On Thu, Sep 07, 2023 at 02:32:51PM -0400, Jason Merrill wrote:
> On 9/7/23 11:23, Marek Polacek wrote:
> > On Tue, Sep 05, 2023 at 04:36:34PM -0400, Jason Merrill wrote:
> > > On 9/5/23 15:59, Marek Polacek wrote:
> > > > On Tue, Sep 05, 2023 at 10:52:04AM -0400, Jason Merrill wrote:
> > > > > On 9/1/23 13:23, Marek Polacek wrote:
> > > > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > > > >
> > > > > > -- >8 --
> > > > > >
> > > > > > In the review of P2564:
> > > > > > <https://gcc.gnu.org/pipermail/gcc-patches/2023-August/628747.html>
> > > > > > it turned out that in order to correctly handle an example in the paper,
> > > > > > we should stop doing immediate evaluation in build_over_call and
> > > > > > bot_replace, and instead do it in cp_fold_r. This patch does that.
> > > > > >
> > > > > > Another benefit is that this is a pretty significant simplification, at
> > > > > > least in my opinion. Also, this fixes the c++/110997 ICE (but the test
> > > > > > doesn't compile yet).
> > > > > >
> > > > > > The main drawback seems to be that cp_fold_r doesn't process as much
> > > > > > code as we did before: uninstantiated templates
> > > > >
> > > > > That's acceptable, it's an optional diagnostic.
> > > > >
> > > > > > and things like "false ? foo () : 1".
> > > > >
> > > > > This is a problem. Maybe we want cp_fold_r to recurse into the arms of a
> > > > > COND_EXPR before folding them away? Maybe only if we know we've seen an
> > > > > immediate function?
> > > >
> > > > Unfortunately we had already thrown the dead branch away when we got to
> > > > cp_fold_r. I wonder if we have to adjust cxx_eval_conditional_expression
> > > > to call cp_fold_r on the dead branch too,
> > >
> > > Hmm, I guess so.
> > >
> > > > perhaps with a new ff_ flag to skip the whole second switch in cp_fold_r?
> > >
> > > Or factor out the immediate function handling to a separate walk function
> > > that cp_fold_r also calls?
> >
> > I did that.
> > > > But then it's possible that the in_immediate_context checks have to stay.
> > >
> > > We can just not do the walk in immediate (or mce_true) context, like we
> > > currently avoid calling cp_fold_function.
> >
> > Right. Unfortunately I have to check even when mce_true, consider
> >
> > consteval int bar (int i) { if (i != 1) throw 1; return 0; }
> > constexpr int a = 0 ? bar(3) : 3;
>
> I disagree; the call is in a manifestly constant-evaluated expression, and
> so is now considered an immediate function context, and we should accept
> that example.
Ack. I was still living in pre-P2564 world.
> > > For mce_unknown I guess we'd want
> > > to set *non_constant_p instead of giving an error.
> >
> > I did not do this because I haven't found a case where it would make
> > a difference.
>
> I think it will given the above comment.
Correct. For instance, in:
consteval int bar (int i) { if (i != 1) throw 1; return 0; }
constexpr int
foo (bool b)
{
return b ? bar (3) : 2;
}
static_assert (foo (false) == 2);
we should complain only once. I've implemented your suggestion to set
*non_constant_p instead of giving an error for mce_unknown.
> > diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
> > index 0ca4370deab..397d5c7ec3f 100644
> > --- a/gcc/cp/constexpr.cc
> > +++ b/gcc/cp/constexpr.cc
> > @@ -2311,6 +2311,29 @@ cxx_dynamic_cast_fn_p (tree fndecl)
> > && CP_DECL_CONTEXT (fndecl) == abi_node);
> > }
> > +/* Return true if we are in the body of a consteval function. > + This is in addition to in_immediate_context because that
> > + uses current_function_decl which may not be available. CTX is
> > + the current constexpr context. */
> > +
> > +static bool
> > +in_immediate_context (const constexpr_ctx *ctx)
> > +{
> > + if (in_immediate_context ())
> > + return true;
>
> Can't we check for mce_true here instead of looking at the call chain?
Yes.
> > +/* A wrapper around cp_fold_immediate_r. */
> > +
> > +void
> > +cp_fold_immediate (tree *tp)
> > +{
>
> Maybe return early if consteval isn't supported in the active standard?
Absolutely.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
In the review of P2564:
<https://gcc.gnu.org/pipermail/gcc-patches/2023-August/628747.html>
it turned out that in order to correctly handle an example in the paper,
we should stop doing immediate evaluation in build_over_call and
bot_replace, and instead do it in cp_fold_r. This patch does that.
Another benefit is that this is a pretty significant simplification, at
least in my opinion. Also, this fixes the c++/110997 ICE (but the test
doesn't compile yet).
The main drawback seems to be that cp_fold_r doesn't process
uninstantiated templates. We still have to handle things like
"false ? foo () : 1". To that end, I've added cp_fold_immediate, called
on dead branches in cxx_eval_conditional_expression.
You'll see that I've reintroduced ADDR_EXPR_DENOTES_CALL_P here. This
is to detect
*(&foo)) ()
(s.*&S::foo) ()
which were deemed ill-formed.
gcc/cp/ChangeLog:
* call.cc (build_over_call): Set ADDR_EXPR_DENOTES_CALL_P. Don't handle
immediate_invocation_p here.
* constexpr.cc (in_immediate_context): New overload.
(cxx_eval_call_expression): Use mce_true for DECL_IMMEDIATE_FUNCTION_P.
(cxx_eval_conditional_expression): Call cp_fold_immediate.
* cp-gimplify.cc (maybe_replace_decl): Make static.
