PR sanitizer/79944

	* asan.c (get_mem_refs_of_builtin_call): For BUILT_IN_ATOMIC* and
	BUILT_IN_SYNC*, determine the access type from the size suffix and
	always build a MEM_REF with that type.  Handle forgotten
	BUILT_IN_SYNC_FETCH_AND_NAND_16 and BUILT_IN_SYNC_NAND_AND_FETCH_16.

	* c-c++-common/asan/pr79944.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@245991 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 181 insertions, 164 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3d85fe0e981..80d0aeaa6e4 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2017-03-09  Jakub Jelinek  <jakub@redhat.com>
 
+	PR sanitizer/79944
+	* asan.c (get_mem_refs_of_builtin_call): For BUILT_IN_ATOMIC* and
+	BUILT_IN_SYNC*, determine the access type from the size suffix and
+	always build a MEM_REF with that type.  Handle forgotten
+	BUILT_IN_SYNC_FETCH_AND_NAND_16 and BUILT_IN_SYNC_NAND_AND_FETCH_16.
+
 	PR target/79932
 	* config/i386/avx512vlintrin.h (_mm256_cmpge_epi32_mask,
 	_mm256_cmpge_epi64_mask, _mm256_cmpge_epu32_mask,
diff --git a/gcc/asan.c b/gcc/asan.c
index 7223e3cc68d..edcc6ea5a91 100644
--- a/gcc/asan.c
+++ b/gcc/asan.c
@@ -603,218 +603,208 @@ get_mem_refs_of_builtin_call (const gcall *call,
     case BUILT_IN_STRLEN:
       source0 = gimple_call_arg (call, 0);
       len = gimple_call_lhs (call);
-      break ;
+      break;
 
     /* And now the __atomic* and __sync builtins.
        These are handled differently from the classical memory memory
        access builtins above.  */
 
     case BUILT_IN_ATOMIC_LOAD_1:
-    case BUILT_IN_ATOMIC_LOAD_2:
-    case BUILT_IN_ATOMIC_LOAD_4:
-    case BUILT_IN_ATOMIC_LOAD_8:
-    case BUILT_IN_ATOMIC_LOAD_16:
       is_store = false;
-      /* fall through.  */
-
+      /* FALLTHRU */
     case BUILT_IN_SYNC_FETCH_AND_ADD_1:
-    case BUILT_IN_SYNC_FETCH_AND_ADD_2:
-    case BUILT_IN_SYNC_FETCH_AND_ADD_4:
-    case BUILT_IN_SYNC_FETCH_AND_ADD_8:
-    case BUILT_IN_SYNC_FETCH_AND_ADD_16:
-
     case BUILT_IN_SYNC_FETCH_AND_SUB_1:
-    case BUILT_IN_SYNC_FETCH_AND_SUB_2:
-    case BUILT_IN_SYNC_FETCH_AND_SUB_4:
-    case BUILT_IN_SYNC_FETCH_AND_SUB_8:
-    case BUILT_IN_SYNC_FETCH_AND_SUB_16:
-
     case BUILT_IN_SYNC_FETCH_AND_OR_1:
-    case BUILT_IN_SYNC_FETCH_AND_OR_2:
-    case BUILT_IN_SYNC_FETCH_AND_OR_4:
-    case BUILT_IN_SYNC_FETCH_AND_OR_8:
-    case BUILT_IN_SYNC_FETCH_AND_OR_16:
-
     case BUILT_IN_SYNC_FETCH_AND_AND_1:
-    case BUILT_IN_SYNC_FETCH_AND_AND_2:
-    case BUILT_IN_SYNC_FETCH_AND_AND_4:
-    case BUILT_IN_SYNC_FETCH_AND_AND_8:
-    case BUILT_IN_SYNC_FETCH_AND_AND_16:
-
     case BUILT_IN_SYNC_FETCH_AND_XOR_1:
