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Fix argument and return value alignment in `scm_i_foreign_call'.

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* libguile/foreign.c (scm_i_foreign_call): Fix the computation of
  ARG_SIZE wrt. alignment.  Arrange so that the address ARGS[i] is
  aligned, rather than checking whether OFF is aligned.  Have the RVALUE
  be at least word-aligned, which fixes calls to `char'-returning
  functions on `armv5tel-*-linux-gnueabi'.
This commit is contained in:
Ludovic Courtès 2010-05-30 22:54:39 +02:00
parent 1880c97df1
commit 86425e2653
1 changed files with 21 additions and 16 deletions
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37
libguile/foreign.c
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@ -24,6 +24,8 @@
#include <alignof.h> #include <alignof.h>
#include <string.h> #include <string.h>
#include <assert.h>
#include "libguile/_scm.h" #include "libguile/_scm.h"
#include "libguile/bytevectors.h" #include "libguile/bytevectors.h"
#include "libguile/instructions.h" #include "libguile/instructions.h"
@ -985,32 +987,35 @@ scm_i_foreign_call (SCM foreign, const SCM *argv)
/* Argument pointers. */ /* Argument pointers. */
args = alloca (sizeof (void *) * cif->nargs); args = alloca (sizeof (void *) * cif->nargs);
/* Compute the amount of memory needed to store all the argument values. /* Compute the worst-case amount of memory needed to store all the argument
Note: as of libffi 3.0.9 `cif->bytes' is undocumented and is zero, so it values. Note: as of libffi 3.0.9 `cif->bytes' is undocumented and is zero,
can't be used for that purpose. */ so it can't be used for that purpose. */
for (i = 0, arg_size = 0; for (i = 0, arg_size = 0; i < cif->nargs; i++)
i < cif->nargs; arg_size += cif->arg_types[i]->size + cif->arg_types[i]->alignment - 1;
i++, arg_size)
arg_size += ROUND_UP (cif->arg_types[i]->size,
cif->arg_types[i]->alignment);
/* Space for argument values, followed by return value. */ /* Space for argument values, followed by return value. */
data = alloca (arg_size data = alloca (arg_size + cif->rtype->size
+ ROUND_UP (cif->rtype->size, cif->rtype->alignment)); + max (sizeof (void *), cif->rtype->alignment));
/* Unpack ARGV to native values, setting ARGV pointers. */ /* Unpack ARGV to native values, setting ARGV pointers. */
for (i = 0, off = 0; for (i = 0, off = 0;
i < cif->nargs; i < cif->nargs;
off += cif->arg_types[i]->size, i++) off = (scm_t_uint8 *) args[i] - data + cif->arg_types[i]->size,
i++)
{ {
off = ROUND_UP (off, cif->arg_types[i]->alignment); /* Suitably align the storage area for argument I. */
args[i] = data + off; args[i] = (void *) ROUND_UP ((scm_t_uintptr) data + off,
cif->arg_types[i]->alignment);
assert ((scm_t_uintptr) args[i] % cif->arg_types[i]->alignment == 0);
unpack (cif->arg_types[i], args[i], argv[i]); unpack (cif->arg_types[i], args[i], argv[i]);
} }
/* Prepare space for the return value. */ /* Prepare space for the return value. On some platforms, such as
off = ROUND_UP (off, cif->rtype->alignment); `armv5tel-*-linux-gnueabi', the return value has to be at least
rvalue = data + off; word-aligned, even if its type doesn't have any alignment requirement as is
the case with `char'. */
rvalue = (void *) ROUND_UP ((scm_t_uintptr) data + off,
max (sizeof (void *), cif->rtype->alignment));
/* off we go! */ /* off we go! */
ffi_call (cif, func, rvalue, args); ffi_call (cif, func, rvalue, args);