test: implement "register" action of WAST

11 files changed, 358 insertions, 208 deletions

diff --git a/BUGS.txt b/BUGS.txt
index 0026112..e5d5f63 100644
--- a/BUGS.txt
+++ b/BUGS.txt
@@ -20,12 +20,6 @@
 * NamesTest
 * StartTest
 
-## Register
-
-* RefFuncTest
-* TableCopyTest
-* TableInitTest
-
 ## Misc.
 
 * CustomTest
diff --git a/examples/php-on-wasm/php-wasm.php b/examples/php-on-wasm/php-wasm.php
index 96625b8..336602c 100644
--- a/examples/php-on-wasm/php-wasm.php
+++ b/examples/php-on-wasm/php-wasm.php
@@ -6,6 +6,7 @@ require_once __DIR__ . '/../../vendor/autoload.php';
 
 use Nsfisis\Waddiwasi\BinaryFormat\Decoder;
 use Nsfisis\Waddiwasi\BinaryFormat\InvalidBinaryFormatException;
+use Nsfisis\Waddiwasi\Execution\Extern;
 use Nsfisis\Waddiwasi\Execution\FuncInst;
 use Nsfisis\Waddiwasi\Execution\Refs;
 use Nsfisis\Waddiwasi\Execution\Runtime;
@@ -31,107 +32,114 @@ try {
     exit(1);
 }
 
