Merge pull request #2100 from jhogberg/john/compiler/module-type-optimization

Apply type optimizations across local function calls

15 files changed, 929 insertions, 265 deletions

diff --git a/lib/compiler/src/Makefile b/lib/compiler/src/Makefile
index 074d9b881b..97c73d0e07 100644
--- a/lib/compiler/src/Makefile
+++ b/lib/compiler/src/Makefile
@@ -103,6 +103,7 @@ BEAM_H = $(wildcard ../priv/beam_h/*.h)
 
 HRL_FILES= \
 	beam_disasm.hrl \
+	beam_ssa_opt.hrl \
 	beam_ssa.hrl \
 	core_parse.hrl \
 	v3_kernel.hrl
diff --git a/lib/compiler/src/beam_ssa_bsm.erl b/lib/compiler/src/beam_ssa_bsm.erl
index 9631bf3334..466337db0e 100644
--- a/lib/compiler/src/beam_ssa_bsm.erl
+++ b/lib/compiler/src/beam_ssa_bsm.erl
@@ -877,7 +877,8 @@ annotate_context_parameters(F, ModInfo) ->
                                  %% Assertion.
                                  error(conflicting_parameter_types);
                             (K, suitable_for_reuse, Acc) ->
-                                 Acc#{ K => match_context };
+                                 T = beam_validator:type_anno(match_context),
+                                 Acc#{ K => T };
                             (_K, _V, Acc) ->
                                  Acc
                          end, TypeAnno0, ParamInfo),
diff --git a/lib/compiler/src/beam_ssa_codegen.erl b/lib/compiler/src/beam_ssa_codegen.erl
index fe1a0c8480..c2d5035b19 100644
--- a/lib/compiler/src/beam_ssa_codegen.erl
+++ b/lib/compiler/src/beam_ssa_codegen.erl
@@ -161,7 +161,7 @@ add_parameter_annos([{label, _}=Entry | Body], Anno) ->
            (_K, _V, Acc) ->
                 Acc
         end, [], maps:get(registers, Anno)),
-    [Entry | Annos] ++ Body.
+    [Entry | sort(Annos)] ++ Body.
 
 cg_fun(Blocks, St0) ->
     Linear0 = linearize(Blocks),
@@ -1449,7 +1449,12 @@ cg_call(#cg_set{anno=Anno,op=call,dst=Dst0,args=[#b_local{}=Func0|Args0]},
     Line = call_line(Where, local, Anno),
     Call = build_call(call, Arity, {f,FuncLbl}, Context, Dst),
     Is = setup_args(Args, Anno, Context, St) ++ Line ++ Call,
-    {Is,St};
+    case Anno of
+        #{ result_type := Info } ->
+            {Is ++ [{'%', {type_info, Dst, Info}}], St};
+        #{} ->
+            {Is, St}
+    end;
 cg_call(#cg_set{anno=Anno0,op=call,dst=Dst0,args=[#b_remote{}=Func0|Args0]},
         Where, Context, St) ->
     [Dst|Args] = beam_args([Dst0|Args0], St),
@@ -1725,6 +1730,14 @@ copy(Src, Dst) -> [{move,Src,Dst}].
 
 force_reg({literal,_}=Lit, Reg) ->
     {Reg,[{move,Lit,Reg}]};
+force_reg({integer,_}=Lit, Reg) ->
+    {Reg,[{move,Lit,Reg}]};
+force_reg({atom,_}=Lit, Reg) ->
+    {Reg,[{move,Lit,Reg}]};
+force_reg({float,_}=Lit, Reg) ->
+    {Reg,[{move,Lit,Reg}]};
+force_reg(nil=Lit, Reg) ->
+    {Reg,[{move,Lit,Reg}]};
 force_reg({Kind,_}=R, _) when Kind =:= x; Kind =:= y ->
     {R,[]}.
 
diff --git a/lib/compiler/src/beam_ssa_opt.erl b/lib/compiler/src/beam_ssa_opt.erl
index 6f7044f006..3685c09a2b 100644
--- a/lib/compiler/src/beam_ssa_opt.erl
+++ b/lib/compiler/src/beam_ssa_opt.erl
@@ -18,61 +18,154 @@
 %% %CopyrightEnd%
 %%
 
+%%%
+%%% This is a collection of various optimizations that don't need a separate
+%%% pass by themselves and/or are mutually beneficial to other passes.
+%%%
+%%% The optimizations are applied in "phases," each with a list of sub-passes
+%%% to run. These sub-passes are applied on all functions in a module before
+%%% moving on to the next phase, which lets us gather module-level information
+%%% in one phase and then apply it in the next without having to risk working
+%%% with incomplete information.
+%%%
+%%% Each sub-pass operates on a #st{} record and a func_info_db(), where the
+%%% former is just a #b_function{} whose blocks can be represented either in
+%%% linear or map form, and the latter is a map with information about all
+%%% functions in the module (see beam_ssa_opt.hrl for more details).
+%%%
+
 -module(beam_ssa_opt).
 -export([module/2]).
 
--include("beam_ssa.hrl").
--import(lists, [append/1,foldl/3,keyfind/3,member/2,
+-include("beam_ssa_opt.hrl").
+
+-import(lists, [append/1,duplicate/2,foldl/3,keyfind/3,member/2,
                 reverse/1,reverse/2,
-                splitwith/2,takewhile/2,unzip/1]).
+                splitwith/2,sort/1,takewhile/2,unzip/1]).
+
+-define(DEFAULT_REPETITIONS, 2).
 
 -spec module(beam_ssa:b_module(), [compile:option()]) ->
                     {'ok',beam_ssa:b_module()}.
 
-module(#b_module{body=Fs0}=Module, Opts) ->
-    Ps = passes(Opts),
-    Fs = functions(Fs0, Ps),
-    {ok,Module#b_module{body=Fs}}.
+-record(st, {ssa :: [{beam_ssa:label(),beam_ssa:b_blk()}] |
+                    beam_ssa:block_map(),
+             args :: [beam_ssa:b_var()],
+             cnt :: beam_ssa:label(),
+             anno :: beam_ssa:anno()}).
+-type st_map() :: #{ func_id() => #st{} }.
+
+module(Module, Opts) ->
+    FuncDb0 = case proplists:get_value(no_module_opt, Opts, false) of
+                  false -> build_func_db(Module);
+                  true -> #{}
+              end,
+
+    %% Passes that perform module-level optimizations are often aided by
+    %% optimizing callers before callees and vice versa, so we optimize all
+    %% functions in call order, flipping it as required.
+    StMap0 = build_st_map(Module),
+    Order = get_call_order_po(StMap0, FuncDb0),
+
+    Phases =
+        [{Order, prologue_passes(Opts)}] ++
+        repeat(Opts, repeated_passes(Opts), Order) ++
+        [{Order, epilogue_passes(Opts)}],
+
+    {StMap, _FuncDb} = foldl(fun({FuncIds, Ps}, {StMap, FuncDb}) ->
+                                     phase(FuncIds, Ps, StMap, FuncDb)
+                             end, {StMap0, FuncDb0}, Phases),
+
+    {ok, finish(Module, StMap)}.
+
+phase([FuncId | Ids], Ps, StMap, FuncDb0) ->
+    try
+        {St, FuncDb} =
+            compile:run_sub_passes(Ps, {map_get(FuncId, StMap), FuncDb0}),
+
+        phase(Ids, Ps, StMap#{ FuncId => St }, FuncDb)
+    catch
+        Class:Error:Stack ->
+            #b_local{name=Name,arity=Arity} = FuncId,
+            io:fwrite("Function: ~w/~w\n", [Name,Arity]),
+            erlang:raise(Class, Error, Stack)
+    end;
+phase([], _Ps, StMap, FuncDb) ->
+    {StMap, FuncDb}.
+
+%% Repeats the given passes, alternating the order between runs to make the
+%% type pass more efficient.
+repeat(Opts, Ps, OrderA) ->
+    Repeat = proplists:get_value(ssa_opt_repeat, Opts, ?DEFAULT_REPETITIONS),
+    OrderB = reverse(OrderA),
+    repeat_1(Repeat, Ps, OrderA, OrderB).
+
+repeat_1(0, _Opts, _OrderA, _OrderB) ->
+    [];
+repeat_1(N, Ps, OrderA, OrderB) when N > 0, N rem 2 =:= 0 ->
+    [{OrderA, Ps} | repeat_1(N - 1, Ps, OrderA, OrderB)];
+repeat_1(N, Ps, OrderA, OrderB) when N > 0, N rem 2 =:= 1 ->
+    [{OrderB, Ps} | repeat_1(N - 1, Ps, OrderA, OrderB)].
+
+%%
 
-functions([F|Fs], Ps) ->
-    [function(F, Ps)|functions(Fs, Ps)];
-functions([], _Ps) -> [].
+get_func_id(F) ->
+    {_Mod, Name, Arity} = beam_ssa:get_anno(func_info, F),
+    #b_local{name=#b_literal{val=Name}, arity=Arity}.
+
+-spec build_st_map(#b_module{}) -> st_map().
+build_st_map(#b_module{body=Fs}) ->
+    build_st_map_1(Fs, #{}).
+
+build_st_map_1([F | Fs], Map) ->
+    #b_function{anno=Anno,args=Args,cnt=Counter,bs=Bs} = F,
+    St = #st{anno=Anno,args=Args,cnt=Counter,ssa=Bs},
+    build_st_map_1(Fs, Map#{ get_func_id(F) => St });
+build_st_map_1([], Map) ->
+    Map.
+
+-spec finish(#b_module{}, st_map()) -> #b_module{}.
+finish(#b_module{body=Fs0}=Module, StMap) ->
+    Module#b_module{body=finish_1(Fs0, StMap)}.
+
+finish_1([F0 | Fs], StMap) ->
+    #st{anno=Anno,cnt=Counter,ssa=Blocks} = map_get(get_func_id(F0), StMap),
+    F = F0#b_function{anno=Anno,bs=Blocks,cnt=Counter},
+    [F | finish_1(Fs, StMap)];
+finish_1([], _StMap) ->
+    [].
 
--type b_blk() :: beam_ssa:b_blk().
--type b_var() :: beam_ssa:b_var().
--type label() :: beam_ssa:label().
+%%
 
--record(st, {ssa :: beam_ssa:block_map() | [{label(),b_blk()}],
-             args :: [b_var()],
-             cnt :: label()}).
 -define(PASS(N), {N,fun N/1}).
 
