diff options
Diffstat (limited to 'gcc/cp/init.cc')
| -rw-r--r-- | gcc/cp/init.cc | 43 |
1 files changed, 40 insertions, 3 deletions
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc index 09fb4f3..f19794c 100644 --- a/gcc/cp/init.cc +++ b/gcc/cp/init.cc @@ -3557,9 +3557,19 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts, alloc_expr = maybe_wrap_new_for_constexpr (alloc_expr, type, cookie_size); + bool std_placement = std_placement_new_fn_p (alloc_fn); + + /* For std placement new, clobber the object if the constructor won't do it + in start_preparsed_function. This is most important for activating an + array in a union (c++/121068), but should also help the optimizers. */ + const bool do_clobber + = (std_placement && !*init && flag_lifetime_dse > 1 + && (!CLASS_TYPE_P (elt_type) + || type_has_non_user_provided_default_constructor (elt_type))); + /* In the simple case, we can stop now. */ pointer_type = build_pointer_type (type); - if (!cookie_size && !is_initialized && !member_delete_p) + if (!cookie_size && !is_initialized && !member_delete_p && !do_clobber) return build_nop (pointer_type, alloc_expr); /* Store the result of the allocation call in a variable so that we can @@ -3593,8 +3603,7 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts, So check for a null exception spec on the op new we just called. */ nothrow = TYPE_NOTHROW_P (TREE_TYPE (alloc_fn)); - check_new - = flag_check_new || (nothrow && !std_placement_new_fn_p (alloc_fn)); + check_new = flag_check_new || (nothrow && !std_placement); if (cookie_size) { @@ -3649,6 +3658,29 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts, /* Any further uses of alloc_node will want this type, too. */ alloc_node = fold_convert (non_const_pointer_type, alloc_node); + tree clobber_expr = NULL_TREE; + if (do_clobber) + { + tree clobber = build_clobber (elt_type, CLOBBER_OBJECT_BEGIN); + CONSTRUCTOR_IS_DIRECT_INIT (clobber) = true; + if (array_p) + { + /* Clobber each element rather than the array at once. */ + tree maxindex = cp_build_binary_op (input_location, + MINUS_EXPR, outer_nelts, + integer_one_node, + complain); + clobber_expr = build_vec_init (data_addr, maxindex, clobber, + /*valinit*/false, /*from_arr*/0, + complain, nullptr); + } + else + { + tree targ = cp_build_fold_indirect_ref (data_addr); + clobber_expr = cp_build_init_expr (targ, clobber); + } + } + /* Now initialize the allocated object. Note that we preevaluate the initialization expression, apart from the actual constructor call or assignment--we do this because we want to delay the allocation as long @@ -3877,6 +3909,8 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts, if (init_expr) rval = build2 (COMPOUND_EXPR, TREE_TYPE (rval), init_expr, rval); + if (clobber_expr) + rval = build2 (COMPOUND_EXPR, TREE_TYPE (rval), clobber_expr, rval); if (cookie_expr) rval = build2 (COMPOUND_EXPR, TREE_TYPE (rval), cookie_expr, rval); @@ -4717,6 +4751,9 @@ build_vec_init (tree base, tree maxindex, tree init, the partially constructed array if an exception is thrown. But don't do this if we're assigning. */ if (flag_exceptions && TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type) + /* And don't clean up from clobbers, the actual initialization will + follow as a separate build_vec_init. */ + && !(init && TREE_CLOBBER_P (init)) && from_array != 2) { tree e; |