-$hostFuncs = [
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__invoke_iii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiii(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__env__invoke_v(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__invoke_ii(...)),
-    makeHostFunc('() -> ()', hostFunc__env__abort(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__env__exit(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viii(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__invoke_vii(...)),
-    makeHostFunc('(i32, i32) -> ()', hostFunc__env__invoke_vi(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__invoke_i(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiii(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env____assert_fail(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiiiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__strftime(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__getaddrinfo(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__gethostbyname_r(...)),
-    makeHostFunc('() -> (i32)', hostFunc__env__getdtablesize(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobyname(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobynumber(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__strptime(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__getnameinfo(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiiii(...)),
-    makeHostFunc('(i32, i32, i32, f64, i32, i32) -> ()', hostFunc__env__invoke_viidii(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__getcontext(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__makecontext(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__swapcontext(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_sizes_get(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_get(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_fcntl64(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ioctl(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_close(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_read(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_write(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__wasi_snapshot_preview1__proc_exit(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_faccessat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_chdir(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_chmod(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_fchownat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_dup(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_dup3(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__emscripten_memcpy_js(...)),
-    makeHostFunc('() -> (f64)', hostFunc__env__emscripten_date_now(...)),
-    makeHostFunc('() -> (i32)', hostFunc__env___emscripten_get_now_is_monotonic(...)),
-    makeHostFunc('() -> (f64)', hostFunc__env__emscripten_get_now(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_fdatasync(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_openat(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_fstat64(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_stat64(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_newfstatat(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_lstat64(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_sync(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_getcwd(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__env__emscripten_err(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_fdstat_get(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_mkdirat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_pipe(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_poll(...)),
-    makeHostFunc('(i32, i32) -> ()', hostFunc__env____call_sighandler(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_getdents64(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_readlinkat(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_renameat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_rmdir(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall__newselect(...)),
-    makeHostFunc('(i32, f64) -> (i32)', hostFunc__env___setitimer_js(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_statfs64(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_symlink(...)),
-    makeHostFunc('() -> (i32)', hostFunc__env__emscripten_get_heap_max(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___tzset_js(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_unlinkat(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_utimensat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__emscripten_resize_heap(...)),
-    makeHostFunc('() -> ()', hostFunc__env___emscripten_throw_longjmp(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_accept4(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_bind(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_connect(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getpeername(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockname(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockopt(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_listen(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_recvfrom(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_sendto(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_socket(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ftruncate64(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_seek(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env___mktime_js(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___localtime_js(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___gmtime_js(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___munmap_js(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___mmap_js(...)),
+$importModules = [
+    'env' => [
+        'invoke_iii' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__invoke_iii(...)),
+        'invoke_iiiii' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiii(...)),
+        'invoke_v' => makeHostFunc('(i32) -> ()', hostFunc__env__invoke_v(...)),
+        'invoke_ii' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__invoke_ii(...)),
+        'abort' => makeHostFunc('() -> ()', hostFunc__env__abort(...)),
+        'exit' => makeHostFunc('(i32) -> ()', hostFunc__env__exit(...)),
+        'invoke_viii' => makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viii(...)),
+        'invoke_vii' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__invoke_vii(...)),
+        'invoke_vi' => makeHostFunc('(i32, i32) -> ()', hostFunc__env__invoke_vi(...)),
+        'invoke_i' => makeHostFunc('(i32) -> (i32)', hostFunc__env__invoke_i(...)),
+        'invoke_iiiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiii(...)),
+        'invoke_iiii' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiii(...)),
+        '__assert_fail' => makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env____assert_fail(...)),
+        'invoke_viiii' => makeHostFunc('(i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiii(...)),
+        'invoke_viiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiii(...)),
+        'invoke_iiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiii(...)),
+        'invoke_iiiiiiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiiiiii(...)),
+        'strftime' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__strftime(...)),
+        'getaddrinfo' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__getaddrinfo(...)),
+        'gethostbyname_r' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__gethostbyname_r(...)),
+        'getdtablesize' => makeHostFunc('() -> (i32)', hostFunc__env__getdtablesize(...)),
+        'getprotobyname' => makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobyname(...)),
+        'getprotobynumber' => makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobynumber(...)),
+        'strptime' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__strptime(...)),
+        'getnameinfo' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__getnameinfo(...)),
+        'invoke_viiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiiii(...)),
+        'invoke_viidii' => makeHostFunc('(i32, i32, i32, f64, i32, i32) -> ()', hostFunc__env__invoke_viidii(...)),
+        'getcontext' => makeHostFunc('(i32) -> (i32)', hostFunc__env__getcontext(...)),
+        'makecontext' => makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__makecontext(...)),
+        'swapcontext' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__swapcontext(...)),
+        '__syscall_fcntl64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_fcntl64(...)),
+        '__syscall_ioctl' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ioctl(...)),
+        '__syscall_faccessat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_faccessat(...)),
+        '__syscall_chdir' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_chdir(...)),
+        '__syscall_chmod' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_chmod(...)),
+        '__syscall_fchownat' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_fchownat(...)),
+        '__syscall_dup' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_dup(...)),
+        '__syscall_dup3' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_dup3(...)),
+        'emscripten_memcpy_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__emscripten_memcpy_js(...)),
+        'emscripten_date_now' => makeHostFunc('() -> (f64)', hostFunc__env__emscripten_date_now(...)),
+        '_emscripten_get_now_is_monotonic' => makeHostFunc('() -> (i32)', hostFunc__env___emscripten_get_now_is_monotonic(...)),
+        'emscripten_get_now' => makeHostFunc('() -> (f64)', hostFunc__env__emscripten_get_now(...)),
+        '__syscall_fdatasync' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_fdatasync(...)),
+        '__syscall_openat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_openat(...)),
+        '__syscall_fstat64' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_fstat64(...)),
+        '__syscall_stat64' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_stat64(...)),
+        '__syscall_newfstatat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_newfstatat(...)),
+        '__syscall_lstat64' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_lstat64(...)),
+        '__syscall_getcwd' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_getcwd(...)),
+        'emscripten_err' => makeHostFunc('(i32) -> ()', hostFunc__env__emscripten_err(...)),
+        '__syscall_mkdirat' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_mkdirat(...)),
+        '__syscall_pipe' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_pipe(...)),
+        '__syscall_poll' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_poll(...)),
+        '__call_sighandler' => makeHostFunc('(i32, i32) -> ()', hostFunc__env____call_sighandler(...)),
+        '__syscall_getdents64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_getdents64(...)),
+        '__syscall_readlinkat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_readlinkat(...)),
+        '__syscall_renameat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_renameat(...)),
+        '__syscall_rmdir' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_rmdir(...)),
+        '__syscall__newselect' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall__newselect(...)),
+        '_setitimer_js' => makeHostFunc('(i32, f64) -> (i32)', hostFunc__env___setitimer_js(...)),
+        '__syscall_statfs64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_statfs64(...)),
+        '__syscall_symlink' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_symlink(...)),
+        'emscripten_get_heap_max' => makeHostFunc('() -> (i32)', hostFunc__env__emscripten_get_heap_max(...)),
+        '_tzset_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___tzset_js(...)),
+        '__syscall_unlinkat' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_unlinkat(...)),
+        '__syscall_utimensat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_utimensat(...)),
+        'emscripten_resize_heap' => makeHostFunc('(i32) -> (i32)', hostFunc__env__emscripten_resize_heap(...)),
+        '_emscripten_throw_longjmp' => makeHostFunc('() -> ()', hostFunc__env___emscripten_throw_longjmp(...)),
+        '__syscall_accept4' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_accept4(...)),
+        '__syscall_bind' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_bind(...)),
+        '__syscall_connect' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_connect(...)),
+        '__syscall_getpeername' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getpeername(...)),
+        '__syscall_getsockname' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockname(...)),
+        '__syscall_getsockopt' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockopt(...)),
+        '__syscall_listen' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_listen(...)),
+        '__syscall_recvfrom' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_recvfrom(...)),
+        '__syscall_sendto' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_sendto(...)),
+        '__syscall_socket' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_socket(...)),
+        '__syscall_ftruncate64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ftruncate64(...)),
+        '_mktime_js' => makeHostFunc('(i32) -> (i32)', hostFunc__env___mktime_js(...)),
+        '_localtime_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___localtime_js(...)),
+        '_gmtime_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___gmtime_js(...)),
+        '_munmap_js' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___munmap_js(...)),
+        '_mmap_js' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___mmap_js(...)),
+    ],
+    'wasi_snapshot_preview1' => [
+        'environ_sizes_get' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_sizes_get(...)),
+        'environ_get' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_get(...)),
+        'fd_close' => makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_close(...)),
+        'fd_read' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_read(...)),
+        'fd_write' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_write(...)),
+        'proc_exit' => makeHostFunc('(i32) -> ()', hostFunc__wasi_snapshot_preview1__proc_exit(...)),
+        'fd_sync' => makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_sync(...)),
+        'fd_fdstat_get' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_fdstat_get(...)),
+        'fd_seek' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_seek(...)),
+    ],
 ];
+
 $store = Store::empty();
-$externVals = [];
-foreach ($hostFuncs as $hostFunc) {
-    $externVals[] = $store->registerFunc($hostFunc);
+$importObj = [];
+foreach ($importModules as $importModuleName => $importModule) {
+    foreach ($importModule as $importName => $import) {
+        $importObj[$importModuleName][$importName] = Extern::Func($import);
+    }
 }
-$runtime = Runtime::instantiate($store, $module, $externVals);
+$runtime = Runtime::instantiate($store, $module, $importObj);
 $codePtr = allocateStringOnWasmMemory($runtime, PHP_HELLO_WORLD);
 
