compiler: alias 1/4: Introduce alias analysis pass

This commit inserts an empty analysis pass which will eventually be
extended to do a full alias analysis.

5 files changed, 64 insertions, 4 deletions

diff --git a/lib/compiler/src/Makefile b/lib/compiler/src/Makefile
index 50a3dbd339..645a1de589 100644
--- a/lib/compiler/src/Makefile
+++ b/lib/compiler/src/Makefile
@@ -60,6 +60,7 @@ MODULES =  \
 	beam_listing \
 	beam_opcodes \
 	beam_ssa \
+	beam_ssa_alias \
 	beam_ssa_bc_size \
 	beam_ssa_bool \
 	beam_ssa_bsm \
@@ -212,6 +213,7 @@ $(EBIN)/beam_kernel_to_ssa.beam: v3_kernel.hrl beam_ssa.hrl
 $(EBIN)/beam_listing.beam: core_parse.hrl v3_kernel.hrl beam_ssa.hrl \
      beam_asm.hrl beam_types.hrl
 $(EBIN)/beam_ssa.beam: beam_ssa.hrl
+$(EBIN)/beam_ssa_alias_opt.beam: beam_ssa_opt.hrl beam_types.hrl
 $(EBIN)/beam_ssa_bsm.beam: beam_ssa.hrl
 $(EBIN)/beam_ssa_bool.beam: beam_ssa.hrl
 $(EBIN)/beam_ssa_check.beam: beam_ssa.hrl beam_types.hrl
diff --git a/lib/compiler/src/beam_ssa_alias.erl b/lib/compiler/src/beam_ssa_alias.erl
new file mode 100644
index 0000000000..1fc73c1828
--- /dev/null
+++ b/lib/compiler/src/beam_ssa_alias.erl
@@ -0,0 +1,45 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2023. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+%%
+
+-module(beam_ssa_alias).
+
+-export([opt/2]).
+
+-include("beam_ssa_opt.hrl").
+
+%% -define(DEBUG, true).
+
+-ifdef(DEBUG).
+-define(DP(FMT, ARGS), io:format(FMT, ARGS)).
+-define(DP(FMT), io:format(FMT)).
+-else.
+-define(DP(FMT, ARGS), skip).
+-define(DP(FMT), skip).
+-endif.
+
+%%%
+%%% Optimization pass which calculates the alias status of values and
+%%% uses the results to transform the code.
+%%%
+-spec opt(st_map(), func_info_db()) -> {st_map(), func_info_db()}.
+
+opt(StMap0, FuncDb0) ->
+    {StMap0, FuncDb0}.
diff --git a/lib/compiler/src/beam_ssa_opt.erl b/lib/compiler/src/beam_ssa_opt.erl
index 1d6a45dbe7..97032e0f0a 100644
--- a/lib/compiler/src/beam_ssa_opt.erl
+++ b/lib/compiler/src/beam_ssa_opt.erl
@@ -64,7 +64,9 @@ module(Module, Opts) ->
     Phases = [{once, Order, prologue_passes(Opts)},
               {module, module_passes(Opts)},
               {fixpoint, Order, repeated_passes(Opts)},
-              {once, Order, epilogue_passes(Opts)}],
+              {once, Order, early_epilogue_passes(Opts)},
+              {module, epilogue_module_passes(Opts)},
+              {once, Order, late_epilogue_passes(Opts)}],
 
     StMap = run_phases(Phases, StMap0, FuncDb),
     {ok, finish(Module, StMap)}.
@@ -276,12 +278,21 @@ repeated_passes(Opts) ->
                                                 %clean up phi nodes.
     passes_1(Ps, Opts).
 
-epilogue_passes(Opts) ->
+epilogue_module_passes(Opts) ->
+    Ps0 = [{ssa_opt_alias,
+            fun({StMap, FuncDb}) ->
+                    beam_ssa_alias:opt(StMap, FuncDb)
+            end}],
+    passes_1(Ps0, Opts).
+
+early_epilogue_passes(Opts) ->
     Ps = [?PASS(ssa_opt_type_finish),
           ?PASS(ssa_opt_float),
-          ?PASS(ssa_opt_sw),
+          ?PASS(ssa_opt_sw)],
+    passes_1(Ps, Opts).
 
-          %% Run live one more time to clean up after the previous
+late_epilogue_passes(Opts) ->
+    Ps = [%% Run live one more time to clean up after the previous
           %% epilogue passes.
           ?PASS(ssa_opt_live),
           ?PASS(ssa_opt_bsm),
diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index 06ab3c5345..feb65dacb9 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -2101,6 +2101,7 @@ pre_load() ->
 	 beam_kernel_to_ssa,
 	 beam_opcodes,
 	 beam_ssa,
+	 beam_ssa_alias,
 	 beam_ssa_bc_size,
 	 beam_ssa_bool,
 	 beam_ssa_bsm,
diff --git a/lib/compiler/src/compiler.app.src b/lib/compiler/src/compiler.app.src
index b95c8d52d3..15de283706 100644
--- a/lib/compiler/src/compiler.app.src
+++ b/lib/compiler/src/compiler.app.src
@@ -36,6 +36,7 @@
 	     beam_listing,
 	     beam_opcodes,
              beam_ssa,
+             beam_ssa_alias,
              beam_ssa_bc_size,
              beam_ssa_bool,
              beam_ssa_bsm,