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I got this testcase:
auto f() -> std::optional<std::string>;
for (char c : f().value()) { }
which has a dangling reference: std::optional<T>::value returns
a reference to the contained value, but here it's the f() temporary.
We warn, which is great, but only with -Wsystem-headers, because
the function comes from a system header and warning_enabled_at used
in do_warn_dangling_reference checks diagnostic_report_warnings_p,
which in this case returned false so we didn't warn.
Fixed as below. I could also override dc_warn_system_headers so that
the warning is enabled in system headers always. With that, I found one
issue in libstdc++:
libstdc++-v3/include/bits/fs_path.h:1265:15: warning: possibly dangling reference to a temporary [-Wdangling-reference]
1265 | auto& __last = *--end();
| ^~~~~~
which looks like a true positive as well.
gcc/cp/ChangeLog:
* call.cc (maybe_warn_dangling_reference): Enable the warning in
system headers if the decl isn't in a system header.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wdangling-reference4.C: New test.
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Comparing attributes between declarations of a friend function has been
complicated by pushdecl happening before decl_attributes. I assumed there
was some complicated reason we weren't calling decl_attributes here, but it
doesn't break anything.
gcc/cp/ChangeLog:
* decl.cc (grokdeclarator): Call decl_attributes before do_friend.
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Previously we've been allowing that comma only in C++ when in attribute
form (which was the reason why it has been allowed), but 5.1 allows that
even in pragma form in C/C++ (with clarifications in 5.2) and 5.2
also in Fortran (which this patch doesn't implement).
Note, for directives which take an argument (== unnamed clause),
comma is not allowed in between the directive name and the argument,
like the directive-1.c testcase shows.
2022-10-28 Jakub Jelinek <jakub@redhat.com>
gcc/c/
* c-parser.cc (c_parser_omp_all_clauses): Allow optional
comma before the first clause.
(c_parser_omp_allocate, c_parser_omp_atomic, c_parser_omp_depobj,
c_parser_omp_flush, c_parser_omp_scan_loop_body,
c_parser_omp_ordered, c_finish_omp_declare_variant,
c_parser_omp_declare_target, c_parser_omp_declare_reduction,
c_parser_omp_requires, c_parser_omp_error,
c_parser_omp_assumption_clauses): Likewise.
gcc/cp/
* parser.cc (cp_parser_omp_all_clauses): Allow optional comma
before the first clause even in pragma syntax.
(cp_parser_omp_allocate, cp_parser_omp_atomic, cp_parser_omp_depobj,
cp_parser_omp_flush, cp_parser_omp_scan_loop_body,
cp_parser_omp_ordered, cp_parser_omp_assumption_clauses,
cp_finish_omp_declare_variant, cp_parser_omp_declare_target,
cp_parser_omp_declare_reduction_exprs, cp_parser_omp_requires,
cp_parser_omp_error): Likewise.
gcc/testsuite/
* c-c++-common/gomp/directive-1.c: New test.
* c-c++-common/gomp/clauses-6.c: New test.
* c-c++-common/gomp/declare-variant-2.c (f75a): Declare.
(f75): Use f75a as variant instead of f1 and don't expect error.
* g++.dg/gomp/clause-4.C (foo): Don't expect error on comma
before first clause.
* gcc.dg/gomp/clause-2.c (foo): Likewise.
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C2x adds support for enums with a fixed underlying type specified
("enum e : long long;" and similar). Implement this in the C front
end. The same representation is used for these types as in C++, with
two macros moved from cp-tree.h to c-common.h.
Such enums can have bool as the underlying type, and various C
front-end code checking for boolean types is adjusted to use a new
C_BOOLEAN_TYPE_P to handle such enums the same way as bool. (Note
that for C++ we have bug 96496 that enums with underlying type bool
don't work correctly there.)
There are various issues with the wording for such enums in the
current C2x working draft (including but not limited to wording in the
accepted paper that failed to make it into the working draft), which I
intend to raise in NB comments. I think what I've implemented and
added tests for matches the intent.
Bootstrapped with no regressions for x86_64-pc-linux-gnu.
PR c/61469
gcc/c-family/
* c-common.h (ENUM_UNDERLYING_TYPE, ENUM_FIXED_UNDERLYING_TYPE_P):
New. Moved from cp/cp-tree.h.
* c-warn.cc (warnings_for_convert_and_check): Do not consider
conversions to enum with underlying type bool to overflow.
gcc/c/
* c-convert.cc (c_convert): Handle enums with underlying boolean
type like bool.
* c-decl.cc (shadow_tag_warned): Allow shadowing declarations for
enums with enum type specifier, but give errors for storage class
specifiers, qualifiers or alignment specifiers in non-definition
declarations of such enums.
(grokdeclarator): Give error for non-definition use of type
specifier with an enum type specifier.
(parser_xref_tag): Add argument has_enum_type_specifier. Pass it
to lookup_tag and use it to set ENUM_FIXED_UNDERLYING_TYPE_P.
(xref_tag): Update call to parser_xref_tag.
(start_enum): Add argument fixed_underlying_type. Complete enum
type with a fixed underlying type given in the definition. Give
error for defining without a fixed underlying type in the
definition if one was given in a prior declaration. Do not mark
enums with fixed underlying type as packed for -fshort-enums.
Store the enum type in the_enum.
(finish_enum): Do not adjust types of values or check their range
for an enum with a fixed underlying type. Set underlying type of
enum and variants.
(build_enumerator): Check enumeration constants for enum with
fixed underlying type against that type and convert to that type.
Increment in the underlying integer type, with handling for bool.
(c_simulate_enum_decl): Update call to start_enum.
(declspecs_add_type): Set specs->enum_type_specifier_ref_p.
* c-objc-common.cc (c_get_alias_set): Use ENUM_UNDERLYING_TYPE
rather than recomputing an underlying type based on size.
* c-parser.cc (c_parser_declspecs)
(c_parser_struct_or_union_specifier, c_parser_typeof_specifier):
Set has_enum_type_specifier for type specifiers.
(c_parser_enum_specifier): Handle enum type specifiers.
(c_parser_struct_or_union_specifier): Update call to
parser_xref_tag.
(c_parser_omp_atomic): Check for boolean increment or decrement
using C_BOOLEAN_TYPE_P.
* c-tree.h (C_BOOLEAN_TYPE_P): New.
(struct c_typespec): Add has_enum_type_specifier.
(struct c_declspecs): Add enum_type_specifier_ref_p.
(struct c_enum_contents): Add enum_type.
(start_enum, parser_xref_tag): Update prototypes.
* c-typeck.cc (composite_type): Allow for enumerated types
compatible with bool.
(common_type, comptypes_internal, perform_integral_promotions):
Use ENUM_UNDERLYING_TYPE.
(parser_build_binary_op, build_unary_op, convert_for_assignment)
(c_finish_return, c_start_switch, build_binary_op): Check for
boolean types using C_BOOLEAN_TYPE_P.
gcc/cp/
* cp-tree.h (ENUM_FIXED_UNDERLYING_TYPE_P, ENUM_UNDERLYING_TYPE):
Remove. Moved to c-common.h.
gcc/testsuite/
* gcc.dg/c11-enum-4.c, gcc.dg/c11-enum-5.c, gcc.dg/c11-enum-6.c,
gcc.dg/c2x-enum-6.c, gcc.dg/c2x-enum-7.c, gcc.dg/c2x-enum-8.c,
gcc.dg/gnu2x-enum-1.c: New tests.
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As mentioned in the PR, apparently my r13-2887 P1467R9 changes
regressed these tests on powerpc64le-linux with IEEE quad by default.
I believe my changes just uncovered a latent bug.
The problem is that push_namespace calls find_namespace_slot,
which does:
tree *slot = DECL_NAMESPACE_BINDINGS (ns)
->find_slot_with_hash (name, name ? IDENTIFIER_HASH_VALUE (name) : 0,
create_p ? INSERT : NO_INSERT);
In the <identifier_node 0x7fffe9f55ac0 details> ns case, slot is non-NULL
above with a binding_vector in it.