-passes(Opts0) ->
+prologue_passes(Opts) ->
     Ps = [?PASS(ssa_opt_split_blocks),
           ?PASS(ssa_opt_coalesce_phis),
           ?PASS(ssa_opt_element),
           ?PASS(ssa_opt_linearize),
           ?PASS(ssa_opt_tuple_size),
           ?PASS(ssa_opt_record),
-
-          %% Run ssa_opt_cse twice, because it will help ssa_opt_dead,
-          %% and ssa_opt_dead will help ssa_opt_cse.
-          %%
-          %% Run ssa_opt_live twice, because it will help ssa_opt_dead
-          %% and ssa_opt_dead will help ssa_opt_live.
-          %%
-          %% Run beam_ssa_type twice, because there will be more
-          %% opportunities for optimizations after running beam_ssa_dead.
-          ?PASS(ssa_opt_cse),
-          ?PASS(ssa_opt_type),
-          ?PASS(ssa_opt_live),
+          ?PASS(ssa_opt_cse),                   %Helps the first type pass.
+          ?PASS(ssa_opt_type_start)],
+    passes_1(Ps, Opts).
+
+%% These passes all benefit from each other (in roughly this order), so they
+%% are repeated as required.
+repeated_passes(Opts) ->
+    Ps = [?PASS(ssa_opt_live),
           ?PASS(ssa_opt_bs_puts),
           ?PASS(ssa_opt_dead),
-          ?PASS(ssa_opt_cse),                   %Second time.
-          ?PASS(ssa_opt_float),
-          ?PASS(ssa_opt_type),                  %Second time.
-          ?PASS(ssa_opt_live),                  %Second time.
+          ?PASS(ssa_opt_cse),
+          ?PASS(ssa_opt_type_continue)],        %Must run after ssa_opt_dead to
+                                                %clean up phi nodes.
+    passes_1(Ps, Opts).
 
+epilogue_passes(Opts) ->
+    Ps = [?PASS(ssa_opt_type_finish),
+          ?PASS(ssa_opt_float),
+          ?PASS(ssa_opt_live),                  %One last time to clean up the
+                                                %mess left by the float pass.
           ?PASS(ssa_opt_bsm),
           ?PASS(ssa_opt_bsm_units),
           ?PASS(ssa_opt_bsm_shortcut),
@@ -81,6 +174,9 @@ passes(Opts0) ->
           ?PASS(ssa_opt_sink),
           ?PASS(ssa_opt_merge_blocks),
           ?PASS(ssa_opt_trim_unreachable)],
+    passes_1(Ps, Opts).
+
+passes_1(Ps, Opts0) ->
     Negations = [{list_to_atom("no_"++atom_to_list(N)),N} ||
                     {N,_} <- Ps],
     Opts = proplists:substitute_negations(Negations, Opts0),
@@ -92,36 +188,132 @@ passes(Opts0) ->
              {NoName,fun(S) -> S end}
      end || {Name,_}=P <- Ps].
 
-function(#b_function{anno=Anno,bs=Blocks0,args=Args,cnt=Count0}=F, Ps) ->
+%% Builds a function information map with basic information about incoming and
+%% outgoing local calls, as well as whether the function is exported.
+-spec build_func_db(#b_module{}) -> func_info_db().
+build_func_db(#b_module{body=Fs,exports=Exports}) ->
     try
-        St = #st{ssa=Blocks0,args=Args,cnt=Count0},
-        #st{ssa=Blocks,cnt=Count} = compile:run_sub_passes(Ps, St),
-        F#b_function{bs=Blocks,cnt=Count}
+        fdb_1(Fs, gb_sets:from_list(Exports), #{})
     catch
-        Class:Error:Stack ->
-            #{func_info:={_,Name,Arity}} = Anno,
-            io:fwrite("Function: ~w/~w\n", [Name,Arity]),
-            erlang:raise(Class, Error, Stack)
+        %% All module-level optimizations are invalid when a NIF can override a
+        %% function, so we have to bail out.
+        throw:load_nif -> #{}
     end.
 
+fdb_1([#b_function{ args=Args,bs=Bs }=F | Fs], Exports, FuncDb0) ->
+    Id = get_func_id(F),
+
+    #b_local{name=#b_literal{val=Name}, arity=Arity} = Id,
+    Exported = gb_sets:is_element({Name, Arity}, Exports),
+    ArgTypes = duplicate(length(Args), #{}),
+
+    FuncDb1 = case FuncDb0 of
+                  %% We may have an entry already if someone's called us.
+                  #{ Id := Info } ->
+                      FuncDb0#{ Id := Info#func_info{ exported=Exported,
+                                                      arg_types=ArgTypes }};
+                  #{} ->
+                      FuncDb0#{ Id => #func_info{ exported=Exported,
+                                                  arg_types=ArgTypes }}
+              end,
+
+    FuncDb = beam_ssa:fold_rpo(fun(_L, #b_blk{is=Is}, FuncDb) ->
+                                       fdb_is(Is, Id, FuncDb)
+                               end, FuncDb1, Bs),
+
+    fdb_1(Fs, Exports, FuncDb);
+fdb_1([], _Exports, FuncDb) ->
+    FuncDb.
+
+fdb_is([#b_set{op=call,
+               args=[#b_local{}=Callee | _]} | Is],
+       Caller, FuncDb) ->
+    fdb_is(Is, Caller, fdb_update(Caller, Callee, FuncDb));
+fdb_is([#b_set{op=call,
+               args=[#b_remote{mod=#b_literal{val=erlang},
+                               name=#b_literal{val=load_nif}},
+                     _Path, _LoadInfo]} | _Is], _Caller, _FuncDb) ->
+    throw(load_nif);
+fdb_is([_ | Is], Caller, FuncDb) ->
+    fdb_is(Is, Caller, FuncDb);
+fdb_is([], _Caller, FuncDb) ->
+    FuncDb.
+
+fdb_update(Caller, Callee, FuncDb) ->
+    CallerVertex = maps:get(Caller, FuncDb, #func_info{}),
+    CalleeVertex = maps:get(Callee, FuncDb, #func_info{}),
+
+    Calls = ordsets:add_element(Callee, CallerVertex#func_info.out),
+    CalledBy = ordsets:add_element(Caller, CalleeVertex#func_info.in),
+
+    FuncDb#{ Caller => CallerVertex#func_info{out=Calls},
+             Callee => CalleeVertex#func_info{in=CalledBy} }.
+
+%% Returns the post-order of all local calls in this module. That is, it starts
+%% with the functions that don't call any others and then walks up the call
+%% chain.
+%%
+%% Functions where module-level optimization is disabled are added last in
+%% arbitrary order.
+
+get_call_order_po(StMap, FuncDb) ->
+    Leaves = maps:fold(fun(Id, #func_info{out=[]}, Acc) ->
+                               [Id | Acc];
+                          (_, _, Acc) ->
+                               Acc
+                       end, [], FuncDb),
+
+    Order = gco_po_1(sort(Leaves), FuncDb, [], #{}),
+
+    Order ++ maps:fold(fun(K, _V, Acc) ->
+                               case is_map_key(K, FuncDb) of
+                                   false -> [K | Acc];
+                                   true -> Acc
+                               end
+                       end, [], StMap).
+
+gco_po_1([Id | Ids], FuncDb, Children, Seen) when not is_map_key(Id, Seen) ->
+    [Id | gco_po_1(Ids, FuncDb, [Id | Children], Seen#{ Id => true })];
+gco_po_1([_Id | Ids], FuncDb, Children, Seen) ->
+    gco_po_1(Ids, FuncDb, Children, Seen);
+gco_po_1([], FuncDb, [_|_]=Children, Seen) ->
+    gco_po_1(gco_po_parents(Children, FuncDb), FuncDb, [], Seen);
+gco_po_1([], _FuncDb, [], _Seen) ->
+    [].
+
+gco_po_parents([Child | Children], FuncDb) ->
+    #{ Child := #func_info{in=Parents}} = FuncDb,
+    Parents ++ gco_po_parents(Children, FuncDb);
+gco_po_parents([], _FuncDb) ->
+    [].
+
 %%%
 %%% Trivial sub passes.
 %%%
 
-ssa_opt_dead(#st{ssa=Linear}=St) ->
-    St#st{ssa=beam_ssa_dead:opt(Linear)}.
+ssa_opt_dead({#st{ssa=Linear}=St, FuncDb}) ->
+    {St#st{ssa=beam_ssa_dead:opt(Linear)}, FuncDb}.
+
+ssa_opt_linearize({#st{ssa=Blocks}=St, FuncDb}) ->
+    {St#st{ssa=beam_ssa:linearize(Blocks)}, FuncDb}.
 
-ssa_opt_linearize(#st{ssa=Blocks}=St) ->
-    St#st{ssa=beam_ssa:linearize(Blocks)}.
+ssa_opt_type_start({#st{ssa=Linear0,args=Args,anno=Anno}=St0, FuncDb0}) ->
+    {Linear, FuncDb} = beam_ssa_type:opt_start(Linear0, Args, Anno, FuncDb0),
+    {St0#st{ssa=Linear}, FuncDb}.
 
-ssa_opt_type(#st{ssa=Linear,args=Args}=St) ->
-    St#st{ssa=beam_ssa_type:opt(Linear, Args)}.
+ssa_opt_type_continue({#st{ssa=Linear0,args=Args,anno=Anno}=St0, FuncDb0}) ->
+    {Linear, FuncDb} = beam_ssa_type:opt_continue(Linear0, Args, Anno, FuncDb0),
+    {St0#st{ssa=Linear}, FuncDb}.
 
-ssa_opt_blockify(#st{ssa=Linear}=St) ->
-    St#st{ssa=maps:from_list(Linear)}.
+ssa_opt_type_finish({#st{args=Args,anno=Anno0}=St0, FuncDb0}) ->
+    {Anno, FuncDb} = beam_ssa_type:opt_finish(Args, Anno0, FuncDb0),
+    {St0#st{anno=Anno}, FuncDb}.
 
-ssa_opt_trim_unreachable(#st{ssa=Blocks}=St) ->
-    St#st{ssa=beam_ssa:trim_unreachable(Blocks)}.
+ssa_opt_blockify({#st{ssa=Linear}=St, FuncDb}) ->
+    {St#st{ssa=maps:from_list(Linear)}, FuncDb}.
+
+ssa_opt_trim_unreachable({#st{ssa=Blocks}=St, FuncDb}) ->
+    {St#st{ssa=beam_ssa:trim_unreachable(Blocks)}, FuncDb}.
 
 %%%
 %%% Split blocks before certain instructions to enable more optimizations.
@@ -133,14 +325,14 @@ ssa_opt_trim_unreachable(#st{ssa=Blocks}=St) ->
 %%% for sinking get_tuple_element instructions.
 %%%
 
-ssa_opt_split_blocks(#st{ssa=Blocks0,cnt=Count0}=St) ->
+ssa_opt_split_blocks({#st{ssa=Blocks0,cnt=Count0}=St, FuncDb}) ->
     P = fun(#b_set{op={bif,element}}) -> true;
            (#b_set{op=call}) -> true;
            (#b_set{op=make_fun}) -> true;
            (_) -> false
         end,
     {Blocks,Count} = beam_ssa:split_blocks(P, Blocks0, Count0),
-    St#st{ssa=Blocks,cnt=Count}.
+    {St#st{ssa=Blocks,cnt=Count}, FuncDb}.
 
