rtl-ssa: Support for creating new uses [PR113070]

This exposes an interface for users to create new uses in RTL-SSA.
This is needed for updating uses after inserting a new store pair insn
in the aarch64 load/store pair fusion pass.

gcc/ChangeLog:

	PR target/113070
	* rtl-ssa/accesses.cc (function_info::create_use): New.
	* rtl-ssa/changes.cc (function_info::finalize_new_accesses):
	Ensure new uses end up referring to permanent defs.
	* rtl-ssa/functions.h (function_info::create_use): Declare.

diff --git a/gcc/rtl-ssa/accesses.cc b/gcc/rtl-ssa/accesses.cc
index ce4a8b8dc00f8ed5b6573d7fcae736696b0c0e2e..3f1304fc5bff26c19b60328b88c38a46d7e05663 100644 (file)
--- a/gcc/rtl-ssa/accesses.cc
+++ b/gcc/rtl-ssa/accesses.cc
@@ -1466,6 +1466,16 @@ function_info::create_set (obstack_watermark &watermark,
   return set;
 }
 
+use_info *
+function_info::create_use (obstack_watermark &watermark,
+                          insn_info *insn,
+                          set_info *set)
+{
+  auto use = change_alloc<use_info> (watermark, insn, set->resource (), set);
+  use->m_is_temp = true;
+  return use;
+}
+
 // Return true if ACCESS1 can represent ACCESS2 and if ACCESS2 can
 // represent ACCESS1.
 static bool

diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
index e538b637848d291c54753f88df3a1c483cc68c0c..8181e5248c54f4db67fae8807e9c620a254c674b 100644 (file)
--- a/gcc/rtl-ssa/changes.cc
+++ b/gcc/rtl-ssa/changes.cc
@@ -609,15 +609,27 @@ function_info::finalize_new_accesses (insn_change &change, insn_info *pos)
          m_temp_uses[i] = use = allocate<use_info> (*use);
          use->m_is_temp = false;
          set_info *def = use->def ();
-         // Handle cases in which the value was previously not used
-         // within the block.
-         if (def && def->m_is_temp)
+         if (!def || !def->m_is_temp)
+           continue;
+
+         if (auto phi = dyn_cast<phi_info *> (def))
            {
-             phi_info *phi = as_a<phi_info *> (def);
+             // Handle cases in which the value was previously not used
+             // within the block.
              gcc_assert (phi->is_degenerate ());
              phi = create_degenerate_phi (phi->ebb (), phi->input_value (0));
              use->set_def (phi);
            }
+         else
+           {
+             // The temporary def may also be a set added with this change, in
+             // which case the permanent set is stored in the last_def link,
+             // and we need to update the use to refer to the permanent set.
+             gcc_assert (is_a<set_info *> (def));
+             auto perm_set = as_a<set_info *> (def->last_def ());
+             gcc_assert (!perm_set->is_temporary ());
+             use->set_def (perm_set);
+           }
        }
     }
 

diff --git a/gcc/rtl-ssa/functions.h b/gcc/rtl-ssa/functions.h
index 58d0b50ea83537665649e8151213824213c841bb..e00a398069a10ef7f35fd16ce6b6086ca9285335 100644 (file)
--- a/gcc/rtl-ssa/functions.h
+++ b/gcc/rtl-ssa/functions.h
@@ -73,6 +73,13 @@ public:
                        insn_info *insn,
                        resource_info resource);
 
+  // Create a temporary use of SET as part of a change to INSN.
+  // SET can be a pre-existing definition or one that is being created
+  // as part of the same change group.
+  use_info *create_use (obstack_watermark &watermark,
+                       insn_info *insn,
+                       set_info *set);
+
   // Create a temporary insn with code INSN_CODE and pattern PAT.
   insn_info *create_insn (obstack_watermark &watermark,
                          rtx_code insn_code,