Then pushdecl is called and this does:
slot = find_namespace_slot (ns, name, ns == current_namespace);
where ns == current_namespace (ns is :: and name is details) is true.
So this again calls
tree *slot = DECL_NAMESPACE_BINDINGS (ns)
->find_slot_with_hash (name, name ? IDENTIFIER_HASH_VALUE (name) : 0,
create_p ? INSERT : NO_INSERT);
but this time with create_p and so INSERT.
At this point we reach
if (insert == INSERT && m_size * 3 <= m_n_elements * 4)
expand ();
and when we are unlucky and the occupancy of the hash table just reached 3/4,
expand () is called and the hash table is reallocated. But when that happens,
it means the slot pointer in the pushdecl caller (push_namespace) points to
freed memory and so any accesses to it in make_namespace_finish will be UB.
The following patch fixes it by calling find_namespace_slot again even if it
was non-NULL, just doesn't assert it is *slot == ns in that case (because
it often is not).
2022-10-27 Jakub Jelinek <jakub@redhat.com>
PR c++/107379
* name-lookup.cc (push_namespace): Call find_namespace_slot again
after pushdecl as the hash table might be expanded during pushdecl.
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(Explicitly) Templated lambdas have a different signature to
implicitly templated lambdas -- '[]<template T> (T) {}' is not the
same as '[](auto) {}'. This should be reflected in the mangling. The
ABI captures this as
https://github.com/itanium-cxx-abi/cxx-abi/issues/31, and clang has
implemented such additions.
It's relatively straight forwards to write out the non-synthetic
template parms, and note if we need to issue an ABI warning.
gcc/cp/
* mangle.cc (write_closure_template_head): New.
(write_closure_type_name): Call it.
gcc/testsuite/
* g++.dg/abi/lambda-ctx1-18.C: Adjust.
* g++.dg/abi/lambda-ctx1-18vs17.C: Adjust.
* g++.dg/abi/lambda-tpl1-17.C: New.
* g++.dg/abi/lambda-tpl1-18.C: New.
* g++.dg/abi/lambda-tpl1-18vs17.C: New.
* g++.dg/abi/lambda-tpl1.h: New.
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The following tests ICE in the gcc_assert (common); in cp_build_binary_op.
I've missed that while for * common is set always, while for +, - and /
it is in some cases not.
If it is not, then
if (!result_type
&& arithmetic_types_p
&& (shorten || common || short_compare))
condition is false, then the following
if (may_need_excess_precision
&& (orig_type0 != type0 || orig_type1 != type1)
&& build_type == NULL_TREE)
would fail the assertion there and if there wouldn't be excess precision,
if (code == SPACESHIP_EXPR)
would be false (for SPACESHIP_EXPR we always have build_type set like for
other comparisons) and then trigger
if (!result_type)
{
if (complain & tf_error)
{
binary_op_rich_location richloc (location,
orig_op0, orig_op1, true);
error_at (&richloc,
"invalid operands of types %qT and %qT to binary %qO",
TREE_TYPE (orig_op0), TREE_TYPE (orig_op1), code);
}
return error_mark_node;
}
So, if result_type is NULL, we don't really need to compute
semantic_result_type because nothing will use it anyway and can get
fall through into the error/return error_mark_node; case.
2022-10-27 Jakub Jelinek <jakub@redhat.com>
PR c++/107382
PR c++/107383
* typeck.cc (cp_build_binary_op): Don't compute semantic_result_type
if result_type is NULL.
* g++.dg/diagnostic/bad-binary-ops2.C: New test.
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This patch implements a new experimental warning (enabled by -Wall) to
detect references bound to temporaries whose lifetime has ended. The
primary motivation is the Note in
<https://en.cppreference.com/w/cpp/algorithm/max>:
Capturing the result of std::max by reference produces a dangling reference
if one of the parameters is a temporary and that parameter is returned:
int n = 1;
const int& r = std::max(n-1, n+1); // r is dangling
That's because both temporaries for n-1 and n+1 are destroyed at the end
of the full expression. With this warning enabled, you'll get:
g.C:3:12: warning: possibly dangling reference to a temporary [-Wdangling-reference]
3 | const int& r = std::max(n-1, n+1);
| ^
g.C:3:24: note: the temporary was destroyed at the end of the full expression 'std::max<int>((n - 1), (n + 1))'
3 | const int& r = std::max(n-1, n+1);
| ~~~~~~~~^~~~~~~~~~
The warning works by checking if a reference is initialized with a function
that returns a reference, and at least one parameter of the function is
a reference that is bound to a temporary. It assumes that such a function
actually returns one of its arguments! (I added code to check_return_expr
to suppress the warning when we've seen the definition of the function
and we can say that it can return a variable with static storage
duration.)
It warns when the function in question is a member function, but only if
the function is invoked on a temporary object, otherwise the warning
would emit loads of warnings for valid code like obj.emplace<T>({0}, 0).
It does detect the dangling reference in:
struct S {
const S& self () { return *this; }
};
const S& s = S().self();
It warns in member initializer lists as well:
const int& f(const int& i) { return i; }
struct S {
const int &r;
S() : r(f(10)) { }
};
I've run the testsuite/bootstrap with the warning enabled by default.
There were just a few FAILs, all of which look like genuine bugs.
A bootstrap with the warning enabled by default passed as well.
When testing a previous version of the patch, there were many FAILs in
libstdc++'s 22_locale/; all of them because the warning triggered on
const test_type& obj = std::use_facet<test_type>(std::locale());
but this code looks valid -- std::use_facet doesn't return a reference
to its parameter. Therefore I added a #pragma and code to suppress the
warning.
PR c++/106393
gcc/c-family/ChangeLog:
* c.opt (Wdangling-reference): New.
gcc/cp/ChangeLog:
* call.cc (expr_represents_temporary_p): New, factored out of...
(conv_binds_ref_to_temporary): ...here. Don't return false just
because a ck_base is missing. Use expr_represents_temporary_p.
(do_warn_dangling_reference): New.
(maybe_warn_dangling_reference): New.
(extend_ref_init_temps): Call maybe_warn_dangling_reference.
* cp-tree.h: Adjust comment.
* typeck.cc (check_return_expr): Suppress -Wdangling-reference
warnings.
gcc/ChangeLog:
* doc/invoke.texi: Document -Wdangling-reference.
libstdc++-v3/ChangeLog:
* include/bits/locale_classes.tcc: Add #pragma to disable
-Wdangling-reference with std::use_facet.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/elision4.C: Use -Wdangling-reference, add dg-warning.
* g++.dg/cpp23/elision7.C: Likewise.
* g++.dg/warn/Wdangling-pointer-2.C: Use -Wno-dangling-reference.
* g++.dg/warn/Wdangling-reference1.C: New test.
* g++.dg/warn/Wdangling-reference2.C: New test.
* g++.dg/warn/Wdangling-reference3.C: New test.
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We intend to mark synthetic template parameters (coming from use of auto
parms), as DECL_VIRTUAL_P. The API of process_template_parm is
awkwardly confusing, and we were marking the previous template parm
(unless this was the first parm). process_template_parm returns the list
of parms, when most (all?) users really want the newly-added final node.
That's a bigger change, so let's not do it right now. With this, we
correctly mark such synthetic parms DECL_VIRTUAL_P.
gcc/cp/
* parser.cc (synthesize_implicit_template_parm): Fix thinko about
mark the new parm DECL_VIRTUAL_P. Avoid unneccessary tree_last call.
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The parameter use_default_args of coerce_template_parms, introduced way
back in r110693, is effectively unused ever since r7-5536-g3c75aaa3d884ef
removed the last 'coerce_template_parms (..., true, false)' call. So
this patch aims to simplify this function's API by getting rid of this
parameter.
