[WIP] Enable nontrapping-fp by default

emcc.py

@@ -391,8 +391,6 @@ def get_clang_flags(user_args):
     # Bulk memory may be enabled via threads or directly via -s.
     if not settings.BULK_MEMORY:
       flags.append('-mno-bulk-memory')
-  if '-mnontrapping-fptoint' not in user_args and '-mno-nontrapping-fptoint' not in user_args:
-    flags.append('-mno-nontrapping-fptoint')
 
   if settings.RELOCATABLE and '-fPIC' not in user_args:
     flags.append('-fPIC')
@@ -1416,6 +1414,12 @@ def consume_arg_file():
                                     override=True)
     elif arg == '-mno-sign-ext':
       feature_matrix.disable_feature(feature_matrix.Feature.SIGN_EXT)
+    elif arg == '-mnontrappting-fptoint':
+      feature_matrix.enable_feature(feature_matrix.Feature.NON_TRAPPING_FPTOINT,
+                                     '-mnontrapping-fptoint',
+                                     override=True)
+    elif arg == '-mno-nontrapping-fptoint':
+      feature_matrix.disable_feature(feature_matrix.Feature.NON_TRAPPING_FPTOINT)
     elif arg == '-fexceptions':
       # TODO Currently -fexceptions only means Emscripten EH. Switch to wasm
       # exception handling by default when -fexceptions is given when wasm

test/test_other.py

@@ -10432,7 +10432,7 @@ def compile(flags):
 
     compile(['-c'])
     verify_features_sec('bulk-memory', False)
-    verify_features_sec('nontrapping-fptoint', False)
+    verify_features_sec('nontrapping-fptoint', True)
     verify_features_sec('sign-ext', True)
     verify_features_sec('mutable-globals', True)
     verify_features_sec('multivalue', True)
@@ -10453,8 +10453,8 @@ def compile(flags):
     compile(['-sMIN_FIREFOX_VERSION=61', '-msign-ext'])
     verify_features_sec_linked('sign-ext', True)
 
-    compile(['-mnontrapping-fptoint', '-c'])
-    verify_features_sec('nontrapping-fptoint', True)
+    compile(['-mno-nontrapping-fptoint'])
+    verify_features_sec_linked('nontrapping-fptoint', False)
 
     # Setting this SAFARI_VERSION should enable bulk memory because it links in emscripten_memcpy_bulkmem
     # However it does not enable nontrapping-fptoint yet because it has no effect at compile time and
@@ -10464,7 +10464,7 @@ def compile(flags):
     verify_features_sec_linked('mutable-globals', True)
     verify_features_sec_linked('multivalue', True)
     verify_features_sec_linked('bulk-memory', True)
-    verify_features_sec_linked('nontrapping-fptoint', False)
+    verify_features_sec_linked('nontrapping-fptoint', True)
 
     compile(['-sMIN_SAFARI_VERSION=150000', '-mno-bulk-memory'])
     # -mno-bulk-memory at link time overrides MIN_SAFARI_VERSION

tools/feature_matrix.py

@@ -46,7 +46,7 @@ class Feature(IntEnum):
   Feature.NON_TRAPPING_FPTOINT: {
     'chrome': 75,
     'firefox': 65,
-    'safari': 150000,
+    'safari': 140100, #TODO: Reset back to 150000 when the default changes
   },
   Feature.SIGN_EXT: {
     'chrome': 74,

tools/link.py

@@ -340,6 +340,9 @@ def get_binaryen_passes():
   if not feature_matrix.caniuse(feature_matrix.Feature.SIGN_EXT):
     logger.debug('lowering sign-ext feature due to incompatible target browser engines')
     passes += ['--signext-lowering']
+  # nontrapping-fp is enabled by default in llvm. Lower it away if requested.
+  if not feature_matrix.caniuse(feature_matrix.Feature.NON_TRAPPING_FPTOINT):
+    passes += ['--llvm-nontrapping-fptoint-lowering']
   if optimizing:
     passes += ['--post-emscripten']
     if settings.SIDE_MODULE: