don't align arguments in stdcall

native/libffi/src/x86/ffi.c

@@ -305,6 +305,9 @@ ffi_status ffi_prep_cif_machdep(ffi_cif *cif)
 
   for (ptr = cif->arg_types, i = cif->nargs; i > 0; i--, ptr++)
     {
+#ifdef X86_WIN32
+      if (cif->abi != FFI_STDCALL)
+#endif
       if (((*ptr)->alignment - 1) & cif->bytes)
         cif->bytes = ALIGN(cif->bytes, (*ptr)->alignment);
       cif->bytes += ALIGN((*ptr)->size, FFI_SIZEOF_ARG);

native/libffi/testsuite/libffi.call/align_stdcall.c

@@ -0,0 +1,42 @@
+/* Area:	ffi_call
+   Purpose:	Check stdcall for argument alignment (always 4) on X86_WIN32 systems.
+   Limitations:	none.
+   PR:		none.
+   Originator:	<twalljava@java.net> (from many_win32.c) */
+
+/* { dg-do run { target i?86-*-cygwin* i?86-*-mingw* } } */
+
+#include "ffitest.h"
+#include <float.h>
+
+static float __attribute__((stdcall)) stdcall_align(int i1,
+                                                    double f2,
+                                                    int i3,
+                                                    double f4)
+{
+  return i1+f2+i3+f4;
+}
+
+int main (void)
+{
+  ffi_cif cif;
+  ffi_type *args[4] = {&ffi_type_int, &ffi_type_double, &ffi_type_int, &ffi_type_double};
+  float fa[2] = {1,2};
+  int ia[2] = {1,2};
+  void *values[4] = {&ia[0], &fa[0], &ia[1], &fa[1]};
+  float f, ff;
+
+  /* Initialize the cif */
+  CHECK(ffi_prep_cif(&cif, FFI_STDCALL, 4,
+		     &ffi_type_float, args) == FFI_OK);
+
+  ff = stdcall_align(ia[0], fa[0], ia[1], fa[1]);
+
+  ffi_call(&cif, FFI_FN(stdcall_align), &f, values);
+
+  if (f - ff < FLT_EPSILON)
+    printf("stdcall many arg tests ok!\n");
+  else
+    CHECK(0);
+  exit(0);
+}