diff mbox series

Adjust string_constant to new STRING_CST semantics

Message ID AM5PR0701MB2657BD440CE00D8E3961E441E4360@AM5PR0701MB2657.eurprd07.prod.outlook.com
State New
Headers show
Series Adjust string_constant to new STRING_CST semantics | expand

Commit Message

Bernd Edlinger Aug. 24, 2018, 9:24 p.m. UTC 
Hi,

I noticed that the latest patches to make STRING_CST
semantics for literals and for initializers consistent
also fixes PR 86711 and PR 86714 (but not PR 87053).

The code change in the string_constant does not change
any test case, the new test cases are already fixed
once we have the unified STRING_CST semantics.
Thus https://gcc.gnu.org/ml/gcc-patches/2018-08/msg01569.html
would be the pre-condition for this patch.

If the pre-condition patch is applied then my earlier patch
to fix PR 86711/86714 is no longer necessary.
Likely neither Martin's patch (at least that part about
PR 86711/86714).


Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
Is it OK for trunk?


Thanks
Bernd.

Comments

Jeff Law Sept. 14, 2018, 1:44 a.m. UTC | #1 
On 8/24/18 3:24 PM, Bernd Edlinger wrote:
> Hi,
> 
> I noticed that the latest patches to make STRING_CST
> semantics for literals and for initializers consistent
> also fixes PR 86711 and PR 86714 (but not PR 87053).
> 
> The code change in the string_constant does not change
> any test case, the new test cases are already fixed
> once we have the unified STRING_CST semantics.
> Thus https://gcc.gnu.org/ml/gcc-patches/2018-08/msg01569.html
> would be the pre-condition for this patch.
> 
> If the pre-condition patch is applied then my earlier patch
> to fix PR 86711/86714 is no longer necessary.
> Likely neither Martin's patch (at least that part about
> PR 86711/86714).
> 
> 
> Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
> Is it OK for trunk?
> 
> 
> Thanks
> Bernd.
> 
> 
> patch-stringconst.diff
> 
> gcc:
> 2018-08-24  Bernd Edlinger  <bernd.edlinger@hotmail.de>
> 
> 	* expr.c (string_constant): Adjust function comment.
> 	Remove bogus check for zero termination.
> 
> testsuite:
> 2018-08-24  Bernd Edlinger  <bernd.edlinger@hotmail.de>
> 
> 	PR middle-end/86711
> 	PR middle-end/86714
> 	* gcc.c-torture/execute/pr86711.c: New test.
> 	* gcc.c-torture/execute/pr86714.c: New test.
So I applied the expr.c part of this patch.  We've already got these
tests in the testsuite.

jeff
diff mbox series

Patch

gcc:
2018-08-24  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* expr.c (string_constant): Adjust function comment.
	Remove bogus check for zero termination.

testsuite:
2018-08-24  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	PR middle-end/86711
	PR middle-end/86714
	* gcc.c-torture/execute/pr86711.c: New test.
	* gcc.c-torture/execute/pr86714.c: New test.

diff -Npur gcc/expr.c gcc/expr.c
--- gcc/expr.c	2018-08-22 22:34:01.000000000 +0200
+++ gcc/expr.c	2018-08-24 20:24:21.592913041 +0200
@@ -11304,8 +11304,9 @@  is_aligning_offset (const_tree offset, c
    if it doesn't.  If we return nonzero, set *PTR_OFFSET to the (possibly
    non-constant) offset in bytes within the string that ARG is accessing.
    The type of the offset is sizetype.  If MEM_SIZE is non-zero the storage
-   size of the memory is returned.  If MEM_SIZE is zero, the string is
-   only returned when it is properly zero terminated.  */
+   size of the memory is returned.  The returned STRING_CST object is
+   valid up to TREE_STRING_LENGTH.  Bytes between TREE_STRING_LENGTH
+   and MEM_SIZE are ZERO.  MEM_SIZE is at least TREE_STRING_LENGTH.  */
 
 tree
 string_constant (tree arg, tree *ptr_offset, tree *mem_size)
@@ -11404,6 +11405,8 @@  string_constant (tree arg, tree *ptr_off
       *ptr_offset = fold_convert (sizetype, offset);
       if (mem_size)
 	*mem_size = TYPE_SIZE_UNIT (TREE_TYPE (array));
+      gcc_checking_assert (tree_to_shwi (TYPE_SIZE_UNIT (TREE_TYPE (array)))
+			   >= TREE_STRING_LENGTH (array));
       return array;
     }
 
@@ -11446,27 +11449,10 @@  string_constant (tree arg, tree *ptr_off
   if (!init || TREE_CODE (init) != STRING_CST)
     return NULL_TREE;
 
-  tree array_size = DECL_SIZE_UNIT (array);
-  if (!array_size || TREE_CODE (array_size) != INTEGER_CST)
-    return NULL_TREE;
-
-  /* Avoid returning a string that doesn't fit in the array
-     it is stored in, like
-     const char a[4] = "abcde";
-     but do handle those that fit even if they have excess
-     initializers, such as in
-     const char a[4] = "abc\000\000";
-     The excess elements contribute to TREE_STRING_LENGTH()
-     but not to strlen().  */
-  unsigned HOST_WIDE_INT charsize
-    = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (init))));
-  unsigned HOST_WIDE_INT length = TREE_STRING_LENGTH (init);
-  length = string_length (TREE_STRING_POINTER (init), charsize,
-			  length / charsize);
   if (mem_size)
     *mem_size = TYPE_SIZE_UNIT (TREE_TYPE (init));
-  else if (compare_tree_int (array_size, length + 1) < 0)
-    return NULL_TREE;
+  gcc_checking_assert (tree_to_shwi (TYPE_SIZE_UNIT (TREE_TYPE (init)))
+		       >= TREE_STRING_LENGTH (init));
 
   *ptr_offset = offset;
   return init;
diff -Npur gcc/testsuite/gcc.c-torture/execute/pr86711.c gcc/testsuite/gcc.c-torture/execute/pr86711.c
--- gcc/testsuite/gcc.c-torture/execute/pr86711.c	1970-01-01 01:00:00.000000000 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr86711.c	2018-08-24 20:29:15.960882045 +0200
@@ -0,0 +1,11 @@ 
+/* PR middle-end/86711 */
+
+static const char a[2][4] = { "1234", "5678" };
+
+int main ()
+{
+  void *p = __builtin_memchr (a, 0, 5);
+
+  if (p)
+    __builtin_abort ();
+}
diff -Npur gcc/testsuite/gcc.c-torture/execute/pr86714.c gcc/testsuite/gcc.c-torture/execute/pr86714.c
--- gcc/testsuite/gcc.c-torture/execute/pr86714.c	1970-01-01 01:00:00.000000000 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr86714.c	2018-08-24 20:29:15.960882045 +0200
@@ -0,0 +1,12 @@ 
+/* PR middle-end/86714 */
+
+const char a[2][3] = { "1234", "xyz" };
+char b[6];
+
+int main ()
+{
+  __builtin_memcpy (b, a, 4);
+  __builtin_memset (b + 4, 'a', 2);
+  if (__builtin_memcmp (b, "123xaa", 6))
+    __builtin_abort ();
+}