[ubsan PATCH] Clear up unnecessary code

Marek Polacek polacek@redhat.com
Fri Sep 25 11:30:00 GMT 2015


As discussed earlier, this patch removes now useless code and adds
tests to ensure we don't regress in diagnostics.

Bootstrapped/regtested on x86_64-linux, applying to trunk.

2015-09-25  Marek Polacek  <polacek@redhat.com>

	* c-ubsan.c (ubsan_instrument_division): Remove unnecessary code.
	(ubsan_instrument_shift): Likewise.

	* c-c++-common/ubsan/bounds-11.c: New test.
	* c-c++-common/ubsan/bounds-12.c: New test.

diff --git gcc/c-family/c-ubsan.c gcc/c-family/c-ubsan.c
index d2bc264..672762c 100644
--- gcc/c-family/c-ubsan.c
+++ gcc/c-family/c-ubsan.c
@@ -89,20 +89,7 @@ ubsan_instrument_division (location_t loc, tree op0, tree op1)
     return NULL_TREE;
 
   /* In case we have a SAVE_EXPR in a conditional context, we need to
-     make sure it gets evaluated before the condition.  If the OP0 is
-     an instrumented array reference, mark it as having side effects so
-     it's not folded away.  */
-  if (flag_sanitize & SANITIZE_BOUNDS)
-    {
-      tree xop0 = op0;
-      while (CONVERT_EXPR_P (xop0))
-	xop0 = TREE_OPERAND (xop0, 0);
-      if (TREE_CODE (xop0) == ARRAY_REF)
-	{
-	  TREE_SIDE_EFFECTS (xop0) = 1;
-	  TREE_SIDE_EFFECTS (op0) = 1;
-	}
-    }
+     make sure it gets evaluated before the condition.  */
   t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), unshare_expr (op0), t);
   t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), unshare_expr (op1), t);
   if (flag_sanitize_undefined_trap_on_error)
@@ -187,20 +174,7 @@ ubsan_instrument_shift (location_t loc, enum tree_code code,
     return NULL_TREE;
 
   /* In case we have a SAVE_EXPR in a conditional context, we need to
-     make sure it gets evaluated before the condition.  If the OP0 is
-     an instrumented array reference, mark it as having side effects so
-     it's not folded away.  */
-  if (flag_sanitize & SANITIZE_BOUNDS)
-    {
-      tree xop0 = op0;
-      while (CONVERT_EXPR_P (xop0))
-	xop0 = TREE_OPERAND (xop0, 0);
-      if (TREE_CODE (xop0) == ARRAY_REF)
-	{
-	  TREE_SIDE_EFFECTS (xop0) = 1;
-	  TREE_SIDE_EFFECTS (op0) = 1;
-	}
-    }
+     make sure it gets evaluated before the condition.  */
   t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), unshare_expr (op0), t);
   t = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, t,
 		   tt ? tt : integer_zero_node);
diff --git gcc/testsuite/c-c++-common/ubsan/bounds-11.c gcc/testsuite/c-c++-common/ubsan/bounds-11.c
index e69de29..c3e0f22 100644
--- gcc/testsuite/c-c++-common/ubsan/bounds-11.c
+++ gcc/testsuite/c-c++-common/ubsan/bounds-11.c
@@ -0,0 +1,23 @@
+/* { dg-do run } */
+/* { dg-options "-fsanitize=bounds" } */
+
+struct S
+{
+  unsigned long a[1];
+  int l;
+};
+
+static inline unsigned long
+fn (const struct S *s, int i)
+{
+  return s->a[i] / i;
+}
+
+int
+main ()
+{
+  struct S s;
+  fn (&s, 1);
+}
+
+/* { dg-output "index 1 out of bounds for type 'long unsigned int \\\[1\\\]'" } */
diff --git gcc/testsuite/c-c++-common/ubsan/bounds-12.c gcc/testsuite/c-c++-common/ubsan/bounds-12.c
index e69de29..3cd3a4a 100644
--- gcc/testsuite/c-c++-common/ubsan/bounds-12.c
+++ gcc/testsuite/c-c++-common/ubsan/bounds-12.c
@@ -0,0 +1,23 @@
+/* { dg-do run } */
+/* { dg-options "-fsanitize=bounds" } */
+
+struct S
+{
+  unsigned long a[1];
+  int l;
+};
+
+static inline unsigned long
+fn (const struct S *s, int i)
+{
+  return s->a[i] << i;
+}
+
+int
+main ()
+{
+  struct S s;
+  fn (&s, 1);
+}
+
+/* { dg-output "index 1 out of bounds for type 'long unsigned int \\\[1\\\]'" } */

	Marek



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