 %%%
 %%% Coalesce phi nodes.
@@ -164,10 +356,10 @@ ssa_opt_split_blocks(#st{ssa=Blocks0,cnt=Count0}=St) ->
 %%% different registers).
 %%%
 
-ssa_opt_coalesce_phis(#st{ssa=Blocks0}=St) ->
+ssa_opt_coalesce_phis({#st{ssa=Blocks0}=St, FuncDb}) ->
     Ls = beam_ssa:rpo(Blocks0),
     Blocks = c_phis_1(Ls, Blocks0),
-    St#st{ssa=Blocks}.
+    {St#st{ssa=Blocks}, FuncDb}.
 
 c_phis_1([L|Ls], Blocks0) ->
     case maps:get(L, Blocks0) of
@@ -247,7 +439,7 @@ c_fix_branches([], _, Blocks) -> Blocks.
 %%% be replaced with get_tuple_element/3 instructions.
 %%%
 
-ssa_opt_element(#st{ssa=Blocks}=St) ->
+ssa_opt_element({#st{ssa=Blocks}=St, FuncDb}) ->
     %% Collect the information about element instructions in this
     %% function.
     GetEls = collect_element_calls(beam_ssa:linearize(Blocks)),
@@ -259,7 +451,7 @@ ssa_opt_element(#st{ssa=Blocks}=St) ->
 
     %% For each chain, swap the first element call with the
     %% element call with the highest index.
-    St#st{ssa=swap_element_calls(Chains, Blocks)}.
+    {St#st{ssa=swap_element_calls(Chains, Blocks)}, FuncDb}.
 
 collect_element_calls([{L,#b_blk{is=Is0,last=Last}}|Bs]) ->
     case {Is0,Last} of
@@ -320,9 +512,9 @@ swap_element_calls_1([], _, Blocks) ->
 %%% when applicable.
 %%%
 
-ssa_opt_record(#st{ssa=Linear}=St) ->
+ssa_opt_record({#st{ssa=Linear}=St, FuncDb}) ->
     Blocks = maps:from_list(Linear),
-    St#st{ssa=record_opt(Linear, Blocks)}.
+    {St#st{ssa=record_opt(Linear, Blocks)}, FuncDb}.
 
 record_opt([{L,#b_blk{is=Is0,last=Last}=Blk0}|Bs], Blocks) ->
     Is = record_opt_is(Is0, Last, Blocks),
@@ -406,9 +598,9 @@ is_tagged_tuple_4([], _, _) -> no.
 %%% subexpressions across instructions that clobber the X registers.
 %%%
 
-ssa_opt_cse(#st{ssa=Linear}=St) ->
+ssa_opt_cse({#st{ssa=Linear}=St, FuncDb}) ->
     M = #{0=>#{}},
-    St#st{ssa=cse(Linear, #{}, M)}.
+    {St#st{ssa=cse(Linear, #{}, M)}, FuncDb}.
 
 cse([{L,#b_blk{is=Is0,last=Last0}=Blk}|Bs], Sub0, M0) ->
     Es0 = maps:get(L, M0),
@@ -549,13 +741,13 @@ cse_suitable(#b_set{}) -> false.
          bs :: beam_ssa:block_map()
         }).
 
-ssa_opt_float(#st{ssa=Linear0,cnt=Count0}=St) ->
+ssa_opt_float({#st{ssa=Linear0,cnt=Count0}=St, FuncDb}) ->
     NonGuards0 = float_non_guards(Linear0),
     NonGuards = gb_sets:from_list(NonGuards0),
     Blocks = maps:from_list(Linear0),
     Fs = #fs{non_guards=NonGuards,bs=Blocks},
     {Linear,Count} = float_opt(Linear0, Count0, Fs),
-    St#st{ssa=Linear,cnt=Count}.
+    {St#st{ssa=Linear,cnt=Count}, FuncDb}.
 
 float_non_guards([{L,#b_blk{is=Is}}|Bs]) ->
     case Is of
@@ -793,12 +985,12 @@ float_flush_regs(#fs{regs=Rs}) ->
 %%% with a cheaper instructions
 %%%
 
-ssa_opt_live(#st{ssa=Linear0}=St) ->
+ssa_opt_live({#st{ssa=Linear0}=St, FuncDb}) ->
     RevLinear = reverse(Linear0),
     Blocks0 = maps:from_list(RevLinear),
     Blocks = live_opt(RevLinear, #{}, Blocks0),
     Linear = beam_ssa:linearize(Blocks),
-    St#st{ssa=Linear}.
+    {St#st{ssa=Linear}, FuncDb}.
 
 live_opt([{L,Blk0}|Bs], LiveMap0, Blocks) ->
     Blk1 = beam_ssa_share:block(Blk0, Blocks),
@@ -911,10 +1103,10 @@ live_opt_unused(_) -> keep.
 %%%   with bs_test_tail.
 %%%
 
-ssa_opt_bsm(#st{ssa=Linear}=St) ->
+ssa_opt_bsm({#st{ssa=Linear}=St, FuncDb}) ->
     Extracted0 = bsm_extracted(Linear),
     Extracted = cerl_sets:from_list(Extracted0),
-    St#st{ssa=bsm_skip(Linear, Extracted)}.
+    {St#st{ssa=bsm_skip(Linear, Extracted)}, FuncDb}.
 
 bsm_skip([{L,#b_blk{is=Is0}=Blk}|Bs0], Extracted) ->
     Bs = bsm_skip(Bs0, Extracted),
@@ -924,9 +1116,10 @@ bsm_skip([], _) -> [].
 
 bsm_skip_is([I0|Is], Extracted) ->
     case I0 of
-        #b_set{op=bs_match,args=[#b_literal{val=string}|_]} ->
-            [I0|bsm_skip_is(Is, Extracted)];
-        #b_set{op=bs_match,dst=Ctx,args=[Type,PrevCtx|Args0]} ->
+        #b_set{op=bs_match,
+               dst=Ctx,
+               args=[#b_literal{val=T}=Type,PrevCtx|Args0]}
+          when T =/= string, T =/= skip ->
             I = case cerl_sets:is_element(Ctx, Extracted) of
                     true ->
                         I0;
@@ -1011,14 +1204,14 @@ coalesce_skips_is(_, _, _) ->
 %%% Short-cutting binary matching instructions.
 %%%
 
-ssa_opt_bsm_shortcut(#st{ssa=Linear}=St) ->
+ssa_opt_bsm_shortcut({#st{ssa=Linear}=St, FuncDb}) ->
     Positions = bsm_positions(Linear, #{}),
     case map_size(Positions) of
         0 ->
             %% No binary matching instructions.
-            St;
+            {St, FuncDb};
         _ ->
-            St#st{ssa=bsm_shortcut(Linear, Positions)}
+            {St#st{ssa=bsm_shortcut(Linear, Positions)}, FuncDb}
     end.
 
 bsm_positions([{L,#b_blk{is=Is,last=Last}}|Bs], PosMap0) ->
@@ -1080,8 +1273,8 @@ bsm_shortcut([], _PosMap) -> [].
 %%% Eliminate redundant bs_test_unit2 instructions.
 %%%
 
-ssa_opt_bsm_units(#st{ssa=Linear}=St) ->
-    St#st{ssa=bsm_units(Linear, #{})}.
+ssa_opt_bsm_units({#st{ssa=Linear}=St, FuncDb}) ->
+    {St#st{ssa=bsm_units(Linear, #{})}, FuncDb}.
 
 bsm_units([{L,#b_blk{last=#b_br{succ=Succ,fail=Fail}}=Block0} | Bs], UnitMaps0) ->
     UnitsIn = maps:get(L, UnitMaps0, #{}),
@@ -1189,9 +1382,9 @@ bsm_units_join_1([], _MapA, Right) ->
 %%% to bs_put_string instructions in later pass.
 %%%
 
-ssa_opt_bs_puts(#st{ssa=Linear0,cnt=Count0}=St) ->
+ssa_opt_bs_puts({#st{ssa=Linear0,cnt=Count0}=St, FuncDb}) ->
     {Linear,Count} = opt_bs_puts(Linear0, Count0, []),
-    St#st{ssa=Linear,cnt=Count}.
+    {St#st{ssa=Linear,cnt=Count}, FuncDb}.
 
 opt_bs_puts([{L,#b_blk{is=Is}=Blk0}|Bs], Count0, Acc0) ->
     case Is of
@@ -1409,9 +1602,9 @@ opt_bs_put_split_int_1(Int, L, R) ->
 %%% is_tuple_of_arity instruction by the loader.
 %%%
 
-ssa_opt_tuple_size(#st{ssa=Linear0,cnt=Count0}=St) ->
+ssa_opt_tuple_size({#st{ssa=Linear0,cnt=Count0}=St, FuncDb}) ->
     {Linear,Count} = opt_tup_size(Linear0, Count0, []),
-    St#st{ssa=Linear,cnt=Count}.
+    {St#st{ssa=Linear,cnt=Count}, FuncDb}.
 
 opt_tup_size([{L,#b_blk{is=Is,last=Last}=Blk}|Bs], Count0, Acc0) ->
     case {Is,Last} of
@@ -1484,9 +1677,9 @@ opt_tup_size_is([], _, _, _Acc) -> none.
 %%% is 'true' or 'false' can be rewritten to a is_boolean test.
 %%%
 
-ssa_opt_sw(#st{ssa=Linear0,cnt=Count0}=St) ->
+ssa_opt_sw({#st{ssa=Linear0,cnt=Count0}=St, FuncDb}) ->
     {Linear,Count} = opt_sw(Linear0, #{}, Count0, []),
-    St#st{ssa=Linear,cnt=Count}.
+    {St#st{ssa=Linear,cnt=Count}, FuncDb}.
 
 opt_sw([{L,#b_blk{is=Is,last=#b_switch{}=Last0}=Blk0}|Bs], Phis0, Count0, Acc) ->
     Phis = opt_sw_phis(Is, Phis0),
@@ -1577,9 +1770,10 @@ opt_sw_literals([], Acc) -> Acc.
 %%% Merge blocks.
 %%%
 
-ssa_opt_merge_blocks(#st{ssa=Blocks}=St) ->
+ssa_opt_merge_blocks({#st{ssa=Blocks}=St, FuncDb}) ->
     Preds = beam_ssa:predecessors(Blocks),
-    St#st{ssa=merge_blocks_1(beam_ssa:rpo(Blocks), Preds, Blocks)}.
+    Merged = merge_blocks_1(beam_ssa:rpo(Blocks), Preds, Blocks),
+    {St#st{ssa=Merged}, FuncDb}.
 
 merge_blocks_1([L|Ls], Preds0, Blocks0) ->
     case Preds0 of
@@ -1589,6 +1783,7 @@ merge_blocks_1([L|Ls], Preds0, Blocks0) ->
                 true ->
                     #b_blk{is=Is0} = Blk0,
                     #b_blk{is=Is1} = Blk1,
+                    verify_merge_is(Is1),
                     Is = Is0 ++ Is1,
                     Blk = Blk1#b_blk{is=Is},
                     Blocks1 = maps:remove(L, Blocks0),
@@ -1614,6 +1809,13 @@ merge_update_preds([], _, _, Preds) -> Preds.
 rename_label(From, From, To) -> To;
 rename_label(Lbl, _, _) -> Lbl.
 
