Hi,
On 11/14/2014 03:35 AM, Jason Merrill wrote:
On 11/13/2014 04:31 PM, Paolo Carlini wrote:
I think this should be replaced with fold_ if
(processing_template_decl) in build_enumerator.
Ok. The value can be NULL_TREE, thus in a straightforward change (per
the below) I have to check for that, otherwise we crash in
maybe_constant_value. Either that or just check for NULL_TREE at the
beginning of maybe_constant_value itself, I guess.
The current fold_ already checks for NULL_TREE; I think we want to
preserve that behavior.
Ok, I added it to the new fold_.
This is the relatively most tricky change: we have a regression for
init/array11.C, because the gcc_assert at the end of
maybe_constant_value (called by maybe_constant_init) triggers:
gcc_assert (r == t
|| CONVERT_EXPR_P (t)
|| (TREE_CONSTANT (t) && !TREE_CONSTANT (r))
|| !cp_tree_equal (r, t));
we have VIEW_CONVERT_EXPRs, neither is constant, r != t and
cp_tree_equal is true. Wild guess: are VIEW_CONVERT_EXPRs also Ok?
Yes.
Ok.
What did you think about avoiding the duplicate
instantiation_dependent_expression_p and potential_constant_expression
checks?
Frankly at some point I forgot that, sorry.
Today I figured out the below: the new fold_non_dependent_expr is much
bigger but definitely calls instantiation_dependent_expression_p and
potential_constant_expression at most once and should be always
logically equivalent to instantiate_non_dependent_expr_sfinae followed
by maybe_constant_value, even in the special cases of those
TREE_OVERFLOW_Ps. Note: among various other simplifications, I tried
removing the early return via the conditional:
if (type_unknown_p (t)
|| BRACE_ENCLOSED_INITIALIZER_P (t))
but it's actually used by eg, g++.dg/cpp0x/constexpr-initlist5.C.
I'm attaching what passed testing on x86_64-linux.
Thanks!
Paolo.
//////////////////////////////
Index: cp/call.c
===================================================================
--- cp/call.c (revision 217547)
+++ cp/call.c (working copy)
@@ -572,7 +572,7 @@ null_ptr_cst_p (tree t)
{
/* Core issue 903 says only literal 0 is a null pointer constant. */
if (cxx_dialect < cxx11)
- t = maybe_constant_value (fold_non_dependent_expr_sfinae (t, tf_none));
+ t = fold_non_dependent_expr (t);
STRIP_NOPS (t);
if (integer_zerop (t) && !TREE_OVERFLOW (t))
return true;
@@ -7437,8 +7437,8 @@ build_over_call (struct z_candidate *cand, int fla
return error_mark_node;
if (DECL_VINDEX (fn) && (flags & LOOKUP_NONVIRTUAL) == 0
- /* Don't mess with virtual lookup in fold_non_dependent_expr; virtual
- functions can't be constexpr. */
+ /* Don't mess with virtual lookup in instantiate_non_dependent_expr;
+ virtual functions can't be constexpr. */
&& !in_template_function ())
{
tree t;
@@ -9361,7 +9361,7 @@ perform_implicit_conversion_flags (tree type, tree
type of non-dependent expressions, so we do not have to
perform the actual conversion. But for initializers, we
need to be able to perform it at instantiation
- (or fold_non_dependent_expr) time. */
+ (or instantiate_non_dependent_expr) time. */
expr = build1 (IMPLICIT_CONV_EXPR, type, expr);
if (!(flags & LOOKUP_ONLYCONVERTING))
IMPLICIT_CONV_EXPR_DIRECT_INIT (expr) = true;
Index: cp/class.c
===================================================================
--- cp/class.c (revision 217547)
+++ cp/class.c (working copy)
@@ -359,9 +359,9 @@ build_base_path (enum tree_code code,
/* Don't bother with the calculations inside sizeof; they'll ICE if the
source type is incomplete and the pointer value doesn't matter. In a
- template (even in fold_non_dependent_expr), we don't have vtables set
