Revert update-ssa assert in vectorizer
The following reverts the just added assert that virtual SSA does not
need updating. It instead goes for a select whitelist of transforms
known to be prone to difficulties with virtual SSA update.
* tree-vect-loop-manip.cc (vect_do_peeling): Revert assert
and update virtual SSA form again. Assert we do so for
a known set of transforms only.
* tree-vectorizer.h (vec_info::any_known_not_updated_vssa): New.
* tree-vect-stmts.cc (vectorizable_load): When vectorizing
using load-lanes allow virtual SSA update.
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 7b7af94..5c31f0a 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -2683,11 +2683,12 @@
class loop *first_loop = loop;
bool irred_flag = loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP;
- /* Historically we might have a queued need to update virtual SSA form.
- As we delete the update SSA machinery below after doing a regular
- incremental SSA update during loop copying make sure we don't
- lose that fact. */
- gcc_assert (!need_ssa_update_p (cfun));
+ /* We should not have to update virtual SSA form here but some
+ transforms involve creating new virtual definitions which makes
+ updating difficult. */
+ gcc_assert (!need_ssa_update_p (cfun)
+ || loop_vinfo->any_known_not_updated_vssa);
+ update_ssa (TODO_update_ssa_only_virtuals);
create_lcssa_for_virtual_phi (loop);
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index d6a6fe3..72107af 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -8979,6 +8979,9 @@
dump_printf_loc (MSG_NOTE, vect_location,
"Vectorizing an unaligned access.\n");
+ if (memory_access_type == VMAT_LOAD_STORE_LANES)
+ vinfo->any_known_not_updated_vssa = true;
+
STMT_VINFO_TYPE (stmt_info) = load_vec_info_type;
vect_model_load_cost (vinfo, stmt_info, ncopies, vf, memory_access_type,
alignment_support_scheme, misalignment,
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 642eb0a..e5fdc9e 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -444,6 +444,10 @@
/* Whether the above mapping is complete. */
bool stmt_vec_info_ro;
+ /* Whether we've done a transform we think OK to not update virtual
+ SSA form. */
+ bool any_known_not_updated_vssa;
+
/* The SLP graph. */
auto_vec<slp_instance> slp_instances;
