On Fri, Sep 30, 2011 at 05:17:00PM +0200, Jakub Jelinek wrote:
> 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.
And here is the backport I've just committed. 4.6 doesn't handle
BUILT_IN_*_CHK in tree-ssa-alias.c at all, so the patch is shorter.
2011-09-30 Jakub Jelinek <ja...@redhat.com>
Richard Guenther <rguent...@suse.de>
* tree-ssa-alias.c (call_may_clobber_ref_p_1): Fix
handling of BUILT_IN_STRNCAT.
(ref_maybe_used_by_call_p_1): Fix handling of BUILT_IN_STRCAT,
and BUILT_IN_STRNCAT.
--- 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
@@ -1208,8 +1208,20 @@ 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:
@@ -1217,8 +1229,6 @@ 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;
@@ -1449,7 +1459,12 @@ 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),
Jakub
