASSERTIONS=2'])
+    self.run_process([EMCC, 'src.c', '-O0'])
     out = self.run_js('a.out.js', assert_returncode=NON_ZERO)
     self.assertContained('native code called abort()', out)
 
@@ -13405,7 +13405,7 @@ def test_standard_library_mapping(self):
 
     # Check that the linker was run with `-mt` variants because `-pthread` was passed.
     self.assertContained(' -lc-mt-debug ', err)
-    self.assertContained(' -ldlmalloc-mt ', err)
+    self.assertContained(' -ldlmalloc-mt-debug ', err)
     self.assertContained(' -lcompiler_rt-mt ', err)
 
   def test_explicit_gl_linking(self):

tools/system_libs.py

@@ -1766,7 +1766,7 @@ def vary_on(cls):
   def get_default_variation(cls, **kwargs):
     return super().get_default_variation(
       malloc=settings.MALLOC,
-      is_debug=settings.ASSERTIONS >= 2,
+      is_debug=settings.ASSERTIONS,
       is_tracing=settings.EMSCRIPTEN_TRACING,
       memvalidate='memvalidate' in settings.MALLOC,
       verbose='verbose' in settings.MALLOC,