Adjust by-value function vec arguments to by-reference.

gcc/c/ChangeLog:

	* c-parser.c (c_parser_declaration_or_fndef): Adjust by-value function
	vec arguments to by-reference.
	(c_finish_omp_declare_simd): Same.
	(c_parser_compound_statement_nostart): Same.
	(c_parser_for_statement): Same.
	(c_parser_objc_methodprotolist): Same.
	(c_parser_oacc_routine): Same.
	(c_parser_omp_for_loop): Same.
	(c_parser_omp_declare_simd): Same.

gcc/ChangeLog:

	* dominance.c (prune_bbs_to_update_dominators): Adjust by-value vec
	arguments to by-reference.
	(iterate_fix_dominators): Same.
	* dominance.h (iterate_fix_dominators): Same.
	* ipa-prop.h: Call auto_vec::to_vec_legacy.
	* tree-data-ref.c (dump_data_dependence_relation): Adjust by-value vec
	arguments to by-reference.
	(debug_data_dependence_relation): Same.
	(dump_data_dependence_relations): Same.
	* tree-data-ref.h (debug_data_dependence_relation): Same.
	(dump_data_dependence_relations): Same.
	* tree-predcom.c (dump_chains): Same.
	(initialize_root_vars_lm): Same.
	(determine_unroll_factor): Same.
	(replace_phis_by_defined_names): Same.
	(insert_init_seqs): Same.
	(pcom_worker::tree_predictive_commoning_loop): Call
	 auto_vec::to_vec_legacy.
	* tree-ssa-pre.c (insert_into_preds_of_block): Adjust by-value vec
	arguments to by-reference.
	* tree-ssa-threadbackward.c (populate_worklist): Same.
	(back_threader::resolve_def): Same.
	* tree-vect-data-refs.c (vect_check_nonzero_value): Same.
	(vect_enhance_data_refs_alignment): Same.
	(vect_check_lower_bound): Same.
	(vect_prune_runtime_alias_test_list): Same.
	(vect_permute_store_chain): Same.
	* tree-vect-slp-patterns.c (vect_normalize_conj_loc): Same.
	* tree-vect-stmts.c (vect_create_vectorized_demotion_stmts): Same.
	* tree-vectorizer.h (vect_permute_store_chain): Same.
	* vec.c (test_init): New function.
	(vec_c_tests): Call new function.
	* vec.h (vec): Declare ctors, dtor, and assignment.
	(auto_vec::vec_to_legacy): New function.
	(vec::copy): Adjust initialization.

1 files changed, 52 insertions, 14 deletions

diff --git a/gcc/vec.h b/gcc/vec.h
index 30ef9a6..b3f47b1 100644
--- a/gcc/vec.h
+++ b/gcc/vec.h
@@ -541,18 +541,16 @@ vec_copy_construct (T *dst, const T *src, unsigned n)
     ::new (static_cast<void*>(dst)) T (*src);
 }
 
-/* Type to provide NULL values for vec<T, A, L>.  This is used to
-   provide nil initializers for vec instances.  Since vec must be
-   a POD, we cannot have proper ctor/dtor for it.  To initialize
-   a vec instance, you can assign it the value vNULL.  This isn't
-   needed for file-scope and function-local static vectors, which
-   are zero-initialized by default.  */
-struct vnull
-{
-  template <typename T, typename A, typename L>
-  CONSTEXPR operator vec<T, A, L> () const { return vec<T, A, L>(); }
-};
-extern vnull vNULL;
+/* Type to provide zero-initialized values for vec<T, A, L>.  This is
+   used to  provide nil initializers for vec instances.  Since vec must
+   be a trivially copyable type that can be copied by memcpy and zeroed
+   out by memset, it must have defaulted default and copy ctor and copy
+   assignment.  To initialize a vec either use value initialization
+   (e.g., vec() or vec v{ };) or assign it the value vNULL.  This isn't
+   needed for file-scope and function-local static vectors, which are
+   zero-initialized by default.  */
+struct vnull { };
+constexpr vnull vNULL{ };
 
 
 /* Embeddable vector.  These vectors are suitable to be embedded
@@ -1431,10 +1429,34 @@ gt_pch_nx (vec<T, A, vl_embed> *v, gt_pointer_operator op, void *cookie)
    As long as we use C++03, we cannot have constructors nor
    destructors in classes that are stored in unions.  */
 
+template<typename T, size_t N = 0>
+class auto_vec;
+
 template<typename T>
 struct vec<T, va_heap, vl_ptr>
 {
 public:
+  /* Default ctors to ensure triviality.  Use value-initialization
+     (e.g., vec() or vec v{ };) or vNULL to create a zero-initialized
+     instance.  */
+  vec () = default;
+  vec (const vec &) = default;
+  /* Initialization from the generic vNULL.  */
+  vec (vnull): m_vec () { }
+  /* Same as default ctor: vec storage must be released manually.  */
+  ~vec () = default;
+
+  /* Defaulted same as copy ctor.  */
+  vec& operator= (const vec &) = default;
+
+  /* Prevent implicit conversion from auto_vec.  Use auto_vec::to_vec()
+     instead.  */
+  template <size_t N>
+  vec (auto_vec<T, N> &) = delete;
+
+  template <size_t N>
+  void operator= (auto_vec<T, N> &) = delete;
+
   /* Memory allocation and deallocation for the embedded vector.
      Needed because we cannot have proper ctors/dtors defined.  */
   void create (unsigned nelems CXX_MEM_STAT_INFO);
@@ -1522,7 +1544,7 @@ public:
    want to ask for internal storage for vectors on the stack because if the
    size of the vector is larger than the internal storage that space is wasted.
    */
-template<typename T, size_t N = 0>
+template<typename T, size_t N /* = 0 */>
 class auto_vec : public vec<T, va_heap>
 {
 public:
@@ -1549,6 +1571,14 @@ public:
     this->release ();
   }
 
+  /* Explicitly convert to the base class.  There is no conversion
+     from a const auto_vec because a copy of the returned vec can
+     be used to modify *THIS.
+     This is a legacy function not to be used in new code.  */
+  vec<T, va_heap> to_vec_legacy () {
+    return *static_cast<vec<T, va_heap> *>(this);
+  }
+
 private:
   vec<T, va_heap, vl_embed> m_auto;
   T m_data[MAX (N - 1, 1)];
@@ -1602,6 +1632,14 @@ public:
       return *this;
     }
 
+  /* Explicitly convert to the base class.  There is no conversion
+     from a const auto_vec because a copy of the returned vec can
+     be used to modify *THIS.
+     This is a legacy function not to be used in new code.  */
+  vec<T, va_heap> to_vec_legacy () {
+    return *static_cast<vec<T, va_heap> *>(this);
+  }
+
   // You probably don't want to copy a vector, so these are deleted to prevent
   // unintentional use.  If you really need a copy of the vectors contents you
   // can use copy ().
@@ -1781,7 +1819,7 @@ template<typename T>
 inline vec<T, va_heap, vl_ptr>
 vec<T, va_heap, vl_ptr>::copy (ALONE_MEM_STAT_DECL) const
 {
-  vec<T, va_heap, vl_ptr> new_vec = vNULL;
+  vec<T, va_heap, vl_ptr> new_vec{ };
   if (length ())
     new_vec.m_vec = m_vec->copy (ALONE_PASS_MEM_STAT);
   return new_vec;