In passing, I noticed we currently define wrapper overloads of
coerce_template_parms that act as defacto default arguments for complain
and require_all_args. It seems cleaner however to just specify real
default arguments for the main overload instead. And I suppose we
should also give c_innermost_t_p the same defaults.
But I'm not sure about defaulting complain to tf_none, which is
inconsistent with how we default it in other places to either tf_error
or tf_warning_or_error (as a convenience for non-SFINAE callers). And
since in general it's probably better to not default complain as that's
a source of SFINAE bugs, and only a handful of callers use this defacto
complain=tf_none default, this patch gets rid of this complain default
(but keeps the require_all_args default).
gcc/cp/ChangeLog:
* constraint.cc (resolve_function_concept_overload): Explicitly
pass complain=tf_none to coerce_template_parms.
(resolve_concept_check): Likewise.
(normalize_concept_check): Likewise.
* cp-tree.h (coerce_template_parms): Declare the main overload
and default its last parameter to true. Remove wrapper overloads.
* pt.cc (determine_specialization): Adjust calls to
coerce_template_parms and coerce_innermost_template_parms after
removing their last parameter.
(coerce_template_args_for_ttp): Likewise.
(coerce_ttp_args_for_tta): Likewise.
(coerce_template_template_parms): Likewise.
(coerce_template_parms): Remove use_default_args parameter and
adjust function comment. Document default argument. Remove
wrapper overloads. No longer static.
(coerce_innermost_template_parms): Remove use_default_args
parameter. Default require_all_args to true.
(lookup_template_class): As with determine_specialization.
(finish_template_variable): Likewise.
(tsubst_decl): Likewise.
(instantiate_alias_template): Likewise.
(fn_type_unification): Likewise.
(resolve_overloaded_unification): Likewise.
(resolve_nondeduced_context): Likewise.
(get_partial_spec_bindings): Likewise.
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Still want the conversion to bool.
gcc/cp/ChangeLog:
* constexpr.cc (find_failing_clause_r): Re-add the call to
contextual_conv_bool.
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In the frontend, the TYPE_MIN/MAX_VALUE of ENUMERAL_TYPE is the same as
that of the enum's underlying type (see start_enum). And the underlying
type of an enum is always known, even for an opaque enum that lacks a
definition.
But currently, we stream TYPE_MIN/MAX_VALUE of an enum only as part of
its definition. So if the enum is declared but never defined, the
ENUMERAL_TYPE we stream in will have empty TYPE_MIN/MAX_VALUE fields
despite these fields being non-empty on stream out.
And even if the enum is defined, read_enum_def updates these fields only
on the main variant of the enum type, so for other variants (that we may
have streamed in earlier) these fields remain empty. That these fields
are unexpectedly empty for some ENUMERAL_TYPEs is ultimately the cause
of the below two PRs.
This patch fixes this by making us stream TYPE_MIN/MAX_VALUE directly
for each ENUMERAL_TYPE rather than as part of the enum's definition, so
that we naturally also stream these fields for opaque enums (and each
enum type variant).
PR c++/106848
PR c++/102600
gcc/cp/ChangeLog:
* module.cc (trees_out::core_vals): Stream TYPE_MAX_VALUE and
TYPE_MIN_VALUE of ENUMERAL_TYPE.
(trees_in::core_vals): Likewise.
(trees_out::write_enum_def): Don't stream them here.
(trees_in::read_enum_def): Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/modules/enum-9_a.H: New test.
* g++.dg/modules/enum-9_b.C: New test.
* g++.dg/modules/enum-10_a.H: New test.
* g++.dg/modules/enum-10_b.C: New test.
* g++.dg/modules/enum-11_a.H: New test.
* g++.dg/modules/enum-11_b.C: New test.
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The initial [[assume]] support avoided evaluating assumes with
TREE_SIDE_EFFECTS set, such as calls, because we don't want any side-effects
that change the constexpr state. This patch allows us to evaluate
expressions with that flag set by tracking which variables the evaluation is
allowed to modify, and giving up if it tries to touch any others.
I considered allowing changes to other variables and then rolling them back,
but that seems like a rare enough situation that it doesn't seem worth
working to handle nicely at this point.
gcc/cp/ChangeLog:
* constexpr.cc (class constexpr_global_ctx): Add modifiable field,
get_value, get_value_ptr, put_value, remove_value, flush_modifiable
member functions.
(class modifiable_tracker): New.
(cxx_eval_internal_function): Use it.
(diagnose_failing_condition): Strip CLEANUP_POINT_EXPR.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/attr-assume9.C: New test.
* g++.dg/cpp23/attr-assume10.C: New test.
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I noticed that we were printing "the comparison reduces to (x == 42)" when
we should be able to give the value of x. Fixed by doing the same
evaluation in diagnose_failing_condition that we already do in
find_failing_clause.
gcc/cp/ChangeLog:
* constexpr.cc (fold_operand): New function.
(find_failing_clause_r): Add const.
(find_failing_clause): Add const.
(diagnose_failing_condition): Add ctx parameter.
(cxx_eval_internal_function): Pass it.
* semantics.cc (diagnose_failing_condition): Move to constexpr.cc.
* cp-tree.h: Adjust.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/attr-assume2.C: Expect constant values.
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Simplify several calls to build_string_literal by not requiring redundant
strlen or IDENTIFIER_* in the caller.
I also corrected a wrong comment on IDENTIFIER_LENGTH.
gcc/ChangeLog:
* tree.h (build_string_literal): New one-argument overloads that
take tree (identifier) and const char *.
* builtins.cc (fold_builtin_FILE)
(fold_builtin_FUNCTION)
* gimplify.cc (gimple_add_init_for_auto_var)
* vtable-verify.cc (verify_bb_vtables): Simplify calls.
gcc/cp/ChangeLog:
* cp-gimplify.cc (fold_builtin_source_location)
* vtable-class-hierarchy.cc (register_all_pairs): Simplify calls to
build_string_literal.
(build_string_from_id): Remove.
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This test ICEs in C++23 because we reach the new code in do_auto_deduction:
30468 if (cxx_dialect >= cxx23
30469 && context == adc_return_type
30470 && (!AUTO_IS_DECLTYPE (auto_node)
30471 || !unparenthesized_id_or_class_member_access_p (init))
30472 && (r = treat_lvalue_as_rvalue_p (maybe_undo_parenthesized_ref (init),
30473 /*return*/true)))
where 'init' is "VIEW_CONVERT_EXPR<<<< error >>>>(y)", and then the move
in treat_lvalue_as_rvalue_p returns error_mark_node whereupon
set_implicit_rvalue_p crashes.
I don't think such V_C_Es are useful so let's not create them. But that
won't fix the ICE so I'm checking the return value of move. A structured
bindings decl can have an error type, that is set in cp_finish_decomp:
8908 TREE_TYPE (first) = error_mark_node;
therefore I think treat_lvalue_as_rvalue_p just needs to cope.
PR c++/107276
gcc/cp/ChangeLog:
* typeck.cc (treat_lvalue_as_rvalue_p): Check the return value of move.
gcc/ChangeLog:
* tree.cc (maybe_wrap_with_location): Don't create a location wrapper
when the type is erroneous.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/decomp4.C: New test.
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[PR107358]
As mentioned earlier in the C++ excess precision support mail, the following
testcase is broken with excess precision both in C and C++ (though just in C++
it was triggered in real-world code).
scalar_to_vector is called in both FEs after the excess precision promotions
(or stripping of EXCESS_PRECISION_EXPR), so we can then get invalid
diagnostics that say float vector + float involves truncation (on ia32
from long double to float).