- up properly yet, and the value doesn't matter there either; we're just
- interested in the result of overload resolution. */
+ template (even in instantiate_non_dependent_expr), we don't have vtables
+ set up properly yet, and the value doesn't matter there either; we're
+ just interested in the result of overload resolution. */
if (cp_unevaluated_operand != 0
|| in_template_function ())
{
@@ -6933,7 +6933,8 @@ resolves_to_fixed_type_p (tree instance, int* nonn
tree fixed;
/* processing_template_decl can be false in a template if we're in
- fold_non_dependent_expr, but we still want to suppress this check. */
+ instantiate_non_dependent_expr, but we still want to suppress
+ this check. */
if (in_template_function ())
{
/* In a template we only care about the type of the result. */
Index: cp/constexpr.c
===================================================================
--- cp/constexpr.c (revision 217547)
+++ cp/constexpr.c (working copy)
@@ -2908,6 +2908,7 @@ maybe_constant_value (tree t, tree decl)
/* cp_tree_equal looks through NOPs, so allow them. */
gcc_assert (r == t
|| CONVERT_EXPR_P (t)
+ || TREE_CODE (t) == VIEW_CONVERT_EXPR
|| (TREE_CONSTANT (t) && !TREE_CONSTANT (r))
|| !cp_tree_equal (r, t));
#endif
@@ -2914,6 +2915,71 @@ maybe_constant_value (tree t, tree decl)
return r;
}
+/* Like maybe_constant_value but first fully constant fold the argument. */
+
+tree
+fold_non_dependent_expr (tree t)
+{
+ if (t == NULL_TREE)
+ return NULL_TREE;
+
+ /* If we're in a template, but T isn't value dependent, simplify
+ it. We're supposed to treat:
+
+ template <typename T> void f(T[1 + 1]);
+ template <typename T> void f(T[2]);
+
+ as two declarations of the same function, for example. */
+ if (processing_template_decl)
+ {
+ if (!instantiation_dependent_expression_p (t)
+ && potential_constant_expression (t))
+ {
+ HOST_WIDE_INT saved_processing_template_decl;
+
+ saved_processing_template_decl = processing_template_decl;
+ processing_template_decl = 0;
+ t = tsubst_copy_and_build (t,
+ /*args=*/NULL_TREE,
+ tf_none,
+ /*in_decl=*/NULL_TREE,
+ /*function_p=*/false,
+ /*integral_constant_expression_p=*/true);
+ processing_template_decl = saved_processing_template_decl;
+
+ if (type_unknown_p (t)
+ || BRACE_ENCLOSED_INITIALIZER_P (t))
+ {
+ if (TREE_OVERFLOW_P (t))
+ {
+ t = build_nop (TREE_TYPE (t), t);
+ TREE_CONSTANT (t) = false;
+ }
+ return t;
+ }
+
+ tree r = cxx_eval_outermost_constant_expr (t, true, NULL_TREE);
+#ifdef ENABLE_CHECKING
+ /* cp_tree_equal looks through NOPs, so allow them. */
+ gcc_assert (r == t
+ || CONVERT_EXPR_P (t)
+ || TREE_CODE (t) == VIEW_CONVERT_EXPR
+ || (TREE_CONSTANT (t) && !TREE_CONSTANT (r))
+ || !cp_tree_equal (r, t));
+#endif
+ return r;
+ }
+ else if (TREE_OVERFLOW_P (t))
+ {
+ t = build_nop (TREE_TYPE (t), t);
+ TREE_CONSTANT (t) = false;
+ }
+ return t;
+ }
+
+ return maybe_constant_value (t);
+}
+
/* Like maybe_constant_value, but returns a CONSTRUCTOR directly, rather
than wrapped in a TARGET_EXPR. */
@@ -3386,7 +3452,7 @@ potential_constant_expression_1 (tree t, bool want
if (!potential_constant_expression_1 (denom, rval, flags))
return false;
/* We can't call cxx_eval_outermost_constant_expr on an expression
- that hasn't been through fold_non_dependent_expr yet. */
+ that hasn't been through instantiate_non_dependent_expr yet. */
if (!processing_template_decl)
denom = cxx_eval_outermost_constant_expr (denom, true);
if (integer_zerop (denom))
Index: cp/cp-tree.h
===================================================================
--- cp/cp-tree.h (revision 217547)
+++ cp/cp-tree.h (working copy)