 $results = $runtime->invoke("php_wasm_run", [$codePtr]);
diff --git a/examples/rubyvm-on-php-on-wasm/php-wasm.php b/examples/rubyvm-on-php-on-wasm/php-wasm.php
index 1efb89f..5d411cc 100644
--- a/examples/rubyvm-on-php-on-wasm/php-wasm.php
+++ b/examples/rubyvm-on-php-on-wasm/php-wasm.php
@@ -6,6 +6,7 @@ require_once __DIR__ . '/vendor/autoload.php';
 
 use Nsfisis\Waddiwasi\BinaryFormat\Decoder;
 use Nsfisis\Waddiwasi\BinaryFormat\InvalidBinaryFormatException;
+use Nsfisis\Waddiwasi\Execution\Extern;
 use Nsfisis\Waddiwasi\Execution\FuncInst;
 use Nsfisis\Waddiwasi\Execution\MemInst;
 use Nsfisis\Waddiwasi\Execution\Refs;
@@ -32,107 +33,114 @@ try {
     exit(1);
 }
 
-$hostFuncs = [
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__invoke_iii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiii(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__env__invoke_v(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__invoke_ii(...)),
-    makeHostFunc('() -> ()', hostFunc__env__abort(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__env__exit(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viii(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__invoke_vii(...)),
-    makeHostFunc('(i32, i32) -> ()', hostFunc__env__invoke_vi(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__invoke_i(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiii(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env____assert_fail(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiiiiii(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__strftime(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__getaddrinfo(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__gethostbyname_r(...)),
-    makeHostFunc('() -> (i32)', hostFunc__env__getdtablesize(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobyname(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobynumber(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__strptime(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__getnameinfo(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiiii(...)),
-    makeHostFunc('(i32, i32, i32, f64, i32, i32) -> ()', hostFunc__env__invoke_viidii(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__getcontext(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__makecontext(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__swapcontext(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_sizes_get(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_get(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_fcntl64(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ioctl(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_close(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_read(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_write(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__wasi_snapshot_preview1__proc_exit(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_faccessat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_chdir(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_chmod(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_fchownat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_dup(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_dup3(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__emscripten_memcpy_js(...)),
-    makeHostFunc('() -> (f64)', hostFunc__env__emscripten_date_now(...)),
-    makeHostFunc('() -> (i32)', hostFunc__env___emscripten_get_now_is_monotonic(...)),
-    makeHostFunc('() -> (f64)', hostFunc__env__emscripten_get_now(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_fdatasync(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_openat(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_fstat64(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_stat64(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_newfstatat(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_lstat64(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_sync(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_getcwd(...)),
-    makeHostFunc('(i32) -> ()', hostFunc__env__emscripten_err(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_fdstat_get(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_mkdirat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_pipe(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_poll(...)),
-    makeHostFunc('(i32, i32) -> ()', hostFunc__env____call_sighandler(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_getdents64(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_readlinkat(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_renameat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_rmdir(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall__newselect(...)),
-    makeHostFunc('(i32, f64) -> (i32)', hostFunc__env___setitimer_js(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_statfs64(...)),
-    makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_symlink(...)),
-    makeHostFunc('() -> (i32)', hostFunc__env__emscripten_get_heap_max(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___tzset_js(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_unlinkat(...)),
-    makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_utimensat(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env__emscripten_resize_heap(...)),
