tree-ssa-structalias.c (find_func_aliases_for_builtin_call): Handle BUILT_IN_STRDUP and BUILT_IN_STRNDUP.

	* 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.

Co-Authored-By: Richard Guenther <rguenther@suse.de>

From-SVN: r179387

1 files changed, 52 insertions, 8 deletions

diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 10c529b114f..82307decaf4 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -1178,8 +1178,20 @@ ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
       && 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 +1199,6 @@ ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
 	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 +1209,23 @@ ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
 					   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 +1245,19 @@ ref_maybe_used_by_call_p_1 (gimple call, ao_ref *ref)
 					   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 +1499,12 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	  {
 	    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 +1523,12 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	  {
 	    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 +1548,8 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	   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))