analyzer: handle array-initialization from a string_cst [PR113999]

[thirdparty/gcc.git] / gcc / analyzer / region-model-manager.cc

diff --git a/gcc/analyzer/region-model-manager.cc b/gcc/analyzer/region-model-manager.cc
index 21e13b4802573e75d4f71988e52ac68d197dc6cb..93e72ec45a8571236ed78acd95a074654060eb85 100644 (file)
--- a/gcc/analyzer/region-model-manager.cc
+++ b/gcc/analyzer/region-model-manager.cc
@@ -1407,6 +1407,20 @@ get_or_create_const_fn_result_svalue (tree type,
   return const_fn_result_sval;
 }
 
+/* Get a tree for the size of STRING_CST, or NULL_TREE.
+   Note that this may be larger than TREE_STRING_LENGTH (implying
+   a run of trailing zero bytes from TREE_STRING_LENGTH up to this
+   higher limit).  */
+
+tree
+get_string_cst_size (const_tree string_cst)
+{
+  gcc_assert (TREE_CODE (string_cst) == STRING_CST);
+  gcc_assert (TREE_CODE (TREE_TYPE (string_cst)) == ARRAY_TYPE);
+
+  return TYPE_SIZE_UNIT (TREE_TYPE (string_cst));
+}
+
 /* Given STRING_CST, a STRING_CST and BYTE_OFFSET_CST a constant,
    attempt to get the character at that offset, returning either
    the svalue for the character constant, or NULL if unsuccessful.  */
@@ -1420,16 +1434,27 @@ region_model_manager::maybe_get_char_from_string_cst (tree string_cst,
   /* Adapted from fold_read_from_constant_string.  */
   scalar_int_mode char_mode;
   if (TREE_CODE (byte_offset_cst) == INTEGER_CST
-      && compare_tree_int (byte_offset_cst,
-                          TREE_STRING_LENGTH (string_cst)) < 0
       && is_int_mode (TYPE_MODE (TREE_TYPE (TREE_TYPE (string_cst))),
                      &char_mode)
       && GET_MODE_SIZE (char_mode) == 1)
     {
+      /* If we're beyond the string_cst, the read is unsuccessful.  */
+      if (compare_constants (byte_offset_cst,
+                            GE_EXPR,
+                            get_string_cst_size (string_cst)).is_true ())
+       return NULL;
+
+      int char_val;
+      if (compare_tree_int (byte_offset_cst,
+                           TREE_STRING_LENGTH (string_cst)) < 0)
+       /* We're within the area defined by TREE_STRING_POINTER.  */
+       char_val = (TREE_STRING_POINTER (string_cst)
+                   [TREE_INT_CST_LOW (byte_offset_cst)]);
+      else
+       /* We're in the padding area of trailing zeroes.  */
+       char_val = 0;
       tree char_cst
-       = build_int_cst_type (TREE_TYPE (TREE_TYPE (string_cst)),
-                             (TREE_STRING_POINTER (string_cst)
-                              [TREE_INT_CST_LOW (byte_offset_cst)]));
+       = build_int_cst_type (TREE_TYPE (TREE_TYPE (string_cst)), char_val);
       return get_or_create_constant_svalue (char_cst);
     }
   return NULL;