Handle -Wl,--stack-first being passed explicitly

Fixes: emscripten-core#21215

Author: sbc100

test/test_other.py

@@ -1197,6 +1197,15 @@ def test_wl_linkflags(self):
     self.run_process([EMCC, 'main.c', '-Wl,-L.', '-Wl,-lfoo'])
     self.run_process([EMCC, 'main.c', '-Wl,@linkflags.txt'])
 
+  def test_wl_stackfirst(self):
+    cmd = [EMCC, test_file('hello_world.c'), '-Wl,--stack-first']
+    self.run_process(cmd + ['-O0'])
+    self.run_process(cmd + ['-O2'])
+    err = self.expect_fail(cmd + ['-fsanitize=address'])
+    self.assertContained('error: --stack-first is not compatible with asan', err)
+    err = self.expect_fail(cmd + ['-sGLOBAL_BASE=1024'])
+    self.assertContained('error: --stack-first is not compatible with -sGLOBAL_BASE', err)
+
   def test_l_link(self):
     # Linking with -lLIBNAME and -L/DIRNAME should work, also should work with spaces
     create_file('main.c', '''

tools/link.py

@@ -879,14 +879,6 @@ def phase_linker_setup(options, state, newargs):
     else:
       default_setting('INCOMING_MODULE_JS_API', [])
 
-  if 'GLOBAL_BASE' not in user_settings and not settings.SHRINK_LEVEL and not settings.OPT_LEVEL:
-    # When optimizing for size it helps to put static data first before
-    # the stack (since this makes instructions for accessing this data
-    # use a smaller LEB encoding).
-    # However, for debugability is better to have the stack come first
-    # (because stack overflows will trap rather than corrupting data).
-    settings.STACK_FIRST = True
-
   # Default to TEXTDECODER=2 (always use TextDecoder to decode UTF-8 strings)
   # in -Oz builds, since custom decoder for UTF-8 takes up space.
   # In pthreads enabled builds, TEXTDECODER==2 may not work, see
@@ -1592,7 +1584,6 @@ def check_memory_setting(setting):
     # We start our global data after the shadow memory.
     # We don't need to worry about alignment here.  wasm-ld will take care of that.
     settings.GLOBAL_BASE = shadow_size
-    settings.STACK_FIRST = False
 
     if not settings.ALLOW_MEMORY_GROWTH:
       settings.INITIAL_MEMORY = total_mem
@@ -1615,6 +1606,21 @@ def check_memory_setting(setting):
   if sanitize and settings.GENERATE_SOURCE_MAP:
     settings.LOAD_SOURCE_MAP = 1
 
+  if 'GLOBAL_BASE' not in user_settings and not settings.SHRINK_LEVEL and not settings.OPT_LEVEL and not settings.USE_ASAN:
+    # When optimizing for size it helps to put static data first before
+    # the stack (since this makes instructions for accessing this data
+    # use a smaller LEB encoding).
+    # However, for debugability is better to have the stack come first
+    # (because stack overflows will trap rather than corrupting data).
+    settings.STACK_FIRST = True
+
+  if '--stack-first' in [x for _, x in state.link_flags]:
+    settings.STACK_FIRST = True
+    if settings.USE_ASAN:
+      exit_with_error('--stack-first is not compatible with asan')
+    if 'GLOBAL_BASE' in user_settings:
+      exit_with_error('--stack-first is not compatible with -sGLOBAL_BASE')
+
   set_max_memory()
 
   # check if we can address the 2GB mark and higher.