Tested x86_64-pc-linux-gnu, OK for trunk?
-- 8< --
The change to only cache constexpr calls that are
reduced_constant_expression_p tripped on bit-cast3.C, which failed that
predicate due to the presence of an empty field in the result of
native_interpret_aggregate, which reduced_constant_expression_p rejects to
avoid confusing output_constructor.
This patch proposes to skip such fields in native_interpret_aggregate, since
they aren't actually involved in the value representation.
gcc/ChangeLog:
* fold-const.cc (native_interpret_aggregate): Skip empty fields.
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_bit_cast): Check that the result of
native_interpret_aggregate doesn't need more evaluation.
---
gcc/cp/constexpr.cc | 9 +++++++++
gcc/fold-const.cc | 3 ++-
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 9d85c3be5cc..6e8f1c2b61e 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -1440,6 +1440,8 @@ enum value_cat {
static tree cxx_eval_constant_expression (const constexpr_ctx *, tree,
value_cat, bool *, bool *, tree * =
NULL);
+static tree cxx_eval_bare_aggregate (const constexpr_ctx *, tree,
+ value_cat, bool *, bool *);
static tree cxx_fold_indirect_ref (const constexpr_ctx *, location_t, tree,
tree,
bool * = NULL);
static tree find_heap_var_refs (tree *, int *, void *);
@@ -4803,6 +4805,13 @@ cxx_eval_bit_cast (const constexpr_ctx *ctx, tree t,
bool *non_constant_p,
{
clear_type_padding_in_mask (TREE_TYPE (t), mask);
clear_uchar_or_std_byte_in_mask (loc, r, mask);
+ if (CHECKING_P)
+ {
+ tree e = cxx_eval_bare_aggregate (ctx, r, vc_prvalue,
+ non_constant_p, overflow_p);
+ gcc_checking_assert (e == r);
+ r = e;
+ }
}
}
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index a02ede79fed..db8f7de5680 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -8935,7 +8935,8 @@ native_interpret_aggregate (tree type, const unsigned
char *ptr, int off,
return NULL_TREE;
for (tree field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
{
- if (TREE_CODE (field) != FIELD_DECL || DECL_PADDING_P (field))
+ if (TREE_CODE (field) != FIELD_DECL || DECL_PADDING_P (field)
+ || integer_zerop (DECL_SIZE (field)))
continue;
tree fld = field;
HOST_WIDE_INT bitoff = 0, pos = 0, sz = 0;
base-commit: caabf0973a4e9a26421c94d540e3e20051e93e77
--
2.39.3