-    case BUILT_IN_SYNC_FETCH_AND_XOR_2:
-    case BUILT_IN_SYNC_FETCH_AND_XOR_4:
-    case BUILT_IN_SYNC_FETCH_AND_XOR_8:
-    case BUILT_IN_SYNC_FETCH_AND_XOR_16:
-
     case BUILT_IN_SYNC_FETCH_AND_NAND_1:
-    case BUILT_IN_SYNC_FETCH_AND_NAND_2:
-    case BUILT_IN_SYNC_FETCH_AND_NAND_4:
-    case BUILT_IN_SYNC_FETCH_AND_NAND_8:
-
     case BUILT_IN_SYNC_ADD_AND_FETCH_1:
-    case BUILT_IN_SYNC_ADD_AND_FETCH_2:
-    case BUILT_IN_SYNC_ADD_AND_FETCH_4:
-    case BUILT_IN_SYNC_ADD_AND_FETCH_8:
-    case BUILT_IN_SYNC_ADD_AND_FETCH_16:
-
     case BUILT_IN_SYNC_SUB_AND_FETCH_1:
-    case BUILT_IN_SYNC_SUB_AND_FETCH_2:
-    case BUILT_IN_SYNC_SUB_AND_FETCH_4:
-    case BUILT_IN_SYNC_SUB_AND_FETCH_8:
-    case BUILT_IN_SYNC_SUB_AND_FETCH_16:
-
     case BUILT_IN_SYNC_OR_AND_FETCH_1:
-    case BUILT_IN_SYNC_OR_AND_FETCH_2:
-    case BUILT_IN_SYNC_OR_AND_FETCH_4:
-    case BUILT_IN_SYNC_OR_AND_FETCH_8:
-    case BUILT_IN_SYNC_OR_AND_FETCH_16:
-
     case BUILT_IN_SYNC_AND_AND_FETCH_1:
-    case BUILT_IN_SYNC_AND_AND_FETCH_2:
-    case BUILT_IN_SYNC_AND_AND_FETCH_4:
-    case BUILT_IN_SYNC_AND_AND_FETCH_8:
-    case BUILT_IN_SYNC_AND_AND_FETCH_16:
-
     case BUILT_IN_SYNC_XOR_AND_FETCH_1:
-    case BUILT_IN_SYNC_XOR_AND_FETCH_2:
-    case BUILT_IN_SYNC_XOR_AND_FETCH_4:
-    case BUILT_IN_SYNC_XOR_AND_FETCH_8:
-    case BUILT_IN_SYNC_XOR_AND_FETCH_16:
-
     case BUILT_IN_SYNC_NAND_AND_FETCH_1:
-    case BUILT_IN_SYNC_NAND_AND_FETCH_2:
-    case BUILT_IN_SYNC_NAND_AND_FETCH_4:
-    case BUILT_IN_SYNC_NAND_AND_FETCH_8:
-
     case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1:
-    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2:
-    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4:
-    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8:
-    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16:
-
     case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_1:
-    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_2:
-    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_4:
-    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_8:
-    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_16:
-
     case BUILT_IN_SYNC_LOCK_TEST_AND_SET_1:
-    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_2:
-    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_4:
-    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_8:
-    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_16:
-
     case BUILT_IN_SYNC_LOCK_RELEASE_1:
-    case BUILT_IN_SYNC_LOCK_RELEASE_2:
-    case BUILT_IN_SYNC_LOCK_RELEASE_4:
-    case BUILT_IN_SYNC_LOCK_RELEASE_8:
-    case BUILT_IN_SYNC_LOCK_RELEASE_16:
-
     case BUILT_IN_ATOMIC_EXCHANGE_1:
-    case BUILT_IN_ATOMIC_EXCHANGE_2:
-    case BUILT_IN_ATOMIC_EXCHANGE_4:
-    case BUILT_IN_ATOMIC_EXCHANGE_8:
-    case BUILT_IN_ATOMIC_EXCHANGE_16:
-
     case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1:
-    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2:
-    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4:
-    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8:
-    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16:
-
     case BUILT_IN_ATOMIC_STORE_1:
-    case BUILT_IN_ATOMIC_STORE_2:
-    case BUILT_IN_ATOMIC_STORE_4:
-    case BUILT_IN_ATOMIC_STORE_8:
-    case BUILT_IN_ATOMIC_STORE_16:
-
     case BUILT_IN_ATOMIC_ADD_FETCH_1:
-    case BUILT_IN_ATOMIC_ADD_FETCH_2:
-    case BUILT_IN_ATOMIC_ADD_FETCH_4:
-    case BUILT_IN_ATOMIC_ADD_FETCH_8:
-    case BUILT_IN_ATOMIC_ADD_FETCH_16:
-
     case BUILT_IN_ATOMIC_SUB_FETCH_1:
-    case BUILT_IN_ATOMIC_SUB_FETCH_2:
-    case BUILT_IN_ATOMIC_SUB_FETCH_4:
-    case BUILT_IN_ATOMIC_SUB_FETCH_8:
-    case BUILT_IN_ATOMIC_SUB_FETCH_16:
-
     case BUILT_IN_ATOMIC_AND_FETCH_1:
-    case BUILT_IN_ATOMIC_AND_FETCH_2:
-    case BUILT_IN_ATOMIC_AND_FETCH_4:
-    case BUILT_IN_ATOMIC_AND_FETCH_8:
-    case BUILT_IN_ATOMIC_AND_FETCH_16:
-
     case BUILT_IN_ATOMIC_NAND_FETCH_1:
-    case BUILT_IN_ATOMIC_NAND_FETCH_2:
-    case BUILT_IN_ATOMIC_NAND_FETCH_4:
-    case BUILT_IN_ATOMIC_NAND_FETCH_8:
-    case BUILT_IN_ATOMIC_NAND_FETCH_16:
-
     case BUILT_IN_ATOMIC_XOR_FETCH_1:
-    case BUILT_IN_ATOMIC_XOR_FETCH_2:
-    case BUILT_IN_ATOMIC_XOR_FETCH_4:
-    case BUILT_IN_ATOMIC_XOR_FETCH_8:
-    case BUILT_IN_ATOMIC_XOR_FETCH_16:
-
     case BUILT_IN_ATOMIC_OR_FETCH_1:
-    case BUILT_IN_ATOMIC_OR_FETCH_2:
-    case BUILT_IN_ATOMIC_OR_FETCH_4:
-    case BUILT_IN_ATOMIC_OR_FETCH_8:
-    case BUILT_IN_ATOMIC_OR_FETCH_16:
-
     case BUILT_IN_ATOMIC_FETCH_ADD_1:
-    case BUILT_IN_ATOMIC_FETCH_ADD_2:
-    case BUILT_IN_ATOMIC_FETCH_ADD_4:
-    case BUILT_IN_ATOMIC_FETCH_ADD_8:
-    case BUILT_IN_ATOMIC_FETCH_ADD_16:
-
     case BUILT_IN_ATOMIC_FETCH_SUB_1:
-    case BUILT_IN_ATOMIC_FETCH_SUB_2:
-    case BUILT_IN_ATOMIC_FETCH_SUB_4:
-    case BUILT_IN_ATOMIC_FETCH_SUB_8:
-    case BUILT_IN_ATOMIC_FETCH_SUB_16:
-
     case BUILT_IN_ATOMIC_FETCH_AND_1:
-    case BUILT_IN_ATOMIC_FETCH_AND_2:
-    case BUILT_IN_ATOMIC_FETCH_AND_4:
-    case BUILT_IN_ATOMIC_FETCH_AND_8:
-    case BUILT_IN_ATOMIC_FETCH_AND_16:
-
     case BUILT_IN_ATOMIC_FETCH_NAND_1:
-    case BUILT_IN_ATOMIC_FETCH_NAND_2:
-    case BUILT_IN_ATOMIC_FETCH_NAND_4:
-    case BUILT_IN_ATOMIC_FETCH_NAND_8:
