On Thu, Sep 29, 2011 at 11:17 PM, Jakub Jelinek <[email protected]> wrote:
> Hi!
>
> This patch teaches PTA/aliasing about strdup/strndup (that the passed in
> string is just read and doesn't escape in any way, and that otherwise it
> acts as malloc or other allocation calls.
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2011-09-29 Jakub Jelinek <[email protected]>
>
> * tree-ssa-structalias.c (find_func_aliases_for_builtin_call): Handle
> BUILT_IN_STRDUP and BUILT_IN_STRNDUP.
> * tree-ssa-alias.c (call_may_clobber_ref_p_1): Likewise.
>
> * gcc.dg/strlenopt-21.c: New test.
>
> --- gcc/tree-ssa-structalias.c.jj 2011-09-29 15:27:17.000000000 +0200
> +++ gcc/tree-ssa-structalias.c 2011-09-29 15:31:02.000000000 +0200
> @@ -4130,6 +4130,16 @@ find_func_aliases_for_builtin_call (gimp
> case BUILT_IN_REMQUOL:
> case BUILT_IN_FREE:
> return true;
> + case BUILT_IN_STRDUP:
> + case BUILT_IN_STRNDUP:
> + {
> + varinfo_t uses = get_call_use_vi (t);
You don't want to deal with call-uses at this point. I think you want
a similar effect as
p = malloc (...);
memcpy (p, src, ...);
thus,
if (gimple_call_lhs (t))
{
/* The result gets a heap tag assigned. */
handle_lhs_call (t, gimple_call_lhs (t), gimple_call_flags
(t), NULL, fndecl);
/* Transfer all pointers from the source to the destination memory. */
get_constraint_for_ptr_offset (gimple_call_lhs (t), NULL_TREE, &lhsc);
get_constraint_for_ptr_offset (gimple_call_rhs1 (t), NULL_TREE, &rhsc);
do_deref (&lhsc);
do_deref (&rhsc);
process_all_all_constraints (lhsc, rhsc);
}
return true;
Richard.
> + make_constraint_to (uses->id, gimple_call_arg (t, 0));
> + if (gimple_call_lhs (t))
> + handle_lhs_call (t, gimple_call_lhs (t), gimple_call_flags (t),
> + NULL, fndecl);
> + return true;
> + }
> /* Trampolines are special - they set up passing the static
> frame. */
> case BUILT_IN_INIT_TRAMPOLINE:
> --- gcc/tree-ssa-alias.c.jj 2011-09-29 15:27:17.000000000 +0200
> +++ gcc/tree-ssa-alias.c 2011-09-29 15:31:02.000000000 +0200
> @@ -1506,6 +1506,8 @@ call_may_clobber_ref_p_1 (gimple call, a
> being the definition point for the pointer. */
> case BUILT_IN_MALLOC:
> case BUILT_IN_CALLOC:
> + case BUILT_IN_STRDUP:
> + case BUILT_IN_STRNDUP:
> /* Unix98 specifies that errno is set on allocation failure. */
> if (flag_errno_math
> && targetm.ref_may_alias_errno (ref))
> --- gcc/testsuite/gcc.dg/strlenopt-21.c.jj 2011-09-29 15:42:19.000000000
> +0200
> +++ gcc/testsuite/gcc.dg/strlenopt-21.c 2011-09-29 15:42:00.000000000 +0200
> @@ -0,0 +1,66 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fdump-tree-strlen -fdump-tree-optimized" } */
> +
> +#include "strlenopt.h"
> +
> +struct S { char *p; size_t l; };
> +
> +__attribute__((noinline, noclone)) struct S
> +foo (char *x, int n)
> +{
> + int i;
> + char a[64];
> + char *p = strchr (x, '\0');
> + struct S s;
> + /* strcpy here is optimized into memcpy, length computed as p - x + 1. */
> + strcpy (a, x);
> + /* strcat here is optimized into memcpy. */
> + strcat (p, "abcd");
> + for (i = 0; i < n; i++)
> + if ((i % 123) == 53)
> + /* strcat here is optimized into strlen and memcpy. */
> + strcat (a, "efg");
> + s.p = strdup (a);
> + /* The strlen should be optimized here into 4. */
> + s.l = strlen (p);
> + return s;
> +}
> +
> +int
> +main ()
> +{
> + char buf[32];
> + struct S s;
> + buf[0] = 'z';
> + buf[1] = '\0';
> + s = foo (buf, 0);
> + if (s.l != 4 || memcmp (buf, "zabcd", 6) != 0)
> + abort ();
> + if (s.p == NULL)
> + return 0;
> + if (memcmp (s.p, "z", 2) != 0)
> + abort ();
> + s = foo (buf, 60);
> + if (s.l != 4 || memcmp (buf, "zabcdabcd", 10) != 0)
> + abort ();
> + if (s.p == NULL)
> + return 0;
> + if (memcmp (s.p, "zabcdefg", 9) != 0)
> + abort ();
> + s = foo (buf, 240);
> + if (s.l != 4 || memcmp (buf, "zabcdabcdabcd", 14) != 0)
> + abort ();
> + if (s.p == NULL)
> + return 0;
> + if (memcmp (s.p, "zabcdabcdefgefg", 16) != 0)
> + abort ();
> + return 0;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "strlen \\(" 1 "strlen" } } */
> +/* { dg-final { scan-tree-dump-times "memcpy \\(" 3 "strlen" } } */
> +/* { dg-final { scan-tree-dump-times "strcpy \\(" 0 "strlen" } } */
> +/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
> +/* { dg-final { scan-tree-dump-times "strchr \\(" 1 "strlen" } } */
> +/* { dg-final { scan-tree-dump-times "stpcpy \\(" 0 "strlen" } } */
> +/* { dg-final { cleanup-tree-dump "strlen" } } */
>
> Jakub
>