(cp_fold_r): Expand immediate invocations.
(cp_fold_immediate_r): New.
(cp_fold_immediate): New.
* cp-tree.h (ADDR_EXPR_DENOTES_CALL_P): Define.
(cp_fold_immediate): Declare.
* tree.cc (bot_replace): Don't handle immediate invocations here.
libstdc++-v3/ChangeLog:
* testsuite/20_util/allocator/105975.cc: Add dg-error.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/consteval-if2.C: Add xfail.
* g++.dg/cpp2a/consteval-memfn1.C: Adjust.
* g++.dg/cpp2a/consteval11.C: Remove dg-message.
* g++.dg/cpp2a/consteval3.C: Remove dg-message and dg-error.
* g++.dg/cpp2a/consteval9.C: Remove dg-message.
* g++.dg/cpp2a/consteval32.C: New test.
* g++.dg/cpp2a/consteval33.C: New test.
* g++.dg/cpp2a/consteval34.C: New test.
* g++.dg/cpp2a/consteval35.C: New test.
---
gcc/cp/call.cc | 40 +------
gcc/cp/constexpr.cc | 23 +++-
gcc/cp/cp-gimplify.cc | 108 ++++++++++++++----
gcc/cp/cp-tree.h | 42 ++++---
gcc/cp/tree.cc | 23 +---
gcc/testsuite/g++.dg/cpp23/consteval-if2.C | 3 +-
gcc/testsuite/g++.dg/cpp2a/consteval-memfn1.C | 7 ++
gcc/testsuite/g++.dg/cpp2a/consteval11.C | 33 +++---
gcc/testsuite/g++.dg/cpp2a/consteval3.C | 3 +-
gcc/testsuite/g++.dg/cpp2a/consteval32.C | 4 +
gcc/testsuite/g++.dg/cpp2a/consteval33.C | 34 ++++++
gcc/testsuite/g++.dg/cpp2a/consteval34.C | 18 +++
gcc/testsuite/g++.dg/cpp2a/consteval35.C | 10 ++
gcc/testsuite/g++.dg/cpp2a/consteval9.C | 3 +-
.../testsuite/20_util/allocator/105975.cc | 2 +-
15 files changed, 234 insertions(+), 119 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval32.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval33.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval34.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval35.C
base-commit: b96b554592c5cbb6a2c1797ffcb5706fd295f4fd
On 9/8/23 14:24, Marek Polacek wrote:
> On Thu, Sep 07, 2023 at 02:32:51PM -0400, Jason Merrill wrote:
>> On 9/7/23 11:23, Marek Polacek wrote:
>>> On Tue, Sep 05, 2023 at 04:36:34PM -0400, Jason Merrill wrote:
>>>> On 9/5/23 15:59, Marek Polacek wrote:
>>>>> On Tue, Sep 05, 2023 at 10:52:04AM -0400, Jason Merrill wrote:
>>>>>> On 9/1/23 13:23, Marek Polacek wrote:
>>>>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>>>>>>>
>>>>>>> -- >8 --
>>>>>>>
>>>>>>> In the review of P2564:
>>>>>>> <https://gcc.gnu.org/pipermail/gcc-patches/2023-August/628747.html>
>>>>>>> it turned out that in order to correctly handle an example in the paper,
>>>>>>> we should stop doing immediate evaluation in build_over_call and
>>>>>>> bot_replace, and instead do it in cp_fold_r. This patch does that.
>>>>>>>
>>>>>>> Another benefit is that this is a pretty significant simplification, at
>>>>>>> least in my opinion. Also, this fixes the c++/110997 ICE (but the test
>>>>>>> doesn't compile yet).
>>>>>>>
>>>>>>> The main drawback seems to be that cp_fold_r doesn't process as much
>>>>>>> code as we did before: uninstantiated templates
>>>>>>
>>>>>> That's acceptable, it's an optional diagnostic.
>>>>>>
>>>>>>> and things like "false ? foo () : 1".
>>>>>>
>>>>>> This is a problem. Maybe we want cp_fold_r to recurse into the arms of a
>>>>>> COND_EXPR before folding them away? Maybe only if we know we've seen an
>>>>>> immediate function?
>>>>>
>>>>> Unfortunately we had already thrown the dead branch away when we got to
>>>>> cp_fold_r. I wonder if we have to adjust cxx_eval_conditional_expression
>>>>> to call cp_fold_r on the dead branch too,
>>>>
>>>> Hmm, I guess so.
>>>>
>>>>> perhaps with a new ff_ flag to skip the whole second switch in cp_fold_r?
>>>>
>>>> Or factor out the immediate function handling to a separate walk function
>>>> that cp_fold_r also calls?
>>>
>>> I did that.
>>>>> But then it's possible that the in_immediate_context checks have to stay.
>>>>
>>>> We can just not do the walk in immediate (or mce_true) context, like we
>>>> currently avoid calling cp_fold_function.
>>>
>>> Right. Unfortunately I have to check even when mce_true, consider
>>>
>>> consteval int bar (int i) { if (i != 1) throw 1; return 0; }
>>> constexpr int a = 0 ? bar(3) : 3;
>>
>> I disagree; the call is in a manifestly constant-evaluated expression, and
>> so is now considered an immediate function context, and we should accept
>> that example.
>
> Ack. I was still living in pre-P2564 world.
>
>>>> For mce_unknown I guess we'd want
>>>> to set *non_constant_p instead of giving an error.
>>>
>>> I did not do this because I haven't found a case where it would make
>>> a difference.
>>
>> I think it will given the above comment.