+verify_merge_is([#b_set{op=Op}|_]) ->
+    %% The merged block has only one predecessor, so it should not have any phi
+    %% nodes.
+    true = Op =/= phi;                          %Assertion.
+verify_merge_is(_) ->
+    ok.
+
 is_merge_allowed(_, _, #b_blk{is=[#b_set{op=peek_message}|_]}) ->
     false;
 is_merge_allowed(L, Blk0, #b_blk{}) ->
@@ -1638,7 +1840,7 @@ is_merge_allowed(L, Blk0, #b_blk{}) ->
 %%% extracted values.
 %%%
 
-ssa_opt_sink(#st{ssa=Blocks0}=St) ->
+ssa_opt_sink({#st{ssa=Blocks0}=St, FuncDb}) ->
     Linear = beam_ssa:linearize(Blocks0),
 
     %% Create a map with all variables that define get_tuple_element
@@ -1679,7 +1881,7 @@ ssa_opt_sink(#st{ssa=Blocks0}=St) ->
                            From = maps:get(V, Defs),
                            move_defs(V, From, To, A)
                    end, Blocks0, DefLoc),
-    St#st{ssa=Blocks}.
+    {St#st{ssa=Blocks}, FuncDb}.
 
 def_blocks([{L,#b_blk{is=Is}}|Bs]) ->
     def_blocks_is(Is, L, def_blocks(Bs));
diff --git a/lib/compiler/src/beam_ssa_opt.hrl b/lib/compiler/src/beam_ssa_opt.hrl
new file mode 100644
index 0000000000..37711a6f48
--- /dev/null
+++ b/lib/compiler/src/beam_ssa_opt.hrl
@@ -0,0 +1,53 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2019. 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%
+%%
+
+-include("beam_ssa.hrl").
+
+-record(func_info,
+        {%% Local calls going in/out of this function.
+         in = ordsets:new() :: ordsets:ordset(func_id()),
+         out = ordsets:new() :: ordsets:ordset(func_id()),
+
+         %% Whether the function is exported or not; some optimizations may
+         %% need to be suppressed if it is.
+         exported = true :: boolean(),
+
+         %% The inferred types of each argument (as opposed to parameter),
+         %% indexed by call site.
+         %%
+         %% This is more effective than the naive approach of joining into a
+         %% "parameter_type" as we go as it lets us narrow parameter types
+         %% without having to visit all callers on each pass, which helps a lot
+         %% when dealing with co-recursive functions.
+         arg_types = [] :: list(arg_type_map()),
+
+         %% The inferred return type of this function, this is either [type()]
+         %% or [] to note absence.
+         ret_type = [] :: list()}).
+
+-type arg_key() :: {CallerId :: func_id(),
+                    CallDst :: beam_ssa:b_var()}.
+-type arg_type_map() :: #{ arg_key() => term() }.
+
+%% Per-function metadata used by various optimization passes to perform
+%% module-level optimization. If a function is absent it means that
+%% module-level optimization has been turned off for said function.
+-type func_id() :: beam_ssa:b_local().
+-type func_info_db() :: #{ func_id() => #func_info{} }.
diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl
index 39b778f174..9b2bb65911 100644
--- a/lib/compiler/src/beam_ssa_pre_codegen.erl
+++ b/lib/compiler/src/beam_ssa_pre_codegen.erl
@@ -1031,7 +1031,7 @@ need_frame_1([#b_set{op=call,args=[Func|_]}|Is], Context) ->
     case Func of
         #b_remote{mod=#b_literal{val=Mod},
                   name=#b_literal{val=Name},
-                  arity=Arity} ->
+                  arity=Arity} when is_atom(Mod), is_atom(Name) ->
             case erl_bifs:is_exit_bif(Mod, Name, Arity) of
                 true ->
                     false;
@@ -1993,6 +1993,12 @@ reserve_zregs(Blocks, Intervals, Res) ->
         end,
     beam_ssa:fold_rpo(F, [0], Res, Blocks).
 
+reserve_zreg([#b_set{op=call,dst=Dst}],
+              #b_br{bool=Dst}, _ShortLived, A) ->
+    %% If type optimization has determined that the result of a call can be
+    %% used directly in a branch, we must avoid reserving a z register or code
+    %% generation will fail.
+    A;
 reserve_zreg([#b_set{op={bif,tuple_size},dst=Dst},
               #b_set{op={bif,'=:='},args=[Dst,Val]}], Last, ShortLived, A0) ->
     case {Val,Last} of
diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl
index ede57875e2..38ea5e6914 100644
--- a/lib/compiler/src/beam_ssa_type.erl
+++ b/lib/compiler/src/beam_ssa_type.erl
@@ -19,19 +19,22 @@
 %%
 
 -module(beam_ssa_type).
--export([opt/2]).
+-export([opt_start/4, opt_continue/4, opt_finish/3]).
 
--include("beam_ssa.hrl").
+-include("beam_ssa_opt.hrl").
 -import(lists, [all/2,any/2,droplast/1,foldl/3,last/1,member/2,
                 partition/2,reverse/1,sort/1]).
 
 -define(UNICODE_INT, #t_integer{elements={0,16#10FFFF}}).
 
--record(d, {ds :: #{beam_ssa:b_var():=beam_ssa:b_set()},
-            ls :: #{beam_ssa:label():=type_db()},
-            once :: cerl_sets:set(beam_ssa:b_var()),
-            sub :: #{beam_ssa:b_var():=beam_ssa:value()}
-           }).
+-record(d,
+        {ds :: #{beam_ssa:b_var():=beam_ssa:b_set()},
+         ls :: #{beam_ssa:label():=type_db()},
+         once :: cerl_sets:set(beam_ssa:b_var()),
+         func_id :: func_id(),
+         func_db :: func_info_db(),
+         sub = #{} :: #{beam_ssa:b_var():=beam_ssa:value()},
+         ret_type = [] :: [type()]}).
 
 -define(ATOM_SET_SIZE, 5).
 
@@ -49,36 +52,155 @@
                 {'binary',pos_integer()} | 'cons' | 'float' | 'list' | 'map' | 'nil' |'number'.
 -type type_db() :: #{beam_ssa:var_name():=type()}.
 
--spec opt([{Label0,Block0}], Args) -> [{Label,Block}] when
-      Label0 :: beam_ssa:label(),
-      Block0 :: beam_ssa:b_blk(),
+-spec opt_start(Linear, Args, Anno, FuncDb) -> {Linear, FuncDb} when
+      Linear :: [{non_neg_integer(), beam_ssa:b_blk()}],
       Args :: [beam_ssa:b_var()],
-      Label :: beam_ssa:label(),
-      Block :: beam_ssa:b_blk().
-
-opt(Linear, Args) ->
-    UsedOnce = used_once(Linear, Args),
+      Anno :: beam_ssa:anno(),
+      FuncDb :: func_info_db().
+opt_start(Linear, Args, Anno, FuncDb) ->
+    %% This is the first run through the module, so our arg_types can be
+    %% incomplete as we may not have visited all call sites at least once.
     Ts = maps:from_list([{V,any} || #b_var{}=V <- Args]),
+    opt_continue_1(Linear, Args, get_func_id(Anno), Ts, FuncDb).
+
+-spec opt_continue(Linear, Args, Anno, FuncDb) -> {Linear, FuncDb} when
+      Linear :: [{non_neg_integer(), beam_ssa:b_blk()}],
+      Args :: [beam_ssa:b_var()],
+      Anno :: beam_ssa:anno(),
+      FuncDb :: func_info_db().
+opt_continue(Linear, Args, Anno, FuncDb) ->
+    Id = get_func_id(Anno),
+    case FuncDb of
+        #{ Id := #func_info{exported=false,arg_types=ArgTypes} } ->
+            %% This is a local function and we're guaranteed to have visited
+            %% every call site at least once, so we know that the parameter
+            %% types are at least as narrow as the join of all argument types.
+            Ts = join_arg_types(Args, ArgTypes, Anno),
+            opt_continue_1(Linear, Args, Id, Ts, FuncDb);
+        #{} ->
+            %% We can't infer the parameter types of exported functions, nor
+            %% the ones where module-level optimization is disabled, but
+            %% running the pass again could still help other functions.
+            Ts = maps:from_list([{V,any} || #b_var{}=V <- Args]),
+            opt_continue_1(Linear, Args, Id, Ts, FuncDb)
+    end.
+
+join_arg_types(Args, ArgTypes, Anno) ->
+    %% We suppress type optimization for parameters that have already been
+    %% optimized by another pass, as they may have done things we have no idea
+    %% how to interpret and running them over could generate incorrect code.
+    ParamTypes = maps:get(parameter_type_info, Anno, #{}),
+    Ts0 = join_arg_types_1(Args, ArgTypes, #{}),
+    maps:fold(fun(Arg, _V, Ts) ->
+                      maps:put(Arg, any, Ts)
+              end, Ts0, ParamTypes).
+
+join_arg_types_1([Arg | Args], [TM | TMs], Ts) when map_size(TM) =/= 0 ->
+    join_arg_types_1(Args, TMs, Ts#{ Arg => join(maps:values(TM))});
+join_arg_types_1([Arg | Args], [_TM | TMs], Ts) ->
+    join_arg_types_1(Args, TMs, Ts#{ Arg => any });
+join_arg_types_1([], [], Ts) ->
+    Ts.
+
+-spec opt_continue_1(Linear, Args, Id, Ts, FuncDb) -> Result when
+      Linear :: [{non_neg_integer(), beam_ssa:b_blk()}],
+      Args :: [beam_ssa:b_var()],
+      Id :: func_id(),
+      Ts :: type_db(),
+      FuncDb :: func_info_db(),
+      Result :: {Linear, FuncDb}.
+opt_continue_1(Linear0, Args, Id, Ts, FuncDb0) ->
+    UsedOnce = used_once(Linear0, Args),
     FakeCall = #b_set{op=call,args=[#b_remote{mod=#b_literal{val=unknown},
                                               name=#b_literal{val=unknown},
                                               arity=0}]},
     Defs = maps:from_list([{Var,FakeCall#b_set{dst=Var}} ||
                               #b_var{}=Var <- Args]),
-    D = #d{ds=Defs,ls=#{0=>Ts,?BADARG_BLOCK=>#{}},
-           once=UsedOnce,sub=#{}},
-    opt_1(Linear, D).
 