The following patch fixes that by calling scalar_to_vector on the operands
before the excess precision promotions, let scalar_to_vector just do the
diagnostics (it does e.g. fold_for_warn so it will fold
EXCESS_PRECISION_EXPR around REAL_CST to constants etc.) but will then
do the actual conversions using the excess precision promoted operands
(so say if we have vector double + (float + float) we don't actually do
vector double + (float) ((long double) float + (long double) float)
but
vector double + (double) ((long double) float + (long double) float)
2022-10-24 Jakub Jelinek <jakub@redhat.com>
PR c++/107358
gcc/c/
* c-typeck.cc (build_binary_op): Pass operands before excess precision
promotions to scalar_to_vector call.
gcc/cp/
* typeck.cc (cp_build_binary_op): Pass operands before excess precision
promotions to scalar_to_vector call.
gcc/testsuite/
* c-c++-common/pr107358.c: New test.
* g++.dg/cpp1y/pr68180.C: Remove -fexcess-precision=fast from
dg-options.
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inc/decrement [PR105774]
signed char, char or short int pre/post inc/decrement are represented by
normal {PRE,POST}_{INC,DEC}REMENT_EXPRs in the FE and only gimplification
ensures that the {PLUS,MINUS}_EXPR is done in unsigned version of those
types:
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
{
tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
{
if (!TYPE_OVERFLOW_WRAPS (type))
type = unsigned_type_for (type);
return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
}
break;
}
This means during constant evaluation we need to do it similarly (either
using unsigned_type_for or using widening to integer_type_node).
The following patch does the latter.
2022-10-24 Jakub Jelinek <jakub@redhat.com>
PR c++/105774
* constexpr.cc (cxx_eval_increment_expression): For signed types
that promote to int, evaluate PLUS_EXPR or MINUS_EXPR in int type.
* g++.dg/cpp1y/constexpr-105774.C: New test.
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... unless marked noreturn.
This should not get in anyone's way, but should permit the use of main()
in freestanding more easily, especially for writing test cases that
should work both in freestanding and hosted modes.
gcc/c/ChangeLog:
* c-decl.cc (finish_function): Ignore hosted when deciding
whether to implicitly return zero, but check noreturn.
* c-objc-common.cc (c_missing_noreturn_ok_p): Loosen the
requirements to just MAIN_NAME_P when hosted, or `int main'
otherwise.
gcc/cp/ChangeLog:
* cp-tree.h (DECL_MAIN_P): Move most logic, besides the hosted
check, from here...
(DECL_MAIN_ANY_P): ... to here, so that it can be reused ...
(DECL_MAIN_FREESTANDING_P): ... here, with an additional
constraint on (hosted OR return type == int)
* decl.cc (finish_function): Use DECL_MAIN_FREESTANDING_P
instead of DECL_MAIN_P, to loosen the hosted requirement, but
check noreturn, before adding implicit returns.
gcc/testsuite/ChangeLog:
* gcc.dg/noreturn-4.c: Removed.
* g++.dg/freestanding-main.C: New test.
* g++.dg/freestanding-nonint-main.C: New test.
* gcc.dg/freestanding-main.c: New test.
* gcc.dg/freestanding-nonint-main.c: New test.
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cxx_eval_constant_expression [PR107295]
The excess precision support broke building skia (dependency of firefox)
on ia32 (it has something like the a constexpr variable), but as the other
cases show, it is actually a preexisting problem if one uses casts from
constants with wider floating point types.
The problem is that cxx_eval_constant_expression tries to short-cut
processing of TREE_CONSTANT CONSTRUCTORs if they satisfy
reduced_constant_expression_p - instead of calling cxx_eval_bare_aggregate
on them it just verifies flags and if they are TREE_CONSTANT even after
that, just fold.
Now, on the testcase we have a TREE_CONSTANT CONSTRUCTOR containing
TREE_CONSTANT NOP_EXPR of REAL_CST. And, fold, which isn't recursive,
doesn't optimize that into VECTOR_CST, while later on we are only able
to optimize VECTOR_CST arithmetics, not arithmetics with vector
CONSTRUCTORs.
The following patch fixes that by rejecting CONSTRUCTORs with vector type
in reduced_constant_expression_p regardless of whether they have
CONSTRUCTOR_NO_CLEARING set or not, folding result in cxx_eval_bare_aggregate
even if nothing has changed but it wasn't non-constant and removing folding
from the TREE_CONSTANT reduced_constant_expression_p short-cut.
2022-10-21 Jakub Jelinek <jakub@redhat.com>
PR c++/107295
* constexpr.cc (reduced_constant_expression_p) <case CONSTRUCTOR>:
Return false for VECTOR_TYPE CONSTRUCTORs even without
CONSTRUCTOR_NO_CLEARING set on them.
(cxx_eval_bare_aggregate): If constant but !changed, fold before
returning VECTOR_TYPE_P CONSTRUCTOR.
(cxx_eval_constant_expression) <case CONSTRUCTOR>: Don't fold
TREE_CONSTANT CONSTRUCTOR, just return it.
* g++.dg/ext/vector42.C: New test.
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We ICE on the following testcase during mangling, finish_compound_literal
returns for void{} void_node and the mangler doesn't handle it.
Handling void_node in the mangler seems problematic to me, because
we don't know for which case it has been created.
The following patch arranges to mangle it as other compound literals
with no operands, so it demangles as void{}, by returning a void type
COMPOUND_LITERAL_P with no elements if processing_template_decl.
Otherwise it keeps returning void_node.
2022-10-21 Jakub Jelinek <jakub@redhat.com>
PR c++/106863
* semantics.cc (finish_compound_literal): For void{}, if
processing_template_decl return a COMPOUND_LITERAL_P
CONSTRUCTOR rather than void_node.
* g++.dg/cpp0x/dr2351-2.C: New test.
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Here we're crashing during constraint matching for the instantiated
hidden friends due to two issues with dependent substitution into a
TEMPLATE_ID_EXPR that names a template from the current instantiation
(as for C<1> with T=T from maybe_substitute_reqs_for):
* tsubst_copy substitutes into such a TEMPLATE_DECL by looking it up
from the substituted class scope. But for this lookup to work when
the args are dependent, we need to substitute the class scope with
entering_scope=true so that we obtain the primary template type
A<T> (which has TYPE_BINFO) instead of the implicit instantiation
A<T> (which doesn't).
* lookup_and_finish_template_variable shouldn't instantiate a
TEMPLATE_ID_EXPR that names a TEMPLATE_DECL which has more than
one level of (unsubstituted) parameters (such as A<T>::C).
gcc/cp/ChangeLog:
* pt.cc (lookup_and_finish_template_variable): Don't
instantiate if the template's scope is dependent.
(tsubst_copy) <case TEMPLATE_DECL>: Pass entering_scope=true
when substituting the class scope.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-friend10.C: New test.
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Here node_template_info is overlooking that CONCEPT_DECL has TEMPLATE_INFO
too, which causes get_originating_module_decl for the CONCEPT_DECL to not
return the corresponding TEMPLATE_DECL, which leads to an ICE from
import_entity_index while pretty printing the CONCEPT_DECL's module
suffix as part of the static assert failure elaboration.
PR c++/102963
gcc/cp/ChangeLog:
* module.cc (node_template_info): Handle CONCEPT_DECL.
gcc/testsuite/ChangeLog:
* g++.dg/modules/concept-7_a.C: New test.
* g++.dg/modules/concept-7_b.C: New test.
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This patch adds a CSV file with information about the API of the
standard C++ library. This information can be used in multiple ways.
So far there are two use cases:
- to generate the module export list for the standard C++ library
- to create the name hints to compiler emits when symbols in the
std namespace are not found
Adding more uses can be easily done by potentially adding more columns
to the CSV file and adding to the Python script which generates the
output file.
contrib/
2022-10-18 Jonathan Wakely <jwakely@redhat.com>
Ulrich Drepper <drepper@redhat.com>
* gcc_update: Add rule for gcc/cp/std-name-hint.gperf.
gcc/cp/
2022-10-18 Jonathan Wakely <jwakely@redhat.com>
Ulrich Drepper <drepper@redhat.com>
* Make-lang.in: Add rules to generate std-name-hint.gperf. Adjust
rule to generate std-name-hint.h to allow chain rule.
