On Fri, Nov 20, 2015 at 2:08 PM, Ilya Enkovich <enkovich....@gmail.com> wrote:
> On 19 Nov 18:19, Richard Biener wrote:
>> On November 19, 2015 6:12:30 PM GMT+01:00, Bernd Schmidt
>> <bschm...@redhat.com> wrote:
>> >On 11/19/2015 05:31 PM, Ilya Enkovich wrote:
>> >> Currently we fold all memcpy/memmove calls with a known data size.
>> >> It causes two problems when used with Pointer Bounds Checker.
>> >> The first problem is that we may copy pointers as integer data
>> >> and thus loose bounds. The second problem is that if we inline
>> >> memcpy, we also have to inline bounds copy and this may result
>> >> in a huge amount of code and significant compilation time growth.
>> >> This patch disables folding for functions we want to instrument.
>> >>
>> >> Does it look reasonable for trunk and GCC5 branch? Bootstrapped
>> >> and regtested on x86_64-unknown-linux-gnu.
>> >
>> >Can't see anything wrong with it. Ok.
>>
>> But for small sizes this can have a huge impact on optimization. Which is
>> why we have the code in the first place. I'd make the check less broad, for
>> example inlining copies of size less than a pointer shouldn't be affected.
>
> Right. We also may inline in case we know no pointers are copied. Below is
> a version with extended condition and a couple more tests. Bootstrapped and
> regtested on x86_64-unknown-linux-gnu. Does it OK for trunk and gcc-5-branch?
>
>>
>> Richard.
>>
>> >
>> >Bernd
>>
>>
>
> Thanks,
> Ilya
> --
> gcc/
>
> 2015-11-20 Ilya Enkovich <enkovich....@gmail.com>
>
> * gimple-fold.c (gimple_fold_builtin_memory_op): Don't
> fold call if we are going to instrument it and it may
> copy pointers.
>
> gcc/testsuite/
>
> 2015-11-20 Ilya Enkovich <enkovich....@gmail.com>
>
> * gcc.target/i386/mpx/pr68337-1.c: New test.
> * gcc.target/i386/mpx/pr68337-2.c: New test.
> * gcc.target/i386/mpx/pr68337-3.c: New test.
>
>
> diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
> index 1ab20d1..dd9f80b 100644
> --- a/gcc/gimple-fold.c
> +++ b/gcc/gimple-fold.c
> @@ -53,6 +53,8 @@ along with GCC; see the file COPYING3. If not see
> #include "gomp-constants.h"
> #include "optabs-query.h"
> #include "omp-low.h"
> +#include "tree-chkp.h"
> +#include "ipa-chkp.h"
>
>
> /* Return true when DECL can be referenced from current unit.
> @@ -664,6 +666,23 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
> unsigned int src_align, dest_align;
> tree off0;
>
> + /* Inlining of memcpy/memmove may cause bounds lost (if we copy
> + pointers as wide integer) and also may result in huge function
> + size because of inlined bounds copy. Thus don't inline for
> + functions we want to instrument in case pointers are copied. */
> + if (flag_check_pointer_bounds
> + && chkp_instrumentable_p (cfun->decl)
> + /* Even if data may contain pointers we can inline if copy
> + less than a pointer size. */
> + && (!tree_fits_uhwi_p (len)
> + || compare_tree_int (len, POINTER_SIZE_UNITS) >= 0)
|| tree_to_uhwi (len) >= POINTER_SIZE_UNITS
> + /* Check data type for pointers. */
> + && (!TREE_TYPE (src)
> + || !TREE_TYPE (TREE_TYPE (src))
> + || VOID_TYPE_P (TREE_TYPE (TREE_TYPE (src)))
> + || chkp_type_has_pointer (TREE_TYPE (TREE_TYPE (src)))))
I don't think you can in any way rely on the pointer type of the src argument
as all pointer conversions are useless and memcpy and friends take void *
anyway.
Note that you also disable memmove to memcpy simplification with this
early check.
Where is pointer transfer handled for MPX? I suppose it's not done
transparently
for all memory move instructions but explicitely by instrumented block copy
routines in libmpx? In which case how does that identify pointers vs.
non-pointers?
Richard.
> + return false;
> +
> /* Build accesses at offset zero with a ref-all character type. */
> off0 = build_int_cst (build_pointer_type_for_mode (char_type_node,
> ptr_mode, true), 0);
> diff --git a/gcc/testsuite/gcc.target/i386/mpx/pr68337-1.c
> b/gcc/testsuite/gcc.target/i386/mpx/pr68337-1.c
> new file mode 100644
> index 0000000..3f8d79d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/mpx/pr68337-1.c
> @@ -0,0 +1,32 @@
> +/* { dg-do run } */
> +/* { dg-options "-fcheck-pointer-bounds -mmpx" } */
> +
> +#include "mpx-check.h"
> +
> +#define N 2
> +
> +extern void abort ();
> +
> +static int
> +mpx_test (int argc, const char **argv)
> +{
> + char ** src = (char **)malloc (sizeof (char *) * N);
> + char ** dst = (char **)malloc (sizeof (char *) * N);
> + int i;
> +
> + for (i = 0; i < N; i++)
> + src[i] = __bnd_set_ptr_bounds (argv[0] + i, i + 1);
> +
> + __builtin_memcpy(dst, src, sizeof (char *) * N);
> +
> + for (i = 0; i < N; i++)
> + {
> + char *p = dst[i];
> + if (p != argv[0] + i
> + || __bnd_get_ptr_lbound (p) != p
> + || __bnd_get_ptr_ubound (p) != p + i)
> + abort ();
> + }
> +
> + return 0;
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/mpx/pr68337-2.c
> b/gcc/testsuite/gcc.target/i386/mpx/pr68337-2.c
> new file mode 100644
> index 0000000..16736b4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/mpx/pr68337-2.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fcheck-pointer-bounds -mmpx" } */
> +/* { dg-final { scan-assembler-not "memcpy" } } */
> +
> +void
> +test1 (char *dst, char *src)
> +{
> + __builtin_memcpy (dst, src, sizeof (char *) * 2);
> +}
> +
> +void
> +test2 (void *dst, void *src)
> +{
> + __builtin_memcpy (dst, src, sizeof (char *) / 2);
> +}
> +
> +struct s
> +{
> + int a;
> + int b;
> +};
> +
> +void
> +test3 (struct s *dst, struct s *src)
> +{
> + __builtin_memcpy (dst, src, sizeof (struct s));
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/mpx/pr68337-3.c
> b/gcc/testsuite/gcc.target/i386/mpx/pr68337-3.c
> new file mode 100644
> index 0000000..095425a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/mpx/pr68337-3.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fcheck-pointer-bounds -mmpx" } */
> +/* { dg-final { scan-assembler-times "bnd\[^\n\]*__mpx_wrapper_memcpy" 3 } }
> */
> +
> +void
> +test1 (char **dst, char **src)
> +{
> + __builtin_memcpy (dst, src, sizeof (char *) * 2);
> +}
> +
> +void
> +test2 (void *dst, void *src)
> +{
> + __builtin_memcpy (dst, src, sizeof (char *));
> +}
> +
> +struct s
> +{
> + int a;
> + int *b;
> +};
> +
> +void
> +test3 (struct s *dst, struct s *src)
> +{
> + __builtin_memcpy (dst, src, sizeof (struct s));
> +}