-    case BUILT_IN_ATOMIC_FETCH_NAND_16:
-
     case BUILT_IN_ATOMIC_FETCH_XOR_1:
-    case BUILT_IN_ATOMIC_FETCH_XOR_2:
-    case BUILT_IN_ATOMIC_FETCH_XOR_4:
-    case BUILT_IN_ATOMIC_FETCH_XOR_8:
-    case BUILT_IN_ATOMIC_FETCH_XOR_16:
-
     case BUILT_IN_ATOMIC_FETCH_OR_1:
+      access_size = 1;
+      goto do_atomic;
+
+    case BUILT_IN_ATOMIC_LOAD_2:
+      is_store = false;
+      /* FALLTHRU */
+    case BUILT_IN_SYNC_FETCH_AND_ADD_2:
+    case BUILT_IN_SYNC_FETCH_AND_SUB_2:
+    case BUILT_IN_SYNC_FETCH_AND_OR_2:
+    case BUILT_IN_SYNC_FETCH_AND_AND_2:
+    case BUILT_IN_SYNC_FETCH_AND_XOR_2:
+    case BUILT_IN_SYNC_FETCH_AND_NAND_2:
+    case BUILT_IN_SYNC_ADD_AND_FETCH_2:
+    case BUILT_IN_SYNC_SUB_AND_FETCH_2:
+    case BUILT_IN_SYNC_OR_AND_FETCH_2:
+    case BUILT_IN_SYNC_AND_AND_FETCH_2:
+    case BUILT_IN_SYNC_XOR_AND_FETCH_2:
+    case BUILT_IN_SYNC_NAND_AND_FETCH_2:
+    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2:
+    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_2:
+    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_2:
+    case BUILT_IN_SYNC_LOCK_RELEASE_2:
+    case BUILT_IN_ATOMIC_EXCHANGE_2:
+    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2:
+    case BUILT_IN_ATOMIC_STORE_2:
+    case BUILT_IN_ATOMIC_ADD_FETCH_2:
+    case BUILT_IN_ATOMIC_SUB_FETCH_2:
+    case BUILT_IN_ATOMIC_AND_FETCH_2:
+    case BUILT_IN_ATOMIC_NAND_FETCH_2:
+    case BUILT_IN_ATOMIC_XOR_FETCH_2:
+    case BUILT_IN_ATOMIC_OR_FETCH_2:
+    case BUILT_IN_ATOMIC_FETCH_ADD_2:
+    case BUILT_IN_ATOMIC_FETCH_SUB_2:
+    case BUILT_IN_ATOMIC_FETCH_AND_2:
+    case BUILT_IN_ATOMIC_FETCH_NAND_2:
+    case BUILT_IN_ATOMIC_FETCH_XOR_2:
     case BUILT_IN_ATOMIC_FETCH_OR_2:
+      access_size = 2;
+      goto do_atomic;
+
+    case BUILT_IN_ATOMIC_LOAD_4:
+      is_store = false;
+      /* FALLTHRU */
+    case BUILT_IN_SYNC_FETCH_AND_ADD_4:
+    case BUILT_IN_SYNC_FETCH_AND_SUB_4:
+    case BUILT_IN_SYNC_FETCH_AND_OR_4:
+    case BUILT_IN_SYNC_FETCH_AND_AND_4:
+    case BUILT_IN_SYNC_FETCH_AND_XOR_4:
+    case BUILT_IN_SYNC_FETCH_AND_NAND_4:
+    case BUILT_IN_SYNC_ADD_AND_FETCH_4:
+    case BUILT_IN_SYNC_SUB_AND_FETCH_4:
+    case BUILT_IN_SYNC_OR_AND_FETCH_4:
+    case BUILT_IN_SYNC_AND_AND_FETCH_4:
+    case BUILT_IN_SYNC_XOR_AND_FETCH_4:
+    case BUILT_IN_SYNC_NAND_AND_FETCH_4:
+    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4:
+    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_4:
+    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_4:
+    case BUILT_IN_SYNC_LOCK_RELEASE_4:
+    case BUILT_IN_ATOMIC_EXCHANGE_4:
+    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4:
+    case BUILT_IN_ATOMIC_STORE_4:
+    case BUILT_IN_ATOMIC_ADD_FETCH_4:
+    case BUILT_IN_ATOMIC_SUB_FETCH_4:
+    case BUILT_IN_ATOMIC_AND_FETCH_4:
+    case BUILT_IN_ATOMIC_NAND_FETCH_4:
+    case BUILT_IN_ATOMIC_XOR_FETCH_4:
+    case BUILT_IN_ATOMIC_OR_FETCH_4:
+    case BUILT_IN_ATOMIC_FETCH_ADD_4:
+    case BUILT_IN_ATOMIC_FETCH_SUB_4:
+    case BUILT_IN_ATOMIC_FETCH_AND_4:
+    case BUILT_IN_ATOMIC_FETCH_NAND_4:
+    case BUILT_IN_ATOMIC_FETCH_XOR_4:
     case BUILT_IN_ATOMIC_FETCH_OR_4:
+      access_size = 4;
+      goto do_atomic;
+
+    case BUILT_IN_ATOMIC_LOAD_8:
+      is_store = false;
+      /* FALLTHRU */
+    case BUILT_IN_SYNC_FETCH_AND_ADD_8:
+    case BUILT_IN_SYNC_FETCH_AND_SUB_8:
+    case BUILT_IN_SYNC_FETCH_AND_OR_8:
+    case BUILT_IN_SYNC_FETCH_AND_AND_8:
+    case BUILT_IN_SYNC_FETCH_AND_XOR_8:
+    case BUILT_IN_SYNC_FETCH_AND_NAND_8:
+    case BUILT_IN_SYNC_ADD_AND_FETCH_8:
+    case BUILT_IN_SYNC_SUB_AND_FETCH_8:
+    case BUILT_IN_SYNC_OR_AND_FETCH_8:
+    case BUILT_IN_SYNC_AND_AND_FETCH_8:
+    case BUILT_IN_SYNC_XOR_AND_FETCH_8:
+    case BUILT_IN_SYNC_NAND_AND_FETCH_8:
+    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8:
+    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_8:
+    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_8:
+    case BUILT_IN_SYNC_LOCK_RELEASE_8:
+    case BUILT_IN_ATOMIC_EXCHANGE_8:
+    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8:
+    case BUILT_IN_ATOMIC_STORE_8:
+    case BUILT_IN_ATOMIC_ADD_FETCH_8:
+    case BUILT_IN_ATOMIC_SUB_FETCH_8:
+    case BUILT_IN_ATOMIC_AND_FETCH_8:
+    case BUILT_IN_ATOMIC_NAND_FETCH_8:
+    case BUILT_IN_ATOMIC_XOR_FETCH_8:
+    case BUILT_IN_ATOMIC_OR_FETCH_8:
+    case BUILT_IN_ATOMIC_FETCH_ADD_8:
+    case BUILT_IN_ATOMIC_FETCH_SUB_8:
+    case BUILT_IN_ATOMIC_FETCH_AND_8:
+    case BUILT_IN_ATOMIC_FETCH_NAND_8:
+    case BUILT_IN_ATOMIC_FETCH_XOR_8:
     case BUILT_IN_ATOMIC_FETCH_OR_8:
+      access_size = 8;
+      goto do_atomic;
+
+    case BUILT_IN_ATOMIC_LOAD_16:
+      is_store = false;
+      /* FALLTHRU */
+    case BUILT_IN_SYNC_FETCH_AND_ADD_16:
+    case BUILT_IN_SYNC_FETCH_AND_SUB_16:
+    case BUILT_IN_SYNC_FETCH_AND_OR_16:
+    case BUILT_IN_SYNC_FETCH_AND_AND_16:
+    case BUILT_IN_SYNC_FETCH_AND_XOR_16:
+    case BUILT_IN_SYNC_FETCH_AND_NAND_16:
+    case BUILT_IN_SYNC_ADD_AND_FETCH_16:
+    case BUILT_IN_SYNC_SUB_AND_FETCH_16:
+    case BUILT_IN_SYNC_OR_AND_FETCH_16:
+    case BUILT_IN_SYNC_AND_AND_FETCH_16:
+    case BUILT_IN_SYNC_XOR_AND_FETCH_16:
+    case BUILT_IN_SYNC_NAND_AND_FETCH_16:
+    case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16:
+    case BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_16:
+    case BUILT_IN_SYNC_LOCK_TEST_AND_SET_16:
+    case BUILT_IN_SYNC_LOCK_RELEASE_16:
+    case BUILT_IN_ATOMIC_EXCHANGE_16:
+    case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16:
+    case BUILT_IN_ATOMIC_STORE_16:
+    case BUILT_IN_ATOMIC_ADD_FETCH_16:
+    case BUILT_IN_ATOMIC_SUB_FETCH_16:
+    case BUILT_IN_ATOMIC_AND_FETCH_16:
+    case BUILT_IN_ATOMIC_NAND_FETCH_16:
+    case BUILT_IN_ATOMIC_XOR_FETCH_16:
+    case BUILT_IN_ATOMIC_OR_FETCH_16:
+    case BUILT_IN_ATOMIC_FETCH_ADD_16:
+    case BUILT_IN_ATOMIC_FETCH_SUB_16:
+    case BUILT_IN_ATOMIC_FETCH_AND_16:
+    case BUILT_IN_ATOMIC_FETCH_NAND_16:
+    case BUILT_IN_ATOMIC_FETCH_XOR_16:
     case BUILT_IN_ATOMIC_FETCH_OR_16:
+      access_size = 16;
+      /* FALLTHRU */
+    do_atomic:
       {
 	dest = gimple_call_arg (call, 0);
 	/* DEST represents the address of a memory location.
 	   instrument_derefs wants the memory location, so lets
 	   dereference the address DEST before handing it to
 	   instrument_derefs.  */
-	if (TREE_CODE (dest) == ADDR_EXPR)
-	  dest = TREE_OPERAND (dest, 0);
-	else if (TREE_CODE (dest) == SSA_NAME || TREE_CODE (dest) == INTEGER_CST)
-	  dest = build2 (MEM_REF, TREE_TYPE (TREE_TYPE (dest)),
-			 dest, build_int_cst (TREE_TYPE (dest), 0));
-	else
-	  gcc_unreachable ();
-
-	access_size = int_size_in_bytes (TREE_TYPE (dest));
+	tree type = build_nonstandard_integer_type (access_size
+						    * BITS_PER_UNIT, 1);
+	dest = build2 (MEM_REF, type, dest,
+		       build_int_cst (build_pointer_type (char_type_node), 0));
+	break;
       }
 
     default:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 45839d25ddc..13218ac30eb 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2017-03-09  Jakub Jelinek  <jakub@redhat.com>
 
+	PR sanitizer/79944
+	* c-c++-common/asan/pr79944.c: New test.
+
 	PR target/79932
 	* gcc.target/i386/pr79932-2.c: New test.
 
diff --git a/gcc/testsuite/c-c++-common/asan/pr79944.c b/gcc/testsuite/c-c++-common/asan/pr79944.c
new file mode 100644
index 00000000000..62c56981b20
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/asan/pr79944.c
@@ -0,0 +1,18 @@
+/* PR sanitizer/79944 */
+/* { dg-do run } */
+
+struct S { int i; char p[1024]; };
+
+int
+main ()
+{
+  struct S *p = (struct S *) __builtin_malloc (__builtin_offsetof (struct S, p) + 64);
+  p->i = 5;
+  asm volatile ("" : "+r" (p) : : "memory");
+  __atomic_fetch_add ((int *) p, 5, __ATOMIC_RELAXED);
+  asm volatile ("" : "+r" (p) : : "memory");
+  if (p->i != 10)
+    __builtin_abort ();
+  __builtin_free (p);
+  return 0;
+}