-    makeHostFunc('() -> ()', hostFunc__env___emscripten_throw_longjmp(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_accept4(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_bind(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_connect(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getpeername(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockname(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockopt(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_listen(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_recvfrom(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_sendto(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_socket(...)),
-    makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ftruncate64(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_seek(...)),
-    makeHostFunc('(i32) -> (i32)', hostFunc__env___mktime_js(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___localtime_js(...)),
-    makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___gmtime_js(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___munmap_js(...)),
-    makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___mmap_js(...)),
+$importModules = [
+    'env' => [
+        'invoke_iii' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__invoke_iii(...)),
+        'invoke_iiiii' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiii(...)),
+        'invoke_v' => makeHostFunc('(i32) -> ()', hostFunc__env__invoke_v(...)),
+        'invoke_ii' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__invoke_ii(...)),
+        'abort' => makeHostFunc('() -> ()', hostFunc__env__abort(...)),
+        'exit' => makeHostFunc('(i32) -> ()', hostFunc__env__exit(...)),
+        'invoke_viii' => makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viii(...)),
+        'invoke_vii' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__invoke_vii(...)),
+        'invoke_vi' => makeHostFunc('(i32, i32) -> ()', hostFunc__env__invoke_vi(...)),
+        'invoke_i' => makeHostFunc('(i32) -> (i32)', hostFunc__env__invoke_i(...)),
+        'invoke_iiiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiii(...)),
+        'invoke_iiii' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiii(...)),
+        '__assert_fail' => makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env____assert_fail(...)),
+        'invoke_viiii' => makeHostFunc('(i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiii(...)),
+        'invoke_viiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiii(...)),
+        'invoke_iiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiii(...)),
+        'invoke_iiiiiiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__invoke_iiiiiiiiii(...)),
+        'strftime' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__strftime(...)),
+        'getaddrinfo' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env__getaddrinfo(...)),
+        'gethostbyname_r' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__gethostbyname_r(...)),
+        'getdtablesize' => makeHostFunc('() -> (i32)', hostFunc__env__getdtablesize(...)),
+        'getprotobyname' => makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobyname(...)),
+        'getprotobynumber' => makeHostFunc('(i32) -> (i32)', hostFunc__env__getprotobynumber(...)),
+        'strptime' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env__strptime(...)),
+        'getnameinfo' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env__getnameinfo(...)),
+        'invoke_viiiiii' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> ()', hostFunc__env__invoke_viiiiii(...)),
+        'invoke_viidii' => makeHostFunc('(i32, i32, i32, f64, i32, i32) -> ()', hostFunc__env__invoke_viidii(...)),
+        'getcontext' => makeHostFunc('(i32) -> (i32)', hostFunc__env__getcontext(...)),
+        'makecontext' => makeHostFunc('(i32, i32, i32, i32) -> ()', hostFunc__env__makecontext(...)),
+        'swapcontext' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env__swapcontext(...)),
+        '__syscall_fcntl64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_fcntl64(...)),
+        '__syscall_ioctl' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ioctl(...)),
+        '__syscall_faccessat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_faccessat(...)),
+        '__syscall_chdir' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_chdir(...)),
+        '__syscall_chmod' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_chmod(...)),
+        '__syscall_fchownat' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_fchownat(...)),
+        '__syscall_dup' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_dup(...)),
+        '__syscall_dup3' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_dup3(...)),
+        'emscripten_memcpy_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env__emscripten_memcpy_js(...)),
+        'emscripten_date_now' => makeHostFunc('() -> (f64)', hostFunc__env__emscripten_date_now(...)),
+        '_emscripten_get_now_is_monotonic' => makeHostFunc('() -> (i32)', hostFunc__env___emscripten_get_now_is_monotonic(...)),
+        'emscripten_get_now' => makeHostFunc('() -> (f64)', hostFunc__env__emscripten_get_now(...)),
+        '__syscall_fdatasync' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_fdatasync(...)),
+        '__syscall_openat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_openat(...)),
+        '__syscall_fstat64' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_fstat64(...)),