* std-name-hint.h: Regenerated.
* std-name-hint.gperf: This file is now generated.
* cxxapi-data.csv: New file. CSV file with C++ API data.
* gen-cxxapi-file.py: New file. Generate std-name-hint.gperf
and module export source (in future).
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-Wuseless-cast (not part of -Wall/-Wextra) warns here:
struct S { };
void g (S&&);
void f (S&& arg)
{
g (S(arg)); // warning: useless cast to type 'struct S'
}
which is wrong: the code will not compile without the cast because
"arg" is an lvalue which cannot bind to S&&.
This patch disables the warning when an object that isn't a prvalue
is cast to a non-reference type. Therefore we still warn about the
useless cast in "X(X{})".
PR c++/85043
gcc/cp/ChangeLog:
* typeck.cc (maybe_warn_about_useless_cast): Don't warn when
a glvalue is cast to a non-reference type.
gcc/ChangeLog:
* doc/invoke.texi: Update documentation of -Wuseless-cast.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Wuseless-cast.C: Remove dg-warning.
* g++.dg/warn/Wuseless-cast3.C: New test.
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|
This fixes the below testcase in which we neglect to stream the default
argument for T only because the subsequent parameter U doesn't also have
a default argument.
PR c++/105045
gcc/cp/ChangeLog:
* module.cc (trees_out::tpl_parms_fini): Don't assume default
template arguments must be trailing.
(trees_in::tpl_parms_fini): Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr105045_a.C: New test.
* g++.dg/modules/pr105045_b.C: New test.
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|
My earlier patches gimplify the simplest non-side-effects assumptions
into if (cond) ; else __builtin_unreachable (); and throw the rest
on the floor.
The following patch attempts to do something with the rest too.
For -O0, it throws the more complex assumptions on the floor,
we don't expect optimizations and the assumptions are there to allow
optimizations. Otherwise arranges for the assumptions to be
visible in the IL as
.ASSUME (_Z2f4i._assume.0, i_1(D));
call where there is an artificial function like:
bool _Z2f4i._assume.0 (int i)
{
bool _2;
<bb 2> [local count: 1073741824]:
_2 = i_1(D) == 43;
return _2;
}
with the semantics that there is UB unless the assumption function
would return true.
Aldy, could ranger handle this? If it sees .ASSUME call,
walk the body of such function from the edge(s) to exit with the
assumption that the function returns true, so above set _2 [true, true]
and from there derive that i_1(D) [43, 43] and then map the argument
in the assumption function to argument passed to IFN_ASSUME (note,
args there are shifted by 1)?
During gimplification it actually gimplifies it into
[[assume (D.2591)]]
{
{
i = i + 1;
D.2591 = i == 44;
}
}
which is a new GIMPLE_ASSUME statement wrapping a GIMPLE_BIND and
specifying a boolean_type_node variable which contains the result.
The GIMPLE_ASSUME then survives just a couple of passes and is lowered
during gimple lowering into an outlined separate function and
IFN_ASSUME call. Variables declared inside of the
condition (both static and automatic) just change context, automatic
variables from the caller are turned into parameters (note, as the code
is never executed, I handle this way even non-POD types, we don't need to
bother pretending there would be user copy constructors etc. involved).
The assume_function artificial functions are then optimized until the
new assumptions pass which doesn't do much right now but I'd like to see
there the backwards ranger walk and filling up of SSA_NAME_RANGE_INFO
for the parameters.
There are a few further changes I'd like to do, like ignoring the
.ASSUME calls in inlining size estimations (but haven't figured out where
it is done), or for LTO arrange for the assume functions to be emitted
in all partitions that reference those (usually there will be just one,
unless code with the assumption got inlined, versioned etc.).
2022-10-18 Jakub Jelinek <jakub@redhat.com>
PR c++/106654
gcc/
* gimple.def (GIMPLE_ASSUME): New statement kind.
* gimple.h (struct gimple_statement_assume): New type.
(is_a_helper <gimple_statement_assume *>::test,
is_a_helper <const gimple_statement_assume *>::test): New.
(gimple_build_assume): Declare.
(gimple_has_substatements): Return true for GIMPLE_ASSUME.
(gimple_assume_guard, gimple_assume_set_guard,
gimple_assume_guard_ptr, gimple_assume_body_ptr, gimple_assume_body):
New inline functions.
* gsstruct.def (GSS_ASSUME): New.
* gimple.cc (gimple_build_assume): New function.
(gimple_copy): Handle GIMPLE_ASSUME.
* gimple-pretty-print.cc (dump_gimple_assume): New function.
(pp_gimple_stmt_1): Handle GIMPLE_ASSUME.
* gimple-walk.cc (walk_gimple_op): Handle GIMPLE_ASSUME.
* omp-low.cc (WALK_SUBSTMTS): Likewise.
(lower_omp_1): Likewise.
* omp-oacc-kernels-decompose.cc (adjust_region_code_walk_stmt_fn):
Likewise.
* tree-cfg.cc (verify_gimple_stmt, verify_gimple_in_seq_2): Likewise.
* function.h (struct function): Add assume_function bitfield.
* gimplify.cc (gimplify_call_expr): If the assumption isn't
simple enough, expand it into GIMPLE_ASSUME wrapped block or
for -O0 drop it.
* gimple-low.cc: Include attribs.h.
(create_assumption_fn): New function.
(struct lower_assumption_data): New type.
(find_assumption_locals_r, assumption_copy_decl,
adjust_assumption_stmt_r, adjust_assumption_stmt_op,
lower_assumption): New functions.
(lower_stmt): Handle GIMPLE_ASSUME.
* tree-ssa-ccp.cc (pass_fold_builtins::execute): Remove
IFN_ASSUME calls.
* lto-streamer-out.cc (output_struct_function_base): Pack
assume_function bit.
* lto-streamer-in.cc (input_struct_function_base): And unpack it.
* cgraphunit.cc (cgraph_node::expand): Don't verify assume_function
has TREE_ASM_WRITTEN set and don't release its body.
(symbol_table::compile): Allow assume functions not to have released
body.
* internal-fn.cc (expand_ASSUME): Remove gcc_unreachable.
* passes.cc (execute_one_pass): For TODO_discard_function don't
release body of assume functions.
* cgraph.cc (cgraph_node::verify_node): Don't verify cgraph nodes
of PROP_assumptions_done functions.
* tree-pass.h (PROP_assumptions_done): Define.
(TODO_discard_function): Adjust comment.
(make_pass_assumptions): Declare.
* passes.def (pass_assumptions): Add.
* timevar.def (TV_TREE_ASSUMPTIONS): New.
* tree-inline.cc (remap_gimple_stmt): Handle GIMPLE_ASSUME.
* tree-vrp.cc (pass_data_assumptions): New variable.
(pass_assumptions): New class.
(make_pass_assumptions): New function.
gcc/cp/
* cp-tree.h (build_assume_call): Declare.
* parser.cc (cp_parser_omp_assumption_clauses): Use build_assume_call.
* cp-gimplify.cc (build_assume_call): New function.
(process_stmt_assume_attribute): Use build_assume_call.
* pt.cc (tsubst_copy_and_build): Likewise.
gcc/testsuite/
* g++.dg/cpp23/attr-assume5.C: New test.
* g++.dg/cpp23/attr-assume6.C: New test.
* g++.dg/cpp23/attr-assume7.C: New test.
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It looks like we currently avoid streaming the RESULT_DECL and PARM_DECLs
of a constexpr_fundef entry under the assumption that they're just copies
of the DECL_RESULT and DECL_ARGUMENTS of the FUNCTION_DECL. Thus we can
just make new copies of DECL_RESULT and DECL_ARGUMENTS on stream in rather
than separately streaming them.
