builtins.c (unterminated_array): Pass in c_strlen_data * to c_strlen rather than just a tree *.

	* builtins.c (unterminated_array): Pass in c_strlen_data * to
	c_strlen rather than just a tree *.
	(c_strlen): Change NONSTR argument to a c_strlen_data pointer.
	Update recursive calls appropriately.  If caller did not provide a
	suitable data pointer, create a local one.  When a non-terminated
	string is discovered, bubble up information about the string via the
	c_strlen_data object.
	* builtins.h (c_strlen): Update prototype.
	(c_strlen_data): New structure.
	* gimple-fold.c (get_range_strlen): Update calls to c_strlen.
	For a type 2 call, if c_strlen indicates a non-terminated string
	use the length of the non-terminated string.
	(gimple_fold_builtin_stpcpy): Update calls to c_strlen.

From-SVN: r264712

4 files changed, 92 insertions, 36 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 859984c..29f52fd 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,19 @@
+2018-09-29  Jeff Law  <law@redhat.com>
+
+	* builtins.c (unterminated_array): Pass in c_strlen_data * to
+	c_strlen rather than just a tree *.
+	(c_strlen): Change NONSTR argument to a c_strlen_data pointer.
+	Update recursive calls appropriately.  If caller did not provide a
+	suitable data pointer, create a local one.  When a non-terminated
+	string is discovered, bubble up information about the string via the
+	c_strlen_data object.
+	* builtins.h (c_strlen): Update prototype.
+	(c_strlen_data): New structure.
+	* gimple-fold.c (get_range_strlen): Update calls to c_strlen.
+	For a type 2 call, if c_strlen indicates a non-terminated string
+	use the length of the non-terminated string.
+	(gimple_fold_builtin_stpcpy): Update calls to c_strlen.
+
 2018-09-29  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/87467
@@ -302,8 +318,8 @@
 	* config/i386/i386.h (NUM_MODES_FOR_MODE_SWITCHING): Update
 	for removed I387_MASK_PM entity.
 
-2018-09-26  Jeff Law  <law@redhat.com>
 
+2018-09-26  Jeff Law  <law@redhat.com>
 	Revert
 	2018-09-26  Alexey Neyman  <stilor@att.net>
 
diff --git a/gcc/builtins.c b/gcc/builtins.c
index e655623..fe411ef 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -570,9 +570,10 @@ warn_string_no_nul (location_t loc, const char *fn, tree arg, tree decl)
 tree
 unterminated_array (tree exp)
 {
-  tree nonstr = NULL;
-  c_strlen (exp, 1, &nonstr);
-  return nonstr;
+  c_strlen_data data;
+  memset (&data, 0, sizeof (c_strlen_data));
+  c_strlen (exp, 1, &data);
+  return data.decl;
 }
 
 /* Compute the length of a null-terminated character string or wide
@@ -592,10 +593,12 @@ unterminated_array (tree exp)
    accesses.  Note that this implies the result is not going to be emitted
    into the instruction stream.
 
-   If a not zero-terminated string value is encountered and NONSTR is
-   non-zero, the declaration of the string value is assigned to *NONSTR.
-   *NONSTR is accumulating, thus not cleared on success, therefore it has
-   to be initialized to NULL_TREE by the caller.
+   Additional information about the string accessed may be recorded
+   in DATA.  For example, if SRC references an unterminated string,
+   then the declaration will be stored in the DECL field.   If the
+   length of the unterminated string can be determined, it'll be
+   stored in the LEN field.  Note this length could well be different
+   than what a C strlen call would return.
 