>
> Correct. For instance, in:
>
> consteval int bar (int i) { if (i != 1) throw 1; return 0; }
>
> constexpr int
> foo (bool b)
> {
> return b ? bar (3) : 2;
> }
>
> static_assert (foo (false) == 2);
>
> we should complain only once. I've implemented your suggestion to set
> *non_constant_p instead of giving an error for mce_unknown.
>
>>> diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
>>> index 0ca4370deab..397d5c7ec3f 100644
>>> --- a/gcc/cp/constexpr.cc
>>> +++ b/gcc/cp/constexpr.cc
>>> @@ -2311,6 +2311,29 @@ cxx_dynamic_cast_fn_p (tree fndecl)
>>> && CP_DECL_CONTEXT (fndecl) == abi_node);
>>> }
>>> +/* Return true if we are in the body of a consteval function. > + This is in addition to in_immediate_context because that
>>> + uses current_function_decl which may not be available. CTX is
>>> + the current constexpr context. */
>>> +
>>> +static bool
>>> +in_immediate_context (const constexpr_ctx *ctx)
>>> +{
>>> + if (in_immediate_context ())
>>> + return true;
>>
>> Can't we check for mce_true here instead of looking at the call chain?
>
> Yes.
>
>>> +/* A wrapper around cp_fold_immediate_r. */
>>> +
>>> +void
>>> +cp_fold_immediate (tree *tp)
>>> +{
>>
>> Maybe return early if consteval isn't supported in the active standard?
>
> Absolutely.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> -- >8 --
> In the review of P2564:
> <https://gcc.gnu.org/pipermail/gcc-patches/2023-August/628747.html>
> it turned out that in order to correctly handle an example in the paper,
> we should stop doing immediate evaluation in build_over_call and
> bot_replace, and instead do it in cp_fold_r. This patch does that.
>
> Another benefit is that this is a pretty significant simplification, at
> least in my opinion. Also, this fixes the c++/110997 ICE (but the test
> doesn't compile yet).
>
> The main drawback seems to be that cp_fold_r doesn't process
> uninstantiated templates. We still have to handle things like
> "false ? foo () : 1". To that end, I've added cp_fold_immediate, called
> on dead branches in cxx_eval_conditional_expression.
>
> You'll see that I've reintroduced ADDR_EXPR_DENOTES_CALL_P here. This
> is to detect
>
> *(&foo)) ()
> (s.*&S::foo) ()
>
> which were deemed ill-formed.
>
> gcc/cp/ChangeLog:
>
> * call.cc (build_over_call): Set ADDR_EXPR_DENOTES_CALL_P. Don't handle
> immediate_invocation_p here.
> * constexpr.cc (in_immediate_context): New overload.
> (cxx_eval_call_expression): Use mce_true for DECL_IMMEDIATE_FUNCTION_P.
> (cxx_eval_conditional_expression): Call cp_fold_immediate.
> * cp-gimplify.cc (maybe_replace_decl): Make static.
> (cp_fold_r): Expand immediate invocations.
> (cp_fold_immediate_r): New.
> (cp_fold_immediate): New.
> * cp-tree.h (ADDR_EXPR_DENOTES_CALL_P): Define.
> (cp_fold_immediate): Declare.
> * tree.cc (bot_replace): Don't handle immediate invocations here.
>
> libstdc++-v3/ChangeLog:
>
> * testsuite/20_util/allocator/105975.cc: Add dg-error.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp23/consteval-if2.C: Add xfail.
> * g++.dg/cpp2a/consteval-memfn1.C: Adjust.
> * g++.dg/cpp2a/consteval11.C: Remove dg-message.
> * g++.dg/cpp2a/consteval3.C: Remove dg-message and dg-error.
> * g++.dg/cpp2a/consteval9.C: Remove dg-message.
> * g++.dg/cpp2a/consteval32.C: New test.
> * g++.dg/cpp2a/consteval33.C: New test.
> * g++.dg/cpp2a/consteval34.C: New test.
> * g++.dg/cpp2a/consteval35.C: New test.
> ---
> gcc/cp/call.cc | 40 +------
> gcc/cp/constexpr.cc | 23 +++-
> gcc/cp/cp-gimplify.cc | 108 ++++++++++++++----
> gcc/cp/cp-tree.h | 42 ++++---
> gcc/cp/tree.cc | 23 +---
> gcc/testsuite/g++.dg/cpp23/consteval-if2.C | 3 +-
> gcc/testsuite/g++.dg/cpp2a/consteval-memfn1.C | 7 ++
> gcc/testsuite/g++.dg/cpp2a/consteval11.C | 33 +++---
> gcc/testsuite/g++.dg/cpp2a/consteval3.C | 3 +-
> gcc/testsuite/g++.dg/cpp2a/consteval32.C | 4 +
> gcc/testsuite/g++.dg/cpp2a/consteval33.C | 34 ++++++
> gcc/testsuite/g++.dg/cpp2a/consteval34.C | 18 +++
> gcc/testsuite/g++.dg/cpp2a/consteval35.C | 10 ++
> gcc/testsuite/g++.dg/cpp2a/consteval9.C | 3 +-
> .../testsuite/20_util/allocator/105975.cc | 2 +-
> 15 files changed, 234 insertions(+), 119 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval32.C
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval33.C
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval34.C
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval35.C
>
> diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
> index 0ca4370deab..8c077aa22fe 100644
> --- a/gcc/cp/constexpr.cc
> +++ b/gcc/cp/constexpr.cc
> @@ -3837,12 +3841,25 @@ cxx_eval_conditional_expression (const constexpr_ctx *ctx, tree t,
> boolean_type_node);
> }
> /* Don't VERIFY_CONSTANT the other operands. */
> - if (integer_zerop (val))
> + const bool zero_p = integer_zerop (val);
> + if (zero_p)
> val = TREE_OPERAND (t, 2);
> else
> val = TREE_OPERAND (t, 1);
> if (TREE_CODE (t) == IF_STMT && !val)
> val = void_node;
> +
> + if (!in_immediate_context ()
> + /* P2564: a subexpression of a manifestly constant-evaluated expression
> + or conversion is an immediate function context. */
> + && ctx->manifestly_const_eval != mce_true
I might check this first as a tiny optimization.
