diff --git a/.gitignore b/.gitignore
index 28042929af5..b6219851acf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -30,6 +30,7 @@ trace.cpp
 test/wasm-binaries-*.tbz2
 test/wasm-torture-s-*.tbz2
 test/wasm-install/
+test/validator/*.wasm
 
 *.pyc
 CMakeFiles/
diff --git a/check.py b/check.py
index e0d56937336..4d025eb1bdb 100755
--- a/check.py
+++ b/check.py
@@ -22,7 +22,7 @@
 
 from scripts.test.support import run_command, split_wast
 from scripts.test.shared import (
-    ASM2WASM, BIN_DIR, EMCC, MOZJS, NATIVECC, NATIVEXX, NODEJS, S2WASM_EXE,
+    BIN_DIR, EMCC, MOZJS, NATIVECC, NATIVEXX, NODEJS, S2WASM_EXE,
     WASM_AS, WASM_CTOR_EVAL, WASM_OPT, WASM_SHELL, WASM_MERGE, WASM_SHELL_EXE,
     WASM_DIS, WASM_REDUCE, binary_format_check, delete_from_orbit, fail, fail_with_error,
     fail_if_not_identical, fail_if_not_contained, has_vanilla_emcc,
@@ -30,6 +30,7 @@
     requested, warnings, has_shell_timeout
 )
 
+import scripts.test.asm2wasm as asm2wasm
 import scripts.test.s2wasm as s2wasm
 import scripts.test.wasm2asm as wasm2asm
 
@@ -144,6 +145,7 @@ def run_wasm_opt_tests():
       actual = actual.replace('printing before:\n', '')
 
       expected = open(f, 'rb').read()
+
       if actual != expected:
         fail(actual, expected)
 
@@ -152,126 +154,6 @@ def run_wasm_opt_tests():
 
       minify_check(t)
 
-def run_asm2wasm_tests():
-  print '[ checking asm2wasm testcases... ]\n'
-
-  for asm in tests:
-    if asm.endswith('.asm.js'):
-      for precise in [0, 1, 2]:
-        for opts in [1, 0]:
-          cmd = ASM2WASM + [os.path.join(options.binaryen_test, asm)]
-          wasm = asm.replace('.asm.js', '.fromasm')
-          if not precise:
-            cmd += ['--emit-potential-traps', '--ignore-implicit-traps']
-            wasm += '.imprecise'
-          elif precise == 2:
-            cmd += ['--emit-clamped-potential-traps']
-            wasm += '.clamp'
-          if not opts:
-            wasm += '.no-opts'
-            if precise:
-              cmd += ['-O0'] # test that -O0 does nothing
-          else:
-            cmd += ['-O']
-          if 'debugInfo' in asm:
-            cmd += ['-g']
-          if 'noffi' in asm:
-            cmd += ['--no-legalize-javascript-ffi']
-          if precise and opts:
-            # test mem init importing
-            open('a.mem', 'wb').write(asm)
-            cmd += ['--mem-init=a.mem']
-            if asm[0] == 'e':
-              cmd += ['--mem-base=1024']
-          if 'i64' in asm or 'wasm-only' in asm or 'noffi' in asm:
-            cmd += ['--wasm-only']
-          wasm = os.path.join(options.binaryen_test, wasm)
-          print '..', asm, wasm
-
-          def do_asm2wasm_test():
-            actual = run_command(cmd)
-
-            # verify output
-            if not os.path.exists(wasm):
-              fail_with_error('output .wast file %s does not exist' % wasm)
-            expected = open(wasm, 'rb').read()
-            if actual != expected:
-              fail(actual, expected)
-
-            binary_format_check(wasm, verify_final_result=False)
-
-          # test both normally and with pass debug (so each inter-pass state is validated)
-          old_pass_debug = os.environ.get('BINARYEN_PASS_DEBUG')
-          try:
-            os.environ['BINARYEN_PASS_DEBUG'] = '1'
-            do_asm2wasm_test()
-            del os.environ['BINARYEN_PASS_DEBUG']
-            do_asm2wasm_test()
-          finally:
-            if old_pass_debug is not None:
-              os.environ['BINARYEN_PASS_DEBUG'] = old_pass_debug
-            else:
-              if 'BINARYEN_PASS_DEBUG' in os.environ:
-                del os.environ['BINARYEN_PASS_DEBUG']
-
-          # verify in wasm
-          if options.interpreter:
-            # remove imports, spec interpreter doesn't know what to do with them
-            subprocess.check_call(WASM_OPT + ['--remove-imports', wasm], stdout=open('ztemp.wast', 'w'), stderr=subprocess.PIPE)
-            proc = subprocess.Popen([options.interpreter, 'ztemp.wast'], stderr=subprocess.PIPE)
-            out, err = proc.communicate()
-            if proc.returncode != 0:
-              try: # to parse the error
-                reported = err.split(':')[1]
-                start, end = reported.split('-')
-                start_line, start_col = map(int, start.split('.'))
-                lines = open('ztemp.wast').read().split('\n')
-                print
-                print '='*80
-                print lines[start_line-1]
-                print (' '*(start_col-1)) + '^'
-                print (' '*(start_col-2)) + '/_\\'
-                print '='*80
-                print err
-              except Exception, e:
-                fail_with_error('wasm interpreter error: ' + err) # failed to pretty-print
-              fail_with_error('wasm interpreter error')
-
-          # verify debug info
-          if 'debugInfo' in asm:
-            jsmap = 'a.wasm.map'
-            cmd += ['--source-map', jsmap,
-                    '--source-map-url', 'http://example.org/' + jsmap,
-                    '-o', 'a.wasm']
-            run_command(cmd)
-            if not os.path.isfile(jsmap):
-              fail_with_error('Debug info map not created: %s' % jsmap)
-            with open(wasm + '.map', 'rb') as expected:
-              with open(jsmap, 'rb') as actual:
-                fail_if_not_identical(actual.read(), expected.read())
-            with open('a.wasm', 'rb') as binary:
-              url_section_name = bytearray([16]) + bytearray('sourceMappingURL')
-              payload = 'http://example.org/' + jsmap
-              assert len(payload) < 256, 'name too long'
-              url_section_contents = bytearray([len(payload)]) + bytearray(payload)
-              print url_section_name
-              binary_contents = bytearray(binary.read())
-              if url_section_name not in binary_contents:
-                fail_with_error('source map url section not found in binary')
-              if url_section_contents not in binary_contents[binary_contents.index(url_section_name):]:
-                fail_with_error('source map url not found in url section')
-
-
-  print '\n[ checking asm2wasm binary reading/writing... ]\n'
-
-  asmjs = os.path.join(options.binaryen_test, 'hello_world.asm.js')
-  delete_from_orbit('a.wasm')
-  delete_from_orbit('b.wast')
-  run_command(ASM2WASM + [asmjs, '-o', 'a.wasm'])
-  assert open('a.wasm', 'rb').read()[0] == '\0', 'we emit binary by default'
-  run_command(ASM2WASM + [asmjs, '-o', 'b.wast', '-S'])
-  assert open('b.wast', 'rb').read()[0] != '\0', 'we emit text with -S'
-
 def run_wasm_dis_tests():
   print '\n[ checking wasm-dis on provided binaries... ]\n'
 
@@ -717,7 +599,8 @@ def execute():
 # Run all the tests
 run_help_tests()
 run_wasm_opt_tests()
-run_asm2wasm_tests()
+asm2wasm.test_asm2wasm()
+asm2wasm.test_asm2wasm_binary()
 run_wasm_dis_tests()
 run_wasm_merge_tests()
 run_ctor_eval_tests()
diff --git a/scripts/test/asm2wasm.py b/scripts/test/asm2wasm.py
new file mode 100644
index 00000000000..db37a237aff
--- /dev/null
+++ b/scripts/test/asm2wasm.py
@@ -0,0 +1,160 @@
+#!/usr/bin/env python
+
+# Copyright 2017 WebAssembly Community Group participants
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import subprocess
+
+from support import run_command
+from shared import (
+    ASM2WASM, WASM_OPT, binary_format_check, delete_from_orbit,
+    fail, fail_with_error, fail_if_not_identical, options, tests
+)
+
+
+def test_asm2wasm():
+  print '[ checking asm2wasm testcases... ]\n'
+
+  for asm in tests:
+    if not asm.endswith('.asm.js'):
+      continue
+    for precise in [0, 1, 2]:
+      for opts in [1, 0]:
+        cmd = ASM2WASM + [os.path.join(options.binaryen_test, asm)]
+        wasm = asm.replace('.asm.js', '.fromasm')
+        if not precise:
+          cmd += ['--emit-potential-traps', '--ignore-implicit-traps']
+          wasm += '.imprecise'
+        elif precise == 2:
+          cmd += ['--emit-clamped-potential-traps']
+          wasm += '.clamp'
+        if not opts:
+          wasm += '.no-opts'
+          if precise:
+            cmd += ['-O0']  # test that -O0 does nothing
+        else:
+          cmd += ['-O']
+        if 'debugInfo' in asm:
+          cmd += ['-g']
+        if 'noffi' in asm:
+          cmd += ['--no-legalize-javascript-ffi']
+        if precise and opts:
+          # test mem init importing
+          open('a.mem', 'wb').write(asm)
+          cmd += ['--mem-init=a.mem']
+          if asm[0] == 'e':
+            cmd += ['--mem-base=1024']
+        if 'i64' in asm or 'wasm-only' in asm or 'noffi' in asm:
+          cmd += ['--wasm-only']
+        wasm = os.path.join(options.binaryen_test, wasm)
+        print '..', asm, wasm
+
+        def do_asm2wasm_test():
+          actual = run_command(cmd)
+
+          # verify output
+          if not os.path.exists(wasm):
+            fail_with_error('output .wast file %s does not exist' % wasm)
+          expected = open(wasm, 'rb').read()
+          if actual != expected:
+            fail(actual, expected)
+
+          binary_format_check(wasm, verify_final_result=False)
+
+        # test both normally and with pass debug (so each inter-pass state
+        # is validated)
+        old_pass_debug = os.environ.get('BINARYEN_PASS_DEBUG')
+        try:
+          os.environ['BINARYEN_PASS_DEBUG'] = '1'
+          print "With BINARYEN_PASS_DEBUG=1:"
+          do_asm2wasm_test()
+          del os.environ['BINARYEN_PASS_DEBUG']
+          print "With BINARYEN_PASS_DEBUG disabled:"
+          do_asm2wasm_test()
+        finally:
+          if old_pass_debug is not None:
+            os.environ['BINARYEN_PASS_DEBUG'] = old_pass_debug
+          else:
+            if 'BINARYEN_PASS_DEBUG' in os.environ:
+              del os.environ['BINARYEN_PASS_DEBUG']
+
+        # verify in wasm
+        if options.interpreter:
+          # remove imports, spec interpreter doesn't know what to do with them
+          subprocess.check_call(WASM_OPT + ['--remove-imports', wasm],
+                                stdout=open('ztemp.wast', 'w'),
+                                stderr=subprocess.PIPE)
+          proc = subprocess.Popen([options.interpreter, 'ztemp.wast'],
+                                  stderr=subprocess.PIPE)
+          out, err = proc.communicate()
+          if proc.returncode != 0:
+            try:  # to parse the error
+              reported = err.split(':')[1]
+              start, end = reported.split('-')
+              start_line, start_col = map(int, start.split('.'))
+              lines = open('ztemp.wast').read().split('\n')
+              print
+              print '=' * 80
+              print lines[start_line - 1]
+              print (' ' * (start_col - 1)) + '^'
+              print (' ' * (start_col - 2)) + '/_\\'
+              print '=' * 80
+              print err
+            except Exception:
+              # failed to pretty-print
+              fail_with_error('wasm interpreter error: ' + err)
+            fail_with_error('wasm interpreter error')
+
+        # verify debug info
+        if 'debugInfo' in asm:
+          jsmap = 'a.wasm.map'
+          cmd += ['--source-map', jsmap,
+                  '--source-map-url', 'http://example.org/' + jsmap,
+                  '-o', 'a.wasm']
+          run_command(cmd)
+          if not os.path.isfile(jsmap):
+            fail_with_error('Debug info map not created: %s' % jsmap)
+          with open(wasm + '.map', 'rb') as expected:
+            with open(jsmap, 'rb') as actual:
+              fail_if_not_identical(actual.read(), expected.read())
+          with open('a.wasm', 'rb') as binary:
+            url_section_name = bytearray([16]) + bytearray('sourceMappingURL')
+            url = 'http://example.org/' + jsmap
+            assert len(url) < 256, 'name too long'
+            url_section_contents = bytearray([len(url)]) + bytearray(url)
+            print url_section_name
+            binary_contents = bytearray(binary.read())
+            if url_section_name not in binary_contents:
+              fail_with_error('source map url section not found in binary')
+            url_section_index = binary_contents.index(url_section_name)
+            if url_section_contents not in binary_contents[url_section_index:]:
+              fail_with_error('source map url not found in url section')
+
+
+def test_asm2wasm_binary():
+  print '\n[ checking asm2wasm binary reading/writing... ]\n'
+
+  asmjs = os.path.join(options.binaryen_test, 'hello_world.asm.js')
+  delete_from_orbit('a.wasm')
+  delete_from_orbit('b.wast')
+  run_command(ASM2WASM + [asmjs, '-o', 'a.wasm'])
+  assert open('a.wasm', 'rb').read()[0] == '\0', 'we emit binary by default'
+  run_command(ASM2WASM + [asmjs, '-o', 'b.wast', '-S'])
+  assert open('b.wast', 'rb').read()[0] != '\0', 'we emit text with -S'
+
+
+if __name__ == '__main__':
+  test_asm2wasm()
+  test_asm2wasm_binary()
diff --git a/scripts/test/s2wasm.py b/scripts/test/s2wasm.py
index 3f38acbace0..fcba17d1836 100755
--- a/scripts/test/s2wasm.py
+++ b/scripts/test/s2wasm.py
@@ -32,38 +32,48 @@ def test_s2wasm():
   fail_if_not_contained(
       output, '(import "env" "memory" (memory $0 1))')
 
