The next patch in this series exposes an interface for creating new uses
in RTL-SSA. The intent is that new user-created uses can consume new
user-created defs in the same change group. This is so that we can
correctly update uses of memory when inserting a new store pair insn in
the aarch64 load/store pair fusion pass (the affected uses need to
consume the new store pair insn).
As it stands, finalize_new_accesses is called as part of the backwards
insn placement loop within change_insns, but if we want new uses to be
able to depend on new defs in the same change group, we need
finalize_new_accesses to be called on earlier insns first. This is so
that when we process temporary uses and turn them into permanent uses,
we can follow the last_def link on the temporary def to ensure we end up
with a permanent use consuming a permanent def.
Bootstrapped/regtested on aarch64-linux-gnu, OK for trunk?
Thanks,
Alex
gcc/ChangeLog:
PR target/113070
* rtl-ssa/changes.cc (function_info::change_insns): Split out the call
to finalize_new_accesses from the backwards placement loop, run it
forwards in a separate loop.
---
gcc/rtl-ssa/changes.cc | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
index 2fac45ae885..e538b637848 100644
--- a/gcc/rtl-ssa/changes.cc
+++ b/gcc/rtl-ssa/changes.cc
@@ -775,15 +775,26 @@ function_info::change_insns (array_slice<insn_change *> changes)
placeholder = add_placeholder_after (after);
following_insn = placeholder;
}
-
- // Finalize the new list of accesses for the change. Don't install
- // them yet, so that we still have access to the old lists below.
- finalize_new_accesses (change,
- placeholder ? placeholder : insn);
}
placeholders[i] = placeholder;
}
+ // Finalize the new list of accesses for each change. Don't install them yet,
+ // so that we still have access to the old lists below.
+ //
+ // Note that we do this forwards instead of in the backwards loop above so
+ // that any new defs being inserted are processed before new uses of those
+ // defs, so that the (initially) temporary uses referring to temporary defs
+ // can be easily updated to become permanent uses referring to permanent defs.
+ for (unsigned i = 0; i < changes.size (); i++)
+ {
+ insn_change &change = *changes[i];
+ insn_info *placeholder = placeholders[i];
+ if (!change.is_deletion ())
+ finalize_new_accesses (change,
+ placeholder ? placeholder : change.insn ());
+ }
+
// Remove all definitions that are no longer needed. After the above,
// the only uses of such definitions should be dead phis and now-redundant
// live-out uses.