@@ -5690,8 +5690,8 @@ extern tree template_for_substitution (tree);
extern tree build_non_dependent_expr (tree);
extern void make_args_non_dependent (vec<tree, va_gc> *);
extern bool reregister_specialization (tree, tree, tree);
-extern tree fold_non_dependent_expr (tree);
-extern tree fold_non_dependent_expr_sfinae (tree, tsubst_flags_t);
+extern tree instantiate_non_dependent_expr (tree);
+extern tree instantiate_non_dependent_expr_sfinae (tree, tsubst_flags_t);
extern bool alias_type_or_template_p (tree);
extern bool alias_template_specialization_p (const_tree);
extern bool dependent_alias_template_spec_p (const_tree);
@@ -6331,6 +6331,7 @@ extern bool require_potential_rvalue_constant_expr
extern tree cxx_constant_value (tree, tree = NULL_TREE);
extern tree maybe_constant_value (tree, tree = NULL_TREE);
extern tree maybe_constant_init (tree, tree =
NULL_TREE);
+extern tree fold_non_dependent_expr (tree);
extern bool is_sub_constant_expr (tree);
extern bool reduced_constant_expression_p (tree);
extern bool is_instantiation_of_constexpr (tree);
Index: cp/decl.c
===================================================================
--- cp/decl.c (revision 217547)
+++ cp/decl.c (working copy)
@@ -8356,7 +8356,7 @@ compute_array_index_type (tree name, tree size, ts
NOP_EXPR with TREE_SIDE_EFFECTS; don't fold in that case. */;
else
{
- size = fold_non_dependent_expr_sfinae (size, complain);
+ size = instantiate_non_dependent_expr_sfinae (size, complain);
if (CLASS_TYPE_P (type)
&& CLASSTYPE_LITERAL_P (type))
@@ -12999,6 +12999,11 @@ build_enumerator (tree name, tree value, tree enum
tree context;
tree type;
+ /* integral_constant_value will pull out this expression, so make sure
+ it's folded as appropriate. */
+ if (processing_template_decl)
+ value = fold_non_dependent_expr (value);
+
/* If the VALUE was erroneous, pretend it wasn't there; that will
result in the enum being assigned the next value in sequence. */
if (value == error_mark_node)
Index: cp/decl2.c
===================================================================
--- cp/decl2.c (revision 217547)
+++ cp/decl2.c (working copy)
@@ -4951,7 +4951,7 @@ mark_used (tree decl, tsubst_flags_t complain)
if (processing_template_decl)
return true;
- /* Check this too in case we're within fold_non_dependent_expr. */
+ /* Check this too in case we're within instantiate_non_dependent_expr. */
if (DECL_TEMPLATE_INFO (decl)
&& uses_template_parms (DECL_TI_ARGS (decl)))
return true;
Index: cp/parser.c
===================================================================
--- cp/parser.c (revision 217547)
+++ cp/parser.c (working copy)
@@ -6886,7 +6886,7 @@ cp_parser_parenthesized_expression_list (cp_parser
}
if (fold_expr_p)
- expr = fold_non_dependent_expr (expr);
+ expr = instantiate_non_dependent_expr (expr);
/* If we have an ellipsis, then this is an expression
expansion. */
@@ -15996,10 +15996,6 @@ cp_parser_enumerator_definition (cp_parser* parser
if (check_for_bare_parameter_packs (value))
value = error_mark_node;
- /* integral_constant_value will pull out this expression, so make sure
- it's folded as appropriate. */
- value = fold_non_dependent_expr (value);
-
/* Create the enumerator. */
build_enumerator (identifier, value, type, loc);
}
Index: cp/pt.c
===================================================================
--- cp/pt.c (revision 217547)
+++ cp/pt.c (working copy)
@@ -5216,7 +5216,7 @@ redeclare_class_template (tree type, tree parms)
(possibly simplified) expression. */
tree
-fold_non_dependent_expr_sfinae (tree expr, tsubst_flags_t complain)
+instantiate_non_dependent_expr_sfinae (tree expr, tsubst_flags_t complain)