But the FUNCTION_DECL's DECL_RESULT and DECL_ARGUMENTS eventually get
genericized, whereas the constexpr_fundef entry consists of a copy of the
FUNCTION_DECL's pre-GENERIC trees. And notably during genericization we
lower invisref parms (which entails changing their TREE_TYPE and setting
DECL_BY_REFERENCE), the lowered form of which the constexpr evaluator
doesn't expect to see, and so this copying approach causes us to ICE for
the below testcase.
This patch fixes this by faithfully streaming the RESULT_DECL and
PARM_DECLs of a constexpr_fundef entry, which seems to just work.
Nathan says[1]: Hm, the reason for the complexity was that I wanted to
recreate the tree graph where the fndecl came from one TU and the defn
came from another one -- we need the definition to refer to argument
decls from the already-read decl. However, it seems that for constexpr
fns here, that is not needed, resulting in a significant simplification.
[1]: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603662.html
PR c++/101449
gcc/cp/ChangeLog:
* module.cc (trees_out::write_function_def): Stream the
parms and result of the constexpr_fundef entry.
(trees_in::read_function_def): Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/modules/cexpr-3_a.C: New test.
* g++.dg/modules/cexpr-3_b.C: New test.
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|
The FUNCTION_DECL we build for __dynamic_cast has an empty DECL_CONTEXT
but trees_out::tree_node expects FUNCTION_DECLs to have non-empty
DECL_CONTEXT, thus we crash when streaming out the dynamic_cast in the
below testcase.
This patch naively fixes this by setting DECL_CONTEXT for __dynamic_cast
appropriately. I suppose we should push it into the namespace too, like
we do for __cxa_atexit which is similarly lazily declared.
PR c++/106304
gcc/cp/ChangeLog:
* constexpr.cc (cxx_dynamic_cast_fn_p): Check for abi_node
instead of global_namespace.
* rtti.cc (build_dynamic_cast_1): Set DECL_CONTEXT and
DECL_SOURCE_LOCATION when building dynamic_cast_node. Push
it into the namespace.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr106304_a.C: New test.
* g++.dg/modules/pr106304_b.C: New test.
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Here is a complete patch to add std::bfloat16_t support on
x86 (AArch64 and ARM left for later). Almost no BFmode optabs
are added by the patch, so for binops/unops it extends to SFmode
first and then truncates back to BFmode.
For {HF,SF,DF,XF,TF}mode -> BFmode conversions libgcc has implementations
of all those conversions so that we avoid double rounding, for
BFmode -> {DF,XF,TF}mode conversions to avoid growing libgcc too much
it emits BFmode -> SFmode conversion first and then converts to the even
wider mode, neither step should be imprecise.
For BFmode -> HFmode, it first emits a precise BFmode -> SFmode conversion
and then SFmode -> HFmode, because neither format is subset or superset
of the other, while SFmode is superset of both.
expr.cc then contains a -ffast-math optimization of the BF -> SF and
SF -> BF conversions if we don't optimize for space (and for the latter
if -frounding-math isn't enabled either).
For x86, perhaps truncsfbf2 optab could be defined for TARGET_AVX512BF16
but IMNSHO should FAIL if !flag_finite_math || flag_rounding_math
|| !flag_unsafe_math_optimizations, because I think the insn doesn't
raise on sNaNs, hardcodes round to nearest and flushes denormals to zero.
By default (unless x86 -fexcess-precision=16) we use float excess
precision for BFmode, so truncate only on explicit casts and assignments.
The patch introduces a single __bf16 builtin - __builtin_nansf16b,
because (__bf16) __builtin_nansf ("") will drop the sNaN into qNaN,
and uses f16b suffix instead of bf16 because there would be ambiguity on
log vs. logb - __builtin_logbf16 could be either log with bf16 suffix
or logb with f16 suffix. In other cases libstdc++ should mostly use
__builtin_*f for std::bfloat16_t overloads (we have a problem with
std::nextafter though but that one we have also for std::float16_t).
2022-10-14 Jakub Jelinek <jakub@redhat.com>
gcc/
* tree-core.h (enum tree_index): Add TI_BFLOAT16_TYPE.
* tree.h (bfloat16_type_node): Define.
* tree.cc (excess_precision_type): Promote bfloat16_type_mode
like float16_type_mode.
(build_common_tree_nodes): Initialize bfloat16_type_node if
BFmode is supported.
* expmed.h (maybe_expand_shift): Declare.
* expmed.cc (maybe_expand_shift): No longer static.
* expr.cc (convert_mode_scalar): Don't ICE on BF -> HF or HF -> BF
conversions. If there is no optab, handle BF -> {DF,XF,TF,HF}
conversions as separate BF -> SF -> {DF,XF,TF,HF} conversions, add
-ffast-math generic implementation for BF -> SF and SF -> BF
conversions.
* builtin-types.def (BT_BFLOAT16, BT_FN_BFLOAT16_CONST_STRING): New.
* builtins.def (BUILT_IN_NANSF16B): New builtin.
* fold-const-call.cc (fold_const_call): Handle CFN_BUILT_IN_NANSF16B.
* config/i386/i386.cc (classify_argument): Handle E_BCmode.
(ix86_libgcc_floating_mode_supported_p): Also return true for BFmode
for -msse2.
(ix86_mangle_type): Mangle BFmode as DF16b.
(ix86_invalid_conversion, ix86_invalid_unary_op,
ix86_invalid_binary_op): Remove.
(TARGET_INVALID_CONVERSION, TARGET_INVALID_UNARY_OP,
TARGET_INVALID_BINARY_OP): Don't redefine.
* config/i386/i386-builtins.cc (ix86_bf16_type_node): Remove.
(ix86_register_bf16_builtin_type): Use bfloat16_type_node rather than
ix86_bf16_type_node, only create it if still NULL.
* config/i386/i386-builtin-types.def (BFLOAT16): Likewise.
* config/i386/i386.md (cbranchbf4, cstorebf4): New expanders.
gcc/c-family/
* c-cppbuiltin.cc (c_cpp_builtins): If bfloat16_type_node,
predefine __BFLT16_*__ macros and for C++23 also
__STDCPP_BFLOAT16_T__. Predefine bfloat16_type_node related
macros for -fbuilding-libgcc.
* c-lex.cc (interpret_float): Handle CPP_N_BFLOAT16.
gcc/c/
* c-typeck.cc (convert_arguments): Don't promote __bf16 to
double.
gcc/cp/
* cp-tree.h (extended_float_type_p): Return true for
bfloat16_type_node.
* typeck.cc (cp_compare_floating_point_conversion_ranks): Set
extended{1,2} if mv{1,2} is bfloat16_type_node. Adjust comment.
gcc/testsuite/
* lib/target-supports.exp (check_effective_target_bfloat16,
check_effective_target_bfloat16_runtime, add_options_for_bfloat16):
New.
* gcc.dg/torture/bfloat16-basic.c: New test.
* gcc.dg/torture/bfloat16-builtin.c: New test.
* gcc.dg/torture/bfloat16-builtin-issignaling-1.c: New test.
* gcc.dg/torture/bfloat16-complex.c: New test.
* gcc.dg/torture/builtin-issignaling-1.c: Allow to be includable
from bfloat16-builtin-issignaling-1.c.
* gcc.dg/torture/floatn-basic.h: Allow to be includable from
bfloat16-basic.c.
* gcc.target/i386/vect-bfloat16-typecheck_2.c: Adjust expected
diagnostics.
* gcc.target/i386/sse2-bfloat16-scalar-typecheck.c: Likewise.
* gcc.target/i386/vect-bfloat16-typecheck_1.c: Likewise.
* g++.target/i386/bfloat_cpp_typecheck.C: Likewise.
libcpp/
* include/cpplib.h (CPP_N_BFLOAT16): Define.
* expr.cc (interpret_float_suffix): Handle bf16 and BF16 suffixes for
C++.
libgcc/
* config/i386/t-softfp (softfp_extensions): Add bfsf.