    ELTSIZE is 1 for normal single byte character strings, and 2 or
    4 for wide characer strings.  ELTSIZE is by default 1.
@@ -603,8 +606,16 @@ unterminated_array (tree exp)
    The value returned is of type `ssizetype'.  */
 
 tree
-c_strlen (tree src, int only_value, tree *nonstr, unsigned eltsize)
+c_strlen (tree src, int only_value, c_strlen_data *data, unsigned eltsize)
 {
+  /* If we were not passed a DATA pointer, then get one to a local
+     structure.  That avoids having to check DATA for NULL before
+     each time we want to use it.  */
+  c_strlen_data local_strlen_data;
+  memset (&local_strlen_data, 0, sizeof (c_strlen_data));
+  if (!data)
+    data = &local_strlen_data;
+
   gcc_checking_assert (eltsize == 1 || eltsize == 2 || eltsize == 4);
   STRIP_NOPS (src);
   if (TREE_CODE (src) == COND_EXPR
@@ -612,15 +623,15 @@ c_strlen (tree src, int only_value, tree *nonstr, unsigned eltsize)
     {
       tree len1, len2;
 
-      len1 = c_strlen (TREE_OPERAND (src, 1), only_value, nonstr, eltsize);
-      len2 = c_strlen (TREE_OPERAND (src, 2), only_value, nonstr, eltsize);
+      len1 = c_strlen (TREE_OPERAND (src, 1), only_value, data, eltsize);
+      len2 = c_strlen (TREE_OPERAND (src, 2), only_value, data, eltsize);
       if (tree_int_cst_equal (len1, len2))
 	return len1;
     }
 
   if (TREE_CODE (src) == COMPOUND_EXPR
       && (only_value || !TREE_SIDE_EFFECTS (TREE_OPERAND (src, 0))))
-    return c_strlen (TREE_OPERAND (src, 1), only_value, nonstr, eltsize);
+    return c_strlen (TREE_OPERAND (src, 1), only_value, data, eltsize);
 
   location_t loc = EXPR_LOC_OR_LOC (src, input_location);
 
@@ -666,13 +677,15 @@ c_strlen (tree src, int only_value, tree *nonstr, unsigned eltsize)
 	 start searching for it.  */
       unsigned len = string_length (ptr, eltsize, strelts);
 
-      /* Return when an embedded null character is found or none at all.  */
+      /* Return when an embedded null character is found or none at all.
+	 In the latter case, set the DECL/LEN field in the DATA structure
+	 so that callers may examine them.  */
       if (len + 1 < strelts)
 	return NULL_TREE;
       else if (len >= maxelts)
 	{
-	  if (nonstr && decl)
-	    *nonstr = decl;
+	  data->decl = decl;
+	  data->len = ssize_int (len);
 	  return NULL_TREE;
 	}
 
@@ -737,11 +750,12 @@ c_strlen (tree src, int only_value, tree *nonstr, unsigned eltsize)
 				strelts - eltoff);
 
   /* Don't know what to return if there was no zero termination.
-     Ideally this would turn into a gcc_checking_assert over time.  */
+     Ideally this would turn into a gcc_checking_assert over time.
+     Set DECL/LEN so callers can examine them.  */
   if (len >= maxelts - eltoff)
     {
-      if (nonstr && decl)
-	*nonstr = decl;
+      data->decl = decl;
+      data->len = ssize_int (len);
       return NULL_TREE;
     }
 
@@ -3965,13 +3979,14 @@ expand_builtin_stpcpy_1 (tree exp, rtx target, machine_mode mode)
 	 compile-time, not an expression containing a string.  This is
 	 because the latter will potentially produce pessimized code
 	 when used to produce the return value.  */
-      tree nonstr = NULL_TREE;
+      c_strlen_data data;
+      memset (&data, 0, sizeof (c_strlen_data));
       if (!c_getstr (src, NULL)
-	  || !(len = c_strlen (src, 0, &nonstr, 1)))
+	  || !(len = c_strlen (src, 0, &data, 1)))
 	return expand_movstr (dst, src, target, /*endp=*/2);
 