> + && cp_fold_immediate (&TREE_OPERAND (t, zero_p ? 1 : 2),
> + ctx->manifestly_const_eval))
> + {
> + *non_constant_p = true;
> + return t;
> + }
> +
> /* A TARGET_EXPR may be nested inside another TARGET_EXPR, but still
> serve as the initializer for the same object as the outer TARGET_EXPR,
> as in
> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
> index 206e791fcfd..9901513461c 100644
> --- a/gcc/cp/cp-gimplify.cc
> +++ b/gcc/cp/cp-gimplify.cc
> @@ -1000,7 +1000,7 @@ cp_genericize_target_expr (tree *stmt_p)
> replacement when cp_folding TARGET_EXPR to preserve the invariant that
> AGGR_INIT_EXPR_SLOT agrees with the enclosing TARGET_EXPR_SLOT. */
>
> -bool
> +static bool
> maybe_replace_decl (tree *tp, tree decl, tree replacement)
> {
> if (!*tp || !VOID_TYPE_P (TREE_TYPE (*tp)))
> @@ -1029,44 +1029,73 @@ struct cp_genericize_data
> bool handle_invisiref_parm_p;
> };
>
> -/* Perform any pre-gimplification folding of C++ front end trees to
> - GENERIC.
> - Note: The folding of non-omp cases is something to move into
> - the middle-end. As for now we have most foldings only on GENERIC
> - in fold-const, we need to perform this before transformation to
> - GIMPLE-form. */
> +/* A subroutine of cp_fold_r to handle immediate functions. */
>
> static tree
> -cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
> +cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
> {
> - cp_fold_data *data = (cp_fold_data*)data_;
> + auto data = static_cast<cp_fold_data *>(data_);
> tree stmt = *stmt_p;
> - enum tree_code code = TREE_CODE (stmt);
> + const tsubst_flags_t complain = (data->flags == ff_none ? tf_none : tf_error);
>
> - switch (code)
> + /* No need to look into types or unevaluated operands.
> + NB: This affects cp_fold_r as well. */
> + if (TYPE_P (stmt) || unevaluated_p (TREE_CODE (stmt)))
> {
> + *walk_subtrees = 0;
> + return NULL_TREE;
> + }
> +
> + switch (TREE_CODE (stmt))
> + {
> + /* Unfortunately we must handle code like
> + false ? bar () : 42
> + where we have to check bar too. */
> + case COND_EXPR:
> + if (cp_fold_immediate_r (&TREE_OPERAND (stmt, 1), walk_subtrees, data))
> + return error_mark_node;
> + if (TREE_OPERAND (stmt, 2)
> + && cp_fold_immediate_r (&TREE_OPERAND (stmt, 2), walk_subtrees, data))
> + return error_mark_node;
Is this necessary? Doesn't walk_tree already walk into the arms of
COND_EXPR?
> + break;
> +
> case PTRMEM_CST:
> if (TREE_CODE (PTRMEM_CST_MEMBER (stmt)) == FUNCTION_DECL
> && DECL_IMMEDIATE_FUNCTION_P (PTRMEM_CST_MEMBER (stmt)))
> {
> - if (!data->pset.add (stmt))
> + if (!data->pset.add (stmt) && (complain & tf_error))
> error_at (PTRMEM_CST_LOCATION (stmt),
> "taking address of an immediate function %qD",
> PTRMEM_CST_MEMBER (stmt));
> stmt = *stmt_p = build_zero_cst (TREE_TYPE (stmt));
It looks like this will overwrite *stmt_p even if we didn't give an error.
> - break;
> + return error_mark_node;
> }
> break;
>
> + /* Expand immediate invocations. */
> + case CALL_EXPR:
> + case AGGR_INIT_EXPR:
> + if (tree fn = cp_get_callee (stmt))
> + if (TREE_CODE (fn) != ADDR_EXPR || ADDR_EXPR_DENOTES_CALL_P (fn))
> + if (tree fndecl = cp_get_fndecl_from_callee (fn, /*fold*/false))
> + if (DECL_IMMEDIATE_FUNCTION_P (fndecl))
> + {
> + *stmt_p = stmt = cxx_constant_value (stmt, complain);
Likewise.
> + if (stmt == error_mark_node)
> + return error_mark_node;
> + }
> + break;
> +
> case ADDR_EXPR:
> if (TREE_CODE (TREE_OPERAND (stmt, 0)) == FUNCTION_DECL
> && DECL_IMMEDIATE_FUNCTION_P (TREE_OPERAND (stmt, 0)))
> {
> - error_at (EXPR_LOCATION (stmt),
> - "taking address of an immediate function %qD",
> - TREE_OPERAND (stmt, 0));
> + if (complain & tf_error)
> + error_at (EXPR_LOCATION (stmt),
> + "taking address of an immediate function %qD",
> + TREE_OPERAND (stmt, 0));
> stmt = *stmt_p = build_zero_cst (TREE_TYPE (stmt));
Likewise.