(softfp_truncations): Add tfbf xfbf dfbf sfbf hfbf.
(CFLAGS-extendbfsf2.c, CFLAGS-truncsfbf2.c, CFLAGS-truncdfbf2.c,
CFLAGS-truncxfbf2.c, CFLAGS-trunctfbf2.c, CFLAGS-trunchfbf2.c): Add
-msse2.
* config/i386/libgcc-glibc.ver (GCC_13.0.0): Export
__extendbfsf2 and __trunc{s,d,x,t,h}fbf2.
* config/i386/sfp-machine.h (_FP_NANSIGN_B): Define.
* config/i386/64/sfp-machine.h (_FP_NANFRAC_B): Define.
* config/i386/32/sfp-machine.h (_FP_NANFRAC_B): Define.
* soft-fp/brain.h: New file.
* soft-fp/truncsfbf2.c: New file.
* soft-fp/truncdfbf2.c: New file.
* soft-fp/truncxfbf2.c: New file.
* soft-fp/trunctfbf2.c: New file.
* soft-fp/trunchfbf2.c: New file.
* soft-fp/truncbfhf2.c: New file.
* soft-fp/extendbfsf2.c: New file.
libiberty/
* cp-demangle.h (D_BUILTIN_TYPE_COUNT): Increment.
* cp-demangle.c (cplus_demangle_builtin_types): Add std::bfloat16_t
entry.
(cplus_demangle_type): Demangle DF16b.
* testsuite/demangle-expected (_Z3xxxDF16b): New test.
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PR87390]
The following incremental patch implements the C11 behavior (for all C++
versions) for
cond ? int : float
cond ? float : int
int cmp float
float cmp int
where int is any integral type, float any floating point type with
excess precision and cmp ==, !=, >, <, >=, <= and <=>.
2022-10-14 Jakub Jelinek <jakub@redhat.com>
PR c/82071
PR c/87390
PR c++/107097
gcc/cp/
* cp-tree.h (cp_ep_convert_and_check): Remove.
* cvt.cc (cp_ep_convert_and_check): Remove.
* call.cc (build_conditional_expr): Use excess precision for ?: with
one arm floating and another integral. Don't convert first to
semantic result type from integral types.
(convert_like_internal): Don't call cp_ep_convert_and_check, instead
just strip EXCESS_PRECISION_EXPR before calling cp_convert_and_check
or cp_convert.
* typeck.cc (cp_build_binary_op): Set may_need_excess_precision
for comparisons or SPACESHIP_EXPR with at least one operand integral.
Don't compute semantic_result_type if build_type is non-NULL. Call
cp_convert_and_check instead of cp_ep_convert_and_check.
gcc/testsuite/
* gcc.target/i386/excess-precision-8.c: For C++ wrap abort and
exit declarations into extern "C" block.
* gcc.target/i386/excess-precision-10.c: Likewise.
* g++.target/i386/excess-precision-7.C: Remove.
* g++.target/i386/excess-precision-8.C: New test.
* g++.target/i386/excess-precision-9.C: Remove.
* g++.target/i386/excess-precision-10.C: New test.
* g++.target/i386/excess-precision-12.C: New test.
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The following patch implements excess precision support for C++.
Like for C, it uses EXCESS_PRECISION_EXPR tree to say that its operand
is evaluated in excess precision and what the semantic type of the
expression is.
In most places I've followed what the C FE does in similar spots, so
e.g. for binary ops if one or both operands are already
EXCESS_PRECISION_EXPR, strip those away or for operations that might need
excess precision (+, -, *, /) check if the operands should use excess
precision and convert to that type and at the end wrap into
EXCESS_PRECISION_EXPR with the common semantic type.
This patch follows the C99 handling where it differs from C11 handling.
There are some cases which needed to be handled differently, the C FE can
just strip EXCESS_PRECISION_EXPR (replace it with its operand) when handling
explicit cast, but that IMHO isn't right for C++ - the discovery what exact
conversion should be used (e.g. if user conversion or standard or their
sequence) should be decided based on the semantic type (i.e. type of
EXCESS_PRECISION_EXPR), and that decision continues in convert_like* where
we pick the right user conversion, again, if say some class has ctor
from double and long double and we are on ia32 with standard excess
precision promoting float/double to long double, then we should pick the
ctor from double. Or when some other class has ctor from just double,
and EXCESS_PRECISION_EXPR semantic type is float, we should choose the
user ctor from double, but actually just convert the long double excess
precision to double and not to float first. We need to make sure
even identity conversion converts from excess precision to the semantic one
though, but if identity is chained with other conversions, we don't want
the identity next_conversion to drop to semantic precision only to widen
afterwards.
The existing testcases tweaks were for cases on i686-linux where excess
precision breaks those tests, e.g. if we have
double d = 4.2;
if (d == 4.2)
then it does the expected thing only with -fexcess-precision=fast,
because with -fexcess-precision=standard it is actually
double d = 4.2;
if ((long double) d == 4.2L)
where 4.2L is different from 4.2. I've added -fexcess-precision=fast
to some tests and changed other tests to use constants that are exactly
representable and don't suffer from these excess precision issues.
There is one exception, pr68180.C looks like a bug in the patch which is
also present in the C FE (so I'd like to get it resolved incrementally
in both). Reduced testcase:
typedef float __attribute__((vector_size (16))) float32x4_t;
float32x4_t foo(float32x4_t x, float y) { return x + y; }
with -m32 -std=c11 -Wno-psabi or -m32 -std=c++17 -Wno-psabi
it is rejected with:
pr68180.c:2:52: error: conversion of scalar ‘long double’ to vector ‘float32x4_t’ {aka ‘__vector(4) float’} involves truncation
but without excess precision (say just -std=c11 -Wno-psabi or -std=c++17 -Wno-psabi)
it is accepted. Perhaps we should pass down the semantic type to
scalar_to_vector and use the semantic type rather than excess precision type
in the diagnostics.
2022-10-14 Jakub Jelinek <jakub@redhat.com>
PR middle-end/323
PR c++/107097
gcc/
* doc/invoke.texi (-fexcess-precision=standard): Mention that the
option now also works in C++.
gcc/c-family/
* c-common.def (EXCESS_PRECISION_EXPR): Remove comment part about
the tree being specific to C/ObjC.
* c-opts.cc (c_common_post_options): Handle flag_excess_precision
in C++ the same as in C.
* c-lex.cc (interpret_float): Set const_type to excess_precision ()
even for C++.
gcc/cp/
* parser.cc (cp_parser_primary_expression): Handle
EXCESS_PRECISION_EXPR with REAL_CST operand the same as REAL_CST.
* cvt.cc (cp_ep_convert_and_check): New function.
* call.cc (build_conditional_expr): Add excess precision support.
When type_after_usual_arithmetic_conversions returns error_mark_node,
use gcc_checking_assert that it is because of uncomparable floating
point ranks instead of checking all those conditions and make it
work also with complex types.
(convert_like_internal): Likewise. Add NESTED_P argument, pass true
to recursive calls to convert_like.
(convert_like): Add NESTED_P argument, pass it through to
convert_like_internal. For other overload pass false to it.
(convert_like_with_context): Pass false to NESTED_P.
(convert_arg_to_ellipsis): Add excess precision support.
(magic_varargs_p): For __builtin_is{finite,inf,inf_sign,nan,normal}
and __builtin_fpclassify return 2 instead of 1, document what it
means.
(build_over_call): Don't handle former magic 2 which is no longer
used, instead for magic 1 remove EXCESS_PRECISION_EXPR.
(perform_direct_initialization_if_possible): Pass false to NESTED_P
convert_like argument.
* constexpr.cc (cxx_eval_constant_expression): Handle
EXCESS_PRECISION_EXPR.
(potential_constant_expression_1): Likewise.
* pt.cc (tsubst_copy, tsubst_copy_and_build): Likewise.