-      if (nonstr && !TREE_NO_WARNING (exp))
-	warn_string_no_nul (EXPR_LOCATION (exp), "stpcpy", src, nonstr);
+      if (data.decl && !TREE_NO_WARNING (exp))
+	warn_string_no_nul (EXPR_LOCATION (exp), "stpcpy", src, data.decl);
 
       lenp1 = size_binop_loc (loc, PLUS_EXPR, len, ssize_int (1));
       ret = expand_builtin_mempcpy_args (dst, src, lenp1,
@@ -8444,22 +8459,23 @@ fold_builtin_strlen (location_t loc, tree type, tree arg)
     return NULL_TREE;
   else
     {
-      tree nonstr = NULL_TREE;
-      tree len = c_strlen (arg, 0, &nonstr);
+      c_strlen_data data;
+      memset (&data, 0, sizeof (c_strlen_data));
+      tree len = c_strlen (arg, 0, &data);
 
       if (len)
 	return fold_convert_loc (loc, type, len);
 
-      if (!nonstr)
-	c_strlen (arg, 1, &nonstr);
+      if (!data.decl)
+	c_strlen (arg, 1, &data);
 
-      if (nonstr)
+      if (data.decl)
 	{
 	  if (EXPR_HAS_LOCATION (arg))
 	    loc = EXPR_LOCATION (arg);
 	  else if (loc == UNKNOWN_LOCATION)
 	    loc = input_location;
-	  warn_string_no_nul (loc, "strlen", arg, nonstr);
+	  warn_string_no_nul (loc, "strlen", arg, data.decl);
 	}
 
       return NULL_TREE;
diff --git a/gcc/builtins.h b/gcc/builtins.h
index 45ad684..3801251 100644
--- a/gcc/builtins.h
+++ b/gcc/builtins.h
@@ -57,7 +57,14 @@ extern bool get_pointer_alignment_1 (tree, unsigned int *,
 				     unsigned HOST_WIDE_INT *);
 extern unsigned int get_pointer_alignment (tree);
 extern unsigned string_length (const void*, unsigned, unsigned);
-extern tree c_strlen (tree, int, tree * = NULL, unsigned = 1);
+struct c_strlen_data
+{
+  tree decl;
+  tree len;
+  tree off;
+};
+
+extern tree c_strlen (tree, int, c_strlen_data * = NULL, unsigned = 1);
 extern void expand_builtin_setjmp_setup (rtx, rtx);
 extern void expand_builtin_setjmp_receiver (rtx);
 extern void expand_builtin_update_setjmp_buf (rtx);
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index 1e84722..cf04c92 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -1337,7 +1337,23 @@ get_range_strlen (tree arg, tree length[2], bitmap *visited, int type,
 	    return false;
 	}
       else
-	val = c_strlen (arg, 1, nonstr, eltsize);
+	{
+	  c_strlen_data data;
+	  memset (&data, 0, sizeof (c_strlen_data));
+	  val = c_strlen (arg, 1, &data, eltsize);
+
+	  /* If we potentially had a non-terminated string, then
+	     bubble that information up to the caller.  */
+	  if (!val)
+	    {
+	      *nonstr = data.decl;
+	      /* If TYPE is asking for a maximum, then use any
+		 length (including the length of an unterminated
+		 string) for VAL.  */
+	      if (type == 2)
+		val = data.len;
+	    }
+	}
 
       if (!val && fuzzy)
 	{
@@ -2812,21 +2828,22 @@ gimple_fold_builtin_stpcpy (gimple_stmt_iterator *gsi)
     }
 
   /* Set to non-null if ARG refers to an unterminated array.  */
-  tree nonstr = NULL;
-  tree len = c_strlen (src, 1, &nonstr, 1);
+  c_strlen_data data;
+  memset (&data, 0, sizeof (c_strlen_data));
+  tree len = c_strlen (src, 1, &data, 1);
   if (!len
       || TREE_CODE (len) != INTEGER_CST)
     {
-      nonstr = unterminated_array (src);
-      if (!nonstr)
+      data.decl = unterminated_array (src);
+      if (!data.decl)
 	return false;
     }
 
-  if (nonstr)
+  if (data.decl)
     {
       /* Avoid folding calls with unterminated arrays.  */
       if (!gimple_no_warning_p (stmt))
-	warn_string_no_nul (loc, "stpcpy", src, nonstr);
+	warn_string_no_nul (loc, "stpcpy", src, data.decl);
       gimple_set_no_warning (stmt, true);
       return false;
     }