{
if (expr == NULL_TREE)
return NULL_TREE;
@@ -5248,9 +5248,9 @@ tree
}
tree
-fold_non_dependent_expr (tree expr)
+instantiate_non_dependent_expr (tree expr)
{
- return fold_non_dependent_expr_sfinae (expr, tf_error);
+ return instantiate_non_dependent_expr_sfinae (expr, tf_error);
}
/* Return TRUE iff T is a type alias, a TEMPLATE_DECL for an alias
@@ -5740,7 +5740,7 @@ convert_nontype_argument (tree type, tree expr, ts
&& has_value_dependent_address (expr))
/* If we want the address and it's value-dependent, don't fold. */;
else if (!type_unknown_p (expr))
- expr = fold_non_dependent_expr_sfinae (expr, complain);
+ expr = instantiate_non_dependent_expr_sfinae (expr, complain);
if (error_operand_p (expr))
return error_mark_node;
expr_type = TREE_TYPE (expr);
@@ -8314,7 +8314,7 @@ uses_template_parms (tree t)
/* Returns true iff current_function_decl is an incompletely instantiated
template. Useful instead of processing_template_decl because the latter
- is set to 0 during fold_non_dependent_expr. */
+ is set to 0 during instantiate_non_dependent_expr. */
bool
in_template_function (void)
@@ -15138,8 +15138,7 @@ tsubst_copy_and_build (tree t,
case COND_EXPR:
{
tree cond = RECUR (TREE_OPERAND (t, 0));
- tree folded_cond = (maybe_constant_value
- (fold_non_dependent_expr_sfinae (cond, tf_none)));
+ tree folded_cond = fold_non_dependent_expr (cond);
tree exp1, exp2;
if (TREE_CODE (folded_cond) == INTEGER_CST)
@@ -21110,7 +21109,7 @@ value_dependent_expression_p (tree expression)
case STMT_EXPR:
/* Treat a GNU statement expression as dependent to avoid crashing
- under fold_non_dependent_expr; it can't be constant. */
+ under instantiate_non_dependent_expr; it can't be constant. */
return true;
default:
@@ -21864,7 +21863,7 @@ build_non_dependent_expr (tree expr)
/* Try to get a constant value for all non-dependent expressions in
order to expose bugs in *_dependent_expression_p and constexpr. */
if (cxx_dialect >= cxx11)
- maybe_constant_value (fold_non_dependent_expr_sfinae (expr, tf_none));
+ fold_non_dependent_expr (expr);
#endif
/* Preserve OVERLOADs; the functions must be available to resolve
Index: cp/semantics.c
===================================================================
--- cp/semantics.c (revision 217547)
+++ cp/semantics.c (working copy)
@@ -511,8 +511,7 @@ begin_maybe_infinite_loop (tree cond)
bool maybe_infinite = true;
if (cond)
{
- cond = fold_non_dependent_expr_sfinae (cond, tf_none);
- cond = maybe_constant_value (cond);
+ cond = fold_non_dependent_expr (cond);
maybe_infinite = integer_nonzerop (cond);
}
vec_safe_push (cp_function_chain->infinite_loops,
@@ -543,7 +542,6 @@ end_maybe_infinite_loop (tree cond)
if (current != NULL_TREE)
{
cond = fold_non_dependent_expr (cond);
- cond = maybe_constant_value (cond);
if (integer_nonzerop (cond))
current_function_infinite_loop = 1;
}
@@ -7043,7 +7041,7 @@ finish_static_assert (tree condition, tree message
}
/* Fold the expression and convert it to a boolean value. */
- condition = fold_non_dependent_expr (condition);
+ condition = instantiate_non_dependent_expr (condition);
condition = cp_convert (boolean_type_node, condition, tf_warning_or_error);
condition = maybe_constant_value (condition);
Index: cp/tree.c
===================================================================
--- cp/tree.c (revision 217547)
+++ cp/tree.c (working copy)
@@ -4143,7 +4143,7 @@ fold_if_not_in_template (tree expr)
/* In the body of a template, there is never any need to call
"fold". We will call fold later when actually instantiating the
template. Integral constant expressions in templates will be