Jason
@@ -10436,6 +10436,10 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
fn = build_addr_func (fn, complain);
if (fn == error_mark_node)
return error_mark_node;
+
+ /* We're actually invoking the function. (Immediate functions get an
+ & when invoking it even though the user didn't use &.) */
+ ADDR_EXPR_DENOTES_CALL_P (fn) = true;
}
tree call = build_cxx_call (fn, nargs, argarray, complain|decltype_flag);
@@ -10453,41 +10457,7 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
if (TREE_CODE (c) == CALL_EXPR)
suppress_warning (c /* Suppress all warnings. */);
}
- if (TREE_CODE (fn) == ADDR_EXPR)
- {
- tree fndecl = STRIP_TEMPLATE (TREE_OPERAND (fn, 0));
- if (immediate_invocation_p (fndecl))
- {
- tree obj_arg = NULL_TREE;
- /* Undo convert_from_reference called by build_cxx_call. */
- if (REFERENCE_REF_P (call))
- call = TREE_OPERAND (call, 0);
- if (DECL_CONSTRUCTOR_P (fndecl))
- obj_arg = cand->first_arg ? cand->first_arg : (*args)[0];
- if (obj_arg && is_dummy_object (obj_arg))
- {
- call = build_cplus_new (DECL_CONTEXT (fndecl), call, complain);
- obj_arg = NULL_TREE;
- }
- /* Look through *(const T *)&obj. */
- else if (obj_arg && INDIRECT_REF_P (obj_arg))
- {
- tree addr = TREE_OPERAND (obj_arg, 0);
- STRIP_NOPS (addr);
- if (TREE_CODE (addr) == ADDR_EXPR)
- {
- tree typeo = TREE_TYPE (obj_arg);
- tree typei = TREE_TYPE (TREE_OPERAND (addr, 0));
- if (same_type_ignoring_top_level_qualifiers_p (typeo, typei))
- obj_arg = TREE_OPERAND (addr, 0);
- }
- }
- call = cxx_constant_value (call, obj_arg, complain);
- if (obj_arg && !error_operand_p (call))
- call = cp_build_init_expr (obj_arg, call);
- call = convert_from_reference (call);
- }
- }
+
return call;
}
@@ -3135,6 +3135,11 @@ cxx_eval_call_expression (const constexpr_ctx *ctx, tree t,
unsigned save_heap_alloc_count = ctx->global->heap_vars.length ();
unsigned save_heap_dealloc_count = ctx->global->heap_dealloc_count;
+ /* Make sure we fold std::is_constant_evaluated to true in an
+ immediate function. */
+ if (DECL_IMMEDIATE_FUNCTION_P (fun))
+ call_ctx.manifestly_const_eval = mce_true;
+
/* If this is a constexpr destructor, the object's const and volatile
semantics are no longer in effect; see [class.dtor]p5. */
if (new_obj && DECL_DESTRUCTOR_P (fun))
@@ -3807,8 +3812,7 @@ cxx_eval_binary_expression (const constexpr_ctx *ctx, tree t,
}
/* Subroutine of cxx_eval_constant_expression.
- Attempt to evaluate condition expressions. Dead branches are not
- looked into. */
+ Attempt to evaluate condition expressions. */
static tree
cxx_eval_conditional_expression (const constexpr_ctx *ctx, tree t,
@@ -3837,12 +3841,25 @@ cxx_eval_conditional_expression (const constexpr_ctx *ctx, tree t,
boolean_type_node);
}
/* Don't VERIFY_CONSTANT the other operands. */
- if (integer_zerop (val))
+ const bool zero_p = integer_zerop (val);
+ if (zero_p)
val = TREE_OPERAND (t, 2);
else
val = TREE_OPERAND (t, 1);
if (TREE_CODE (t) == IF_STMT && !val)
val = void_node;
+
+ if (!in_immediate_context ()
+ /* P2564: a subexpression of a manifestly constant-evaluated expression
+ or conversion is an immediate function context. */
+ && ctx->manifestly_const_eval != mce_true
+ && cp_fold_immediate (&TREE_OPERAND (t, zero_p ? 1 : 2),
+ ctx->manifestly_const_eval))
+ {
+ *non_constant_p = true;
+ return t;
+ }
+
/* A TARGET_EXPR may be nested inside another TARGET_EXPR, but still
serve as the initializer for the same object as the outer TARGET_EXPR,
as in
@@ -1000,7 +1000,7 @@ cp_genericize_target_expr (tree *stmt_p)
replacement when cp_folding TARGET_EXPR to preserve the invariant that
AGGR_INIT_EXPR_SLOT agrees with the enclosing TARGET_EXPR_SLOT. */
-bool
+static bool
maybe_replace_decl (tree *tp, tree decl, tree replacement)
{
if (!*tp || !VOID_TYPE_P (TREE_TYPE (*tp)))
@@ -1029,44 +1029,73 @@ struct cp_genericize_data
bool handle_invisiref_parm_p;
};
-/* Perform any pre-gimplification folding of C++ front end trees to
- GENERIC.
- Note: The folding of non-omp cases is something to move into
- the middle-end. As for now we have most foldings only on GENERIC
- in fold-const, we need to perform this before transformation to
- GIMPLE-form. */
+/* A subroutine of cp_fold_r to handle immediate functions. */
static tree
-cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
+cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_)
{
- cp_fold_data *data = (cp_fold_data*)data_;
+ auto data = static_cast<cp_fold_data *>(data_);
tree stmt = *stmt_p;
- enum tree_code code = TREE_CODE (stmt);
+ const tsubst_flags_t complain = (data->flags == ff_none ? tf_none : tf_error);
- switch (code)
+ /* No need to look into types or unevaluated operands.
