PHI translation simplifies/canonicalizes expressions now but the
previous limitations as of what NAME results we allow are ineffective
and we're now even encoding those previously rejected NAMEs as NARY.
The following fixes this by making sure to restore the original
unsimplified NARY in such cases.
I have noticed this on the testcase for PR126965
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
* tree-ssa-pre.cc (get_or_alloc_expr_for_nary): Assert we
do not try to encode a SSA name or a constant as NARY.
(phi_translate_1): Save the translated NARY so we can
restore it if we want to reject a simplification to a
SSA name.
---
gcc/tree-ssa-pre.cc | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/gcc/tree-ssa-pre.cc b/gcc/tree-ssa-pre.cc
index e5c33f80395..9353f19d405 100644
--- a/gcc/tree-ssa-pre.cc
+++ b/gcc/tree-ssa-pre.cc
@@ -431,6 +431,8 @@ get_or_alloc_expr_for_nary (vn_nary_op_t nary, unsigned
value_id,
unsigned int result_id;
gcc_assert (value_id == 0 || !value_id_constant_p (value_id));
+ gcc_assert (nary->opcode != SSA_NAME
+ && TREE_CODE_CLASS (nary->opcode) != tcc_constant);
expr.kind = NARY;
expr.id = 0;
@@ -1626,6 +1628,12 @@ phi_translate_1 (bitmap_set_t dest,
{
unsigned int new_val_id;
+ vn_nary_op_t saved_newnary
+ = XALLOCAVAR (struct vn_nary_op_s,
+ sizeof_vn_nary_op (newnary->length));
+ memcpy (saved_newnary, newnary,
+ sizeof_vn_nary_op (newnary->length));
+
/* Try to simplify the new NARY. */
tree res = vn_nary_simplify (newnary);
if (res)
@@ -1673,6 +1681,10 @@ phi_translate_1 (bitmap_set_t dest,
return constant;
}
}
+ /* Restore the unsimplified newnary, it was simplified
+ to a NAME that we do not want (not as NARY anyway). */
+ memcpy (newnary, saved_newnary,
+ sizeof_vn_nary_op (saved_newnary->length));
}
tree result = vn_nary_op_lookup_pieces (newnary->length,
--
2.51.0