- evaluated via fold_non_dependent_expr, as necessary. */
+ evaluated via instantiate_non_dependent_expr, as necessary. */
if (processing_template_decl)
return expr;
Index: cp/typeck.c
===================================================================
--- cp/typeck.c (revision 217547)
+++ cp/typeck.c (working copy)
@@ -1787,7 +1787,7 @@ cxx_alignas_expr (tree e)
/* Leave value-dependent expression alone for now. */
return e;
- e = fold_non_dependent_expr (e);
+ e = instantiate_non_dependent_expr (e);
e = mark_rvalue_use (e);
/* [dcl.align]/2 says:
@@ -4135,8 +4135,7 @@ cp_build_binary_op (location_t location,
|| code1 == COMPLEX_TYPE || code1 == VECTOR_TYPE))
{
enum tree_code tcode0 = code0, tcode1 = code1;
- tree cop1 = fold_non_dependent_expr_sfinae (op1, tf_none);
- cop1 = maybe_constant_value (cop1);
+ tree cop1 = fold_non_dependent_expr (op1);
doing_div_or_mod = true;
warn_for_div_by_zero (location, cop1);
@@ -4175,8 +4174,7 @@ cp_build_binary_op (location_t location,
case TRUNC_MOD_EXPR:
case FLOOR_MOD_EXPR:
{
- tree cop1 = fold_non_dependent_expr_sfinae (op1, tf_none);
- cop1 = maybe_constant_value (cop1);
+ tree cop1 = fold_non_dependent_expr (op1);
doing_div_or_mod = true;
warn_for_div_by_zero (location, cop1);
}
@@ -4270,8 +4268,7 @@ cp_build_binary_op (location_t location,
}
else if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
{
- tree const_op1 = fold_non_dependent_expr_sfinae (op1, tf_none);
- const_op1 = maybe_constant_value (const_op1);
+ tree const_op1 = fold_non_dependent_expr (op1);
if (TREE_CODE (const_op1) != INTEGER_CST)
const_op1 = op1;
result_type = type0;
@@ -4320,8 +4317,7 @@ cp_build_binary_op (location_t location,
}
else if (code0 == INTEGER_TYPE && code1 == INTEGER_TYPE)
{
- tree const_op1 = fold_non_dependent_expr_sfinae (op1, tf_none);
- const_op1 = maybe_constant_value (const_op1);
+ tree const_op1 = fold_non_dependent_expr (op1);
if (TREE_CODE (const_op1) != INTEGER_CST)
const_op1 = op1;
result_type = type0;
@@ -4993,10 +4989,8 @@ cp_build_binary_op (location_t location,
/* OP0 and/or OP1 might have side-effects. */
op0 = cp_save_expr (op0);
op1 = cp_save_expr (op1);
- op0 = maybe_constant_value (fold_non_dependent_expr_sfinae (op0,
- tf_none));
- op1 = maybe_constant_value (fold_non_dependent_expr_sfinae (op1,
- tf_none));
+ op0 = fold_non_dependent_expr (op0);
+ op1 = fold_non_dependent_expr (op1);
if (doing_div_or_mod && (flag_sanitize & (SANITIZE_DIVIDE
| SANITIZE_FLOAT_DIVIDE)))
{
Index: cp/typeck2.c
===================================================================
--- cp/typeck2.c (revision 217547)
+++ cp/typeck2.c (working copy)
@@ -797,7 +797,7 @@ store_init_value (tree decl, tree init, vec<tree,
if (decl_maybe_constant_var_p (decl) || TREE_STATIC (decl))
{
bool const_init;
- value = fold_non_dependent_expr (value);
+ value = instantiate_non_dependent_expr (value);
if (DECL_DECLARED_CONSTEXPR_P (decl)
|| DECL_IN_AGGR_P (decl))
{
@@ -872,7 +872,7 @@ check_narrowing (tree type, tree init, tsubst_flag
return ok;
}
- init = maybe_constant_value (fold_non_dependent_expr_sfinae (init, tf_none));
+ init = fold_non_dependent_expr (init);
if (TREE_CODE (type) == INTEGER_TYPE
&& TREE_CODE (ftype) == REAL_TYPE)
@@ -1176,7 +1176,7 @@ massage_init_elt (tree type, tree init, tsubst_fla
init = TARGET_EXPR_INITIAL (init);
/* When we defer constant folding within a statement, we may want to
defer this folding as well. */
- tree t = fold_non_dependent_expr_sfinae (init, complain);
+ tree t = fold_non_dependent_expr (init);
t = maybe_constant_init (t);
if (TREE_CONSTANT (t))
init = t;