+        '__syscall_stat64' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_stat64(...)),
+        '__syscall_newfstatat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_newfstatat(...)),
+        '__syscall_lstat64' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_lstat64(...)),
+        '__syscall_getcwd' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_getcwd(...)),
+        'emscripten_err' => makeHostFunc('(i32) -> ()', hostFunc__env__emscripten_err(...)),
+        '__syscall_mkdirat' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_mkdirat(...)),
+        '__syscall_pipe' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_pipe(...)),
+        '__syscall_poll' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_poll(...)),
+        '__call_sighandler' => makeHostFunc('(i32, i32) -> ()', hostFunc__env____call_sighandler(...)),
+        '__syscall_getdents64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_getdents64(...)),
+        '__syscall_readlinkat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_readlinkat(...)),
+        '__syscall_renameat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_renameat(...)),
+        '__syscall_rmdir' => makeHostFunc('(i32) -> (i32)', hostFunc__env____syscall_rmdir(...)),
+        '__syscall__newselect' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall__newselect(...)),
+        '_setitimer_js' => makeHostFunc('(i32, f64) -> (i32)', hostFunc__env___setitimer_js(...)),
+        '__syscall_statfs64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_statfs64(...)),
+        '__syscall_symlink' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__env____syscall_symlink(...)),
+        'emscripten_get_heap_max' => makeHostFunc('() -> (i32)', hostFunc__env__emscripten_get_heap_max(...)),
+        '_tzset_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___tzset_js(...)),
+        '__syscall_unlinkat' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_unlinkat(...)),
+        '__syscall_utimensat' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_utimensat(...)),
+        'emscripten_resize_heap' => makeHostFunc('(i32) -> (i32)', hostFunc__env__emscripten_resize_heap(...)),
+        '_emscripten_throw_longjmp' => makeHostFunc('() -> ()', hostFunc__env___emscripten_throw_longjmp(...)),
+        '__syscall_accept4' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_accept4(...)),
+        '__syscall_bind' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_bind(...)),
+        '__syscall_connect' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_connect(...)),
+        '__syscall_getpeername' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getpeername(...)),
+        '__syscall_getsockname' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockname(...)),
+        '__syscall_getsockopt' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_getsockopt(...)),
+        '__syscall_listen' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_listen(...)),
+        '__syscall_recvfrom' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_recvfrom(...)),
+        '__syscall_sendto' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_sendto(...)),
+        '__syscall_socket' => makeHostFunc('(i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env____syscall_socket(...)),
+        '__syscall_ftruncate64' => makeHostFunc('(i32, i32, i32) -> (i32)', hostFunc__env____syscall_ftruncate64(...)),
+        '_mktime_js' => makeHostFunc('(i32) -> (i32)', hostFunc__env___mktime_js(...)),
+        '_localtime_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___localtime_js(...)),
+        '_gmtime_js' => makeHostFunc('(i32, i32, i32) -> ()', hostFunc__env___gmtime_js(...)),
+        '_munmap_js' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___munmap_js(...)),
+        '_mmap_js' => makeHostFunc('(i32, i32, i32, i32, i32, i32, i32, i32) -> (i32)', hostFunc__env___mmap_js(...)),
+    ],
+    'wasi_snapshot_preview1' => [
+        'environ_sizes_get' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_sizes_get(...)),
+        'environ_get' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__environ_get(...)),
+        'fd_close' => makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_close(...)),
+        'fd_read' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_read(...)),
+        'fd_write' => makeHostFunc('(i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_write(...)),
+        'proc_exit' => makeHostFunc('(i32) -> ()', hostFunc__wasi_snapshot_preview1__proc_exit(...)),
+        'fd_sync' => makeHostFunc('(i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_sync(...)),
+        'fd_fdstat_get' => makeHostFunc('(i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_fdstat_get(...)),
+        'fd_seek' => makeHostFunc('(i32, i32, i32, i32, i32) -> (i32)', hostFunc__wasi_snapshot_preview1__fd_seek(...)),
+    ],
 ];
+
 $store = Store::empty();
-$externVals = [];
-foreach ($hostFuncs as $hostFunc) {
-    $externVals[] = $store->registerFunc($hostFunc);
+$importObj = [];
+foreach ($importModules as $importModuleName => $importModule) {
+    foreach ($importModule as $importName => $import) {
+        $importObj[$importModuleName][$importName] = Extern::Func($import);
+    }
 }
-$runtime = Runtime::instantiate($store, $module, $externVals);
+$runtime = Runtime::instantiate($store, $module, $importObj);
 $codePtr = allocateStringOnWasmMemory($runtime, strtr(PHP_HELLO_WORLD, ['%DIR%' => __DIR__]));
 