+  extension_arg_map = {
+      '.wast': [],
+      '.clamp.wast': ['--emit-clamped-potential-traps'],
+      '.js.wast': ['--emit-jsified-potential-traps'],
+  }
   for dot_s_dir in ['dot_s', 'llvm_autogenerated']:
     dot_s_path = os.path.join(options.binaryen_test, dot_s_dir)
     for s in sorted(os.listdir(dot_s_path)):
       if not s.endswith('.s'):
         continue
       print '..', s
-      wasm = s.replace('.s', '.wast')
-      full = os.path.join(options.binaryen_test, dot_s_dir, s)
-      stack_alloc = (['--allocate-stack=1024']
-                     if dot_s_dir == 'llvm_autogenerated'
-                     else [])
-      cmd = S2WASM + [full, '--emscripten-glue'] + stack_alloc
-      if s.startswith('start_'):
-        cmd.append('--start')
-      actual = run_command(cmd)
-
-      # verify output
-      expected_file = os.path.join(options.binaryen_test, dot_s_dir, wasm)
-      if not os.path.exists(expected_file):
-        print actual
-        fail_with_error('output ' + expected_file + ' does not exist')
-      expected = open(expected_file, 'rb').read()
-      if actual != expected:
-        fail(actual, expected)
-
-      # verify with options
-      cmd = S2WASM + [full, '--global-base=1024'] + stack_alloc
-      run_command(cmd)
-
-      # run wasm-shell on the .wast to verify that it parses
-      cmd = WASM_SHELL + [expected_file]
-      run_command(cmd)
+      for ext, ext_args in extension_arg_map.iteritems():
+        wasm = s.replace('.s', ext)
+        expected_file = os.path.join(options.binaryen_test, dot_s_dir, wasm)
+        expected_exists = os.path.exists(expected_file)
+        if ext != '.wast' and not expected_exists:
+          continue
+
+        full = os.path.join(options.binaryen_test, dot_s_dir, s)
+        stack_alloc = (['--allocate-stack=1024']
+                       if dot_s_dir == 'llvm_autogenerated'
+                       else [])
+        cmd = S2WASM + [full, '--emscripten-glue'] + stack_alloc + ext_args
+        if s.startswith('start_'):
+          cmd.append('--start')
+        actual = run_command(cmd)
+
+        # verify output
+        if not expected_exists:
+          print actual
+          fail_with_error('output ' + expected_file + ' does not exist')
+        expected = open(expected_file, 'rb').read()
+        if actual != expected:
+          fail(actual, expected)
+
+        # verify with options
+        cmd = S2WASM + [full, '--global-base=1024'] + stack_alloc
+        run_command(cmd)
+
+        # run wasm-shell on the .wast to verify that it parses
+        cmd = WASM_SHELL + [expected_file]
+        run_command(cmd)
 
 
 def test_linker():
diff --git a/src/asm2wasm.h b/src/asm2wasm.h
index 044517d12ba..7d4ce5fbeb5 100644
--- a/src/asm2wasm.h
+++ b/src/asm2wasm.h
@@ -33,6 +33,7 @@
 #include "parsing.h"
 #include "ast_utils.h"
 #include "ast/branch-utils.h"
+#include "ast/trapping.h"
 #include "wasm-builder.h"
 #include "wasm-emscripten.h"
 #include "wasm-module-building.h"
@@ -88,10 +89,6 @@ Name I32_CTTZ("i32_cttz"),
      I64_CTTZ("i64_cttz"),
      I64_CTLZ("i64_ctlz"),
      I64_CTPOP("i64_ctpop"),
-     I64S_REM("i64s-rem"),
-     I64U_REM("i64u-rem"),
-     I64S_DIV("i64s-div"),
-     I64U_DIV("i64u-div"),
      F32_COPYSIGN("f32_copysign"),
      F64_COPYSIGN("f64_copysign"),
      LOAD1("load1"),
@@ -356,12 +353,6 @@ struct AdjustDebugInfo : public WalkerPass<PostWalker<AdjustDebugInfo, Visitor<A
 
 class Asm2WasmBuilder {
 public:
-  enum class TrapMode {
-    Allow,
-    Clamp,
-    JS
-  };
-
   Module& wasm;
 
   MixedArena &allocator;
@@ -388,6 +379,7 @@ class Asm2WasmBuilder {
   bool debug;
     
   TrapMode trapMode;
+  TrappingFunctionContainer trappingFunctions;
   PassOptions passOptions;
   bool legalizeJavaScriptFFI;
   bool runOptimizationPasses;
@@ -522,6 +514,7 @@ class Asm2WasmBuilder {
        preprocessor(preprocessor),
        debug(debug),
        trapMode(trapMode),
+       trappingFunctions(trapMode, wasm, /* immediate = */ true),
        passOptions(passOptions),
        legalizeJavaScriptFFI(legalizeJavaScriptFFI),
        runOptimizationPasses(runOptimizationPasses),
@@ -701,277 +694,8 @@ class Asm2WasmBuilder {
     return ret;
   }
 
-  // converts an f32 to an f64 if necessary
   Expression* ensureDouble(Expression* expr) {
-    if (expr->type == f32) {
-      auto conv = allocator.alloc<Unary>();
-      conv->op = PromoteFloat32;
-      conv->value = expr;
-      conv->type = WasmType::f64;
-      return conv;
-    }
-    assert(expr->type == f64);
-    return expr;
-  }
-
-  // Some binary opts might trap, so emit them safely if necessary
-  Expression* makeTrappingI32Binary(BinaryOp op, Expression* left, Expression* right) {
-    if (trapMode == TrapMode::Allow) return builder.makeBinary(op, left, right);
-    // the wasm operation might trap if done over 0, so generate a safe call
-    auto *call = allocator.alloc<Call>();
-    switch (op) {
-      case BinaryOp::RemSInt32: call->target = I32S_REM; break;
-      case BinaryOp::RemUInt32: call->target = I32U_REM; break;
-      case BinaryOp::DivSInt32: call->target = I32S_DIV; break;
-      case BinaryOp::DivUInt32: call->target = I32U_DIV; break;
-      default: WASM_UNREACHABLE();
-    }
-    call->operands.push_back(left);
-    call->operands.push_back(right);
-    call->type = i32;
-    static std::set<Name> addedFunctions;
-    if (addedFunctions.count(call->target) == 0) {
-      Expression* result = builder.makeBinary(op,
-        builder.makeGetLocal(0, i32),
-        builder.makeGetLocal(1, i32)
-      );
-      if (op == DivSInt32) {
-        // guard against signed division overflow
-        result = builder.makeIf(
-          builder.makeBinary(AndInt32,
-            builder.makeBinary(EqInt32,
-              builder.makeGetLocal(0, i32),
-              builder.makeConst(Literal(std::numeric_limits<int32_t>::min()))
-            ),
-            builder.makeBinary(EqInt32,
-              builder.makeGetLocal(1, i32),
-              builder.makeConst(Literal(int32_t(-1)))
-            )
-          ),
-          builder.makeConst(Literal(int32_t(0))),
-          result
-        );
-      }
-      addedFunctions.insert(call->target);
-      auto func = new Function;
-      func->name = call->target;
-      func->params.push_back(i32);
-      func->params.push_back(i32);
-      func->result = i32;
-      func->body = builder.makeIf(
-        builder.makeUnary(EqZInt32,
-          builder.makeGetLocal(1, i32)
-        ),
-        builder.makeConst(Literal(int32_t(0))),
-        result
-      );
-      wasm.addFunction(func);
-    }
-    return call;
-  }
-
-  // Some binary opts might trap, so emit them safely if necessary
-  Expression* makeTrappingI64Binary(BinaryOp op, Expression* left, Expression* right) {
-    if (trapMode == TrapMode::Allow) return builder.makeBinary(op, left, right);
-    // wasm operation might trap if done over 0, so generate a safe call
-    auto *call = allocator.alloc<Call>();
-    switch (op) {
-      case BinaryOp::RemSInt64: call->target = I64S_REM; break;
-      case BinaryOp::RemUInt64: call->target = I64U_REM; break;
-      case BinaryOp::DivSInt64: call->target = I64S_DIV; break;
-      case BinaryOp::DivUInt64: call->target = I64U_DIV; break;
-      default: WASM_UNREACHABLE();
-    }
-    call->operands.push_back(left);
-    call->operands.push_back(right);
-    call->type = i64;
-    static std::set<Name> addedFunctions;
-    if (addedFunctions.count(call->target) == 0) {
-      Expression* result = builder.makeBinary(op,
-        builder.makeGetLocal(0, i64),
-        builder.makeGetLocal(1, i64)
-      );
-      if (op == DivSInt64) {
-        // guard against signed division overflow
-        result = builder.makeIf(
-          builder.makeBinary(AndInt32,
-            builder.makeBinary(EqInt64,
-              builder.makeGetLocal(0, i64),
-              builder.makeConst(Literal(std::numeric_limits<int64_t>::min()))
-            ),
-            builder.makeBinary(EqInt64,
-              builder.makeGetLocal(1, i64),
-              builder.makeConst(Literal(int64_t(-1)))
-            )
-          ),
-          builder.makeConst(Literal(int64_t(0))),
-          result
-        );
-      }
-      addedFunctions.insert(call->target);
-      auto func = new Function;
-      func->name = call->target;
-      func->params.push_back(i64);
-      func->params.push_back(i64);
-      func->result = i64;
-      func->body = builder.makeIf(
-        builder.makeUnary(EqZInt64,
-          builder.makeGetLocal(1, i64)
-        ),
-        builder.makeConst(Literal(int64_t(0))),
-        result
-      );
-      wasm.addFunction(func);
-    }
-    return call;
-  }
-
-  // Some conversions might trap, so emit them safely if necessary
-  Expression* makeTrappingFloatToInt32(bool signed_, Expression* value) {
-    if (trapMode == TrapMode::Allow) {
-      auto ret = allocator.alloc<Unary>();
-      ret->value = value;
-      bool isF64 = ret->value->type == f64;
-      if (signed_) {
-        ret->op = isF64 ? TruncSFloat64ToInt32 : TruncSFloat32ToInt32;
-      } else {
-        ret->op = isF64 ? TruncUFloat64ToInt32 : TruncUFloat32ToInt32;
-      }
-      ret->type = WasmType::i32;
-      return ret;
-    }
-    // WebAssembly traps on float-to-int overflows, but asm.js wouldn't, so we must do something
-    // First, normalize input to f64
-    auto input = ensureDouble(value);
-    // We can handle this in one of two ways: clamping, which is fast, or JS, which
-    // is precisely like JS but in order to do that we do a slow ffi
-    if (trapMode == TrapMode::JS) {
-      // WebAssembly traps on float-to-int overflows, but asm.js wouldn't, so we must emulate that
-      CallImport *ret = allocator.alloc<CallImport>();
-      ret->target = F64_TO_INT;
-      ret->operands.push_back(input);
-      ret->type = i32;
-      static bool addedImport = false;
-      if (!addedImport) {
-        addedImport = true;
-        auto import = new Import; // f64-to-int = asm2wasm.f64-to-int;
-        import->name = F64_TO_INT;
-        import->module = ASM2WASM;
-        import->base = F64_TO_INT;
-        import->functionType = ensureFunctionType("id", &wasm)->name;
-        import->kind = ExternalKind::Function;
-        wasm.addImport(import);
-      }
-      return ret;
-    }
-    assert(trapMode == TrapMode::Clamp);
-    Call *ret = allocator.alloc<Call>();
-    ret->target = F64_TO_INT;
-    ret->operands.push_back(input);
-    ret->type = i32;
-    static bool added = false;
-    if (!added) {
-      added = true;
-      auto func = new Function;
-      func->name = ret->target;
-      func->params.push_back(f64);
-      func->result = i32;
-      func->body = builder.makeUnary(TruncSFloat64ToInt32,
-        builder.makeGetLocal(0, f64)
-      );
-      // too small XXX this is different than asm.js, which does frem. here we clamp, which is much simpler/faster, and similar to native builds
-      func->body = builder.makeIf(
-        builder.makeBinary(LeFloat64,
-          builder.makeGetLocal(0, f64),
-          builder.makeConst(Literal(double(std::numeric_limits<int32_t>::min()) - 1))
-        ),
-        builder.makeConst(Literal(int32_t(std::numeric_limits<int32_t>::min()))),
-        func->body
-      );
-      // too big XXX see above
-      func->body = builder.makeIf(
-        builder.makeBinary(GeFloat64,
-          builder.makeGetLocal(0, f64),
-          builder.makeConst(Literal(double(std::numeric_limits<int32_t>::max()) + 1))
-        ),
-        builder.makeConst(Literal(int32_t(std::numeric_limits<int32_t>::min()))), // NB: min here as well. anything out of range => to the min
-        func->body
-      );
-      // nan
-      func->body = builder.makeIf(
-        builder.makeBinary(NeFloat64,
-          builder.makeGetLocal(0, f64),
-          builder.makeGetLocal(0, f64)
-        ),
-        builder.makeConst(Literal(int32_t(std::numeric_limits<int32_t>::min()))), // NB: min here as well. anything invalid => to the min
-        func->body
-      );
-      wasm.addFunction(func);
-    }
-    return ret;
-  }
-
-  Expression* makeTrappingFloatToInt64(bool signed_, Expression* value) {
-    if (trapMode == TrapMode::Allow) {
-      auto ret = allocator.alloc<Unary>();
-      ret->value = value;
-      bool isF64 = ret->value->type == f64;
-      if (signed_) {
-        ret->op = isF64 ? TruncSFloat64ToInt64 : TruncSFloat32ToInt64;
-      } else {
-        ret->op = isF64 ? TruncUFloat64ToInt64 : TruncUFloat32ToInt64;
-      }
-      ret->type = WasmType::i64;
-      return ret;
-    }
-    // WebAssembly traps on float-to-int overflows, but asm.js wouldn't, so we must do something
-    // First, normalize input to f64
-    auto input = ensureDouble(value);
-    // There is no "JS" way to handle this, as no i64s in JS, so always clamp if we don't allow traps
-    Call *ret = allocator.alloc<Call>();
-    ret->target = F64_TO_INT64;
-    ret->operands.push_back(input);
-    ret->type = i64;
-    static bool added = false;
-    if (!added) {
-      added = true;
-      auto func = new Function;
-      func->name = ret->target;
-      func->params.push_back(f64);
-      func->result = i64;
-      func->body = builder.makeUnary(TruncSFloat64ToInt64,
-        builder.makeGetLocal(0, f64)
-      );
-      // too small
-      func->body = builder.makeIf(
-        builder.makeBinary(LeFloat64,
-          builder.makeGetLocal(0, f64),
-          builder.makeConst(Literal(double(std::numeric_limits<int64_t>::min()) - 1))
-        ),
-        builder.makeConst(Literal(int64_t(std::numeric_limits<int64_t>::min()))),
-        func->body
-      );
-      // too big
-      func->body = builder.makeIf(
-        builder.makeBinary(GeFloat64,
-          builder.makeGetLocal(0, f64),
-          builder.makeConst(Literal(double(std::numeric_limits<int64_t>::max()) + 1))
-        ),
-        builder.makeConst(Literal(int64_t(std::numeric_limits<int64_t>::min()))), // NB: min here as well. anything out of range => to the min
-        func->body
-      );
-      // nan
-      func->body = builder.makeIf(
-        builder.makeBinary(NeFloat64,
-          builder.makeGetLocal(0, f64),
-          builder.makeGetLocal(0, f64)
-        ),
-        builder.makeConst(Literal(int64_t(std::numeric_limits<int64_t>::min()))), // NB: min here as well. anything invalid => to the min
-        func->body
-      );
-      wasm.addFunction(func);
-    }
-    return ret;
+    return wasm::ensureDouble(expr, allocator);
   }
 
   Expression* truncateToInt32(Expression* value) {
@@ -1433,15 +1157,23 @@ void Asm2WasmBuilder::processAsm(Ref ast) {
           }
         }
       }
-      auto importResult = getModule()->getFunctionType(getModule()->getImport(curr->target)->functionType)->result;
+      Module* wasm = getModule();
+      auto importResult = wasm->getFunctionType(wasm->getImport(curr->target)->functionType)->result;
       if (curr->type != importResult) {
         auto old = curr->type;
         curr->type = importResult;
         if (importResult == f64) {
           // we use a JS f64 value which is the most general, and convert to it
           switch (old) {
-            case i32: replaceCurrent(parent->makeTrappingFloatToInt32(true /* signed, asm.js ffi */, curr)); break;
-            case f32: replaceCurrent(parent->builder.makeUnary(DemoteFloat64, curr)); break;
+            case i32:  {
+              Unary* trunc = parent->builder.makeUnary(TruncSFloat64ToInt32, curr);
+              replaceCurrent(makeTrappingUnary(trunc, parent->trappingFunctions));
+              break;
+            }
+            case f32: {
+              replaceCurrent(parent->builder.makeUnary(DemoteFloat64, curr));
+              break;
+            }
             case none: {
               // this function returns a value, but we are not using it, so it must be dropped.
               // autodrop will do that for us.
@@ -1896,12 +1628,8 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
           wasm.addImport(import);
         }
         return call;
-      } else if (trapMode != TrapMode::Allow &&
-                 (ret->op == BinaryOp::RemSInt32 || ret->op == BinaryOp::RemUInt32 ||
-                  ret->op == BinaryOp::DivSInt32 || ret->op == BinaryOp::DivUInt32)) {
-        return makeTrappingI32Binary(ret->op, ret->left, ret->right);
       }
-      return ret;
+      return makeTrappingBinary(ret, trappingFunctions);
     } else if (what == SUB) {
       Ref target = ast[1];
       assert(target->isString());
@@ -1969,7 +1697,20 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
         // ~, might be ~~ as a coercion or just a not
         if (ast[2]->isArray(UNARY_PREFIX) && ast[2][1] == B_NOT) {
           // if we have an unsigned coercion on us, it is an unsigned op
-          return makeTrappingFloatToInt32(!isParentUnsignedCoercion(astStackHelper.getParent()), process(ast[2][2]));
+          Expression* expr = process(ast[2][2]);
+          bool isSigned = !isParentUnsignedCoercion(astStackHelper.getParent());
+          bool isF64 = expr->type == f64;
+          UnaryOp op;
+          if (isSigned && isF64) {
+            op = UnaryOp::TruncSFloat64ToInt32;
+          } else if (isSigned && !isF64) {
+            op = UnaryOp::TruncSFloat32ToInt32;
+          } else if (!isSigned && isF64) {
+            op = UnaryOp::TruncUFloat64ToInt32;
+          } else { // !isSigned && !isF64
+            op = UnaryOp::TruncUFloat32ToInt32;
+          }
+          return makeTrappingUnary(builder.makeUnary(op, expr), trappingFunctions);
         }
         // no bitwise unary not, so do xor with -1
         auto ret = allocator.alloc<Binary>();
@@ -2216,8 +1957,22 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
                 if (name == I64_S2D) return builder.makeUnary(UnaryOp::ConvertSInt64ToFloat64, value);
                 if (name == I64_U2F) return builder.makeUnary(UnaryOp::ConvertUInt64ToFloat32, value);
                 if (name == I64_U2D) return builder.makeUnary(UnaryOp::ConvertUInt64ToFloat64, value);
-                if (name == I64_F2S || name == I64_D2S) return makeTrappingFloatToInt64(true /* signed */, value);
-                if (name == I64_F2U || name == I64_D2U) return makeTrappingFloatToInt64(false /* unsigned */, value);
+                if (name == I64_F2S) {
+                  Unary* conv = builder.makeUnary(UnaryOp::TruncSFloat32ToInt64, value);
+                  return makeTrappingUnary(conv, trappingFunctions);
+                }
+                if (name == I64_D2S) {
+                  Unary* conv = builder.makeUnary(UnaryOp::TruncSFloat64ToInt64, value);
+                  return makeTrappingUnary(conv, trappingFunctions);
+                }
+                if (name == I64_F2U) {
+                  Unary* conv = builder.makeUnary(UnaryOp::TruncUFloat32ToInt64, value);
+                  return makeTrappingUnary(conv, trappingFunctions);
+                }
+                if (name == I64_D2U) {
+                  Unary* conv = builder.makeUnary(UnaryOp::TruncUFloat64ToInt64, value);
+                  return makeTrappingUnary(conv, trappingFunctions);
+                }
                 if (name == I64_BC2D) return builder.makeUnary(UnaryOp::ReinterpretInt64, value);
                 if (name == I64_BC2I) return builder.makeUnary(UnaryOp::ReinterpretFloat64, value);
                 if (name == I64_CTTZ) return builder.makeUnary(UnaryOp::CtzInt64, value);
@@ -2231,10 +1986,22 @@ Function* Asm2WasmBuilder::processFunction(Ref ast) {
                 if (name == I64_ADD) return builder.makeBinary(BinaryOp::AddInt64, left, right);
                 if (name == I64_SUB) return builder.makeBinary(BinaryOp::SubInt64, left, right);
                 if (name == I64_MUL) return builder.makeBinary(BinaryOp::MulInt64, left, right);
-                if (name == I64_UDIV) return makeTrappingI64Binary(BinaryOp::DivUInt64, left, right);
-                if (name == I64_SDIV) return makeTrappingI64Binary(BinaryOp::DivSInt64, left, right);
-                if (name == I64_UREM) return makeTrappingI64Binary(BinaryOp::RemUInt64, left, right);
-                if (name == I64_SREM) return makeTrappingI64Binary(BinaryOp::RemSInt64, left, right);
+                if (name == I64_UDIV) {
+                  Binary* div = builder.makeBinary(BinaryOp::DivUInt64, left, right);
+                  return makeTrappingBinary(div, trappingFunctions);
+                }
+                if (name == I64_SDIV) {
+                  Binary* div = builder.makeBinary(BinaryOp::DivSInt64, left, right);
+                  return makeTrappingBinary(div, trappingFunctions);
+                }
+                if (name == I64_UREM) {
+                  Binary* rem = builder.makeBinary(BinaryOp::RemUInt64, left, right);
+                  return makeTrappingBinary(rem, trappingFunctions);
+                }
+                if (name == I64_SREM) {
+                  Binary* rem = builder.makeBinary(BinaryOp::RemSInt64, left, right);
+                  return makeTrappingBinary(rem, trappingFunctions);
+                }
                 if (name == I64_AND) return builder.makeBinary(BinaryOp::AndInt64, left, right);
                 if (name == I64_OR) return builder.makeBinary(BinaryOp::OrInt64, left, right);
                 if (name == I64_XOR) return builder.makeBinary(BinaryOp::XorInt64, left, right);
diff --git a/src/asm_v_wasm.h b/src/asm_v_wasm.h
index 53881861cf5..d42a1082aee 100644
--- a/src/asm_v_wasm.h
+++ b/src/asm_v_wasm.h
@@ -70,6 +70,9 @@ FunctionType* sigToFunctionType(std::string sig);
 
 FunctionType* ensureFunctionType(std::string sig, Module* wasm);
 
+// converts an f32 to an f64 if necessary
+Expression* ensureDouble(Expression* expr, MixedArena& allocator);
+
 } // namespace wasm
 
 #endif // wasm_asm_v_wasm_h
diff --git a/src/asmjs/asm_v_wasm.cpp b/src/asmjs/asm_v_wasm.cpp
index ae7d320cacf..bfb04a9fd57 100644
--- a/src/asmjs/asm_v_wasm.cpp
+++ b/src/asmjs/asm_v_wasm.cpp
@@ -109,4 +109,16 @@ FunctionType* ensureFunctionType(std::string sig, Module* wasm) {
   return type;
 }
 
+Expression* ensureDouble(Expression* expr, MixedArena& allocator) {
+  if (expr->type == f32) {
+    auto conv = allocator.alloc<Unary>();
+    conv->op = PromoteFloat32;
+    conv->value = expr;
+    conv->type = WasmType::f64;
+    return conv;
+  }
+  assert(expr->type == f64);
+  return expr;
+}
+
 } // namespace wasm
diff --git a/src/asmjs/shared-constants.cpp b/src/asmjs/shared-constants.cpp
index 43c3d106555..f62be6168b3 100644
--- a/src/asmjs/shared-constants.cpp
+++ b/src/asmjs/shared-constants.cpp
@@ -42,7 +42,13 @@ cashew::IString GLOBAL("global"),
                 ASM2WASM("asm2wasm"),
                 F64_REM("f64-rem"),
                 F64_TO_INT("f64-to-int"),
+                F64_TO_UINT("f64-to-uint"),
                 F64_TO_INT64("f64-to-int64"),
+                F64_TO_UINT64("f64-to-uint64"),
+                F32_TO_INT("f32-to-int"),
+                F32_TO_UINT("f32-to-uint"),
+                F32_TO_INT64("f32-to-int64"),
+                F32_TO_UINT64("f32-to-uint64"),
                 I32S_DIV("i32s-div"),
                 I32U_DIV("i32u-div"),
                 I32S_REM("i32s-rem"),
diff --git a/src/asmjs/shared-constants.h b/src/asmjs/shared-constants.h
index ce5cd95a65e..7e4b27c8590 100644
--- a/src/asmjs/shared-constants.h
+++ b/src/asmjs/shared-constants.h
@@ -45,7 +45,13 @@ extern cashew::IString GLOBAL,
                 ASM2WASM,
                 F64_REM,
                 F64_TO_INT,
+                F64_TO_UINT,
                 F64_TO_INT64,
+                F64_TO_UINT64,
+                F32_TO_INT,
+                F32_TO_UINT,
+                F32_TO_INT64,
+                F32_TO_UINT64,
                 I32S_DIV,
                 I32U_DIV,
                 I32S_REM,
diff --git a/src/ast/trapping.h b/src/ast/trapping.h
new file mode 100644
index 00000000000..80cc14da913
--- /dev/null
+++ b/src/ast/trapping.h
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_ast_trapping_h
+#define wasm_ast_trapping_h
+
+#include "pass.h"
+
+namespace wasm {
+
+enum class TrapMode {
+  Allow,
+  Clamp,
+  JS
+};
+
+inline void addTrapModePass(PassRunner& runner, TrapMode trapMode) {
+  if (trapMode == TrapMode::Clamp) {
+    runner.add("trap-mode-clamp");
+  } else if (trapMode == TrapMode::JS) {
+    runner.add("trap-mode-js");
+  }
+}
+
+class TrappingFunctionContainer {
+public:
+  TrappingFunctionContainer(TrapMode mode, Module &wasm, bool immediate = false)
+    : mode(mode),
+      wasm(wasm),
+      immediate(immediate) { }
+
+  bool hasFunction(Name name) {
+    return functions.find(name) != functions.end();
+  }
+  bool hasImport(Name name) {
+    return imports.find(name) != imports.end();
+  }
+
+  void addFunction(Function* function) {
+    functions[function->name] = function;
+    if (immediate) {
+      wasm.addFunction(function);
+    }
+  }
+  void addImport(Import* import) {
+    imports[import->name] = import;
+    if (immediate) {
+      wasm.addImport(import);
+    }
+  }
+
+  void addToModule() {
+    if (!immediate) {
+      for (auto &pair : functions) {
+        wasm.addFunction(pair.second);
+      }
+      for (auto &pair : imports) {
+        wasm.addImport(pair.second);
+      }
+    }
+    functions.clear();
+    imports.clear();
+  }
+
+  TrapMode getMode() {
+    return mode;
+  }
+
+  Module& getModule() {
+    return wasm;
+  }
+
+private:
+  std::map<Name, Function*> functions;
+  std::map<Name, Import*> imports;
+
+  TrapMode mode;
+  Module& wasm;
+  bool immediate;
+};
+
+Expression* makeTrappingBinary(Binary* curr, TrappingFunctionContainer &trappingFunctions);
+Expression* makeTrappingUnary(Unary* curr, TrappingFunctionContainer &trappingFunctions);
+
+} // wasm
+
+#endif // wasm_ast_trapping_h
diff --git a/src/passes/CMakeLists.txt b/src/passes/CMakeLists.txt
index 6870259c4a1..3cb00b79644 100644
--- a/src/passes/CMakeLists.txt
+++ b/src/passes/CMakeLists.txt
@@ -34,6 +34,7 @@ SET(passes_SOURCES
   RemoveUnusedModuleElements.cpp
   ReorderLocals.cpp
   ReorderFunctions.cpp
+  TrapMode.cpp
   SafeHeap.cpp
   SimplifyLocals.cpp
   SSAify.cpp
diff --git a/src/passes/TrapMode.cpp b/src/passes/TrapMode.cpp
new file mode 100644
index 00000000000..e648f66a573
--- /dev/null
+++ b/src/passes/TrapMode.cpp
@@ -0,0 +1,318 @@
+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//
+// Pass that supports potentially-trapping wasm operations.
+// For example, integer division traps when dividing by zero, so this pass
+// generates a check and replaces the result with zero in that case.
+//
+
+#include "asm_v_wasm.h"
+#include "asmjs/shared-constants.h"
+#include "ast/trapping.h"
+#include "mixed_arena.h"
+#include "pass.h"
+#include "wasm.h"
+#include "wasm-builder.h"
+#include "wasm-printing.h"
+#include "wasm-type.h"
+#include "support/name.h"
+
+namespace wasm {
+
+Name I64S_REM("i64s-rem"),
+     I64U_REM("i64u-rem"),
+     I64S_DIV("i64s-div"),
+     I64U_DIV("i64u-div");
+
+Name getBinaryFuncName(Binary* curr) {
+  switch (curr->op) {
+    case RemSInt32: return I32S_REM;
+    case RemUInt32: return I32U_REM;
+    case DivSInt32: return I32S_DIV;
+    case DivUInt32: return I32U_DIV;
+    case RemSInt64: return I64S_REM;
+    case RemUInt64: return I64U_REM;
+    case DivSInt64: return I64S_DIV;
+    case DivUInt64: return I64U_DIV;
+    default:        return Name();
+  }
+}
+
+Name getUnaryFuncName(Unary* curr) {
+  switch (curr->op) {
+  case TruncSFloat32ToInt32: return F32_TO_INT;
+  case TruncUFloat32ToInt32: return F32_TO_UINT;
+  case TruncSFloat32ToInt64: return F32_TO_INT64;
+  case TruncUFloat32ToInt64: return F32_TO_UINT64;
+  case TruncSFloat64ToInt32: return F64_TO_INT;
+  case TruncUFloat64ToInt32: return F64_TO_UINT;
+  case TruncSFloat64ToInt64: return F64_TO_INT64;
+  case TruncUFloat64ToInt64: return F64_TO_UINT64;
+  default:                   return Name();
+  }
+}
+
+bool isTruncOpSigned(UnaryOp op) {
+  switch (op) {
+  case TruncUFloat32ToInt32:
+  case TruncUFloat32ToInt64:
+  case TruncUFloat64ToInt32:
+  case TruncUFloat64ToInt64: return false;
+  default:                   return true;
+  }
+}
+
+Function* generateBinaryFunc(Module& wasm, Binary *curr) {
+  BinaryOp op = curr->op;
+  WasmType type = curr->type;
+  bool isI64 = type == i64;
+  Builder builder(wasm);
+  Expression* result = builder.makeBinary(op,
+    builder.makeGetLocal(0, type),
+    builder.makeGetLocal(1, type)
+  );
+  BinaryOp divSIntOp = isI64 ? DivSInt64 : DivSInt32;
+  UnaryOp eqZOp = isI64 ? EqZInt64 : EqZInt32;
+  Literal minLit = isI64 ? Literal(std::numeric_limits<int64_t>::min())
+                         : Literal(std::numeric_limits<int32_t>::min());
+  Literal zeroLit = isI64 ? Literal(int64_t(0)) : Literal(int32_t(0));
+  if (op == divSIntOp) {
+    // guard against signed division overflow
+    BinaryOp eqOp = isI64 ? EqInt64 : EqInt32;
+    Literal negLit = isI64 ? Literal(int64_t(-1)) : Literal(int32_t(-1));
+    result = builder.makeIf(
+      builder.makeBinary(AndInt32,
+        builder.makeBinary(eqOp,
+          builder.makeGetLocal(0, type),
+          builder.makeConst(minLit)
+        ),
+        builder.makeBinary(eqOp,
+          builder.makeGetLocal(1, type),
+          builder.makeConst(negLit)
+        )
+      ),
+      builder.makeConst(zeroLit),
+      result
+    );
+  }
+  auto func = new Function;
+  func->name = getBinaryFuncName(curr);
+  func->params.push_back(type);
+  func->params.push_back(type);
+  func->result = type;
+  func->body = builder.makeIf(
+    builder.makeUnary(eqZOp,
+      builder.makeGetLocal(1, type)
+    ),
+    builder.makeConst(zeroLit),
+    result
+  );
+  return func;
+}
+
+template <typename IntType, typename FloatType>
+void makeClampLimitLiterals(Literal& iMin, Literal& fMin, Literal& fMax) {
+  IntType minVal = std::numeric_limits<IntType>::min();
+  IntType maxVal = std::numeric_limits<IntType>::max();
+  iMin = Literal(minVal);
+  fMin = Literal(FloatType(minVal) - 1);
+  fMax = Literal(FloatType(maxVal) + 1);
+}
+
+Function* generateUnaryFunc(Module& wasm, Unary *curr) {
+  WasmType type = curr->value->type;
+  WasmType retType = curr->type;
+  UnaryOp truncOp = curr->op;
+  bool isF64 = type == f64;
+
+  Builder builder(wasm);
+
+  BinaryOp leOp = isF64 ? LeFloat64 : LeFloat32;
+  BinaryOp geOp = isF64 ? GeFloat64 : GeFloat32;
+  BinaryOp neOp = isF64 ? NeFloat64 : NeFloat32;
+
+  Literal iMin, fMin, fMax;
+  switch (truncOp) {
+  case TruncSFloat32ToInt32: makeClampLimitLiterals< int32_t,  float>(iMin, fMin, fMax); break;
+  case TruncUFloat32ToInt32: makeClampLimitLiterals<uint32_t,  float>(iMin, fMin, fMax); break;
+  case TruncSFloat32ToInt64: makeClampLimitLiterals< int64_t,  float>(iMin, fMin, fMax); break;
+  case TruncUFloat32ToInt64: makeClampLimitLiterals<uint64_t,  float>(iMin, fMin, fMax); break;
+  case TruncSFloat64ToInt32: makeClampLimitLiterals< int32_t, double>(iMin, fMin, fMax); break;
+  case TruncUFloat64ToInt32: makeClampLimitLiterals<uint32_t, double>(iMin, fMin, fMax); break;
+  case TruncSFloat64ToInt64: makeClampLimitLiterals< int64_t, double>(iMin, fMin, fMax); break;
+  case TruncUFloat64ToInt64: makeClampLimitLiterals<uint64_t, double>(iMin, fMin, fMax); break;
+  default: WASM_UNREACHABLE();
+  }
+
+  auto func = new Function;
+  func->name = getUnaryFuncName(curr);
+  func->params.push_back(type);
+  func->result = retType;
+  func->body = builder.makeUnary(truncOp,
+    builder.makeGetLocal(0, type)
+  );
+  // too small XXX this is different than asm.js, which does frem. here we
+  // clamp, which is much simpler/faster, and similar to native builds
+  func->body = builder.makeIf(
+    builder.makeBinary(leOp,
+      builder.makeGetLocal(0, type),
+      builder.makeConst(fMin)
+    ),
+    builder.makeConst(iMin),
+    func->body
+  );
+  // too big XXX see above
+  func->body = builder.makeIf(
+    builder.makeBinary(geOp,
+      builder.makeGetLocal(0, type),
+      builder.makeConst(fMax)
+    ),
+    // NB: min here as well. anything out of range => to the min
+    builder.makeConst(iMin),
+    func->body
+  );
+  // nan
+  func->body = builder.makeIf(
+    builder.makeBinary(neOp,
+      builder.makeGetLocal(0, type),
+      builder.makeGetLocal(0, type)
+    ),
+    // NB: min here as well. anything invalid => to the min
+    builder.makeConst(iMin),
+    func->body
+  );
+  return func;
+}
+
+void ensureBinaryFunc(Binary* curr, Module& wasm,
+                      TrappingFunctionContainer &trappingFunctions) {
+  Name name = getBinaryFuncName(curr);
+  if (trappingFunctions.hasFunction(name)) {
+    return;
+  }
+  trappingFunctions.addFunction(generateBinaryFunc(wasm, curr));
+}
+
+void ensureUnaryFunc(Unary *curr, Module& wasm,
+                     TrappingFunctionContainer &trappingFunctions) {
+  Name name = getUnaryFuncName(curr);
+  if (trappingFunctions.hasFunction(name)) {
+    return;
+  }
+  trappingFunctions.addFunction(generateUnaryFunc(wasm, curr));
+}
+
+void ensureF64ToI64JSImport(TrappingFunctionContainer &trappingFunctions) {
+  if (trappingFunctions.hasImport(F64_TO_INT)) {
+    return;
+  }
+
+  Module& wasm = trappingFunctions.getModule();
+  auto import = new Import; // f64-to-int = asm2wasm.f64-to-int;
+  import->name = F64_TO_INT;
+  import->module = ASM2WASM;
+  import->base = F64_TO_INT;
+  import->functionType = ensureFunctionType("id", &wasm)->name;
+  import->kind = ExternalKind::Function;
+  trappingFunctions.addImport(import);
+}
+
+Expression* makeTrappingBinary(Binary* curr, TrappingFunctionContainer &trappingFunctions) {
+  Name name = getBinaryFuncName(curr);
+  if (!name.is() || trappingFunctions.getMode() == TrapMode::Allow) {
+    return curr;
+  }
+
+  // the wasm operation might trap if done over 0, so generate a safe call
+  WasmType type = curr->type;
+  Module& wasm = trappingFunctions.getModule();
+  Builder builder(wasm);
+  ensureBinaryFunc(curr, wasm, trappingFunctions);
+  return builder.makeCall(name, {curr->left, curr->right}, type);
+}
+
+Expression* makeTrappingUnary(Unary* curr, TrappingFunctionContainer &trappingFunctions) {
+  Name name = getUnaryFuncName(curr);
+  TrapMode mode = trappingFunctions.getMode();
+  if (!name.is() || mode == TrapMode::Allow) {
+    return curr;
+  }
+
+  Module& wasm = trappingFunctions.getModule();
+  Builder builder(wasm);
+  // WebAssembly traps on float-to-int overflows, but asm.js wouldn't, so we must do something
+  // We can handle this in one of two ways: clamping, which is fast, or JS, which
+  // is precisely like JS but in order to do that we do a slow ffi
+  // If i64, there is no "JS" way to handle this, as no i64s in JS, so always clamp if we don't allow traps
+  // asm.js doesn't have unsigned f64-to-int, so just use the signed one.
+  if (curr->type != i64 && mode == TrapMode::JS) {
+    // WebAssembly traps on float-to-int overflows, but asm.js wouldn't, so we must emulate that
+    ensureF64ToI64JSImport(trappingFunctions);
+    Expression* f64Value = ensureDouble(curr->value, wasm.allocator);
+    return builder.makeCallImport(F64_TO_INT, {f64Value}, i32);
+  }
+
+  ensureUnaryFunc(curr, wasm, trappingFunctions);
+  return builder.makeCall(name, {curr->value}, curr->type);
+}
+
+struct TrapModePass : public WalkerPass<PostWalker<TrapModePass>> {
+public:
+
+  // Needs to be non-parallel so that visitModule gets called after visiting
+  // each node in the module, so we can add the functions that we created.
+  bool isFunctionParallel() override { return false; }
+
+  TrapModePass(TrapMode mode) : mode(mode) {
+    assert(mode != TrapMode::Allow);
+  }
+
+  Pass* create() override { return new TrapModePass(mode); }
+
+  void visitUnary(Unary* curr) {
+    replaceCurrent(makeTrappingUnary(curr, *trappingFunctions));
+  }
+
+  void visitBinary(Binary* curr) {
+    replaceCurrent(makeTrappingBinary(curr, *trappingFunctions));
+  }
+
+  void visitModule(Module* curr) {
+    trappingFunctions->addToModule();
+  }
+
+  void doWalkModule(Module* module) {
+    trappingFunctions = make_unique<TrappingFunctionContainer>(mode, *module);
+    WalkerPass<PostWalker<TrapModePass>>::doWalkModule(module);
+  }
+
+private:
+  TrapMode mode;
+  // Need to defer adding generated functions because adding functions while
+  // iterating over existing functions causes problems.
+  std::unique_ptr<TrappingFunctionContainer> trappingFunctions;
+};
+
+Pass *createTrapModeClamp() {
+  return new TrapModePass(TrapMode::Clamp);
+}
+
+Pass *createTrapModeJS() {
+  return new TrapModePass(TrapMode::JS);
+}
+
+} // namespace wasm
diff --git a/src/passes/pass.cpp b/src/passes/pass.cpp
index a208a03dd28..6cfe77a0190 100644
--- a/src/passes/pass.cpp
+++ b/src/passes/pass.cpp
@@ -109,6 +109,8 @@ void PassRegistry::registerPasses() {
   registerPass("simplify-locals-nostructure", "miscellaneous locals-related optimizations", createSimplifyLocalsNoStructurePass);
   registerPass("simplify-locals-notee-nostructure", "miscellaneous locals-related optimizations", createSimplifyLocalsNoTeeNoStructurePass);
   registerPass("ssa", "ssa-ify variables so that they have a single assignment", createSSAifyPass);
+  registerPass("trap-mode-clamp", "replace trapping operations with clamping semantics", createTrapModeClamp);
+  registerPass("trap-mode-js", "replace trapping operations with js semantics", createTrapModeJS);
   registerPass("untee", "removes tee_locals, replacing them with sets and gets", createUnteePass);
   registerPass("vacuum", "removes obviously unneeded code", createVacuumPass);
 //  registerPass("lower-i64", "lowers i64 into pairs of i32s", createLowerInt64Pass);
diff --git a/src/passes/passes.h b/src/passes/passes.h
index a02216083c8..58a9e2b278d 100644
--- a/src/passes/passes.h
+++ b/src/passes/passes.h
@@ -67,6 +67,8 @@ Pass *createSimplifyLocalsNoTeePass();
 Pass *createSimplifyLocalsNoStructurePass();
 Pass *createSimplifyLocalsNoTeeNoStructurePass();
 Pass *createSSAifyPass();
+Pass *createTrapModeClamp();
+Pass *createTrapModeJS();
 Pass *createUnteePass();
 Pass *createVacuumPass();
 
diff --git a/src/shared-constants.h b/src/shared-constants.h
index 31b5b7c1830..e8f98edb736 100644
--- a/src/shared-constants.h
+++ b/src/shared-constants.h
@@ -15,6 +15,7 @@
  */
 
 #ifndef wasm_shared_constants_h
+#define wasm_shared_constants_h
 
 #include "wasm.h"
 
diff --git a/src/tools/asm2wasm.cpp b/src/tools/asm2wasm.cpp
index 3fa97d9815b..cbc3c486b77 100644
--- a/src/tools/asm2wasm.cpp
+++ b/src/tools/asm2wasm.cpp
@@ -18,6 +18,7 @@
 // asm2wasm console tool
 //
 
+#include "ast/trapping.h"
 #include "support/colors.h"
 #include "support/command-line.h"
 #include "support/file.h"
@@ -34,7 +35,7 @@ using namespace wasm;
 
 int main(int argc, const char *argv[]) {
   bool legalizeJavaScriptFFI = true;
-  Asm2WasmBuilder::TrapMode trapMode = Asm2WasmBuilder::TrapMode::JS;
+  TrapMode trapMode = TrapMode::JS;
   bool wasmOnly = false;
   std::string sourceMapFilename;
   std::string sourceMapUrl;
@@ -79,19 +80,19 @@ int main(int argc, const char *argv[]) {
            })
       .add("--emit-potential-traps", "-i", "Emit instructions that might trap, like div/rem of 0", Options::Arguments::Zero,
            [&trapMode](Options *o, const std::string &) {
-             trapMode = Asm2WasmBuilder::TrapMode::Allow;
+             trapMode = TrapMode::Allow;
            })
       .add("--emit-clamped-potential-traps", "-i", "Clamp instructions that might trap, like float => int", Options::Arguments::Zero,
            [&trapMode](Options *o, const std::string &) {
-             trapMode = Asm2WasmBuilder::TrapMode::Clamp;
+             trapMode = TrapMode::Clamp;
            })
       .add("--emit-jsified-potential-traps", "-i", "Avoid instructions that might trap, handling them exactly like JS would", Options::Arguments::Zero,
            [&trapMode](Options *o, const std::string &) {
-             trapMode = Asm2WasmBuilder::TrapMode::JS;
+             trapMode = TrapMode::JS;
            })
       .add("--imprecise", "-i", "Imprecise optimizations (old name for --emit-potential-traps)", Options::Arguments::Zero,
            [&trapMode](Options *o, const std::string &) {
-             trapMode = Asm2WasmBuilder::TrapMode::Allow;
+             trapMode = TrapMode::Allow;
            })
       .add("--wasm-only", "-w", "Input is in WebAssembly-only format, and not actually valid asm.js", Options::Arguments::Zero,
            [&wasmOnly](Options *o, const std::string &) {
diff --git a/src/tools/s2wasm.cpp b/src/tools/s2wasm.cpp
index a357834796e..559188d1f00 100644
--- a/src/tools/s2wasm.cpp
+++ b/src/tools/s2wasm.cpp
@@ -18,6 +18,7 @@
 // wasm2asm console tool
 //
 
+#include "ast/trapping.h"
 #include "support/colors.h"
 #include "support/command-line.h"
 #include "support/file.h"
@@ -37,6 +38,7 @@ int main(int argc, const char *argv[]) {
   bool importMemory = false;
   std::string startFunction;
   std::vector<std::string> archiveLibraries;
+  TrapMode trapMode = TrapMode::Allow;
   Options options("s2wasm", "Link .s file into .wast");
   options.extra["validate"] = "wasm";
   options
@@ -81,6 +83,24 @@ int main(int argc, const char *argv[]) {
            [&allowMemoryGrowth](Options *, const std::string &) {
              allowMemoryGrowth = true;
            })
+      .add("--emit-potential-traps", "",
+           "Emit instructions that might trap, like div/rem of 0",
+           Options::Arguments::Zero,
+           [&trapMode](Options *o, const std::string &) {
+             trapMode = TrapMode::Allow;
+           })
+      .add("--emit-clamped-potential-traps", "",
+           "Clamp instructions that might trap, like float => int",
+           Options::Arguments::Zero,
+           [&trapMode](Options *o, const std::string &) {
+             trapMode = TrapMode::Clamp;
+           })
+      .add("--emit-jsified-potential-traps", "",
+           "Avoid instructions that might trap, handling them exactly like JS would",
+           Options::Arguments::Zero,
+           [&trapMode](Options *o, const std::string &) {
+             trapMode = TrapMode::JS;
+           })
       .add("--emscripten-glue", "-e", "Generate emscripten glue",
            Options::Arguments::Zero,
            [&generateEmscriptenGlue](Options *, const std::string &) {
@@ -144,6 +164,13 @@ int main(int argc, const char *argv[]) {
   S2WasmBuilder mainbuilder(input.c_str(), options.debug);
   linker.linkObject(mainbuilder);
 
+  if (trapMode != TrapMode::Allow) {
+    Module* wasm = &(linker.getOutput().wasm);
+    PassRunner runner(wasm);
+    addTrapModePass(runner, trapMode);
+    runner.run();
+  }
+
   for (const auto& m : archiveLibraries) {
     auto archiveFile(read_file<std::vector<char>>(m, Flags::Binary, debugFlag));
     bool error;
diff --git a/test/dot_s/traps.clamp.wast b/test/dot_s/traps.clamp.wast
new file mode 100644
index 00000000000..3cab71072da
--- /dev/null
+++ b/test/dot_s/traps.clamp.wast
@@ -0,0 +1,113 @@
+(module
+ (import "env" "memory" (memory $0 1))
+ (table 0 anyfunc)
+ (export "stackSave" (func $stackSave))
+ (export "stackAlloc" (func $stackAlloc))
+ (export "stackRestore" (func $stackRestore))
+ (export "test_traps" (func $test_traps))
+ (func $test_traps (param $0 f32) (param $1 f64) (result i32)
+  (call $i32u-div
+   (call $f32-to-int
+    (get_local $0)
+   )
+   (call $f64-to-uint
+    (get_local $1)
+   )
+  )
+ )
+ (func $f32-to-int (param $0 f32) (result i32)
+  (if (result i32)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const -2147483648)
+   (if (result i32)
+    (f32.ge
+     (get_local $0)
+     (f32.const 2147483648)
+    )
+    (i32.const -2147483648)
+    (if (result i32)
+     (f32.le
+      (get_local $0)
+      (f32.const -2147483648)
+     )
+     (i32.const -2147483648)
+     (i32.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint (param $0 f64) (result i32)
+  (if (result i32)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (f64.ge
+     (get_local $0)
+     (f64.const 4294967296)
+    )
+    (i32.const 0)
+    (if (result i32)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i32.const 0)
+     (i32.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $i32u-div (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.div_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $stackSave (result i32)
+  (i32.load offset=4
+   (i32.const 0)
+  )
+ )
+ (func $stackAlloc (param $0 i32) (result i32)
+  (local $1 i32)
+  (set_local $1
+   (i32.load offset=4
+    (i32.const 0)
+   )
+  )
+  (i32.store offset=4
+   (i32.const 0)
+   (i32.and
+    (i32.sub
+     (get_local $1)
+     (get_local $0)
+    )
+    (i32.const -16)
+   )
+  )
+  (get_local $1)
+ )
+ (func $stackRestore (param $0 i32)
+  (i32.store offset=4
+   (i32.const 0)
+   (get_local $0)
+  )
+ )
+)
+;; METADATA: { "asmConsts": {},"staticBump": 12, "initializers": [] }
diff --git a/test/dot_s/traps.js.wast b/test/dot_s/traps.js.wast
new file mode 100644
index 00000000000..39d08f4c085
--- /dev/null
+++ b/test/dot_s/traps.js.wast
@@ -0,0 +1,65 @@
+(module
+ (type $FUNCSIG$id (func (param f64) (result i32)))
+ (import "asm2wasm" "f64-to-int" (func $f64-to-int (param f64) (result i32)))
+ (import "env" "memory" (memory $0 1))
+ (table 0 anyfunc)
+ (export "stackSave" (func $stackSave))
+ (export "stackAlloc" (func $stackAlloc))
+ (export "stackRestore" (func $stackRestore))
+ (export "test_traps" (func $test_traps))
+ (func $test_traps (param $0 f32) (param $1 f64) (result i32)
+  (call $i32u-div
+   (call $f64-to-int
+    (f64.promote/f32
+     (get_local $0)
+    )
+   )
+   (call $f64-to-int
+    (get_local $1)
+   )
+  )
+ )
+ (func $i32u-div (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.div_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $stackSave (result i32)
+  (i32.load offset=4
+   (i32.const 0)
+  )
+ )
+ (func $stackAlloc (param $0 i32) (result i32)
+  (local $1 i32)
+  (set_local $1
+   (i32.load offset=4
+    (i32.const 0)
+   )
+  )
+  (i32.store offset=4
+   (i32.const 0)
+   (i32.and
+    (i32.sub
+     (get_local $1)
+     (get_local $0)
+    )
+    (i32.const -16)
+   )
+  )
+  (get_local $1)
+ )
+ (func $stackRestore (param $0 i32)
+  (i32.store offset=4
+   (i32.const 0)
+   (get_local $0)
+  )
+ )
+)
+;; METADATA: { "asmConsts": {},"staticBump": 12, "initializers": [] }
diff --git a/test/dot_s/traps.s b/test/dot_s/traps.s
new file mode 100644
index 00000000000..b75cf8d00ee
--- /dev/null
+++ b/test/dot_s/traps.s
@@ -0,0 +1,14 @@
+    .text
+    .file   ""
+    .globl  test_traps
+    .type   test_traps,@function
+test_traps:
+    .param      f32, f64
+    .result     i32
+# BB#0:
+    i32.trunc_s/f32 $push0=, $0
+    i32.trunc_u/f64 $push1=, $1
+    i32.div_u       $push2=, $pop0, $pop1
+    .endfunc
+.Lfunc_end0:
+    .size   test_traps, .Lfunc_end0-test_traps
diff --git a/test/dot_s/traps.wast b/test/dot_s/traps.wast
new file mode 100644
index 00000000000..2ade5362a7c
--- /dev/null
+++ b/test/dot_s/traps.wast
@@ -0,0 +1,49 @@
+(module
+ (import "env" "memory" (memory $0 1))
+ (table 0 anyfunc)
+ (export "stackSave" (func $stackSave))
+ (export "stackAlloc" (func $stackAlloc))
+ (export "stackRestore" (func $stackRestore))
+ (export "test_traps" (func $test_traps))
+ (func $test_traps (param $0 f32) (param $1 f64) (result i32)
+  (i32.div_u
+   (i32.trunc_s/f32
+    (get_local $0)
+   )
+   (i32.trunc_u/f64
+    (get_local $1)
+   )
+  )
+ )
+ (func $stackSave (result i32)
+  (i32.load offset=4
+   (i32.const 0)
+  )
+ )
+ (func $stackAlloc (param $0 i32) (result i32)
+  (local $1 i32)
+  (set_local $1
+   (i32.load offset=4
+    (i32.const 0)
+   )
+  )
+  (i32.store offset=4
+   (i32.const 0)
+   (i32.and
+    (i32.sub
+     (get_local $1)
+     (get_local $0)
+    )
+    (i32.const -16)
+   )
+  )
+  (get_local $1)
+ )
+ (func $stackRestore (param $0 i32)
+  (i32.store offset=4
+   (i32.const 0)
+   (get_local $0)
+  )
+ )
+)
+;; METADATA: { "asmConsts": {},"staticBump": 12, "initializers": [] }
diff --git a/test/emcc_hello_world.fromasm.clamp b/test/emcc_hello_world.fromasm.clamp
index b074afa30cd..e483ed89cf4 100644
--- a/test/emcc_hello_world.fromasm.clamp
+++ b/test/emcc_hello_world.fromasm.clamp
@@ -2214,6 +2214,32 @@
    )
   )
  )
+ (func $f64-to-uint (param $0 f64) (result i32)
+  (if (result i32)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (f64.ge
+     (get_local $0)
+     (f64.const 4294967296)
+    )
+    (i32.const 0)
+    (if (result i32)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i32.const 0)
+     (i32.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $i32s-div (param $0 i32) (param $1 i32) (result i32)
   (if (result i32)
    (get_local $1)
@@ -4587,7 +4613,7 @@
                     (i32.store
                      (get_local $7)
                      (tee_local $5
-                      (call $f64-to-int
+                      (call $f64-to-uint
                        (get_local $15)
                       )
                      )
diff --git a/test/emcc_hello_world.fromasm.clamp.no-opts b/test/emcc_hello_world.fromasm.clamp.no-opts
index 3662e5d3617..36d34018c2c 100644
--- a/test/emcc_hello_world.fromasm.clamp.no-opts
+++ b/test/emcc_hello_world.fromasm.clamp.no-opts
@@ -4658,6 +4658,32 @@
    )
   )
  )
+ (func $f64-to-uint (param $0 f64) (result i32)
+  (if (result i32)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (f64.ge
+     (get_local $0)
+     (f64.const 4294967296)
+    )
+    (i32.const 0)
+    (if (result i32)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i32.const 0)
+     (i32.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $i32s-div (param $0 i32) (param $1 i32) (result i32)
   (if (result i32)
    (i32.eqz
@@ -9934,7 +9960,7 @@
            (loop $while-in60
             (block $while-out59
              (set_local $$conv216$i
-              (call $f64-to-int
+              (call $f64-to-uint
                (get_local $$y$addr$4$i)
               )
              )
diff --git a/test/passes/trap-mode-clamp.txt b/test/passes/trap-mode-clamp.txt
new file mode 100644
index 00000000000..91ba1920352
--- /dev/null
+++ b/test/passes/trap-mode-clamp.txt
@@ -0,0 +1,432 @@
+(module
+ (type $0 (func (param i32 i64)))
+ (type $1 (func (param f32)))
+ (type $2 (func (param f64)))
+ (memory $0 0)
+ (func $test_div (type $0) (param $0 i32) (param $1 i64)
+  (drop
+   (call $i32s-div
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i32u-div
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i64s-div
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+  (drop
+   (call $i64u-div
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+ )
+ (func $test_rem (type $0) (param $0 i32) (param $1 i64)
+  (drop
+   (call $i32s-rem
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i32u-rem
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i64s-rem
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+  (drop
+   (call $i64u-rem
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+ )
+ (func $test_f32_to_int (type $1) (param $0 f32)
+  (drop
+   (call $f32-to-int
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f32-to-uint
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f32-to-int64
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f32-to-uint64
+    (get_local $0)
+   )
+  )
+ )
+ (func $test_f64_to_int (type $2) (param $0 f64)
+  (drop
+   (call $f64-to-int
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f64-to-uint
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f64-to-int64
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f64-to-uint64
+    (get_local $0)
+   )
+  )
+ )
+ (func $f32-to-int (param $0 f32) (result i32)
+  (if (result i32)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const -2147483648)
+   (if (result i32)
+    (f32.ge
+     (get_local $0)
+     (f32.const 2147483648)
+    )
+    (i32.const -2147483648)
+    (if (result i32)
+     (f32.le
+      (get_local $0)
+      (f32.const -2147483648)
+     )
+     (i32.const -2147483648)
+     (i32.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f32-to-int64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f32-to-uint (param $0 f32) (result i32)
+  (if (result i32)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (f32.ge
+     (get_local $0)
+     (f32.const 4294967296)
+    )
+    (i32.const 0)
+    (if (result i32)
+     (f32.le
+      (get_local $0)
+      (f32.const -1)
+     )
+     (i32.const 0)
+     (i32.trunc_u/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f32-to-uint64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-int (param $0 f64) (result i32)
+  (if (result i32)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const -2147483648)
+   (if (result i32)
+    (f64.ge
+     (get_local $0)
+     (f64.const 2147483648)
+    )
+    (i32.const -2147483648)
+    (if (result i32)
+     (f64.le
+      (get_local $0)
+      (f64.const -2147483649)
+     )
+     (i32.const -2147483648)
+     (i32.trunc_s/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-int64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint (param $0 f64) (result i32)
+  (if (result i32)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (f64.ge
+     (get_local $0)
+     (f64.const 4294967296)
+    )
+    (i32.const 0)
+    (if (result i32)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i32.const 0)
+     (i32.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $i32s-div (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (i32.and
+     (i32.eq
+      (get_local $0)
+      (i32.const -2147483648)
+     )
+     (i32.eq
+      (get_local $1)
+      (i32.const -1)
+     )
+    )
+    (i32.const 0)
+    (i32.div_s
+     (get_local $0)
+     (get_local $1)
+    )
+   )
+  )
+ )
+ (func $i32s-rem (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.rem_s
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i32u-div (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.div_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i32u-rem (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.rem_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i64s-div (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (i32.and
+     (i64.eq
+      (get_local $0)
+      (i64.const -9223372036854775808)
+     )
+     (i64.eq
+      (get_local $1)
+      (i64.const -1)
+     )
+    )
+    (i64.const 0)
+    (i64.div_s
+     (get_local $0)
+     (get_local $1)
+    )
+   )
+  )
+ )
+ (func $i64s-rem (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (i64.rem_s
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i64u-div (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (i64.div_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i64u-rem (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (i64.rem_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+)
diff --git a/test/passes/trap-mode-clamp.wast b/test/passes/trap-mode-clamp.wast
new file mode 100644
index 00000000000..5a44e50ec43
--- /dev/null
+++ b/test/passes/trap-mode-clamp.wast
@@ -0,0 +1,26 @@
+(module
+ (func $test_div (param $0 i32) (param $1 i64)
+  (drop (i32.div_s (get_local $0) (get_local $0)))
+  (drop (i32.div_u (get_local $0) (get_local $0)))
+  (drop (i64.div_s (get_local $1) (get_local $1)))
+  (drop (i64.div_u (get_local $1) (get_local $1)))
+ )
+ (func $test_rem (param $0 i32) (param $1 i64)
+  (drop (i32.rem_s (get_local $0) (get_local $0)))
+  (drop (i32.rem_u (get_local $0) (get_local $0)))
+  (drop (i64.rem_s (get_local $1) (get_local $1)))
+  (drop (i64.rem_u (get_local $1) (get_local $1)))
+ )
+ (func $test_f32_to_int (param $0 f32)
+  (drop (i32.trunc_s/f32 (get_local $0)))
+  (drop (i32.trunc_u/f32 (get_local $0)))
+  (drop (i64.trunc_s/f32 (get_local $0)))
+  (drop (i64.trunc_u/f32 (get_local $0)))
+ )
+ (func $test_f64_to_int (param $0 f64)
+  (drop (i32.trunc_s/f64 (get_local $0)))
+  (drop (i32.trunc_u/f64 (get_local $0)))
+  (drop (i64.trunc_s/f64 (get_local $0)))
+  (drop (i64.trunc_u/f64 (get_local $0)))
+ )
+)
diff --git a/test/passes/trap-mode-js.txt b/test/passes/trap-mode-js.txt
new file mode 100644
index 00000000000..57ef09f9179
--- /dev/null
+++ b/test/passes/trap-mode-js.txt
@@ -0,0 +1,334 @@
+(module
+ (type $0 (func (param i32 i64)))
+ (type $1 (func (param f32)))
+ (type $2 (func (param f64)))
+ (type $FUNCSIG$id (func (param f64) (result i32)))
+ (import "asm2wasm" "f64-to-int" (func $f64-to-int (param f64) (result i32)))
+ (memory $0 0)
+ (func $test_div (type $0) (param $0 i32) (param $1 i64)
+  (drop
+   (call $i32s-div
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i32u-div
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i64s-div
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+  (drop
+   (call $i64u-div
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+ )
+ (func $test_rem (type $0) (param $0 i32) (param $1 i64)
+  (drop
+   (call $i32s-rem
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i32u-rem
+    (get_local $0)
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $i64s-rem
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+  (drop
+   (call $i64u-rem
+    (get_local $1)
+    (get_local $1)
+   )
+  )
+ )
+ (func $test_f32_to_int (type $1) (param $0 f32)
+  (drop
+   (call $f64-to-int
+    (f64.promote/f32
+     (get_local $0)
+    )
+   )
+  )
+  (drop
+   (call $f64-to-int
+    (f64.promote/f32
+     (get_local $0)
+    )
+   )
+  )
+  (drop
+   (call $f32-to-int64
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f32-to-uint64
+    (get_local $0)
+   )
+  )
+ )
+ (func $test_f64_to_int (type $2) (param $0 f64)
+  (drop
+   (call $f64-to-int
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f64-to-int
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f64-to-int64
+    (get_local $0)
+   )
+  )
+  (drop
+   (call $f64-to-uint64
+    (get_local $0)
+   )
+  )
+ )
+ (func $f32-to-int64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f32-to-uint64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-int64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $i32s-div (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (i32.and
+     (i32.eq
+      (get_local $0)
+      (i32.const -2147483648)
+     )
+     (i32.eq
+      (get_local $1)
+      (i32.const -1)
+     )
+    )
+    (i32.const 0)
+    (i32.div_s
+     (get_local $0)
+     (get_local $1)
+    )
+   )
+  )
+ )
+ (func $i32s-rem (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.rem_s
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i32u-div (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.div_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i32u-rem (param $0 i32) (param $1 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_local $1)
+   )
+   (i32.const 0)
+   (i32.rem_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i64s-div (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (i32.and
+     (i64.eq
+      (get_local $0)
+      (i64.const -9223372036854775808)
+     )
+     (i64.eq
+      (get_local $1)
+      (i64.const -1)
+     )
+    )
+    (i64.const 0)
+    (i64.div_s
+     (get_local $0)
+     (get_local $1)
+    )
+   )
+  )
+ )
+ (func $i64s-rem (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (i64.rem_s
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i64u-div (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (i64.div_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+ (func $i64u-rem (param $0 i64) (param $1 i64) (result i64)
+  (if (result i64)
+   (i64.eqz
+    (get_local $1)
+   )
+   (i64.const 0)
+   (i64.rem_u
+    (get_local $0)
+    (get_local $1)
+   )
+  )
+ )
+)
diff --git a/test/passes/trap-mode-js.wast b/test/passes/trap-mode-js.wast
new file mode 100644
index 00000000000..5a44e50ec43
--- /dev/null
+++ b/test/passes/trap-mode-js.wast
@@ -0,0 +1,26 @@
+(module
+ (func $test_div (param $0 i32) (param $1 i64)
+  (drop (i32.div_s (get_local $0) (get_local $0)))
+  (drop (i32.div_u (get_local $0) (get_local $0)))
+  (drop (i64.div_s (get_local $1) (get_local $1)))
+  (drop (i64.div_u (get_local $1) (get_local $1)))
+ )
+ (func $test_rem (param $0 i32) (param $1 i64)
+  (drop (i32.rem_s (get_local $0) (get_local $0)))
+  (drop (i32.rem_u (get_local $0) (get_local $0)))
+  (drop (i64.rem_s (get_local $1) (get_local $1)))
+  (drop (i64.rem_u (get_local $1) (get_local $1)))
+ )
+ (func $test_f32_to_int (param $0 f32)
+  (drop (i32.trunc_s/f32 (get_local $0)))
+  (drop (i32.trunc_u/f32 (get_local $0)))
+  (drop (i64.trunc_s/f32 (get_local $0)))
+  (drop (i64.trunc_u/f32 (get_local $0)))
+ )
+ (func $test_f64_to_int (param $0 f64)
+  (drop (i32.trunc_s/f64 (get_local $0)))
+  (drop (i32.trunc_u/f64 (get_local $0)))
+  (drop (i64.trunc_s/f64 (get_local $0)))
+  (drop (i64.trunc_u/f64 (get_local $0)))
+ )
+)
diff --git a/test/unit.fromasm.clamp b/test/unit.fromasm.clamp
index 4393c362c81..c4f1334810f 100644
--- a/test/unit.fromasm.clamp
+++ b/test/unit.fromasm.clamp
@@ -168,6 +168,32 @@
    )
   )
  )
+ (func $f32-to-int (param $0 f32) (result i32)
+  (if (result i32)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const -2147483648)
+   (if (result i32)
+    (f32.ge
+     (get_local $0)
+     (f32.const 2147483648)
+    )
+    (i32.const -2147483648)
+    (if (result i32)
+     (f32.le
+      (get_local $0)
+      (f32.const -2147483648)
+     )
+     (i32.const -2147483648)
+     (i32.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $conversions (param $0 i32) (param $1 f64) (param $2 f32)
   (drop
    (call $f64-to-int
@@ -175,10 +201,8 @@
    )
   )
   (drop
-   (call $f64-to-int
-    (f64.promote/f32
-     (get_local $2)
-    )
+   (call $f32-to-int
+    (get_local $2)
    )
   )
  )
@@ -1186,9 +1210,30 @@
    )
   )
  )
- (func $f2u (param $0 f64) (result i32)
-  (call $f64-to-int
-   (get_local $0)
+ (func $f64-to-uint (param $0 f64) (result i32)
+  (if (result i32)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (f64.ge
+     (get_local $0)
+     (f64.const 4294967296)
+    )
+    (i32.const 0)
+    (if (result i32)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i32.const 0)
+     (i32.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
   )
  )
  (func $keepAlive
@@ -1203,12 +1248,12 @@
    )
   )
   (drop
-   (call $f2u
+   (call $f64-to-uint
     (f64.const 100)
    )
   )
   (drop
-   (call $f2u
+   (call $f64-to-int
     (f64.const 100)
    )
   )
diff --git a/test/unit.fromasm.clamp.no-opts b/test/unit.fromasm.clamp.no-opts
index 00b1814c496..b1b22cf6677 100644
--- a/test/unit.fromasm.clamp.no-opts
+++ b/test/unit.fromasm.clamp.no-opts
@@ -234,6 +234,32 @@
    )
   )
  )
+ (func $f32-to-int (param $0 f32) (result i32)
+  (if (result i32)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const -2147483648)
+   (if (result i32)
+    (f32.ge
+     (get_local $0)
+     (f32.const 2147483648)
+    )
+    (i32.const -2147483648)
+    (if (result i32)
+     (f32.le
+      (get_local $0)
+      (f32.const -2147483648)
+     )
+     (i32.const -2147483648)
+     (i32.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $conversions (param $i i32) (param $d f64) (param $f f32)
   (set_local $i
    (call $f64-to-int
@@ -241,10 +267,8 @@
    )
   )
   (set_local $i
-   (call $f64-to-int
-    (f64.promote/f32
-     (get_local $f)
-    )
+   (call $f32-to-int
+    (get_local $f)
    )
   )
   (set_local $d
@@ -1972,9 +1996,35 @@
    )
   )
  )
+ (func $f64-to-uint (param $0 f64) (result i32)
+  (if (result i32)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i32.const 0)
+   (if (result i32)
+    (f64.ge
+     (get_local $0)
+     (f64.const 4294967296)
+    )
+    (i32.const 0)
+    (if (result i32)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i32.const 0)
+     (i32.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $f2u (param $x f64) (result i32)
   (return
-   (call $f64-to-int
+   (call $f64-to-uint
     (get_local $x)
    )
   )
diff --git a/test/wasm-only.fromasm b/test/wasm-only.fromasm
index 2ac96b8aea9..6eb8bb5feb7 100644
--- a/test/wasm-only.fromasm
+++ b/test/wasm-only.fromasm
@@ -266,6 +266,32 @@
    )
   )
  )
+ (func $f32-to-int64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $f64-to-int64 (param $0 f64) (result i64)
   (if (result i64)
    (f64.ne
@@ -292,6 +318,58 @@
    )
   )
  )
+ (func $f32-to-uint64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $test64
   (local $0 i64)
   (local $1 f32)
@@ -376,15 +454,13 @@
    (get_local $0)
   )
   (drop
-   (call $f64-to-int64
-    (f64.promote/f32
-     (tee_local $1
-      (f32.convert_u/i64
-       (tee_local $0
-        (i64.extend_u/i32
-         (i32.wrap/i64
-          (get_local $0)
-         )
+   (call $f32-to-int64
+    (tee_local $1
+     (f32.convert_u/i64
+      (tee_local $0
+       (i64.extend_u/i32
+        (i32.wrap/i64
+         (get_local $0)
         )
        )
       )
@@ -402,14 +478,12 @@
    )
   )
   (drop
-   (call $f64-to-int64
-    (f64.promote/f32
-     (get_local $1)
-    )
+   (call $f32-to-uint64
+    (get_local $1)
    )
   )
   (drop
-   (call $f64-to-int64
+   (call $f64-to-uint64
     (get_local $2)
    )
   )
diff --git a/test/wasm-only.fromasm.clamp b/test/wasm-only.fromasm.clamp
index 2ac96b8aea9..6eb8bb5feb7 100644
--- a/test/wasm-only.fromasm.clamp
+++ b/test/wasm-only.fromasm.clamp
@@ -266,6 +266,32 @@
    )
   )
  )
+ (func $f32-to-int64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $f64-to-int64 (param $0 f64) (result i64)
   (if (result i64)
    (f64.ne
@@ -292,6 +318,58 @@
    )
   )
  )
+ (func $f32-to-uint64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $test64
   (local $0 i64)
   (local $1 f32)
@@ -376,15 +454,13 @@
    (get_local $0)
   )
   (drop
-   (call $f64-to-int64
-    (f64.promote/f32
-     (tee_local $1
-      (f32.convert_u/i64
-       (tee_local $0
-        (i64.extend_u/i32
-         (i32.wrap/i64
-          (get_local $0)
-         )
+   (call $f32-to-int64
+    (tee_local $1
+     (f32.convert_u/i64
+      (tee_local $0
+       (i64.extend_u/i32
+        (i32.wrap/i64
+         (get_local $0)
         )
        )
       )
@@ -402,14 +478,12 @@
    )
   )
   (drop
-   (call $f64-to-int64
-    (f64.promote/f32
-     (get_local $1)
-    )
+   (call $f32-to-uint64
+    (get_local $1)
    )
   )
   (drop
-   (call $f64-to-int64
+   (call $f64-to-uint64
     (get_local $2)
    )
   )
diff --git a/test/wasm-only.fromasm.clamp.no-opts b/test/wasm-only.fromasm.clamp.no-opts
index c0cfa4676f2..bbb32c5f317 100644
--- a/test/wasm-only.fromasm.clamp.no-opts
+++ b/test/wasm-only.fromasm.clamp.no-opts
@@ -343,6 +343,32 @@
    )
   )
  )
+ (func $f32-to-int64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $f64-to-int64 (param $0 f64) (result i64)
   (if (result i64)
    (f64.ne
@@ -369,6 +395,58 @@
    )
   )
  )
+ (func $f32-to-uint64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $test64
   (local $x i64)
   (local $y i64)
@@ -601,10 +679,8 @@
    )
   )
   (set_local $x
-   (call $f64-to-int64
-    (f64.promote/f32
-     (get_local $float32)
-    )
+   (call $f32-to-int64
+    (get_local $float32)
    )
   )
   (set_local $x
@@ -613,14 +689,12 @@
    )
   )
   (set_local $x
-   (call $f64-to-int64
-    (f64.promote/f32
-     (get_local $float32)
-    )
+   (call $f32-to-uint64
+    (get_local $float32)
    )
   )
   (set_local $x
-   (call $f64-to-int64
+   (call $f64-to-uint64
     (get_local $float64)
    )
   )
diff --git a/test/wasm-only.fromasm.no-opts b/test/wasm-only.fromasm.no-opts
index c0cfa4676f2..bbb32c5f317 100644
--- a/test/wasm-only.fromasm.no-opts
+++ b/test/wasm-only.fromasm.no-opts
@@ -343,6 +343,32 @@
    )
   )
  )
+ (func $f32-to-int64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const -9223372036854775808)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 9223372036854775808)
+    )
+    (i64.const -9223372036854775808)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -9223372036854775808)
+     )
+     (i64.const -9223372036854775808)
+     (i64.trunc_s/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $f64-to-int64 (param $0 f64) (result i64)
   (if (result i64)
    (f64.ne
@@ -369,6 +395,58 @@
    )
   )
  )
+ (func $f32-to-uint64 (param $0 f32) (result i64)
+  (if (result i64)
+   (f32.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f32.ge
+     (get_local $0)
+     (f32.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f32.le
+      (get_local $0)
+      (f32.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f32
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
+ (func $f64-to-uint64 (param $0 f64) (result i64)
+  (if (result i64)
+   (f64.ne
+    (get_local $0)
+    (get_local $0)
+   )
+   (i64.const 0)
+   (if (result i64)
+    (f64.ge
+     (get_local $0)
+     (f64.const 18446744073709551615)
+    )
+    (i64.const 0)
+    (if (result i64)
+     (f64.le
+      (get_local $0)
+      (f64.const -1)
+     )
+     (i64.const 0)
+     (i64.trunc_u/f64
+      (get_local $0)
+     )
+    )
+   )
+  )
+ )
  (func $test64
   (local $x i64)
   (local $y i64)
@@ -601,10 +679,8 @@
    )
   )
   (set_local $x
-   (call $f64-to-int64
-    (f64.promote/f32
-     (get_local $float32)
-    )
+   (call $f32-to-int64
+    (get_local $float32)
    )
   )
   (set_local $x
@@ -613,14 +689,12 @@
    )
   )
   (set_local $x
-   (call $f64-to-int64
-    (f64.promote/f32
-     (get_local $float32)
-    )
+   (call $f32-to-uint64
+    (get_local $float32)
    )
   )
   (set_local $x
-   (call $f64-to-int64
+   (call $f64-to-uint64
     (get_local $float64)
    )
   )