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author | Marek Polacek <polacek@redhat.com> | 2023-08-31 20:11:50 -0400 |
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committer | Marek Polacek <polacek@redhat.com> | 2023-09-19 09:24:44 -0400 |
commit | 6851e3423c2b5ec6516efa0677745d25c905e079 (patch) | |
tree | 72c6c8bc7a321e6f9f6090b9db82fea35931e707 /gcc/cp/constexpr.cc | |
parent | f25960b03834712f312d46fed9a021df36f89f22 (diff) | |
download | gcc-6851e3423c2b5ec6516efa0677745d25c905e079.zip gcc-6851e3423c2b5ec6516efa0677745d25c905e079.tar.gz gcc-6851e3423c2b5ec6516efa0677745d25c905e079.tar.bz2 |
c++: Move consteval folding to cp_fold_r
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 (cxx_eval_call_expression): Use mce_true for
DECL_IMMEDIATE_FUNCTION_P.
(cxx_eval_conditional_expression): Call cp_fold_immediate.
* cp-gimplify.cc (enum fold_flags): Add ff_fold_immediate.
(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.
Diffstat (limited to 'gcc/cp/constexpr.cc')
-rw-r--r-- | gcc/cp/constexpr.cc | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index 0ca4370..a673a60 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -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; + + /* P2564: a subexpression of a manifestly constant-evaluated expression + or conversion is an immediate function context. */ + if (ctx->manifestly_const_eval != mce_true + && !in_immediate_context () + && 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 |