+ NB: This affects cp_fold_r as well. */
+ if (TYPE_P (stmt) || unevaluated_p (TREE_CODE (stmt)))
{
+ *walk_subtrees = 0;
+ return NULL_TREE;
+ }
+
+ switch (TREE_CODE (stmt))
+ {
+ /* Unfortunately we must handle code like
+ false ? bar () : 42
+ where we have to check bar too. */
+ case COND_EXPR:
+ if (cp_fold_immediate_r (&TREE_OPERAND (stmt, 1), walk_subtrees, data))
+ return error_mark_node;
+ if (TREE_OPERAND (stmt, 2)
+ && cp_fold_immediate_r (&TREE_OPERAND (stmt, 2), walk_subtrees, data))
+ return error_mark_node;
+ break;
+
case PTRMEM_CST:
if (TREE_CODE (PTRMEM_CST_MEMBER (stmt)) == FUNCTION_DECL
&& DECL_IMMEDIATE_FUNCTION_P (PTRMEM_CST_MEMBER (stmt)))
{
- if (!data->pset.add (stmt))
+ if (!data->pset.add (stmt) && (complain & tf_error))
error_at (PTRMEM_CST_LOCATION (stmt),
"taking address of an immediate function %qD",
PTRMEM_CST_MEMBER (stmt));
stmt = *stmt_p = build_zero_cst (TREE_TYPE (stmt));
- break;
+ return error_mark_node;
}
break;
+ /* Expand immediate invocations. */
+ case CALL_EXPR:
+ case AGGR_INIT_EXPR:
+ if (tree fn = cp_get_callee (stmt))
+ if (TREE_CODE (fn) != ADDR_EXPR || ADDR_EXPR_DENOTES_CALL_P (fn))
+ if (tree fndecl = cp_get_fndecl_from_callee (fn, /*fold*/false))
+ if (DECL_IMMEDIATE_FUNCTION_P (fndecl))
+ {
+ *stmt_p = stmt = cxx_constant_value (stmt, complain);
+ if (stmt == error_mark_node)
+ return error_mark_node;
+ }
+ break;
+
case ADDR_EXPR:
if (TREE_CODE (TREE_OPERAND (stmt, 0)) == FUNCTION_DECL
&& DECL_IMMEDIATE_FUNCTION_P (TREE_OPERAND (stmt, 0)))
{
- error_at (EXPR_LOCATION (stmt),
- "taking address of an immediate function %qD",
- TREE_OPERAND (stmt, 0));
+ if (complain & tf_error)
+ error_at (EXPR_LOCATION (stmt),
+ "taking address of an immediate function %qD",
+ TREE_OPERAND (stmt, 0));
stmt = *stmt_p = build_zero_cst (TREE_TYPE (stmt));
- break;
+ return error_mark_node;
}
break;
@@ -1074,6 +1103,43 @@ cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
break;
}
+ return NULL_TREE;
+}
+
+/* A wrapper around cp_fold_immediate_r. Return true if we found
+ a non-constant immediate function, or taking the address of an
+ immediate function. */
+
+bool
+cp_fold_immediate (tree *tp, mce_value manifestly_const_eval)
+{
+ if (cxx_dialect <= cxx17)
+ return false;
+
+ fold_flags_t flags = ff_none;
+ if (manifestly_const_eval == mce_false)
+ flags |= ff_mce_false;
+
+ cp_fold_data data (flags);
+ return !!cp_walk_tree (tp, cp_fold_immediate_r, &data, nullptr);
+}
+
+/* Perform any pre-gimplification folding of C++ front end trees to
+ GENERIC.
+ Note: The folding of non-omp cases is something to move into
+ the middle-end. As for now we have most foldings only on GENERIC
+ in fold-const, we need to perform this before transformation to
+ GIMPLE-form. */
+
+static tree
+cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
+{
+ cp_fold_data *data = (cp_fold_data*)data_;
+ tree stmt = *stmt_p;
+ enum tree_code code = TREE_CODE (stmt);
+
+ cp_fold_immediate_r (stmt_p, walk_subtrees, data);
+
*stmt_p = stmt = cp_fold (*stmt_p, data->flags);
if (data->pset.add (stmt))
@@ -1084,7 +1150,7 @@ cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
always the same tree, which the first time cp_fold_r has been
called on it had the subtrees walked. */
*walk_subtrees = 0;
- return NULL;
+ return NULL_TREE;
}
code = TREE_CODE (stmt);
@@ -1136,7 +1202,7 @@ cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
}
cp_walk_tree (&OMP_FOR_PRE_BODY (stmt), cp_fold_r, data, NULL);
*walk_subtrees = 0;
- return NULL;
+ return NULL_TREE;
case IF_STMT:
if (IF_STMT_CONSTEVAL_P (stmt))
@@ -1146,7 +1212,7 @@ cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
cp_walk_tree (&ELSE_CLAUSE (stmt), cp_fold_r, data, NULL);
cp_walk_tree (&IF_SCOPE (stmt), cp_fold_r, data, NULL);
*walk_subtrees = 0;
- return NULL;
+ return NULL_TREE;
}
break;
@@ -1183,7 +1249,7 @@ cp_fold_r (tree *stmt_p, int *walk_subtrees, void *data_)
break;
}
- return NULL;
+ return NULL_TREE;
}
/* Fold ALL the trees! FIXME we should be able to remove this, but
@@ -4784,6 +4784,11 @@ get_vec_init_expr (tree t)
#define PTRMEM_OK_P(NODE) \
TREE_LANG_FLAG_0 (TREE_CHECK3 ((NODE), ADDR_EXPR, OFFSET_REF, SCOPE_REF))
+/* True if this ADDR_EXPR denotes a function call; that is, it's
+ fn() rather than &fn. */
+#define ADDR_EXPR_DENOTES_CALL_P(NODE) \
+ (ADDR_EXPR_CHECK(NODE)->base.protected_flag)
+
/* Get the POINTER_TYPE to the METHOD_TYPE associated with this
pointer to member function. TYPE_PTRMEMFUNC_P _must_ be true,
before using this macro. */
@@ -6580,6 +6585,24 @@ extern int class_dump_id;
extern int module_dump_id;
extern int raw_dump_id;
+/* Whether the current context is manifestly constant-evaluated.