-opt_1([{L,Blk}|Bs], #d{ls=Ls}=D) ->
+    D = #d{ func_db=FuncDb0,
+            func_id=Id,
+            ds=Defs,
+            ls=#{0=>Ts,?BADARG_BLOCK=>#{}},
+            once=UsedOnce },
+
+    {Linear, FuncDb, NewRet} = opt_1(Linear0, D, []),
+
+    case FuncDb of
+        #{ Id := Entry0 } ->
+            Entry = Entry0#func_info{ret_type=NewRet},
+            {Linear, FuncDb#{ Id := Entry }};
+        #{} ->
+            %% Module-level optimizations have been turned off for this
+            %% function.
+            {Linear, FuncDb}
+    end.
+
+-spec opt_finish(Args, Anno, FuncDb) -> {Anno, FuncDb} when
+      Args :: [beam_ssa:b_var()],
+      Anno :: beam_ssa:anno(),
+      FuncDb :: func_info_db().
+opt_finish(Args, Anno, FuncDb) ->
+    Id = get_func_id(Anno),
+    case FuncDb of
+        #{ Id := #func_info{exported=false,arg_types=ArgTypes} } ->
+            ParamInfo0 = maps:get(parameter_type_info, Anno, #{}),
+            ParamInfo = opt_finish_1(Args, ArgTypes, ParamInfo0),
+            {Anno#{ parameter_type_info => ParamInfo }, FuncDb};
+        #{} ->
+            {Anno, FuncDb}
+    end.
+
+opt_finish_1([Arg | Args], [TypeMap | TypeMaps], ParamInfo)
+  when is_map_key(Arg, ParamInfo); %% See join_arg_types/3
+       map_size(TypeMap) =:= 0 ->
+    opt_finish_1(Args, TypeMaps, ParamInfo);
+opt_finish_1([Arg | Args], [TypeMap | TypeMaps], ParamInfo0) ->
+    case join(maps:values(TypeMap)) of
+        any ->
+            opt_finish_1(Args, TypeMaps, ParamInfo0);
+        JoinedType ->
+            JoinedType = verified_type(JoinedType),
+            ParamInfo = ParamInfo0#{ Arg => validator_anno(JoinedType) },
+            opt_finish_1(Args, TypeMaps, ParamInfo)
+    end;
+opt_finish_1([], [], ParamInfo) ->
+    ParamInfo.
+
+validator_anno(#t_tuple{size=Size,exact=Exact}) ->
+    beam_validator:type_anno(tuple, Size, Exact);
+validator_anno(#t_integer{elements={Same,Same}}) ->
+    beam_validator:type_anno(integer, Same);
+validator_anno(#t_integer{}) ->
+    beam_validator:type_anno(integer);
+validator_anno(float) ->
+    beam_validator:type_anno(float);
+validator_anno(#t_atom{elements=[Val]}) ->
+    beam_validator:type_anno(atom, Val);
+validator_anno(#t_atom{}=A) ->
+    case t_is_boolean(A) of
+        true -> beam_validator:type_anno(bool);
+        false -> beam_validator:type_anno(atom)
+    end;
+validator_anno(T) ->
+    beam_validator:type_anno(T).
+
+get_func_id(Anno) ->
+    #{func_info:={_Mod, Name, Arity}} = Anno,
+    #b_local{name=#b_literal{val=Name}, arity=Arity}.
+
+opt_1([{L,Blk}|Bs], #d{ls=Ls}=D, Acc) ->
     case Ls of
         #{L:=Ts} ->
-            opt_2(L, Blk, Bs, Ts, D);
+            opt_2(L, Blk, Bs, Ts, D, Acc);
         #{} ->
             %% This block is never reached. Discard it.
-            opt_1(Bs, D)
+            opt_1(Bs, D, Acc)
     end;
-opt_1([], #d{}) -> [].
+opt_1([], D, Acc) ->
+    #d{func_db=FuncDb,ret_type=NewRet} = D,
+    {reverse(Acc), FuncDb, NewRet}.
 
-opt_2(L, #b_blk{is=Is0}=Blk0, Bs, Ts, #d{sub=Sub}=D0) ->
+opt_2(L, #b_blk{is=Is0}=Blk0, Bs, Ts, #d{sub=Sub}=D0, Acc) ->
     case Is0 of
         [#b_set{op=call,dst=Dst,
                 args=[#b_remote{mod=#b_literal{val=Mod},
@@ -94,34 +216,43 @@ opt_2(L, #b_blk{is=Is0}=Blk0, Bs, Ts, #d{sub=Sub}=D0) ->
                     Ret = #b_ret{arg=Dst},
                     Blk = Blk0#b_blk{is=[I],last=Ret},
                     Ls = maps:remove(L, D0#d.ls),
-                    D = D0#d{ls=Ls},
-                    [{L,Blk}|opt_1(Bs, D)];
+
+                    %% We potentially lack a return value.
+                    RetType = join([none | D0#d.ret_type]),
+
+                    D = D0#d{ls=Ls,ret_type=[RetType]},
+                    opt_1(Bs, D, [{L,Blk} | Acc]);
                 false ->
-                    opt_3(L, Blk0, Bs, Ts, D0)
+                    opt_3(L, Blk0, Bs, Ts, D0, Acc)
             end;
         _ ->
-            opt_3(L, Blk0, Bs, Ts, D0)
+            opt_3(L, Blk0, Bs, Ts, D0, Acc)
     end.
 
 opt_3(L, #b_blk{is=Is0,last=Last0}=Blk0, Bs, Ts0,
-      #d{ds=Ds0,ls=Ls0,sub=Sub0}=D0) ->
-    {Is,Ts,Ds,Sub} = opt_is(Is0, Ts0, Ds0, Ls0, Sub0, []),
-    D1 = D0#d{ds=Ds,sub=Sub},
-    Last1 = simplify_terminator(Last0, Sub, Ts),
+      #d{ds=Ds0,ls=Ls0,sub=Sub0,func_db=Fdb0}=D0, Acc) ->
+    {Is,Ts,Ds,Fdb,Sub} = opt_is(Is0, Ts0, Ds0, Fdb0, Ls0, D0, Sub0, []),
+    D1 = D0#d{ds=Ds,sub=Sub,func_db=Fdb},
+    Last1 = simplify_terminator(Last0, Sub, Ts, Ds),
     Last = opt_terminator(Last1, Ts, Ds),
     D = update_successors(Last, Ts, D1),
     Blk = Blk0#b_blk{is=Is,last=Last},
-    [{L,Blk}|opt_1(Bs, D)].
+    opt_1(Bs, D, [{L,Blk} | Acc]).
 
-simplify_terminator(#b_br{bool=Bool}=Br, Sub, Ts) ->
+simplify_terminator(#b_br{bool=Bool}=Br, Sub, Ts, _Ds) ->
     Br#b_br{bool=simplify_arg(Bool, Sub, Ts)};
-simplify_terminator(#b_switch{arg=Arg}=Sw, Sub, Ts) ->
+simplify_terminator(#b_switch{arg=Arg}=Sw, Sub, Ts, _Ds) ->
     Sw#b_switch{arg=simplify_arg(Arg, Sub, Ts)};
-simplify_terminator(#b_ret{arg=Arg}=Ret, Sub, Ts) ->
-    Ret#b_ret{arg=simplify_arg(Arg, Sub, Ts)}.
+simplify_terminator(#b_ret{arg=Arg}=Ret, Sub, Ts, Ds) ->
+    %% Reducing the result of a call to a literal (fairly common for 'ok')
+    %% breaks tail call optimization.
+    case Ds of
+        #{ Arg := #b_set{op=call}} -> Ret;
+        #{} -> Ret#b_ret{arg=simplify_arg(Arg, Sub, Ts)}
+    end.
 