* cp-tree.h (cp_ep_convert_and_check): Declare.
* cp-gimplify.cc (cp_fold): Handle EXCESS_PRECISION_EXPR.
* typeck.cc (cp_common_type): For COMPLEX_TYPEs, return error_mark_node
if recursive call returned it.
(convert_arguments): For magic 1 remove EXCESS_PRECISION_EXPR.
(cp_build_binary_op): Add excess precision support. When
cp_common_type returns error_mark_node, use gcc_checking_assert that
it is because of uncomparable floating point ranks instead of checking
all those conditions and make it work also with complex types.
(cp_build_unary_op): Likewise.
(cp_build_compound_expr): Likewise.
(build_static_cast_1): Remove EXCESS_PRECISION_EXPR.
gcc/testsuite/
* gcc.target/i386/excess-precision-1.c: For C++ wrap abort and
exit declarations into extern "C" block.
* gcc.target/i386/excess-precision-2.c: Likewise.
* gcc.target/i386/excess-precision-3.c: Likewise. Remove
check_float_nonproto and check_double_nonproto tests for C++.
* gcc.target/i386/excess-precision-7.c: For C++ wrap abort and
exit declarations into extern "C" block.
* gcc.target/i386/excess-precision-9.c: Likewise.
* g++.target/i386/excess-precision-1.C: New test.
* g++.target/i386/excess-precision-2.C: New test.
* g++.target/i386/excess-precision-3.C: New test.
* g++.target/i386/excess-precision-4.C: New test.
* g++.target/i386/excess-precision-5.C: New test.
* g++.target/i386/excess-precision-6.C: New test.
* g++.target/i386/excess-precision-7.C: New test.
* g++.target/i386/excess-precision-9.C: New test.
* g++.target/i386/excess-precision-11.C: New test.
* c-c++-common/dfp/convert-bfp-10.c: Add -fexcess-precision=fast
as dg-additional-options.
* c-c++-common/dfp/compare-eq-const.c: Likewise.
* g++.dg/cpp1z/constexpr-96862.C: Likewise.
* g++.dg/cpp1z/decomp12.C (main): Use 2.25 instead of 2.3 to
avoid excess precision differences.
* g++.dg/other/thunk1.C: Add -fexcess-precision=fast
as dg-additional-options.
* g++.dg/vect/pr64410.cc: Likewise.
* g++.dg/cpp1y/pr68180.C: Likewise.
* g++.dg/vect/pr89653.cc: Likewise.
* g++.dg/cpp0x/variadic-tuple.C: Likewise.
* g++.dg/cpp0x/nsdmi-union1.C: Use 4.25 instead of 4.2 to
avoid excess precision differences.
* g++.old-deja/g++.brendan/copy9.C: Add -fexcess-precision=fast
as dg-additional-options.
* g++.old-deja/g++.brendan/overload7.C: Likewise.
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Split out from the C++ contracts patch.
gcc/cp/ChangeLog:
* cp-tree.h: Fix whitespace.
* parser.h: Fix whitespace.
* decl.cc: Fix whitespace.
* parser.cc: Fix whitespace.
* pt.cc: Fix whitespace.
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gcc/cp/ChangeLog:
* vtable-class-hierarchy.cc (vtv_generate_init_routine): Emit
an artificial variable that would be put into .preinit_array
section.
gcc/ChangeLog:
* output.h (assemble_vtv_preinit_initializer): Remove.
* varasm.cc (assemble_vtv_preinit_initializer): Remove.
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Since r12-8066, in cxx_eval_vec_init we perform expand_vec_init_expr
while processing the default argument in this test. At this point
start_preparsed_function hasn't yet set current_function_decl.
expand_vec_init_expr then leads to maybe_splice_retval_cleanup which
checks DECL_CONSTRUCTOR_P (current_function_decl) without checking that
c_f_d is non-null first. It seems correct that c_f_d is null here, so
it seems to me that maybe_splice_retval_cleanup should check c_f_d as
in the following patch.
PR c++/106925
gcc/cp/ChangeLog:
* except.cc (maybe_splice_retval_cleanup): Check current_function_decl.
Make the bool const.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/initlist-defarg3.C: New test.
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This patch removes the two-stage overload resolution when performing
implicit move, whereby the compiler does two separate overload resolutions:
one treating the operand as an rvalue, and then (if that resolution fails)
another one treating the operand as an lvalue. In the standard this was
introduced via CWG 1579 and implemented in gcc in r251035. In r11-2412,
we disabled the fallback OR in C++20 (but not in C++17). Then C++23 P2266
removed the fallback overload resolution, and changed the implicit move rules
once again. So we wound up with three different behaviors.
The two overload resolutions approach was complicated and quirky, so
users should transition to the newer model. Removing the maybe-rvalue
OR also allows us to simplify our code, for instance, now we can get
rid of LOOKUP_PREFER_RVALUE altogether.
This change means that code that previously didn't compile in C++17 will
now compile, for example:
struct S1 { S1(S1 &&); };
struct S2 : S1 {};
S1
f (S2 s)
{
return s; // OK, derived-to-base, use S1::S1(S1&&)
}
And conversely, code that used to work in C++17 may not compile anymore:
struct W {
W();
};
struct F {
F(W&);
F(W&&) = delete;
};
F fn ()
{
W w;
return w; // use w as rvalue -> use of deleted function F::F(W&&)
}
I plan to add a note to porting_to.html.
gcc/cp/ChangeLog:
* call.cc (standard_conversion): Remove LOOKUP_PREFER_RVALUE code.
(reference_binding): Honor clk_implicit_rval even pre-C++20.
(implicit_conversion_1): Remove LOOKUP_PREFER_RVALUE code.
(build_user_type_conversion_1): Likewise.
(convert_like_internal): Likewise.
(build_over_call): Likewise.
* cp-tree.h (LOOKUP_PREFER_RVALUE): Remove.
(LOOKUP_NO_NARROWING): Adjust definition.
* except.cc (build_throw): Don't perform two overload resolutions.
* typeck.cc (maybe_warn_pessimizing_move): Don't use
LOOKUP_PREFER_RVALUE.
(check_return_expr): Don't perform two overload resolutions.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/Wredundant-move10.C: Adjust dg-warning.
* g++.dg/cpp0x/Wredundant-move7.C: Likewise.
* g++.dg/cpp0x/move-return2.C: Remove dg-error.
* g++.dg/cpp0x/move-return4.C: Likewise.
* g++.dg/cpp0x/ref-qual20.C: Adjust expected return value.
* g++.dg/cpp0x/move-return5.C: New test.
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The proposed resolution of CWG2631 extends our current handling of
source_location::current to all consteval functions: default arguments
are not evaluated until they're used in a call, the same should apply to
evaluation of immediate invocations. And similarly for default member
initializers.
Previously we folded source_location::current in cp_fold_r; now we fold all
consteval calls in default arguments/member initializers in bot_replace.
DR 2631
gcc/cp/ChangeLog:
* cp-tree.h (source_location_current_p): Remove.
* name-lookup.h (struct cp_binding_level): Remove
immediate_fn_ctx_p.
* call.cc (in_immediate_context): All default args
and DMI are potentially immediate context.
(immediate_invocation_p): Don't treat source_location specially.
(struct in_consteval_if_p_temp_override): Move to cp-tree.h.
* constexpr.cc (get_nth_callarg): Move to cp-tree.h.
* cp-gimplify.cc (cp_fold_r): Don't fold consteval.
* name-lookup.cc (begin_scope): Don't set immediate_fn_ctx_p.
* parser.cc (cp_parser_lambda_declarator_opt): Likewise.
(cp_parser_direct_declarator): Likewise.
* pt.cc (tsubst_default_argument): Open sk_function_parms level.
* tree.cc (source_location_current_p): Remove.
(bot_replace): Fold consteval here.
(break_out_target_exprs): Handle errors.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/consteval-defarg3.C: New test.
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