On Fri, Sep 30, 2011 at 12:35:49PM +0200, Richard Guenther wrote:
> On Fri, Sep 30, 2011 at 12:23 PM, Jakub Jelinek <[email protected]> wrote:
> > On Fri, Sep 30, 2011 at 10:25:35AM +0200, Richard Guenther wrote:
> >> > 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?
> >
> > Ok, here is the promissed updated patch.
>
> Ok if it passes bootstrap & test. The str[n]cat changes are probably
> worth backporting.
Here is the updated patch, bootstrapped/regtested on x86_64-linux and
i686-linux, committed to trunk. Will work on 4.6 backport of the str{,n}cat
part.
2011-09-30 Jakub Jelinek <[email protected]>
Richard Guenther <[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. Fix
handling of BUILT_IN_STRNCAT and BUILT_IN_STRNCAT_CHK.
(ref_maybe_used_by_call_p_1): Fix handling of BUILT_IN_STRCAT,
BUILT_IN_STRNCAT, BUILT_IN_STRCAT_CHK and BUILT_IN_STRNCAT_CHK.
* 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 2011-09-30 11:27:06.000000000 +0200
@@ -4130,6 +4130,24 @@ 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:
+ if (gimple_call_lhs (t))
+ {
+ handle_lhs_call (t, gimple_call_lhs (t), gimple_call_flags (t),
+ NULL, fndecl);
+ get_constraint_for_ptr_offset (gimple_call_lhs (t),
+ NULL_TREE, &lhsc);
+ get_constraint_for_ptr_offset (gimple_call_arg (t, 0),
+ NULL_TREE, &rhsc);
+ do_deref (&lhsc);
+ do_deref (&rhsc);
+ process_all_all_constraints (lhsc, rhsc);
+ VEC_free (ce_s, heap, lhsc);
+ VEC_free (ce_s, heap, rhsc);
+ return true;
+ }
+ break;
/* 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 2011-09-30 12:16:20.000000000 +0200
@@ -1178,8 +1177,20 @@ ref_maybe_used_by_call_p_1 (gimple call,
&& DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
switch (DECL_FUNCTION_CODE (callee))
{
- /* All the following functions clobber memory pointed to by
- their first argument. */
+ /* All the following functions read memory pointed to by
+ their second argument. strcat/strncat additionally
+ reads memory pointed to by the first argument. */
+ case BUILT_IN_STRCAT:
+ case BUILT_IN_STRNCAT:
+ {
+ ao_ref dref;
+ ao_ref_init_from_ptr_and_size (&dref,
+ gimple_call_arg (call, 0),
+ NULL_TREE);
+ if (refs_may_alias_p_1 (&dref, ref, false))
+ return true;
+ }
+ /* FALLTHRU */
case BUILT_IN_STRCPY:
case BUILT_IN_STRNCPY:
case BUILT_IN_MEMCPY:
@@ -1187,8 +1198,6 @@ ref_maybe_used_by_call_p_1 (gimple call,
case BUILT_IN_MEMPCPY:
case BUILT_IN_STPCPY:
case BUILT_IN_STPNCPY:
- case BUILT_IN_STRCAT:
- case BUILT_IN_STRNCAT:
{
ao_ref dref;
tree size = NULL_TREE;
@@ -1199,14 +1208,23 @@ ref_maybe_used_by_call_p_1 (gimple call,
size);
return refs_may_alias_p_1 (&dref, ref, false);
}
+ case BUILT_IN_STRCAT_CHK:
+ case BUILT_IN_STRNCAT_CHK:
+ {
+ ao_ref dref;
+ ao_ref_init_from_ptr_and_size (&dref,
+ gimple_call_arg (call, 0),
+ NULL_TREE);
+ if (refs_may_alias_p_1 (&dref, ref, false))
+ return true;
+ }
+ /* FALLTHRU */
case BUILT_IN_STRCPY_CHK:
case BUILT_IN_STRNCPY_CHK:
case BUILT_IN_MEMCPY_CHK:
case BUILT_IN_MEMMOVE_CHK:
case BUILT_IN_MEMPCPY_CHK:
case BUILT_IN_STPCPY_CHK:
- case BUILT_IN_STRCAT_CHK:
- case BUILT_IN_STRNCAT_CHK:
{
ao_ref dref;
tree size = NULL_TREE;
@@ -1226,6 +1244,19 @@ ref_maybe_used_by_call_p_1 (gimple call,
size);
return refs_may_alias_p_1 (&dref, ref, false);
}
+ /* These read memory pointed to by the first argument. */
+ case BUILT_IN_STRDUP:
+ case BUILT_IN_STRNDUP:
+ {
+ ao_ref dref;
+ tree size = NULL_TREE;
+ if (gimple_call_num_args (call) == 2)
+ size = gimple_call_arg (call, 1);
+ ao_ref_init_from_ptr_and_size (&dref,
+ gimple_call_arg (call, 0),
+ size);
+ return refs_may_alias_p_1 (&dref, ref, false);
+ }
/* The following builtins do not read from memory. */
case BUILT_IN_FREE:
case BUILT_IN_MALLOC:
@@ -1467,7 +1498,12 @@ call_may_clobber_ref_p_1 (gimple call, a
{
ao_ref dref;
tree size = NULL_TREE;
- if (gimple_call_num_args (call) == 3)
+ /* Don't pass in size for strncat, as the maximum size
+ is strlen (dest) + n + 1 instead of n, resp.
+ n + 1 at dest + strlen (dest), but strlen (dest) isn't
+ known. */
+ if (gimple_call_num_args (call) == 3
+ && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT)
size = gimple_call_arg (call, 2);
ao_ref_init_from_ptr_and_size (&dref,
gimple_call_arg (call, 0),
@@ -1486,7 +1522,12 @@ call_may_clobber_ref_p_1 (gimple call, a
{
ao_ref dref;
tree size = NULL_TREE;
- if (gimple_call_num_args (call) == 4)
+ /* Don't pass in size for __strncat_chk, as the maximum size
+ is strlen (dest) + n + 1 instead of n, resp.
+ n + 1 at dest + strlen (dest), but strlen (dest) isn't
+ known. */
+ if (gimple_call_num_args (call) == 4
+ && DECL_FUNCTION_CODE (callee) != BUILT_IN_STRNCAT_CHK)
size = gimple_call_arg (call, 2);
ao_ref_init_from_ptr_and_size (&dref,
gimple_call_arg (call, 0),
@@ -1506,6 +1547,8 @@ 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