 opt_is([#b_set{op=phi,dst=Dst,args=Args0}=I0|Is],
-       Ts0, Ds0, Ls, Sub0, Acc) ->
+       Ts0, Ds0, Fdb, Ls, D, Sub0, Acc) ->
     %% Simplify the phi node by removing all predecessor blocks that no
     %% longer exists or no longer branches to this block.
     Args = [{simplify_arg(Arg, Sub0, Ts0),From} ||
@@ -132,28 +263,61 @@ opt_is([#b_set{op=phi,dst=Dst,args=Args0}=I0|Is],
             %% value or if the values are identical.
             [{Val,_}|_] = Args,
             Sub = Sub0#{Dst=>Val},
-            opt_is(Is, Ts0, Ds0, Ls, Sub, Acc);
+            opt_is(Is, Ts0, Ds0, Fdb, Ls, D, Sub, Acc);
         false ->
             I = I0#b_set{args=Args},
             Ts = update_types(I, Ts0, Ds0),
             Ds = Ds0#{Dst=>I},
-            opt_is(Is, Ts, Ds, Ls, Sub0, [I|Acc])
+            opt_is(Is, Ts, Ds, Fdb, Ls, D, Sub0, [I|Acc])
     end;
-opt_is([#b_set{op=succeeded,args=Args0,dst=Dst}=I],
-       Ts0, Ds0, Ls, Sub0, Acc) ->
-    Args = simplify_args(Args0, Sub0, Ts0),
-    Type = type(succeeded, Args, Ts0, Ds0),
-    case get_literal_from_type(Type) of
-        #b_literal{}=Lit ->
-            Sub = Sub0#{Dst=>Lit},
-            opt_is([], Ts0, Ds0, Ls, Sub, Acc);
-        none ->
+opt_is([#b_set{op=call,args=Args0,dst=Dst}=I0 | Is],
+       Ts0, Ds0, Fdb0, Ls, D, Sub, Acc) ->
+    Args = simplify_args(Args0, Sub, Ts0),
+    I1 = beam_ssa:normalize(I0#b_set{args=Args}),
+
+    %% This is a bit of a kludge; we know that any instruction whose return
+    %% type is 'none' will fail at runtime, but we don't yet have a way to cut
+    %% a block short so we move on like nothing nothing happened.
+    %%
+    %% This complicates argument type optimization as unreachable calls can
+    %% add types that will never occur, so we skip optimizing this call if
+    %% the type of any of its arguments is 'none'.
+    [_Callee | Rest] = Args,
+    case all(fun(Arg) -> get_type(Arg, Ts0) =/= none end, Rest) of
+        true ->
+            {Ts, Ds, Fdb, I} = opt_call(I1, D, Ts0, Ds0, Fdb0),
+            opt_is(Is, Ts, Ds, Fdb, Ls, D, Sub, [I|Acc]);
+        false ->
+            Ts = Ts0#{ Dst => any },
+            Ds = Ds0#{ Dst => I1 },
+            opt_is(Is, Ts, Ds, Fdb0, Ls, D, Sub, [I1|Acc])
+    end;
+opt_is([#b_set{op=succeeded,args=[Arg],dst=Dst}=I],
+       Ts0, Ds0, Fdb, Ls, D, Sub0, Acc) ->
+    case Ds0 of
+        #{ Arg := #b_set{op=call} } ->
+            %% The success check of a call is part of exception handling and
+            %% must not be optimized away. We still have to update its type
+            %% though.
             Ts = update_types(I, Ts0, Ds0),
             Ds = Ds0#{Dst=>I},
-            opt_is([], Ts, Ds, Ls, Sub0, [I|Acc])
+
+            opt_is([], Ts, Ds, Fdb, Ls, D, Sub0, [I|Acc]);
+        #{} ->
+            Args = simplify_args([Arg], Sub0, Ts0),
+            Type = type(succeeded, Args, Ts0, Ds0),
+            case get_literal_from_type(Type) of
+                #b_literal{}=Lit ->
+                    Sub = Sub0#{Dst=>Lit},
+                    opt_is([], Ts0, Ds0, Fdb, Ls, D, Sub, Acc);
+                none ->
+                    Ts = Ts0#{Dst=>Type},
+                    Ds = Ds0#{Dst=>I},
+                    opt_is([], Ts, Ds, Fdb, Ls, D, Sub0, [I|Acc])
+            end
     end;
 opt_is([#b_set{args=Args0,dst=Dst}=I0|Is],
-       Ts0, Ds0, Ls, Sub0, Acc) ->
+       Ts0, Ds0, Fdb, Ls, D, Sub0, Acc) ->
     Args = simplify_args(Args0, Sub0, Ts0),
     I1 = beam_ssa:normalize(I0#b_set{args=Args}),
     case simplify(I1, Ts0) of
@@ -161,23 +325,76 @@ opt_is([#b_set{args=Args0,dst=Dst}=I0|Is],
             I = beam_ssa:normalize(I2),
             Ts = update_types(I, Ts0, Ds0),
             Ds = Ds0#{Dst=>I},
-            opt_is(Is, Ts, Ds, Ls, Sub0, [I|Acc]);
+            opt_is(Is, Ts, Ds, Fdb, Ls, D, Sub0, [I|Acc]);
         #b_literal{}=Lit ->
             Sub = Sub0#{Dst=>Lit},
-            opt_is(Is, Ts0, Ds0, Ls, Sub, Acc);
+            opt_is(Is, Ts0, Ds0, Fdb, Ls, D, Sub, Acc);
         #b_var{}=Var ->
             case Is of
                 [#b_set{op=succeeded,dst=SuccDst,args=[Dst]}] ->
                     %% We must remove this 'succeeded' instruction.
                     Sub = Sub0#{Dst=>Var,SuccDst=>#b_literal{val=true}},
-                    opt_is([], Ts0, Ds0, Ls, Sub, Acc);
+                    opt_is([], Ts0, Ds0, Fdb, Ls, D, Sub, Acc);
                 _ ->
                     Sub = Sub0#{Dst=>Var},
-                    opt_is(Is, Ts0, Ds0, Ls, Sub, Acc)
+                    opt_is(Is, Ts0, Ds0, Fdb, Ls, D, Sub, Acc)
             end
     end;
-opt_is([], Ts, Ds, _Ls, Sub, Acc) ->
-    {reverse(Acc),Ts,Ds,Sub}.
+opt_is([], Ts, Ds, Fdb, _Ls, _D, Sub, Acc) ->
+    {reverse(Acc), Ts, Ds, Fdb, Sub}.
+
+opt_call(#b_set{dst=Dst,args=[#b_local{}=Callee|Args]}=I0, D, Ts0, Ds0, Fdb0) ->
+    {Ts, Ds, I} = opt_local_call(I0, Ts0, Ds0, Fdb0),
+    case Fdb0 of
+        #{ Callee := #func_info{exported=false,arg_types=ArgTypes0}=Info } ->
+            %% Update the argument types of *this exact call*, the types
+            %% will be joined later when the callee is optimized.
+            CallId = {D#d.func_id, Dst},
+            ArgTypes = update_arg_types(Args, ArgTypes0, CallId, Ts0),
+
+            Fdb = Fdb0#{ Callee => Info#func_info{arg_types=ArgTypes} },
+            {Ts, Ds, Fdb, I};
+        #{} ->
+            %% We can't narrow the argument types of exported functions as they
+            %% can receive anything as part of an external call.
+            {Ts, Ds, Fdb0, I}
+    end;
+opt_call(#b_set{dst=Dst}=I, _D, Ts0, Ds0, Fdb) ->
+    Ts = update_types(I, Ts0, Ds0),
+    Ds = Ds0#{ Dst => I },
+    {Ts, Ds, Fdb, I}.
+
+opt_local_call(#b_set{dst=Dst,args=[Id|_]}=I0, Ts0, Ds0, Fdb) ->
+    %% We skip propagating 'none' as we don't yet have a good way to cut a
+    %% block short.
+    Type = case Fdb of
+               #{ Id := #func_info{ret_type=[T]} } when T =/= none -> T;
+               #{} -> any
+           end,
+    I = case Type of
+            any -> I0;
+            _ -> beam_ssa:add_anno(result_type, validator_anno(Type), I0)
+        end,
+    Ts = Ts0#{ Dst => Type },
+    Ds = Ds0#{ Dst => I },
+    {Ts, Ds, I}.
+
+update_arg_types([Arg | Args], [TypeMap0 | TypeMaps], CallId, Ts) ->
+    %% Match contexts are treated as bitstrings when optimizing arguments, as
+    %% we don't yet support removing the "bs_start_match3" instruction.
+    NewType = case get_type(Arg, Ts) of
+                  #t_bs_match{} -> {binary, 1};
+                  Type -> Type
+              end,
+    PrevType = maps:get(CallId, TypeMap0, NewType),
+
+    %% The new type must be narrower than the old one.
+    true = meet(NewType, PrevType) =/= none,    %Assertion.
+
+    TypeMap = TypeMap0#{ CallId => NewType },
+    [TypeMap | update_arg_types(Args, TypeMaps, CallId, Ts)];
+update_arg_types([], [], _CallId, _Ts) ->
+    [].
 
 simplify(#b_set{op={bif,'and'},args=Args}=I, Ts) ->
     case is_safe_bool_op(Args, Ts) of
@@ -309,6 +526,8 @@ simplify(#b_set{op=put_tuple,args=Args}=I, _Ts) ->
         none -> I;
         List -> #b_literal{val=list_to_tuple(List)}
     end;
+simplify(#b_set{op=wait_timeout,args=[#b_literal{val=0}]}, _Ts) ->
+    #b_literal{val=true};
 simplify(#b_set{op=wait_timeout,args=[#b_literal{val=infinity}]}=I, _Ts) ->
     I#b_set{op=wait,args=[]};
 simplify(I, _Ts) -> I.
@@ -476,19 +695,36 @@ update_successors(#b_switch{arg=#b_var{}=V,fail=Fail,list=List}, Ts0, D0) ->
                 end,
             foldl(F, D, List);
         false ->
-            FailTs = subtract_types([{V,join_sw_list(List, Ts0, none)}], Ts0),
+            %% V can not be equal to any of the values in List at the fail
+            %% block.
+            FailTs = subtract_sw_list(V, List, Ts0),
             D = update_successor(Fail, FailTs, D0),
             F = fun({Val,S}, A) ->
                         T = get_type(Val, Ts0),
                         update_successor(S, Ts0#{V=>T}, A)
                 end,
             foldl(F, D, List)
-        end;
-update_successors(#b_ret{}, _Ts, D) -> D.
+    end;
+update_successors(#b_ret{arg=Arg}, Ts, D) ->
+    FuncId = D#d.func_id,
+    case D#d.ds of
+        #{ Arg := #b_set{op=call,args=[FuncId | _]} } ->
+            %% Returning a call to ourselves doesn't affect our own return
+            %% type.
+            D;
+        #{} ->
+            RetType = join([get_type(Arg, Ts) | D#d.ret_type]),
+            D#d{ret_type=[RetType]}
+    end.
+
+subtract_sw_list(V, List, Ts) ->
+    Ts#{ V := sub_sw_list_1(get_type(V, Ts), List, Ts) }.
 
-join_sw_list([{Val,_}|T], Ts, Type) ->
-    join_sw_list(T, Ts, join(Type, get_type(Val, Ts)));
-join_sw_list([], _, Type) -> Type.
+sub_sw_list_1(Type, [{Val,_}|T], Ts) ->
+    ValType = get_type(Val, Ts),
+    sub_sw_list_1(subtract(Type, ValType), T, Ts);
+sub_sw_list_1(Type, [], _Ts) ->
+    Type.
 
 update_successor_bool(#b_var{}=Var, BoolValue, S, Ts, D) ->
     case t_is_boolean(get_type(Var, Ts)) of
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index 3d53054f69..15ed267c54 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -26,6 +26,7 @@
 
 %% Interface for compiler.
 -export([module/2, format_error/1]).
+-export([type_anno/1, type_anno/2, type_anno/3]).
 
 -import(lists, [any/2,dropwhile/2,foldl/3,map/2,foreach/2,reverse/1]).
 
@@ -44,6 +45,33 @@ module({Mod,Exp,Attr,Fs,Lc}=Code, _Opts)
 	    {error,[{atom_to_list(Mod),Es}]}
     end.
 
+%% Provides a stable interface for type annotations, used by certain passes to
+%% indicate that we can safely assume that a register has a given type.
+-spec type_anno(term()) -> term().
+type_anno(atom) -> {atom,[]};
+type_anno(bool) -> bool;
+type_anno({binary,_}) -> term;
+type_anno(cons) -> cons;
+type_anno(float) -> {float,[]};
+type_anno(integer) -> {integer,[]};
+type_anno(list) -> list;
+type_anno(map) -> map;
+type_anno(match_context) -> match_context;
+type_anno(number) -> number;
+type_anno(nil) -> nil.
+
+-spec type_anno(term(), term()) -> term().
+type_anno(atom, Value) -> {atom, Value};
+type_anno(float, Value) -> {float, Value};
+type_anno(integer, Value) -> {integer, Value}.
+
+-spec type_anno(term(), term(), term()) -> term().
+type_anno(tuple, Size, Exact) when is_integer(Size) ->
+    case Exact of
+        true -> {tuple, Size};
+        false -> {tuple, [Size]}
+    end.
+
 -spec format_error(term()) -> iolist().
 
 format_error({{_M,F,A},{I,Off,limit}}) ->
@@ -93,28 +121,6 @@ validate(Module, Fs) ->
     Ft = index_parameter_types(Fs, []),
     validate_0(Module, Fs, Ft).
 
