If building with -s SUPPORT_ERRNO=0, make sure that dlmalloc does not reference __errno_location so that it can be optimized out by Closure

Author: juj

embuilder.py

@@ -42,6 +42,10 @@
         dlmalloc_debug
         dlmalloc_threadsafe
         dlmalloc_threadsafe_debug
+        dlmalloc_noerrno
+        dlmalloc_debug_noerrno
+        dlmalloc_threadsafe_noerrno
+        dlmalloc_threadsafe_debug_noerrno
         pthreads
         libc++
         libc++_noexcept
@@ -108,6 +112,8 @@
     'al', 'compiler-rt', 'gl', 'gl-mt', 'libc', 'libc-mt', 'libc-extras',
     'emmalloc', 'emmalloc_debug', 'dlmalloc', 'dlmalloc_threadsafe', 'pthreads',
     'dlmalloc_debug', 'dlmalloc_threadsafe_debug', 'libc++', 'libc++_noexcept',
+    'dlmalloc_debug_noerrno', 'dlmalloc_threadsafe_debug_noerrno',
+    'dlmalloc_noerrno', 'dlmalloc_threadsafe_noerrno',
     'libc++abi', 'html5'
 ]
 USER_TASKS = [
@@ -201,6 +207,14 @@ def main():
       build(C_WITH_MALLOC, ['libdlmalloc_threadsafe_debug.bc'], ['-g', '-s', 'USE_PTHREADS=1', '-s', 'MALLOC="dlmalloc"'])
     elif what in ('dlmalloc_threadsafe', 'libc-mt', 'pthreads'):
       build(C_WITH_MALLOC, ['libc-mt.bc', 'libdlmalloc_threadsafe.bc', 'libpthreads.bc'], ['-s', 'USE_PTHREADS=1', '-s', 'MALLOC="dlmalloc"'])
+    elif what == 'dlmalloc_noerrno':
+      build(C_WITH_MALLOC, ['libdlmalloc_noerrno.bc'], ['-s', 'MALLOC="dlmalloc"', '-s', 'SUPPORT_ERRNO=0'])
+    elif what == 'dlmalloc_debug_noerrno':
+      build(C_WITH_MALLOC, ['libdlmalloc_debug_noerrno.bc'], ['-g', '-s', 'MALLOC="dlmalloc"', '-s', 'SUPPORT_ERRNO=0'])
+    elif what == 'dlmalloc_threadsafe_debug_noerrno':
+      build(C_WITH_MALLOC, ['libdlmalloc_threadsafe_debug_noerrno.bc'], ['-g', '-s', 'USE_PTHREADS=1', '-s', 'MALLOC="dlmalloc"', '-s', 'SUPPORT_ERRNO=0'])
+    elif what == 'dlmalloc_threadsafe_noerrno':
+      build(C_WITH_MALLOC, ['libdlmalloc_threadsafe_noerrno.bc'], ['-s', 'USE_PTHREADS=1', '-s', 'MALLOC="dlmalloc"', '-s', 'SUPPORT_ERRNO=0'])
     elif what == 'libc-wasm':
       build(C_WITH_STDLIB, ['libc-wasm.bc'], ['-s', 'WASM=1'])
     elif what == 'libc++':

tests/test_sanity.py

@@ -723,6 +723,10 @@ def test_embuilder(self):
       ([PYTHON, EMBUILDER, 'build', 'dlmalloc_debug'], ['building and verifying dlmalloc', 'success'], True, ['libdlmalloc_debug.bc']),
       ([PYTHON, EMBUILDER, 'build', 'dlmalloc_threadsafe'], ['building and verifying dlmalloc_threadsafe', 'success'], True, ['libdlmalloc_threadsafe.bc']),
       ([PYTHON, EMBUILDER, 'build', 'dlmalloc_threadsafe_debug'], ['building and verifying dlmalloc', 'success'], True, ['libdlmalloc_threadsafe_debug.bc']),
+      ([PYTHON, EMBUILDER, 'build', 'dlmalloc_noerrno'], ['building and verifying dlmalloc', 'success'], True, ['libdlmalloc_noerrno.bc']),
+      ([PYTHON, EMBUILDER, 'build', 'dlmalloc_debug_noerrno'], ['building and verifying dlmalloc', 'success'], True, ['libdlmalloc_debug_noerrno.bc']),
+      ([PYTHON, EMBUILDER, 'build', 'dlmalloc_threadsafe_noerrno'], ['building and verifying dlmalloc_threadsafe', 'success'], True, ['libdlmalloc_threadsafe_noerrno.bc']),
+      ([PYTHON, EMBUILDER, 'build', 'dlmalloc_threadsafe_debug_noerrno'], ['building and verifying dlmalloc', 'success'], True, ['libdlmalloc_threadsafe_debug_noerrno.bc']),
       ([PYTHON, EMBUILDER, 'build', 'emmalloc'], ['building and verifying emmalloc', 'success'], True, ['libemmalloc.bc']),
       ([PYTHON, EMBUILDER, 'build', 'emmalloc_debug'], ['building and verifying emmalloc', 'success'], True, ['libemmalloc_debug.bc']),
       ([PYTHON, EMBUILDER, 'build', 'pthreads'], ['building and verifying pthreads', 'success'], True, ['libpthreads.bc']),

tools/system_libs.py

@@ -431,6 +431,10 @@ def require_dlmalloc(what):
       extra += '_debug'
     if base == 'dlmalloc':
       source = 'dlmalloc.c'
+
+      # Only dlmalloc interacts with errno, emmalloc does not
+      if not shared.Settings.SUPPORT_ERRNO:
+        extra += '_noerrno'
     elif base == 'emmalloc':
       source = 'emmalloc.cpp'
     return (source, 'lib' + base + extra)
@@ -453,6 +457,8 @@ def create_malloc(out_name):
       # TODO: consider adding -DEMMALLOC_DEBUG, but that is quite slow
     else:
       cflags += ['-DNDEBUG']
+    if not shared.Settings.SUPPORT_ERRNO:
+      cflags += ['-DMALLOC_FAILURE_ACTION=']
     check_call([shared.PYTHON, shared.EMCC, shared.path_from_root('system', 'lib', malloc_source()), '-o', o] + cflags + get_cflags())
     return o