kc3-lang/libffi/src/wasm32/ffi.c

• Show log

  Commit

• Hash : 2687cfc5
  Author :
  Date : 2023-02-02T09:10:00
  

  Add wasm32 emscripten support (#763) * added build script * Apply libffi-emscripten patch * Some changes to wasm32/ffi.c * Remove exit(0); from test suites * Fix LONGDOUBLE argument type * Use more macros in ffi.c * Use switch statements instead of if chains * Implemented struct args * Finish struct implementation * Partially working closures * Got closures working (most of closures test suite passes) * Revert changes to test suite * Update .gitignore * Apply code formatter * Use stackSave and stackRestore rather than directly adjusting stack pointer * Add missing break * Fix visibility of ffi_closure_alloc and ffi_closure_free * Fix FFI_TYPE_STRUCT and FFI_TYPE_LONGDOUBLE when WASM_BIGINT is not used sig needs to be vi here for FFI_TYPE_STRUCT and FFI_TYPE_LONGDOUBLE, noticed this while running the test suite without WASM_BIGINT support. * Always use dynCall rather than direct wasmTable lookup (function pointer cast emulation changes dynCall) * Prevent closures.c from duplicating symbols * Try to set up CI * Add test with bigint * Make test methods static * Remove BigInt shorthand because it messes up terser * Add selenium tests * Update tests a bit to try to make CI work * WASM_BIGINT is a linker flag not a compile flag * Finish getting CI working (#1) * update gitignore * Avoid adding "use strict;" to generated JS This should be controlled by -s STRICT_JS in Emscripten. * Make JavaScript ES5 compliant * Remove redundant EXPORTED_RUNTIME_METHODS settings * Fix definition of DEREF_I16 * Avoid marshalling FFI_TYPE_LONGDOUBLE when WASM_BIGINT is not used * Add missing FFI_TYPE_STRUCT signature * Improve test scripts * Remove redundant EXPORTED_RUNTIME_METHODS settings * Add missing EOL * Add struct unpacking tests * Update ci config to try to actually use WASM_BIGINT * Revert "Avoid marshalling FFI_TYPE_LONGDOUBLE when WASM_BIGINT is not used" This reverts commit 61bd5a3e20891623715604581b6e872ab3dfab80. * Fix single_entry_structs tests * Fix return from closure call * Fix 64 bit return from closures * only allocate as much space on stack for return pointer as needed * Revert "only allocate as much space on stack for return pointer as needed" This reverts commit e54a30faea3803e7ac33eed191bde9e573850fc1. * xfail two tests * Fix err_bad_abi test * Remove test logging junk * Try to set up long double marshalling for closures * xfail err_bad_abi * Fix reference errors in previous commit * Add missing argument pointer assignment * Fix signature of function pointer in cls_dbls_struct * Fix longdouble argument * Try some changes to bigint handling * Fix BigInt handling * Fix cls_longdouble test * Fix long double closure arg with no WASM_BIGINT * Use EM_JS to factor out js helpers * Support for varargs closure calls * Fix varargs calls * Fix err_bad_abi test * Fix typo in previous commit * Add more assertions to closures test suite * Fix some asserts * Add assertions to a few more tests * Fix some tests * Fix more floating point assertions * Update more tests * Var args for ffi_call * Don't do node tests * Macro for allocating on stack * Add some comments, simplify struct handling * Try again to fix varargs calls, add comments * Consolidate WASM_BIGINT conditionals into LOAD_U64 and STORE_U64 macros * A bit of cleanup * Fix another typo * Some fixes to the testsuite * Another testsuite fix * Fix varags with closures? * Another attempt at getting closure varargs to work * sig is initialized later * Allow libffi.closures tests to be run * Improve build script * Remove redundant semicolons * Fix a few libffi.closures test failures * Cleanup * Legacy dynCall API is no longer used * Fix FFI_TYPE_LONGDOUBLE offset * xfail 2 tests for WASM - closure_loc_fn0; not applicable -- codeloc doesn't point to closure. - huge_struct; function signature too long. * Revert some redundant dg-output/printf statements Helps Node. * Revert "Don't do node tests" This reverts commit a341ef4b. * Fix assertions in cls_24byte * More tiny formating fixes to test suite * Revert "Revert "Don't do node tests"" This reverts commit 7722e685ea04e2420e042886816d8c4dd31f5dcb. * Fix 64 bit returns when WASM_BIGINT is absent * Fix print statement in cls_24byte * Add CALL_FUNC_PTR macro to allow pyodide to define custom calling behavior to handle fpcast * Update single_entry_structs tests * More explanations * Fix compile error in last commit * Add more support for pyodide fpcast emulation, update CI to try to test it * Clone via https * Fix path to pyodide emsdk_env * Add asserts to the rest of the test suite * Fix test compile errors * Fix some tests * Fix cls_ulonglong * Fix alignment of <4 byte args * fix cls_ulonglong again * Use snprintf instead of sprintf * Should assert than strncmp returned 0 * Fix va_struct1 and va_struct3 * Change double and long double tests These tests are failing because of a strange bug with prinft and doubles, but I am not convinced it necessarily has anything to do with libffi. This version casts the double to int before printing it and avoids the issue * Enable node tests * Revert "Change double and long double tests" This reverts commit 8f3ff89c6577dc99564181cd9974f2f1ba21f1e9. * Fix PYODIDE_FPCAST flag * add conftest.py back in * Fix emcc error: setting `EXPORTED_FUNCTIONS` expects `<class 'list'>` but got `<class 'str'>` See discussion on https://github.com/pyodide/pyodide/pull/1596 * Remove test.html * Remove duplicate test file * More changes from upstream * Fix some whitespace * Add some basic debug logging statements * Reapply libffi.exp changes * Don't build docs (#7) Works around build issue makeinfo: command not found. * Update long double alignment Emscripten 2.0.26 reduces the aligmnet of long double to 8. Quoting from `ChangeLog.md`: > The alignment of `long double`, which is a 128-bit floating-point > value implemented in software, is reduced from 16 to 8. The lower > alignment allows `max_align_t` to properly match the alignment we > use for malloc, which is 8 (raising malloc's alignment to achieve > correctness the other way would come with a performance regression). > (#10072) * Update long double alignment Emscripten 2.0.26 reduces the aligmnet of long double to 8. Quoting from `ChangeLog.md`: > The alignment of `long double`, which is a 128-bit floating-point > value implemented in software, is reduced from 16 to 8. The lower > alignment allows `max_align_t` to properly match the alignment we > use for malloc, which is 8 (raising malloc's alignment to achieve > correctness the other way would come with a performance regression). > (#10072) * Improve error handling a bit (#8) * Fix handling of signed arguments to ffi_call (#11) * Fix struct argument handling in ffi_call (#10) * Remove fpcast emulation tests * Align the stack to MAX_ALIGN before making call (#12) * Increase MAX_ARGS * Cleanup (#14) * Fix Closure compiler error with -sASSERTIONS=1 (#15) * Remove function pointer cast emulation (#13) This reverts commit 593b402 and cbc54da, as it's no longer needed after PR pyodide/pyodide#2019. * Prefer the `__EMSCRIPTEN__` definition over `EMSCRIPTEN` (#18) "The preprocessor define EMSCRIPTEN is deprecated. Don't pass it to code in strict mode. Code should use the define __EMSCRIPTEN__ instead." https://github.com/emscripten-core/emscripten/blob/84a634167a1cd9e8c47d37a559688153a4ceace6/emcc.py#L887-L890 * Install autoconf 2.71 * Try again with installing autoconf 2.71 * Fix compatibility with Emscripten 3.1.28 * CI: remove use of `EM_CONFIG` env See commit: https://github.com/emscripten-core/emsdk/commit/3d87d5ea8143b3636f872fb05b896eb4a19a070b * Fix cls_multi_schar: cast rest_call to signed char * Remove test xfails (#17) * Fix long double when used as a varargs argument * Enable unwindtest and fix it * Add EM_JS_DEPS * Also require convertJsFunctionToWasm * Run tests very very verbose * Echo the .emscripten file * Remove --experimental-wasm-bigint insertion * Build with assertions * Move verbosity flags back out of LDFLAGS * Remove debug print statement * Use up to date pyodide docker image * Explicitly cast res_call to fix test failure * Put back name of main function in cls_longdouble_va.c * Fix alignment The stack pointer apparently needs to be aligned to 16. There were some terrible subtle bugs caused by not respecting this. stackAlloc knows that the stack should be 16 aligned, so we can use stackAlloc(0) to enforce this. This way if alignment requirements change, as long as Emscripten updates stackAlloc to continue to enforce them we should be okay. * Fix handling of systems with no Js bigint integration When we run the node tests we use node v14 tests (since node v14 is vendored with Emscripten). Node v14 has no Js bigint integration unless the --experimental-wasm-bigint flag is passed. So only the node tests really notice if we get this right. Turns out, it didn't work. We can't call a JavaScript function with 64 bit integer arguments without bigint integration. In ffi_call, we are trying to call a wasm function that takes 64 bit integer arguments. dynCall is designed to do this. We need to go back to tracking the signature when we don't have WASM_BIGINT, and then use dynCall. This works better now that emscripten can dynamically fill in extra dynCall wrappers: https://github.com/emscripten-core/emscripten/pull/17328 On the other hand, for the closures we are not getting a function pointer as a first argument. We need to make our own wasm legalizer adaptor that splits 64 bit integer arguments and then calls the JavaScript trampoline, then the JavaScript trampoline reassembles them, calls the closure, then splits the result (if it's a 64 bit integer) and the adaptor puts it back together. * Improvements to emscripten test shell scripts (#21) This fixes the C++ unwinding tests and makes other minor improvements to the Emscripten test shell scripts. * Rename the test folder and move test files into emscripten test folder * Use docker image that has autoconf-2.71 * Cleanup * Pin emscripten 3.1.30 * Fix build.sh path * Rearrange ci pipeline * Fix bpo_38748 test * Cleanup * Improvements to comments, add static asserts, and update copyright * Use `*_js` instead of `*_helper` for EM_JS functions (#22) * Minor code simplification * Xfail first dejagnu test to work around emscripten cache messages See https://github.com/emscripten-core/emscripten/issues/18607 * Remove unneeded xfails * Shorten conftest.py by using pytest-pyodide * Apply formatters and linters to emscripten directory * Fix Emscripten xfail hack * Fix build-tests script * Patch emscripten to quiet info messages * Clean up compiler flags in scripts and remove some settings from circleci config * Rename emscripten quiet script * Add missing export * Don't remove go.exp * Add reference to emscripten logging issue --------- Co-authored-by: Kleis Auke Wolthuizen <info@kleisauke.nl> Co-authored-by: Kleis Auke Wolthuizen <github@kleisauke.nl> Co-authored-by: Christian Heimes <christian@python.org>

Download

• src/wasm32/ffi.c

• /* -----------------------------------------------------------------------
     ffi.c - Copyright (c) 2018-2023  Hood Chatham, Brion Vibber, Kleis Auke Wolthuizen, and others.
  
     wasm32/emscripten Foreign Function Interface
  
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the
     ``Software''), to deal in the Software without restriction, including
     without limitation the rights to use, copy, modify, merge, publish,
     distribute, sublicense, and/or sell copies of the Software, and to
     permit persons to whom the Software is furnished to do so, subject to
     the following conditions:
  
     The above copyright notice and this permission notice shall be included
     in all copies or substantial portions of the Software.
  
     THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
     HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
     WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     DEALINGS IN THE SOFTWARE.
     ----------------------------------------------------------------------- */
  
  #include <ffi.h>
  #include <ffi_common.h>
  
  #include <stdlib.h>
  #include <stdint.h>
  
  #include <emscripten/emscripten.h>
  
  #ifdef DEBUG_F
  #define LOG_DEBUG(args...)  \
    console.warn(`====LIBFFI(line __LINE__)`, args)
  #else
  #define LOG_DEBUG(args...) 0
  #endif
  
  #define EM_JS_MACROS(ret, name, args, body...) EM_JS(ret, name, args, body)
  
  #if WASM_BIGINT
  EM_JS_DEPS(libffi, "$getWasmTableEntry,$setWasmTableEntry,$getEmptyTableSlot,$convertJsFunctionToWasm");
  #define CALL_FUNCTION_POINTER(ptr, args...) \
    (LOG_DEBUG("CALL_FUNC_PTR", ptr, args),   \
    getWasmTableEntry(ptr).apply(null, args))
  
  #define JS_FUNCTION_TO_WASM convertJsFunctionToWasm
  #else
  EM_JS_DEPS(libffi, "$getWasmTableEntry,$setWasmTableEntry,$getEmptyTableSlot,$convertJsFunctionToWasm,$dynCall,$generateFuncType,$uleb128Encode");
  #define CALL_FUNCTION_POINTER(ptr, args...)     \
    (LOG_DEBUG("CALL_FUNC_PTR", sig, ptr, args),  \
    dynCall(sig, ptr, args))
  
  #define JS_FUNCTION_TO_WASM createLegalizerWrapper
  #endif
  
  // Signature calculations are not needed if WASM_BIGINT is present.
  #if WASM_BIGINT
  #define SIG(sig)
  #else
  #define SIG(sig) sig
  #endif
  
  #define DEREF_U8(addr, offset) HEAPU8[addr + offset]
  #define DEREF_S8(addr, offset) HEAP8[addr + offset]
  #define DEREF_U16(addr, offset) HEAPU16[(addr >> 1) + offset]
  #define DEREF_S16(addr, offset) HEAP16[(addr >> 1) + offset]
  #define DEREF_U32(addr, offset) HEAPU32[(addr >> 2) + offset]
  #define DEREF_S32(addr, offset) HEAP32[(addr >> 2) + offset]
  
  #define DEREF_F32(addr, offset) HEAPF32[(addr >> 2) + offset]
  #define DEREF_F64(addr, offset) HEAPF64[(addr >> 3) + offset]
  
  #if WASM_BIGINT
  // We have HEAPU64 in this case.
  #define DEREF_U64(addr, offset) HEAPU64[(addr >> 3) + offset]
  #endif
  
  
  #define CHECK_FIELD_OFFSET(struct, field, offset)                                  \
    _Static_assert(                                                                  \
      offsetof(struct, field) == offset,                                             \
      "Memory layout of '" #struct "' has changed: '" #field "' is in an unexpected location");
  
  CHECK_FIELD_OFFSET(ffi_cif, abi, 4*0);
  CHECK_FIELD_OFFSET(ffi_cif, nargs, 4*1);
  CHECK_FIELD_OFFSET(ffi_cif, arg_types, 4*2);
  CHECK_FIELD_OFFSET(ffi_cif, rtype, 4*3);
  CHECK_FIELD_OFFSET(ffi_cif, nfixedargs, 4*6);
  
  #define CIF__ABI(addr) DEREF_U32(addr, 0)
  #define CIF__NARGS(addr) DEREF_U32(addr, 1)
  #define CIF__ARGTYPES(addr) DEREF_U32(addr, 2)
  #define CIF__RTYPE(addr) DEREF_U32(addr, 3)
  #define CIF__NFIXEDARGS(addr) DEREF_U32(addr, 6)
  
  CHECK_FIELD_OFFSET(ffi_type, size, 0);
  CHECK_FIELD_OFFSET(ffi_type, alignment, 4);
  CHECK_FIELD_OFFSET(ffi_type, type, 6);
  CHECK_FIELD_OFFSET(ffi_type, elements, 8);
  
  #define FFI_TYPE__SIZE(addr) DEREF_U32(addr, 0)
  #define FFI_TYPE__ALIGN(addr) DEREF_U16(addr + 4, 0)
  #define FFI_TYPE__TYPEID(addr) DEREF_U16(addr + 6, 0)
  #define FFI_TYPE__ELEMENTS(addr) DEREF_U32(addr + 8, 0)
  
  #define ALIGN_ADDRESS(addr, align) (addr &= (~((align) - 1)))
  #define STACK_ALLOC(stack, size, align) ((stack -= (size)), ALIGN_ADDRESS(stack, align))
  
  // Most wasm runtimes support at most 1000 Js trampoline args.
  #define MAX_ARGS 1000
  
  #include <stddef.h>
  
  #define VARARGS_FLAG 1
  
  #define FFI_OK_MACRO 0
  _Static_assert(FFI_OK_MACRO == FFI_OK, "FFI_OK must be 0");
  
  #define FFI_BAD_TYPEDEF_MACRO 1
  _Static_assert(FFI_BAD_TYPEDEF_MACRO == FFI_BAD_TYPEDEF, "FFI_BAD_TYPEDEF must be 1");
  
  ffi_status FFI_HIDDEN
  ffi_prep_cif_machdep(ffi_cif *cif)
  {
    if (cif->abi != FFI_WASM32_EMSCRIPTEN)
      return FFI_BAD_ABI;
    // This is called after ffi_prep_cif_machdep_var so we need to avoid
    // overwriting cif->nfixedargs.
    if (!(cif->flags & VARARGS_FLAG))
      cif->nfixedargs = cif->nargs;
    if (cif->nargs > MAX_ARGS)
      return FFI_BAD_TYPEDEF;
    if (cif->rtype->type == FFI_TYPE_COMPLEX)
      return FFI_BAD_TYPEDEF;
    // If they put the COMPLEX type into a struct we won't notice, but whatever.
    for (int i = 0; i < cif->nargs; i++)
      if (cif->arg_types[i]->type == FFI_TYPE_COMPLEX)
        return FFI_BAD_TYPEDEF;
    return FFI_OK;
  }
  
  ffi_status FFI_HIDDEN
  ffi_prep_cif_machdep_var(ffi_cif *cif, unsigned nfixedargs, unsigned ntotalargs)
  {
    cif->flags |= VARARGS_FLAG;
    cif->nfixedargs = nfixedargs;
    // The varargs takes up one extra argument
    if (cif->nfixedargs + 1 > MAX_ARGS)
      return FFI_BAD_TYPEDEF;
    return FFI_OK;
  }
  
  /**
   * A Javascript helper function. This takes an argument typ which is a wasm
   * pointer to an ffi_type object. It returns a pair a type and a type id.
   *
   *    - If it is not a struct, return its type and its typeid field.
   *    - If it is a struct of size >= 2, return the type and its typeid (which
   *      will be FFI_TYPE_STRUCT)
   *    - If it is a struct of size 0, return FFI_TYPE_VOID (????? this is broken)
   *    - If it is a struct of size 1, replace it with the single field and apply
   *      the same logic again to that.
   *
   * By always unboxing structs up front, we can avoid messy casework later.
   */
  EM_JS_MACROS(
  void,
  unbox_small_structs, (ffi_type type_ptr), {
    var type_id = FFI_TYPE__TYPEID(type_ptr);
    while (type_id === FFI_TYPE_STRUCT) {
      var elements = FFI_TYPE__ELEMENTS(type_ptr);
      var first_element = DEREF_U32(elements, 0);
      if (first_element === 0) {
        type_id = FFI_TYPE_VOID;
        break;
      } else if (DEREF_U32(elements, 1) === 0) {
        type_ptr = first_element;
        type_id = FFI_TYPE__TYPEID(first_element);
      } else {
        break;
      }
    }
    return [type_ptr, type_id];
  })
  
  EM_JS_MACROS(
  void,
  ffi_call_js, (ffi_cif *cif, ffi_fp fn, void *rvalue, void **avalue),
  {
    var abi = CIF__ABI(cif);
    var nargs = CIF__NARGS(cif);
    var nfixedargs = CIF__NFIXEDARGS(cif);
    var arg_types_ptr = CIF__ARGTYPES(cif);
    var rtype_unboxed = unbox_small_structs(CIF__RTYPE(cif));
    var rtype_ptr = rtype_unboxed[0];
    var rtype_id = rtype_unboxed[1];
    var orig_stack_ptr = stackSave();
    var cur_stack_ptr = orig_stack_ptr;
  
    var args = [];
    // Does our onwards call return by argument or normally? We return by argument
    // no matter what.
    var ret_by_arg = false;
  
    if (rtype_id === FFI_TYPE_COMPLEX) {
      throw new Error('complex ret marshalling nyi');
    }
    if (rtype_id < 0 || rtype_id > FFI_TYPE_LAST) {
      throw new Error('Unexpected rtype ' + rtype_id);
    }
    // If the return type is a struct with multiple entries or a long double, the
    // function takes an extra first argument which is a pointer to return value.
    // Conveniently, we've already received a pointer to return value, so we can
    // just use this. We also mark a flag that we don't need to convert the return
    // value of the dynamic call back to C.
    if (rtype_id === FFI_TYPE_LONGDOUBLE || rtype_id === FFI_TYPE_STRUCT) {
      args.push(rvalue);
      ret_by_arg = true;
    }
  
    SIG(var sig = "");
  
  #if !WASM_BIGINT
    switch(rtype_id) {
    case FFI_TYPE_VOID:
      SIG(sig = 'v');
      break;
    case FFI_TYPE_STRUCT:
    case FFI_TYPE_LONGDOUBLE:
      SIG(sig = 'vi');
      break;
    case FFI_TYPE_INT:
    case FFI_TYPE_UINT8:
    case FFI_TYPE_SINT8:
    case FFI_TYPE_UINT16:
    case FFI_TYPE_SINT16:
    case FFI_TYPE_UINT32:
    case FFI_TYPE_SINT32:
    case FFI_TYPE_POINTER:
      SIG(sig = 'i');
      break;
    case FFI_TYPE_FLOAT:
      SIG(sig = 'f');
      break;
    case FFI_TYPE_DOUBLE:
      SIG(sig = 'd');
      break;
    case FFI_TYPE_UINT64:
    case FFI_TYPE_SINT64:
      SIG(sig = 'j');
      break;
    }
  #endif
  
    // Accumulate a Javascript list of arguments for the Javascript wrapper for
    // the wasm function. The Javascript wrapper does a type conversion from
    // Javascript to C automatically, here we manually do the inverse conversion
    // from C to Javascript.
    for (var i = 0; i < nfixedargs; i++) {
      var arg_ptr = DEREF_U32(avalue, i);
      var arg_unboxed = unbox_small_structs(DEREF_U32(arg_types_ptr, i));
      var arg_type_ptr = arg_unboxed[0];
      var arg_type_id = arg_unboxed[1];
  
      // It's okay here to always use unsigned integers as long as the size is 32
      // or 64 bits. Smaller sizes get extended to 32 bits differently according
      // to whether they are signed or unsigned.
      switch (arg_type_id) {
      case FFI_TYPE_INT:
      case FFI_TYPE_SINT32:
      case FFI_TYPE_UINT32:
      case FFI_TYPE_POINTER:
        args.push(DEREF_U32(arg_ptr, 0));
        SIG(sig += 'i');
        break;
      case FFI_TYPE_FLOAT:
        args.push(DEREF_F32(arg_ptr, 0));
        SIG(sig += 'f');
        break;
      case FFI_TYPE_DOUBLE:
        args.push(DEREF_F64(arg_ptr, 0));
        SIG(sig += 'd');
        break;
      case FFI_TYPE_UINT8:
        args.push(DEREF_U8(arg_ptr, 0));
        SIG(sig += 'i');
        break;
      case FFI_TYPE_SINT8:
        args.push(DEREF_S8(arg_ptr, 0));
        SIG(sig += 'i');
        break;
      case FFI_TYPE_UINT16:
        args.push(DEREF_U16(arg_ptr, 0));
        SIG(sig += 'i');
        break;
      case FFI_TYPE_SINT16:
        args.push(DEREF_S16(arg_ptr, 0));
        SIG(sig += 'i');
        break;
      case FFI_TYPE_UINT64:
      case FFI_TYPE_SINT64:
        #if WASM_BIGINT
        args.push(DEREF_U64(arg_ptr, 0));
        #else
        args.push(DEREF_U32(arg_ptr, 0));
        args.push(DEREF_U32(arg_ptr, 1));
        #endif
        SIG(sig += 'j');
        break;
      case FFI_TYPE_LONGDOUBLE:
        // long double is passed as a pair of BigInts.
        #if WASM_BIGINT
        args.push(DEREF_U64(arg_ptr, 0));
        args.push(DEREF_U64(arg_ptr, 1));
        #else
        args.push(DEREF_U32(arg_ptr, 0));
        args.push(DEREF_U32(arg_ptr, 1));
        args.push(DEREF_U32(arg_ptr, 2));
        args.push(DEREF_U32(arg_ptr, 3));
        #endif
        SIG(sig += "jj");
        break;
      case FFI_TYPE_STRUCT:
        // Nontrivial structs are passed by pointer.
        // Have to copy the struct onto the stack though because C ABI says it's
        // call by value.
        var size = FFI_TYPE__SIZE(arg_type_ptr);
        var align = FFI_TYPE__ALIGN(arg_type_ptr);
        STACK_ALLOC(cur_stack_ptr, size, align);
        HEAP8.subarray(cur_stack_ptr, cur_stack_ptr+size).set(HEAP8.subarray(arg_ptr, arg_ptr + size));
        args.push(cur_stack_ptr);
        SIG(sig += 'i');
        break;
      case FFI_TYPE_COMPLEX:
        throw new Error('complex marshalling nyi');
      default:
        throw new Error('Unexpected type ' + arg_type_id);
      }
    }
  
    // Wasm functions can't directly manipulate the callstack, so varargs
    // arguments have to go on a separate stack. A varags function takes one extra
    // argument which is a pointer to where on the separate stack the args are
    // located. Because stacks are allocated backwards, we have to loop over the
    // varargs backwards.
    //
    // We don't have any way of knowing how many args were actually passed, so we
    // just always copy extra nonsense past the end. The ownwards call will know
    // not to look at it.
    if (nfixedargs != nargs) {
      SIG(sig += 'i');
      var struct_arg_info = [];
      for (var i = nargs - 1;  i >= nfixedargs; i--) {
        var arg_ptr = DEREF_U32(avalue, i);
        var arg_unboxed = unbox_small_structs(DEREF_U32(arg_types_ptr, i));
        var arg_type_ptr = arg_unboxed[0];
        var arg_type_id = arg_unboxed[1];
        switch (arg_type_id) {
        case FFI_TYPE_UINT8:
        case FFI_TYPE_SINT8:
          STACK_ALLOC(cur_stack_ptr, 1, 1);
          DEREF_U8(cur_stack_ptr, 0) = DEREF_U8(arg_ptr, 0);
          break;
        case FFI_TYPE_UINT16:
        case FFI_TYPE_SINT16:
          STACK_ALLOC(cur_stack_ptr, 2, 2);
          DEREF_U16(cur_stack_ptr, 0) = DEREF_U16(arg_ptr, 0);
          break;
        case FFI_TYPE_INT:
        case FFI_TYPE_UINT32:
        case FFI_TYPE_SINT32:
        case FFI_TYPE_POINTER:
        case FFI_TYPE_FLOAT:
          STACK_ALLOC(cur_stack_ptr, 4, 4);
          DEREF_U32(cur_stack_ptr, 0) = DEREF_U32(arg_ptr, 0);
          break;
        case FFI_TYPE_DOUBLE:
        case FFI_TYPE_UINT64:
        case FFI_TYPE_SINT64:
          STACK_ALLOC(cur_stack_ptr, 8, 8);
          DEREF_U32(cur_stack_ptr, 0) = DEREF_U32(arg_ptr, 0);
          DEREF_U32(cur_stack_ptr, 1) = DEREF_U32(arg_ptr, 1);
          break;
        case FFI_TYPE_LONGDOUBLE:
          STACK_ALLOC(cur_stack_ptr, 16, 8);
          DEREF_U32(cur_stack_ptr, 0) = DEREF_U32(arg_ptr, 0);
          DEREF_U32(cur_stack_ptr, 1) = DEREF_U32(arg_ptr, 1);
          DEREF_U32(cur_stack_ptr, 2) = DEREF_U32(arg_ptr, 2);
          DEREF_U32(cur_stack_ptr, 3) = DEREF_U32(arg_ptr, 3);
          break;
        case FFI_TYPE_STRUCT:
          // Again, struct must be passed by pointer.
          // But ABI is by value, so have to copy struct onto stack.
          // Currently arguments are going onto stack so we can't put it there now. Come back for this.
          STACK_ALLOC(cur_stack_ptr, 4, 4);
          struct_arg_info.push([cur_stack_ptr, arg_ptr, FFI_TYPE__SIZE(arg_type_ptr), FFI_TYPE__ALIGN(arg_type_ptr)]);
          break;
        case FFI_TYPE_COMPLEX:
          throw new Error('complex arg marshalling nyi');
        default:
          throw new Error('Unexpected argtype ' + arg_type_id);
        }
      }
      // extra normal argument which is the pointer to the varargs.
      args.push(cur_stack_ptr);
      // Now allocate variable struct args on stack too.
      for (var i = 0; i < struct_arg_info.length; i++) {
        var struct_info = struct_arg_info[i];
        var arg_target = struct_info[0];
        var arg_ptr = struct_info[1];
        var size = struct_info[2];
        var align = struct_info[3];
        STACK_ALLOC(cur_stack_ptr, size, align);
        HEAP8.subarray(cur_stack_ptr, cur_stack_ptr+size).set(HEAP8.subarray(arg_ptr, arg_ptr + size));
        DEREF_U32(arg_target, 0) = cur_stack_ptr;
      }
    }
    stackRestore(cur_stack_ptr);
    stackAlloc(0); // stackAlloc enforces alignment invariants on the stack pointer
    var result = CALL_FUNCTION_POINTER(fn, args);
    // Put the stack pointer back (we moved it if there were any struct args or we
    // made a varargs call)
    stackRestore(orig_stack_ptr);
  
    // We need to return by argument. If return value was a nontrivial struct or
    // long double, the onwards call already put the return value in rvalue
    if (ret_by_arg) {
      return;
    }
  
    // Otherwise the result was automatically converted from C into Javascript and
    // we need to manually convert it back to C.
    switch (rtype_id) {
    case FFI_TYPE_VOID:
      break;
    case FFI_TYPE_INT:
    case FFI_TYPE_UINT32:
    case FFI_TYPE_SINT32:
    case FFI_TYPE_POINTER:
      DEREF_U32(rvalue, 0) = result;
      break;
    case FFI_TYPE_FLOAT:
      DEREF_F32(rvalue, 0) = result;
      break;
    case FFI_TYPE_DOUBLE:
      DEREF_F64(rvalue, 0) = result;
      break;
    case FFI_TYPE_UINT8:
    case FFI_TYPE_SINT8:
      DEREF_U8(rvalue, 0) = result;
      break;
    case FFI_TYPE_UINT16:
    case FFI_TYPE_SINT16:
      DEREF_U16(rvalue, 0) = result;
      break;
    case FFI_TYPE_UINT64:
    case FFI_TYPE_SINT64:
      #if WASM_BIGINT
      DEREF_U64(rvalue, 0) = result;
      #else
      DEREF_U32(rvalue, 0) = result;
      DEREF_U32(rvalue, 1) = getTempRet0();
      #endif
      break;
    case FFI_TYPE_COMPLEX:
      throw new Error('complex ret marshalling nyi');
    default:
      throw new Error('Unexpected rtype ' + rtype_id);
    }
  });
  
  void ffi_call(ffi_cif *cif, void (*fn)(void), void *rvalue, void **avalue) {
    ffi_call_js(cif, fn, rvalue, avalue);
  }
  
  CHECK_FIELD_OFFSET(ffi_closure, ftramp, 4*0);
  CHECK_FIELD_OFFSET(ffi_closure, cif, 4*1);
  CHECK_FIELD_OFFSET(ffi_closure, fun, 4*2);
  CHECK_FIELD_OFFSET(ffi_closure, user_data, 4*3);
  
  #define CLOSURE__wrapper(addr) DEREF_U32(addr, 0)
  #define CLOSURE__cif(addr) DEREF_U32(addr, 1)
  #define CLOSURE__fun(addr) DEREF_U32(addr, 2)
  #define CLOSURE__user_data(addr) DEREF_U32(addr, 3)
  
  EM_JS_MACROS(void *, ffi_closure_alloc_js, (size_t size, void **code), {
    var closure = _malloc(size);
    var index = getEmptyTableSlot();
    DEREF_U32(code, 0) = index;
    CLOSURE__wrapper(closure) = index;
    return closure;
  })
  
  void * __attribute__ ((visibility ("default")))
  ffi_closure_alloc(size_t size, void **code) {
    return ffi_closure_alloc_js(size, code);
  }
  
  EM_JS_MACROS(void, ffi_closure_free_js, (void *closure), {
    var index = CLOSURE__wrapper(closure);
    freeTableIndexes.push(index);
    _free(closure);
  })
  
  void __attribute__ ((visibility ("default")))
  ffi_closure_free(void *closure) {
    return ffi_closure_free_js(closure);
  }
  
  #if !WASM_BIGINT
  
  // When !WASM_BIGINT, we assume there is no JS bigint integration, so JavaScript
  // functions cannot take 64 bit integer arguments.
  //
  // We need to make our own wasm legalizer adaptor that splits 64 bit integer
  // arguments and then calls the JavaScript trampoline, then the JavaScript
  // trampoline reassembles them, calls the closure, then splits the result (if
  // it's a 64 bit integer) and the adaptor puts it back together.
  //
  // This is basically the reverse of the Emscripten function
  // createDyncallWrapper.
  EM_JS(void, createLegalizerWrapper, (int trampoline, int sig), {
    if(!sig.includes("j")) {
      return convertJsFunctionToWasm(trampoline, sig);
    }
    var sections = [];
    var prelude = [
      0x00, 0x61, 0x73, 0x6d, // magic ("\0asm")
      0x01, 0x00, 0x00, 0x00, // version: 1
    ];
    sections.push(prelude);
    var wrappersig = [
      // if return type is j, we will put the upper 32 bits into tempRet0.
      sig[0].replace("j", "i"),
      // in the rest of the argument list, one 64 bit integer is legalized into
      // two 32 bit integers.
      sig.slice(1).replace(/j/g, "ii"),
    ].join("");
  
    var typeSectionBody = [
      0x03, // number of types = 3
    ];
    generateFuncType(wrappersig, typeSectionBody); // The signature of the wrapper we are generating
    generateFuncType(sig, typeSectionBody); // the signature of the function pointer we will call
    generateFuncType("i", typeSectionBody); // the signature of getTempRet0
  
    var typeSection = [0x01 /* Type section code */];
    uleb128Encode(typeSectionBody.length, typeSection); // length of section in bytes
    typeSection.push.apply(typeSection, typeSectionBody);
    sections.push(typeSection);
  
    var importSection = [
      0x02, // import section code
      0x0d, // length of section in bytes
      0x02, // number of imports = 2
      // Import the getTempRet0 function, which we will call "r"
      0x01, 0x65, // name "e"
      0x01, 0x72, // name "r"
      0x00, // importing a function
      0x02, // type 2 = () -> i32
      // Import the wrapped function, which we will call "f"
      0x01, 0x65, // name "e"
      0x01, 0x66, // name "f"
      0x00, // importing a function
      0x00, // type 0 = wrappersig
    ];
    sections.push(importSection);
  
    var functionSection = [
      0x03, // function section code
      0x02, // length of section in bytes
      0x01, // number of functions = 1
      0x01, // type 1 = sig
    ];
    sections.push(functionSection);
  
    var exportSection = [
      0x07, // export section code
      0x05, // length of section in bytes
      0x01, // One export
      0x01, 0x66, // name "f"
      0x00, // type: function
      0x02, // function index 2 = the wrapper function
    ];
    sections.push(exportSection);
  
    var convert_code = [];
    convert_code.push(0x00); // no local variables (except the arguments)
  
    function localGet(j) {
      convert_code.push(0x20); // local.get
      uleb128Encode(j, convert_code);
    }
  
    for (var i = 1; i < sig.length; i++) {
      if (sig[i] == "j") {
        localGet(i - 1);
        convert_code.push(
          0xa7 // i32.wrap_i64
        );
        localGet(i - 1);
        convert_code.push(
          0x42, 0x20, // i64.const 32
          0x88,       // i64.shr_u
          0xa7        // i32.wrap_i64
        );
      } else {
        localGet(i - 1);
      }
    }
    convert_code.push(
      0x10, 0x01 // call f
    );
    if (sig[0] === "j") {
      // Need to reassemble a 64 bit integer. Lower 32 bits is on stack. Upper 32
      // bits we get from getTempRet0
      convert_code.push(
        0xad,       // i64.extend_i32_unsigned
        0x10, 0x00, // Call function 0 (r = getTempRet0)
        // join lower 32 bits and upper 32 bits
        0xac,       // i64.extend_i32_signed
        0x42, 0x20, // i64.const 32
        0x86,       // i64.shl,
        0x84        // i64.or
      );
    }
    convert_code.push(0x0b); // end
  
    var codeBody = [0x01]; // one code
    uleb128Encode(convert_code.length, codeBody);
    codeBody.push.apply(codeBody, convert_code);
    var codeSection = [0x0a /* Code section code */];
    uleb128Encode(codeBody.length, codeSection);
    codeSection.push.apply(codeSection, codeBody);
    sections.push(codeSection);
  
    var bytes = new Uint8Array([].concat.apply([], sections));
    // We can compile this wasm module synchronously because it is small.
    var module = new WebAssembly.Module(bytes);
    var instance = new WebAssembly.Instance(module, {
      e: {
        r: getTempRet0,
        f: trampoline,
      },
    });
    return instance.exports.f;
  });
  #endif
  
  EM_JS_MACROS(
  ffi_status,
  ffi_prep_closure_loc_js,
  (ffi_closure *closure, ffi_cif *cif, void *fun, void *user_data, void *codeloc),
  {
    var abi = CIF__ABI(cif);
    var nargs = CIF__NARGS(cif);
    var nfixedargs = CIF__NFIXEDARGS(cif);
    var arg_types_ptr = CIF__ARGTYPES(cif);
    var rtype_unboxed = unbox_small_structs(CIF__RTYPE(cif));
    var rtype_ptr = rtype_unboxed[0];
    var rtype_id = rtype_unboxed[1];
  
    // First construct the signature of the javascript trampoline we are going to create.
    // Important: this is the signature for calling us, the onward call always has sig viiii.
    var sig;
    var ret_by_arg = false;
    switch (rtype_id) {
    case FFI_TYPE_VOID:
      sig = 'v';
      break;
    case FFI_TYPE_STRUCT:
    case FFI_TYPE_LONGDOUBLE:
      // Return via a first pointer argument.
      sig = 'vi';
      ret_by_arg = true;
      break;
    case FFI_TYPE_INT:
    case FFI_TYPE_UINT8:
    case FFI_TYPE_SINT8:
    case FFI_TYPE_UINT16:
    case FFI_TYPE_SINT16:
    case FFI_TYPE_UINT32:
    case FFI_TYPE_SINT32:
    case FFI_TYPE_POINTER:
      sig = 'i';
      break;
    case FFI_TYPE_FLOAT:
      sig = 'f';
      break;
    case FFI_TYPE_DOUBLE:
      sig = 'd';
      break;
    case FFI_TYPE_UINT64:
    case FFI_TYPE_SINT64:
      sig = 'j';
      break;
    case FFI_TYPE_COMPLEX:
      throw new Error('complex ret marshalling nyi');
    default:
      throw new Error('Unexpected rtype ' + rtype_id);
    }
    var unboxed_arg_type_id_list = [];
    var unboxed_arg_type_info_list = [];
    for (var i = 0; i < nargs; i++) {
      var arg_unboxed = unbox_small_structs(DEREF_U32(arg_types_ptr, i));
      var arg_type_ptr = arg_unboxed[0];
      var arg_type_id = arg_unboxed[1];
      unboxed_arg_type_id_list.push(arg_type_id);
      unboxed_arg_type_info_list.push([FFI_TYPE__SIZE(arg_type_ptr), FFI_TYPE__ALIGN(arg_type_ptr)]);
    }
    for (var i = 0; i < nfixedargs; i++) {
      switch (unboxed_arg_type_id_list[i]) {
      case FFI_TYPE_INT:
      case FFI_TYPE_UINT8:
      case FFI_TYPE_SINT8:
      case FFI_TYPE_UINT16:
      case FFI_TYPE_SINT16:
      case FFI_TYPE_UINT32:
      case FFI_TYPE_SINT32:
      case FFI_TYPE_POINTER:
      case FFI_TYPE_STRUCT:
        sig += 'i';
        break;
      case FFI_TYPE_FLOAT:
        sig += 'f';
        break;
      case FFI_TYPE_DOUBLE:
        sig += 'd';
        break;
      case FFI_TYPE_LONGDOUBLE:
        sig += 'jj';
        break;
      case FFI_TYPE_UINT64:
      case FFI_TYPE_SINT64:
        sig += 'j';
        break;
      case FFI_TYPE_COMPLEX:
        throw new Error('complex marshalling nyi');
      default:
        throw new Error('Unexpected argtype ' + arg_type_id);
      }
    }
    if (nfixedargs < nargs) {
      // extra pointer to varargs stack
      sig += "i";
    }
    LOG_DEBUG("CREATE_CLOSURE",  "sig:", sig);
    function trampoline() {
      var args = Array.prototype.slice.call(arguments);
      var size = 0;
      var orig_stack_ptr = stackSave();
      var cur_ptr = orig_stack_ptr;
      var ret_ptr;
      var jsarg_idx = 0;
      // Should we return by argument or not? The onwards call returns by argument
      // no matter what. (Warning: ret_by_arg means the opposite in ffi_call)
      if (ret_by_arg) {
        ret_ptr = args[jsarg_idx++];
      } else {
        // We might return 4 bytes or 8 bytes, allocate 8 just in case.
        STACK_ALLOC(cur_ptr, 8, 8);
        ret_ptr = cur_ptr;
      }
      cur_ptr -= 4 * nargs;
      var args_ptr = cur_ptr;
      var carg_idx = 0;
      // Here we either have the actual argument, or a pair of BigInts for long
      // double, or a pointer to struct. We have to store into args_ptr[i] a
      // pointer to the ith argument. If the argument is a struct, just store the
      // pointer. Otherwise allocate stack space and copy the js argument onto the
      // stack.
      for (; carg_idx < nfixedargs; carg_idx++) {
        // jsarg_idx might start out as 0 or 1 depending on ret_by_arg
        // it advances an extra time for long double
        var cur_arg = args[jsarg_idx++];
        var arg_type_info = unboxed_arg_type_info_list[carg_idx];
        var arg_size = arg_type_info[0];
        var arg_align = arg_type_info[1];
        var arg_type_id = unboxed_arg_type_id_list[carg_idx];
        switch (arg_type_id) {
        case FFI_TYPE_UINT8:
        case FFI_TYPE_SINT8:
          // Bad things happen if we don't align to 4 here
          STACK_ALLOC(cur_ptr, 1, 4);
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          DEREF_U8(cur_ptr, 0) = cur_arg;
          break;
        case FFI_TYPE_UINT16:
        case FFI_TYPE_SINT16:
          // Bad things happen if we don't align to 4 here
          STACK_ALLOC(cur_ptr, 2, 4);
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          DEREF_U16(cur_ptr, 0) = cur_arg;
          break;
        case FFI_TYPE_INT:
        case FFI_TYPE_UINT32:
        case FFI_TYPE_SINT32:
        case FFI_TYPE_POINTER:
          STACK_ALLOC(cur_ptr, 4, 4);
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          DEREF_U32(cur_ptr, 0) = cur_arg;
          break;
        case FFI_TYPE_STRUCT:
          // cur_arg is already a pointer to struct
          // copy it onto stack to pass by value
          STACK_ALLOC(cur_ptr, arg_size, arg_align);
          HEAP8.subarray(cur_ptr, cur_ptr + arg_size).set(HEAP8.subarray(cur_arg, cur_arg + arg_size));
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          break;
        case FFI_TYPE_FLOAT:
          STACK_ALLOC(cur_ptr, 4, 4);
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          DEREF_F32(cur_ptr, 0) = cur_arg;
          break;
        case FFI_TYPE_DOUBLE:
          STACK_ALLOC(cur_ptr, 8, 8);
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          DEREF_F64(cur_ptr, 0) = cur_arg;
          break;
        case FFI_TYPE_UINT64:
        case FFI_TYPE_SINT64:
          STACK_ALLOC(cur_ptr, 8, 8);
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          #if WASM_BIGINT
          DEREF_U64(cur_ptr, 0) = cur_arg;
          #else
          // Bigint arg was split by legalizer adaptor
          DEREF_U32(cur_ptr, 0) = cur_arg;
          cur_arg = args[jsarg_idx++];
          DEREF_U32(cur_ptr, 1) = cur_arg;
          #endif
          break;
        case FFI_TYPE_LONGDOUBLE:
          STACK_ALLOC(cur_ptr, 16, 8);
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
          #if WASM_BIGINT
          DEREF_U64(cur_ptr, 0) = cur_arg;
          cur_arg = args[jsarg_idx++];
          DEREF_U64(cur_ptr, 1) = cur_arg;
          #else
          // Was split by legalizer adaptor
          DEREF_U32(cur_ptr, 0) = cur_arg;
          cur_arg = args[jsarg_idx++];
          DEREF_U32(cur_ptr, 1) = cur_arg;
          cur_arg = args[jsarg_idx++];
          DEREF_U32(cur_ptr, 2) = cur_arg;
          cur_arg = args[jsarg_idx++];
          DEREF_U32(cur_ptr, 3) = cur_arg;
          #endif
          break;
        }
      }
      // If its a varargs call, last js argument is a pointer to the varargs.
      var varargs = args[args.length - 1];
      // We have no way of knowing how many varargs were actually provided, this
      // fills the rest of the stack space allocated with nonsense. The onward
      // call will know to ignore the nonsense.
  
      // We either have a pointer to the argument if the argument is not a struct
      // or a pointer to pointer to struct. We need to store a pointer to the
      // argument into args_ptr[i]
      for (; carg_idx < nargs; carg_idx++) {
        var arg_type_id = unboxed_arg_type_id_list[carg_idx];
        var arg_type_info = unboxed_arg_type_info_list[carg_idx];
        var arg_size = arg_type_info[0];
        var arg_align = arg_type_info[1];
        if (arg_type_id === FFI_TYPE_STRUCT) {
          // In this case varargs is a pointer to pointer to struct so we need to
          // deref once
          var struct_ptr = DEREF_U32(varargs, 0);
          STACK_ALLOC(cur_ptr, arg_size, arg_align);
          HEAP8.subarray(cur_ptr, cur_ptr + arg_size).set(HEAP8.subarray(struct_ptr, struct_ptr + arg_size));
          DEREF_U32(args_ptr, carg_idx) = cur_ptr;
        } else {
          DEREF_U32(args_ptr, carg_idx) = varargs;
        }
        varargs += 4;
      }
      stackRestore(cur_ptr);
      stackAlloc(0); // stackAlloc enforces alignment invariants on the stack pointer
      LOG_DEBUG("CALL_CLOSURE",  "closure:", closure, "fptr", CLOSURE__fun(closure), "cif",  CLOSURE__cif(closure));
      getWasmTableEntry(CLOSURE__fun(closure))(
          CLOSURE__cif(closure), ret_ptr, args_ptr,
          CLOSURE__user_data(closure)
      );
      stackRestore(orig_stack_ptr);
  
      // If we aren't supposed to return by argument, figure out what to return.
      if (!ret_by_arg) {
        switch (sig[0]) {
        case "i":
          return DEREF_U32(ret_ptr, 0);
        case "j":
          #if WASM_BIGINT
          return DEREF_U64(ret_ptr, 0);
          #else
          // Split the return i64, set the upper 32 bits into tempRet0 and return
          // the lower 32 bits.
          setTempRet0(DEREF_U32(ret_ptr, 1));
          return DEREF_U32(ret_ptr, 0);
          #endif
        case "d":
          return DEREF_F64(ret_ptr, 0);
        case "f":
          return DEREF_F32(ret_ptr, 0);
        }
      }
    }
    try {
      var wasm_trampoline = JS_FUNCTION_TO_WASM(trampoline, sig);
    } catch(e) {
      return FFI_BAD_TYPEDEF_MACRO;
    }
    setWasmTableEntry(codeloc, wasm_trampoline);
    CLOSURE__cif(closure) = cif;
    CLOSURE__fun(closure) = fun;
    CLOSURE__user_data(closure) = user_data;
    return FFI_OK_MACRO;
  })
  
  // EM_JS does not correctly handle function pointer arguments, so we need a
  // helper
  ffi_status ffi_prep_closure_loc(ffi_closure *closure, ffi_cif *cif,
                                  void (*fun)(ffi_cif *, void *, void **, void *),
                                  void *user_data, void *codeloc) {
    if (cif->abi != FFI_WASM32_EMSCRIPTEN)
      return FFI_BAD_ABI;
    return ffi_prep_closure_loc_js(closure, cif, (void *)fun, user_data,
                                       codeloc);
  }
  

Download