-index_parameter_types([{function,_,_,Entry,Code0}|Fs], Acc0) ->
-    Code = dropwhile(fun({label,L}) when L =:= Entry -> false;
-			(_) -> true
-		     end, Code0),
-    case Code of
-	[{label,Entry}|Is] ->
-	    Acc = index_parameter_types_1(Is, Entry, Acc0),
-	    index_parameter_types(Fs, Acc);
-	_ ->
-	    %% Something serious is wrong. Ignore it for now.
-	    %% It will be detected and diagnosed later.
-	    index_parameter_types(Fs, Acc0)
-    end;
-index_parameter_types([], Acc) ->
-    gb_trees:from_orddict(lists:sort(Acc)).
-
-index_parameter_types_1([{'%', {type_info, Reg, Type}} | Is], Entry, Acc) ->
-    Key = {Entry, Reg},
-    index_parameter_types_1(Is, Entry, [{Key, Type} | Acc]);
-index_parameter_types_1(_, _, Acc) ->
-    Acc.
-
 validate_0(_Module, [], _) -> [];
 validate_0(Module, [{function,Name,Ar,Entry,Code}|Fs], Ft) ->
     try validate_1(Code, Name, Ar, Entry, Ft) of
@@ -167,6 +173,32 @@ validate_0(Module, [{function,Name,Ar,Entry,Code}|Fs], Ft) ->
 	 slots=0 :: non_neg_integer()		%Number of slots
 	}).
 
+index_parameter_types([{function,_,_,Entry,Code0}|Fs], Acc0) ->
+    Code = dropwhile(fun({label,L}) when L =:= Entry -> false;
+			(_) -> true
+		     end, Code0),
+    case Code of
+	[{label,Entry}|Is] ->
+	    Acc = index_parameter_types_1(Is, Entry, Acc0),
+	    index_parameter_types(Fs, Acc);
+	_ ->
+	    %% Something serious is wrong. Ignore it for now.
+	    %% It will be detected and diagnosed later.
+	    index_parameter_types(Fs, Acc0)
+    end;
+index_parameter_types([], Acc) ->
+    gb_trees:from_orddict(lists:sort(Acc)).
+
+index_parameter_types_1([{'%', {type_info, Reg, Type0}} | Is], Entry, Acc) ->
+    Type = case Type0 of
+                match_context -> #ms{};
+                _ -> Type0
+            end,
+    Key = {Entry, Reg},
+    index_parameter_types_1(Is, Entry, [{Key, Type} | Acc]);
+index_parameter_types_1(_, _, Acc) ->
+    Acc.
+
 validate_1(Is, Name, Arity, Entry, Ft) ->
     validate_2(labels(Is), Name, Arity, Entry, Ft).
 
@@ -386,25 +418,19 @@ valfun_1(remove_message, Vst) ->
     %% The message term is no longer fragile. It can be used
     %% without restrictions.
     remove_fragility(Vst);
-valfun_1({'%', {type_info, Reg, Info0}}, Vst0) ->
+valfun_1({'%', {type_info, Reg, match_context}}, Vst0) ->
+    set_aliased_type(#ms{}, Reg, Vst0);
+valfun_1({'%', {type_info, Reg, NewType0}}, Vst0) ->
     %% Explicit type information inserted by optimization passes to indicate
     %% that Reg has a certain type, so that we can accept cross-function type
     %% optimizations.
-    %%
-    %% At the moment we only allow this when narrowing from 'term' which is
-    %% what to expect with function parameters, but in theory any narrowing
-    %% conversion should be legal.
-    case get_move_term_type(Reg, Vst0) of
-        term ->
-            Type0 = case Info0 of
-                        match_context -> #ms{};
-                        _ -> Info0
-                    end,
-            Type = propagate_fragility(Type0, [Reg], Vst0),
-            set_type_reg(Type, Reg, Vst0);
-        _ ->
-            error(bad_type_info)
-    end;
+    OldType = get_durable_term_type(Reg, Vst0),
+    NewType = case meet(NewType0, OldType) of
+                   none -> error({bad_type_info, Reg, NewType0, OldType});
+                   T -> T
+              end,
+    Type = propagate_fragility(NewType, [Reg], Vst0),
+    set_aliased_type(Type, Reg, Vst0);
 valfun_1({'%',_}, Vst) ->
     Vst;
 valfun_1({line,_}, Vst) ->
@@ -643,7 +669,12 @@ valfun_4({gc_bif,Op,{f,Fail},Live,Src,Dst}, #vst{current=St0}=Vst0) ->
     Vst1 = Vst0#vst{current=St},
     Vst2 = branch_state(Fail, Vst1),
     Vst3 = prune_x_regs(Live, Vst2),
+    SrcType = get_term_type(hd(Src), Vst3),
     Vst = case Op of
+              length when SrcType =/= cons, SrcType =/= nil ->
+                  %% If we already know we have a cons cell or nil, it
+                  %% shouldn't be demoted to list.
+                  set_type(list, hd(Src), Vst3);
               map_size ->
                   set_type(map, hd(Src), Vst3);
               _ ->
@@ -786,6 +817,12 @@ valfun_4({bs_set_position, Ctx, Pos}, Vst) ->
     Vst;
 
 %% Other test instructions.
+valfun_4({test,is_atom,{f,Lbl},[Src]}, Vst) ->
+    assert_term(Src, Vst),
+    set_aliased_type({atom,[]}, Src, branch_state(Lbl, Vst));
+valfun_4({test,is_boolean,{f,Lbl},[Src]}, Vst) ->
+    assert_term(Src, Vst),
+    set_aliased_type(bool, Src, branch_state(Lbl, Vst));
 valfun_4({test,is_float,{f,Lbl},[Float]}, Vst) ->
     assert_term(Float, Vst),
     set_type({float,[]}, Float, branch_state(Lbl, Vst));
@@ -793,6 +830,9 @@ valfun_4({test,is_tuple,{f,Lbl},[Tuple]}, Vst) ->
     Type0 = get_term_type(Tuple, Vst),
     Type = upgrade_tuple_type({tuple,[0]}, Type0),
     set_aliased_type(Type, Tuple, branch_state(Lbl, Vst));
+valfun_4({test,is_integer,{f,Lbl},[Src]}, Vst) ->
+    assert_term(Src, Vst),
+    set_aliased_type({integer,[]}, Src, branch_state(Lbl, Vst));
 valfun_4({test,is_nonempty_list,{f,Lbl},[Cons]}, Vst) ->
     assert_term(Cons, Vst),
     Type = cons,
@@ -830,11 +870,11 @@ valfun_4({test,is_map,{f,Lbl},[Src]}, Vst0) ->
     end;
 valfun_4({test,is_nil,{f,Lbl},[Src]}, Vst0) ->
     Vst = case get_term_type(Src, Vst0) of
-               list ->
-                   branch_state(Lbl, set_type_reg(cons, Src, Vst0));
-               _ ->
-                   branch_state(Lbl, Vst0)
-           end,
+              list ->
+                  branch_state(Lbl, set_type_reg(cons, Src, Vst0));
+              _ ->
+                  branch_state(Lbl, Vst0)
+          end,
     set_aliased_type(nil, Src, Vst);
 valfun_4({test,is_eq_exact,{f,Lbl},[Src,Val]=Ss}, Vst0) ->
     validate_src(Ss, Vst0),
@@ -1081,39 +1121,58 @@ verify_call_args_1(N, Vst) ->
     verify_call_args_1(X, Vst).
 
 verify_local_call(Lbl, Live, Vst) ->
-    F = fun({R, _Ctx}) ->
-                verify_call_match_context(Lbl, R, Vst)
-          end,
-    MsRegs = all_ms_in_x_regs(Live, Vst),
-    verify_no_ms_aliases(MsRegs),
-    foreach(F, MsRegs).
+    F = fun({R, Type}) ->
+                verify_arg_type(Lbl, R, Type, Vst)
+        end,
+    TRegs = typed_call_regs(Live, Vst),
+    verify_no_ms_aliases(TRegs),
+    foreach(F, TRegs).
 
-all_ms_in_x_regs(0, _Vst) ->
+typed_call_regs(0, _Vst) ->
     [];
-all_ms_in_x_regs(Live0, Vst) ->
+typed_call_regs(Live0, Vst) ->
     Live = Live0 - 1,
     R = {x,Live},
-    case get_move_term_type(R, Vst) of
-        #ms{}=M -> [{R,M} | all_ms_in_x_regs(Live, Vst)];
-        _ -> all_ms_in_x_regs(Live, Vst)
-    end.
+    [{R, get_move_term_type(R, Vst)} | typed_call_regs(Live, Vst)].
 
 %% Verifies that the same match context isn't present twice.
-verify_no_ms_aliases(MsRegs) ->
-    CtxIds = [Id || {_, #ms{id=Id}} <- MsRegs],
+verify_no_ms_aliases(Regs) ->
+    CtxIds = [Id || {_, #ms{id=Id}} <- Regs],
     UniqueCtxIds = ordsets:from_list(CtxIds),
     if
         length(UniqueCtxIds) < length(CtxIds) ->
-            error({multiple_match_contexts, MsRegs});
+            error({multiple_match_contexts, Regs});
         length(UniqueCtxIds) =:= length(CtxIds) ->
             ok
     end.
 
-%% Verifies that the target label accepts match contexts in the given register.
-verify_call_match_context(Lbl, Ctx, #vst{ft=Ft}) ->
-    case gb_trees:lookup({Lbl, Ctx}, Ft) of
-        {value, match_context} -> ok;
-        none -> error(no_bs_start_match2)
+%% Verifies that the given argument narrows to what the function expects.
+verify_arg_type(Lbl, Reg, #ms{}, #vst{ft=Ft}) ->
+    %% Match contexts require explicit support, and may not be passed to a
+    %% function that accepts arbitrary terms.
+    case gb_trees:lookup({Lbl, Reg}, Ft) of
+        {value, #ms{}} -> ok;
+        _ -> error(no_bs_start_match2)
+    end;
+verify_arg_type(Lbl, Reg, GivenType, #vst{ft=Ft}) ->
+    case gb_trees:lookup({Lbl, Reg}, Ft) of
+        {value, bool} when GivenType =:= {atom, true};
+                           GivenType =:= {atom, false};
+                           GivenType =:= {atom, []} ->
+            %% We don't yet support upgrading true/false to bool, so we
+            %% assume unknown atoms can be bools when validating calls.
+            ok;
+        {value, #ms{}} ->
+            %% Functions that accept match contexts also accept all other
+            %% terms. This will change once we support union types.
+            ok;
+        {value, RequiredType} ->
+            case meet(GivenType, RequiredType) of
+                none -> error({bad_arg_type, Reg, GivenType, RequiredType});
+                _ -> ok
+            end;
+        none ->
+            ok
     end.
 
 allocate(Zero, Stk, Heap, Live, #vst{current=#st{numy=none}}=Vst0) ->
@@ -1333,27 +1392,27 @@ bsm_restore(Reg, SavePoint, Vst) ->
 	_ -> error({illegal_restore,SavePoint,range})
     end.
 