+ Used by the constexpr machinery to control folding of
+ __builtin_is_constant_evaluated. */
+
+enum class mce_value
+{
+ /* Unknown, so treat __builtin_is_constant_evaluated as non-constant. */
+ mce_unknown = 0,
+ /* Fold it to true. */
+ mce_true = 1,
+ /* Fold it to false. Primarily used during cp_fold_function and
+ cp_fully_fold_init. */
+ mce_false = -1,
+};
+constexpr mce_value mce_unknown = mce_value::mce_unknown;
+constexpr mce_value mce_true = mce_value::mce_true;
+constexpr mce_value mce_false = mce_value::mce_false;
+
/* in call.cc */
extern bool check_dtor_name (tree, tree);
int magic_varargs_p (tree);
@@ -8354,6 +8377,7 @@ extern tree process_stmt_assume_attribute (tree, tree, location_t);
extern bool simple_empty_class_p (tree, tree, tree_code);
extern tree fold_builtin_source_location (const_tree);
extern tree get_source_location_impl_type ();
+extern bool cp_fold_immediate (tree *, mce_value);
/* in name-lookup.cc */
extern tree strip_using_decl (tree);
@@ -8515,24 +8539,6 @@ struct GTY((for_user)) constexpr_fundef {
tree result;
};
-/* Whether the current context is manifestly constant-evaluated.
- Used by the constexpr machinery to control folding of
- __builtin_is_constant_evaluated. */
-
-enum class mce_value
-{
- /* Unknown, so treat __builtin_is_constant_evaluated as non-constant. */
- mce_unknown = 0,
- /* Fold it to true. */
- mce_true = 1,
- /* Fold it to false. Primarily used during cp_fold_function and
- cp_fully_fold_init. */
- mce_false = -1,
-};
-constexpr mce_value mce_unknown = mce_value::mce_unknown;
-constexpr mce_value mce_true = mce_value::mce_true;
-constexpr mce_value mce_false = mce_value::mce_false;
-
extern void fini_constexpr (void);
extern bool literal_type_p (tree);
extern void maybe_save_constexpr_fundef (tree);
@@ -3254,7 +3254,7 @@ bot_manip (tree* tp, int* walk_subtrees, void* data_)
variables. */
static tree
-bot_replace (tree* t, int* walk_subtrees, void* data_)
+bot_replace (tree* t, int */*walk_subtrees*/, void* data_)
{
bot_data &data = *(bot_data*)data_;
splay_tree target_remap = data.target_remap;
@@ -3284,27 +3284,6 @@ bot_replace (tree* t, int* walk_subtrees, void* data_)
/*check_access=*/false, /*nonnull=*/true,
tf_warning_or_error);
}
- else if (cxx_dialect >= cxx20
- && (TREE_CODE (*t) == CALL_EXPR
- || TREE_CODE (*t) == AGGR_INIT_EXPR)
- && !in_immediate_context ())
- {
- /* Expand immediate invocations. */
- if (tree fndecl = cp_get_callee_fndecl_nofold (*t))
- if (DECL_IMMEDIATE_FUNCTION_P (fndecl))
- {
- /* Make in_immediate_context true within the args. */
- in_consteval_if_p_temp_override ito;
- in_consteval_if_p = true;
- int nargs = call_expr_nargs (*t);
- for (int i = 0; i < nargs; ++i)
- cp_walk_tree (&get_nth_callarg (*t, i), bot_replace, data_, NULL);
- *t = cxx_constant_value (*t);
- if (*t == error_mark_node)
- return error_mark_node;
- *walk_subtrees = 0;
- }
- }
return NULL_TREE;
}
@@ -58,6 +58,7 @@ baz (int x)
return r;
}
+// This function is not instantiated so NDR.