 $results = $runtime->invoke("php_wasm_run", [$codePtr]);
diff --git a/src/Execution/Extern.php b/src/Execution/Extern.php
new file mode 100644
index 0000000..e0b695e
--- /dev/null
+++ b/src/Execution/Extern.php
@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nsfisis\Waddiwasi\Execution;
+
+abstract readonly class Extern
+{
+    final public static function Func(FuncInst $func): Externs\Func
+    {
+        return new Externs\Func($func);
+    }
+
+    final public static function Table(TableInst $table): Externs\Table
+    {
+        return new Externs\Table($table);
+    }
+
+    final public static function Mem(MemInst $mem): Externs\Mem
+    {
+        return new Externs\Mem($mem);
+    }
+
+    final public static function Global_(GlobalInst $global): Externs\Global_
+    {
+        return new Externs\Global_($global);
+    }
+}
diff --git a/src/Execution/Externs/Func.php b/src/Execution/Externs/Func.php
new file mode 100644
index 0000000..124309c
--- /dev/null
+++ b/src/Execution/Externs/Func.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nsfisis\Waddiwasi\Execution\Externs;
+
+use Nsfisis\Waddiwasi\Execution\Extern;
+use Nsfisis\Waddiwasi\Execution\FuncInst;
+
+final readonly class Func extends Extern
+{
+    protected function __construct(
+        public FuncInst $func,
+    ) {
+    }
+}
diff --git a/src/Execution/Externs/Global_.php b/src/Execution/Externs/Global_.php
new file mode 100644
index 0000000..ccf9ad0
--- /dev/null
+++ b/src/Execution/Externs/Global_.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nsfisis\Waddiwasi\Execution\Externs;
+
+use Nsfisis\Waddiwasi\Execution\Extern;
+use Nsfisis\Waddiwasi\Execution\GlobalInst;
+
+final readonly class Global_ extends Extern
+{
+    protected function __construct(
+        public GlobalInst $global,
+    ) {
+    }
+}
diff --git a/src/Execution/Externs/Mem.php b/src/Execution/Externs/Mem.php
new file mode 100644
index 0000000..bd1f119
--- /dev/null
+++ b/src/Execution/Externs/Mem.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nsfisis\Waddiwasi\Execution\Externs;
+
+use Nsfisis\Waddiwasi\Execution\Extern;
+use Nsfisis\Waddiwasi\Execution\MemInst;
+
+final readonly class Mem extends Extern
+{
+    protected function __construct(
+        public MemInst $mem,
+    ) {
+    }
+}
diff --git a/src/Execution/Externs/Table.php b/src/Execution/Externs/Table.php
new file mode 100644
index 0000000..fde1e32
--- /dev/null
+++ b/src/Execution/Externs/Table.php
@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Nsfisis\Waddiwasi\Execution\Externs;
+
+use Nsfisis\Waddiwasi\Execution\Extern;
+use Nsfisis\Waddiwasi\Execution\TableInst;
+
+final readonly class Table extends Extern
+{
+    protected function __construct(
+        public TableInst $table,
+    ) {
+    }
+}
diff --git a/src/Execution/Runtime.php b/src/Execution/Runtime.php
index 02c526c..2cc37b2 100644
--- a/src/Execution/Runtime.php
+++ b/src/Execution/Runtime.php
@@ -56,11 +56,30 @@ final class Runtime
     }
 
     /**
-     * @param list<ExternVal> $externVals
+     * @param array<string, array<string, Extern>> $imports
      */
     public static function instantiate(
         Store $store,
         Module $module,
+        array $imports,
+    ): self {
+        $externVals = [];
+        foreach ($module->imports as $import) {
+            $extern = $imports[$import->module][$import->name] ?? null;
+            if ($extern === null) {
+                throw new RuntimeException("instantiate: import not found: {$import->module}::{$import->name}");
+            }
+            $externVals[] = $store->register($extern);
+        }
+        return self::doInstantiate($store, $module, $externVals);
+    }
+
+    /**
+     * @param list<ExternVal> $externVals
+     */
+    private static function doInstantiate(
+        Store $store,
+        Module $module,
         array $externVals,
     ): self {
         $allocator = new Allocator($store);
diff --git a/src/Execution/Store.php b/src/Execution/Store.php
index 2b1a26d..52a8ce1 100644
--- a/src/Execution/Store.php
+++ b/src/Execution/Store.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace Nsfisis\Waddiwasi\Execution;
 
+use RuntimeException;
 use function count;
 
 final class Store
@@ -31,9 +32,21 @@ final class Store
         return new self([], [], [], [], [], []);
     }
 
-    public function registerFunc(FuncInst $func): ExternVals\Func
+    public function register(Extern $extern): ExternVal
     {
-        $this->funcs[] = $func;
-        return ExternVal::Func(count($this->funcs) - 1);
+        match ($extern::class) {
+            Externs\Func::class => $this->funcs[] = $extern->func,
+            Externs\Table::class => $this->tables[] = $extern->table,
+            Externs\Mem::class => $this->mems[] = $extern->mem,
+            Externs\Global_::class => $this->globals[] = $extern->global,
+            default => throw new RuntimeException("unreachable"),
+        };
+        return match ($extern::class) {
+            Externs\Func::class => ExternVal::Func(count($this->funcs) - 1),
+            Externs\Table::class => ExternVal::Table(count($this->tables) - 1),
+            Externs\Mem::class => ExternVal::Mem(count($this->mems) - 1),
+            Externs\Global_::class => ExternVal::Global_(count($this->globals) - 1),
+            default => throw new RuntimeException("unreachable"),
+        };
     }
 }
diff --git a/tests/src/SpecTestsuites/SpecTestsuiteBase.php b/tests/src/SpecTestsuites/SpecTestsuiteBase.php
index 65176a5..2d37d2e 100644
--- a/tests/src/SpecTestsuites/SpecTestsuiteBase.php
+++ b/tests/src/SpecTestsuites/SpecTestsuiteBase.php
@@ -6,6 +6,7 @@ namespace Nsfisis\Waddiwasi\Tests\SpecTestsuites;
 
 use Nsfisis\Waddiwasi\BinaryFormat\Decoder;
 use Nsfisis\Waddiwasi\BinaryFormat\InvalidBinaryFormatException;
+use Nsfisis\Waddiwasi\Execution\Extern;
 use Nsfisis\Waddiwasi\Execution\Ref;
 use Nsfisis\Waddiwasi\Execution\Refs\RefExtern;
 use Nsfisis\Waddiwasi\Execution\Refs\RefFunc;
@@ -25,6 +26,8 @@ abstract class SpecTestsuiteBase extends TestCase
 {
     private static $modules = [];
     private static $runtimes = [];
+    private static $registeredModules = [];
+    private static $registeredRuntimes = [];
 
     protected function runModuleCommand(
         string $filename,
@@ -36,7 +39,15 @@ abstract class SpecTestsuiteBase extends TestCase
         $wasmBinary = file_get_contents($filePath);
         $module = (new Decoder($wasmBinary))->decode();
         self::$modules[$moduleName] = $module;
-        $runtime = Runtime::instantiate(Store::empty(), $module, []);
+        $importObj = [];
+        foreach (self::$registeredModules as $registeredModuleName => $registeredModule) {
+            $registeredRuntime = self::$registeredRuntimes[$registeredModuleName];
+            foreach ($registeredModule->exports as $export) {
+                $fn = $registeredRuntime->store->funcs[$registeredRuntime->getExport($export->name)->addr];
+                $importObj[$registeredModuleName][$export->name] = Extern::Func($fn);
+            }
+        }
+        $runtime = Runtime::instantiate(Store::empty(), $module, $importObj);
         self::$runtimes[$moduleName] = $runtime;
         $this->assertTrue(true);
     }
@@ -146,7 +157,12 @@ abstract class SpecTestsuiteBase extends TestCase
         string $as,
         int $line,
     ): void {
-        $this->assertTrue(false, "register");
+        $targetModuleName = $name ?? '_';
+        $targetModule = self::$modules[$targetModuleName];
+        $runtime = self::$runtimes[$targetModuleName];
+        self::$registeredModules[$as] = $targetModule;
+        self::$registeredRuntimes[$as] = $runtime;
+        $this->assertTrue(true);
     }
 
     /**