template <typename T>
constexpr int
qux (int x)
@@ -65,7 +66,7 @@ qux (int x)
int r = 0;
if not consteval // { dg-warning "'if consteval' only available with" "" { target c++20_only } }
{
- r += foo (x); // { dg-error "'x' is not a constant expression" }
+ r += foo (x); // { dg-error "'x' is not a constant expression" "" { xfail *-*-* } }
}
else
{
@@ -25,3 +25,10 @@ void VerifyHash(fixed_string s) {
fixed_string::size_static(-1); // { dg-message "expansion of" }
s(); // { dg-bogus "" }
}
+
+void
+do_test ()
+{
+ fixed_string f;
+ VerifyHash<int>(f);
+}
@@ -5,21 +5,21 @@ consteval int bar (int i) { if (i != 1) throw 1; return 0; } // { dg-error "is n
constexpr int a = bar (1);
constexpr int b = bar (2); // { dg-message "in 'constexpr' expansion of" }
-constexpr int c = 0 ? bar (3) : 1; // { dg-message "in 'constexpr' expansion of" }
+constexpr int c = 0 ? bar (3) : 1;
const int d = bar (4); // { dg-message "in 'constexpr' expansion of" }
-const int e = 0 ? bar (5) : 1; // { dg-message "in 'constexpr' expansion of" }
+const int e = 0 ? bar (5) : 1;
int f = bar (1);
int g = bar (6); // { dg-message "in 'constexpr' expansion of" }
-int h = 0 ? bar (7) : 1; // { dg-message "in 'constexpr' expansion of" }
+int h = 0 ? bar (7) : 1;
void
foo ()
{
constexpr int a = bar (1);
constexpr int b = bar (2); // { dg-message "in 'constexpr' expansion of" }
- constexpr int c = 0 ? bar (3) : 1; // { dg-message "in 'constexpr' expansion of" }
+ constexpr int c = 0 ? bar (3) : 1;
const int d = bar (4); // { dg-message "in 'constexpr' expansion of" }
- const int e = 0 ? bar (5) : 1; // { dg-message "in 'constexpr' expansion of" }
+ const int e = 0 ? bar (5) : 1;
int f = bar (1);
int g = bar (6); // { dg-message "in 'constexpr' expansion of" }
int h = 0 ? bar (7) : 1; // { dg-message "in 'constexpr' expansion of" }
@@ -33,13 +33,13 @@ foo ()
else
bar (12); // { dg-message "in 'constexpr' expansion of" }
if constexpr (0)
- bar (13); // { dg-message "in 'constexpr' expansion of" }
+ bar (13);
else
bar (14); // { dg-message "in 'constexpr' expansion of" }
if constexpr (1)
bar (15); // { dg-message "in 'constexpr' expansion of" }
else
- bar (16); // { dg-message "in 'constexpr' expansion of" }
+ bar (16);
}
consteval int
@@ -77,22 +77,25 @@ template <typename T>
void
qux ()
{
+ // Used to give errors errors here, but not since we moved consteval
+ // function folding to cp_fold_r which isn't called on uninstantiated
+ // templates.
if (0)
- bar (2); // { dg-message "in 'constexpr' expansion of" }
+ bar (2);
else
- bar (3); // { dg-message "in 'constexpr' expansion of" }
+ bar (3);
if (1)
- bar (4); // { dg-message "in 'constexpr' expansion of" }
+ bar (4);
else
- bar (5); // { dg-message "in 'constexpr' expansion of" }
+ bar (5);
if constexpr (0)
- bar (6); // { dg-message "in 'constexpr' expansion of" }
+ bar (6);
else
- bar (7); // { dg-message "in 'constexpr' expansion of" }
+ bar (7);
if constexpr (1)
- bar (8); // { dg-message "in 'constexpr' expansion of" }
+ bar (8);
else
- bar (9); // { dg-message "in 'constexpr' expansion of" }
+ bar (9);
if (0)
bar ((T) 2);
else
@@ -18,8 +18,7 @@ consteval int f6 (int x) { return x; }
int d = 6; // { dg-message "'int d' is not const" }
int e = f6 (d); // { dg-error "the value of 'd' is not usable in a constant expression" }
constexpr int f7 (int x) { return f6 (x); } // { dg-error "'x' is not a constant expression" }
-constexpr int f = f7 (5); // { dg-error "" }
- // { dg-message "in 'constexpr' expansion of" "" { target *-*-* } .-1 }
+constexpr int f = f7 (5);
using fnptr = int (int);
fnptr *g = f6; // { dg-error "taking address of an immediate function 'consteval int f6\\(int\\)'" }
int f8 (fnptr *);
new file mode 100644
@@ -0,0 +1,4 @@
+// { dg-do compile { target c++20 } }
+
+consteval int foo () { return 42; }
+int bar () { return (*(&foo)) (); } // { dg-error "taking address" }
new file mode 100644
@@ -0,0 +1,34 @@
+// { dg-do compile { target c++20 } }
+
+consteval int id (int i) { return i; }
+consteval int add (int i, int j) { return i + j; }
+
+constexpr int
+foo (int i = id (42))
+{
+ return i + id (id (id (0)));
+}
+
+constexpr int
+bar (int i = id (id (id (42))))
+{
+ return i;
+}
+
+constexpr int
+baz (int i = add (add (id (1), id (2)), id (3)))
+{
+ return i;
+}
+
+void
+g ()
+{
+ foo ();
+ bar ();
+ baz ();
+}
+
+static_assert (foo () == 42);
+static_assert (bar () == 42);
+static_assert (baz () == 6);
new file mode 100644
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++20 } }
+
+consteval int bar (int i) { if (i != 1) throw 1; return 0; } // { dg-error "is not a constant expression" }
+
+constexpr int
+foo (bool b)
+{
+ return b ? bar (3) : 2; // { dg-message "in .constexpr. expansion" }
+}
+
+static_assert (foo (false) == 2);
+
+void
+g ()
+{
+ __extension__ int a1[bar(3)]; // { dg-message "in .constexpr. expansion" }
+ int a2[sizeof (bar(3))];
+}
new file mode 100644
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++20 } }
+
+template <typename T, typename F>
+constexpr bool is_not(T t, F f) {
+ return not f(t);
+}
+
+consteval bool is_even(int i) { return i % 2 == 0; }
+
+static_assert(is_not(5, is_even)); // ok
@@ -15,10 +15,11 @@ void qux ()
int a = bar (N); // { dg-message "in 'constexpr' expansion of 'bar\\(2\\)'" }
}
+// This function is not instantiated so NDR.
template <int N>
void quux ()
{
- int a = bar (5); // { dg-message "in 'constexpr' expansion of 'bar\\(5\\)'" }
+ int a = bar (5);
}
void
@@ -14,6 +14,6 @@ consteval bool test_pr105957()
a.deallocate(p, n);
return true;
}
-static_assert( test_pr105957() );
+static_assert( test_pr105957() ); // { dg-error "non-constant" }
// { dg-error "throw_bad_array_new_length" "" { target *-*-* } 0 }