-
 select_val_branches(Src, Choices, Vst) ->
     Infer = infer_types(Src, Vst),
-    select_val_branches_1(Choices, Infer, Vst).
+    select_val_branches_1(Choices, Src, Infer, Vst).
 
-select_val_branches_1([Val,{f,L}|T], Infer, Vst0) ->
-    Vst = branch_state(L, Infer(Val, Vst0)),
-    select_val_branches_1(T, Infer, Vst);
-select_val_branches_1([], _, Vst) -> Vst.
+select_val_branches_1([Val,{f,L}|T], Src, Infer, Vst0) ->
+    Vst1 = set_aliased_type(Val, Src, Infer(Val, Vst0)),
+    Vst = branch_state(L, Vst1),
+    select_val_branches_1(T, Src, Infer, Vst);
+select_val_branches_1([], _, _, Vst) -> Vst.
 
 infer_types(Src, Vst) ->
     case get_def(Src, Vst) of
         {bif,is_map,{f,_},[Map],_} ->
-            fun({atom,true}, S) -> set_type_reg(map, Map, S);
+            fun({atom,true}, S) -> set_aliased_type(map, Map, S);
                (_, S) -> S
             end;
         {bif,tuple_size,{f,_},[Tuple],_} ->
             fun({integer,Arity}, S) ->
                     Type0 = get_term_type(Tuple, S),
                     Type = upgrade_tuple_type({tuple,Arity}, Type0),
-                    set_type(Type, Tuple, S);
+                    set_aliased_type(Type, Tuple, S);
                (_, S) -> S
             end;
         {bif,'=:=',{f,_},[ArityReg,{integer,_}=Val],_} when ArityReg =/= Src ->
@@ -1626,6 +1685,10 @@ meet(T1, T2) ->
 
 subtract(list, nil) -> cons;
 subtract(list, cons) -> nil;
+subtract(number, {integer,[]}) -> {float,[]};
+subtract(number, {float,[]}) -> {integer,[]};
+subtract(bool, {atom,false}) -> {atom, true};
+subtract(bool, {atom,true}) -> {atom, false};
 subtract(Type, _) -> Type.
 
 assert_type(WantedType, Term, Vst) ->
@@ -1841,7 +1904,7 @@ merge_regs_1([{R1,_}|Rs1], [{R2,_}|_]=Rs2) when R1 < R2 ->
 merge_regs_1([{R1,_}|_]=Rs1, [{R2,_}|Rs2]) when R1 > R2 ->
     merge_regs_1(Rs1, Rs2);
 merge_regs_1([{R,Type1}|Rs1], [{R,Type2}|Rs2]) ->
-    [{R,merge_types(Type1, Type2)}|merge_regs_1(Rs1, Rs2)];
+    [{R,join(Type1, Type2)}|merge_regs_1(Rs1, Rs2)];
 merge_regs_1([], []) -> [];
 merge_regs_1([], [_|_]) -> [];
 merge_regs_1([_|_], []) -> [].
@@ -1860,67 +1923,90 @@ merge_y_regs_1(Y, S, Regs0) when Y >= 0 ->
 	Type0 ->
 	    merge_y_regs_1(Y-1, S, Regs0);
 	Type1 ->
-	    Type = merge_types(Type0, Type1),
+	    Type = join(Type0, Type1),
 	    Regs = gb_trees:update(Y, Type, Regs0),
 	    merge_y_regs_1(Y-1, S, Regs)
     end;
 merge_y_regs_1(_, _, Regs) -> Regs.
 
-%% merge_types(Type1, Type2) -> Type
+%% join(Type1, Type2) -> Type
 %%  Return the most specific type possible.
 %%  Note: Type1 must NOT be the same as Type2.
-merge_types({fragile,Same}=Type, Same) ->
+join({literal,_}=T1, T2) ->
+    join_literal(T1, T2);
+join(T1, {literal,_}=T2) ->
+    join_literal(T2, T1);
+join({fragile,Same}=Type, Same) ->
     Type;
-merge_types({fragile,T1}, T2) ->
-    make_fragile(merge_types(T1, T2));
-merge_types(Same, {fragile,Same}=Type) ->
+join({fragile,T1}, T2) ->
+    make_fragile(join(T1, T2));
+join(Same, {fragile,Same}=Type) ->
     Type;
-merge_types(T1, {fragile,T2}) ->
-    make_fragile(merge_types(T1, T2));
-merge_types(uninitialized=I, _) -> I;
-merge_types(_, uninitialized=I) -> I;
-merge_types(initialized=I, _) -> I;
-merge_types(_, initialized=I) -> I;
-merge_types({catchtag,T0},{catchtag,T1}) ->
+join(T1, {fragile,T2}) ->
+    make_fragile(join(T1, T2));
+join(uninitialized=I, _) -> I;
+join(_, uninitialized=I) -> I;
+join(initialized=I, _) -> I;
+join(_, initialized=I) -> I;
+join({catchtag,T0},{catchtag,T1}) ->
     {catchtag,ordsets:from_list(T0++T1)};
-merge_types({trytag,T0},{trytag,T1}) ->
+join({trytag,T0},{trytag,T1}) ->
     {trytag,ordsets:from_list(T0++T1)};
-merge_types({tuple,A}, {tuple,B}) ->
+join({tuple,A}, {tuple,B}) ->
     {tuple,[min(tuple_sz(A), tuple_sz(B))]};
-merge_types({Type,A}, {Type,B}) 
+join({Type,A}, {Type,B}) 
   when Type =:= atom; Type =:= integer; Type =:= float ->
     if A =:= B -> {Type,A};
        true -> {Type,[]}
     end;
-merge_types({Type,_}, number) 
+join({Type,_}, number) 
   when Type =:= integer; Type =:= float ->
     number;
-merge_types(number, {Type,_}) 
+join(number, {Type,_}) 
   when Type =:= integer; Type =:= float ->
     number;
-merge_types(bool, {atom,A}) ->
+join(bool, {atom,A}) ->
     merge_bool(A);
-merge_types({atom,A}, bool) ->
+join({atom,A}, bool) ->
     merge_bool(A);
-merge_types(cons, {literal,[_|_]}) ->
-    cons;
-merge_types(cons, nil) ->
-    list;
-merge_types(nil, cons) ->
-    list;
-merge_types({literal,[_|_]}, cons) ->
-    cons;
-merge_types({literal,[_|_]}, {literal,[_|_]}) ->
-    cons;
-merge_types(#ms{id=Id1,valid=B1,slots=Slots1},
+join({atom,_}, {atom,_}) ->
+    {atom,[]};
+join(#ms{id=Id1,valid=B1,slots=Slots1},
 	    #ms{id=Id2,valid=B2,slots=Slots2}) ->
     Id = if
              Id1 =:= Id2 -> Id1;
              true -> make_ref()
          end,
     #ms{id=Id,valid=B1 band B2,slots=min(Slots1, Slots2)};
-merge_types(T1, T2) when T1 =/= T2 ->
-    %% Too different. All we know is that the type is a 'term'.
+join(T1, T2) when T1 =/= T2 ->
+    %% We've exhaused all other options, so the type must either be a list or
+    %% a 'term'.
+    join_list(T1, T2).
+
+%% Merges types of literals. Note that the left argument must either be a
+%% literal or exactly equal to the second argument.
+join_literal(Same, Same) ->
+    Same;
+join_literal({literal,[_|_]}, T) ->
+    join_literal(T, cons);
+join_literal({literal,#{}}, T) ->
+    join_literal(T, map);
+join_literal({literal,Tuple}, T) when is_tuple(Tuple) ->
+    join_literal(T, {tuple, tuple_size(Tuple)});
+join_literal({literal,_}, T) ->
+    %% Bitstring, fun, or similar.
+    join_literal(T, term);
+join_literal(T1, T2) ->
+    %% We're done extracting the types, try merging them again.
+    join(T1, T2).
+
+join_list(nil, cons) -> list;
+join_list(nil, list) -> list;
+join_list(cons, list) -> list;
+join_list(T, nil) -> join_list(nil, T);
+join_list(T, cons) -> join_list(cons, T);
+join_list(_, _) ->
+    %% Not a list, so it must be a term.
     term.
 
 tuple_sz([Sz]) -> Sz;
@@ -2031,6 +2117,9 @@ bif_type(abs, [Num], Vst) ->
     end;
 bif_type(float, _, _) -> {float,[]};
 bif_type('/', _, _) -> {float,[]};
+%% Binary operations
+bif_type('byte_size', _, _) -> {integer,[]};
+bif_type('bit_size', _, _) -> {integer,[]};
 %% Integer operations.
 bif_type(ceil, [_], _) -> {integer,[]};
 bif_type('div', [_,_], _) -> {integer,[]};
@@ -2110,11 +2199,13 @@ is_bif_safe(_, _) -> false.
 arith_type([A], Vst) ->
     %% Unary '+' or '-'.
     case get_term_type(A, Vst) of
+	{integer,_} -> {integer,[]};
 	{float,_} -> {float,[]};
         _ -> number
     end;
 arith_type([A,B], Vst) ->
     case {get_term_type(A, Vst),get_term_type(B, Vst)} of
+	{{integer,_},{integer,_}} -> {integer,[]};
 	{{float,_},_} -> {float,[]};
 	{_,{float,_}} -> {float,[]};
 	{_,_} -> number
diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index 73c66e6efc..53d3cec2d7 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -268,6 +268,10 @@ expand_opt(r21, Os) ->
     [no_put_tuple2 | expand_opt(no_bsm3, Os)];
 expand_opt({debug_info_key,_}=O, Os) ->
     [encrypt_debug_info,O|Os];
+expand_opt(no_type_opt, Os) ->
+    [no_ssa_opt_type_start,
+     no_ssa_opt_type_continue,
+     no_ssa_opt_type_finish | Os];
 expand_opt(O, Os) -> [O|Os].
 
 expand_opt_before_21(Os) ->
diff --git a/lib/compiler/test/Makefile b/lib/compiler/test/Makefile
index 40428b7f2d..f042a5cb51 100644
--- a/lib/compiler/test/Makefile
+++ b/lib/compiler/test/Makefile
@@ -105,6 +105,8 @@ CORE_MODULES = \
 	lfe_andor_SUITE \
 	lfe_guard_SUITE
 
+NO_MOD_OPT = $(NO_OPT)
+
 NO_OPT_MODULES= $(NO_OPT:%=%_no_opt_SUITE)
 NO_OPT_ERL_FILES= $(NO_OPT_MODULES:%=%.erl)
 POST_OPT_MODULES= $(NO_OPT:%=%_post_opt_SUITE)
@@ -113,6 +115,8 @@ INLINE_MODULES= $(INLINE:%=%_inline_SUITE)
 INLINE_ERL_FILES= $(INLINE_MODULES:%=%.erl)
 R21_MODULES= $(R21:%=%_r21_SUITE)
 R21_ERL_FILES= $(R21_MODULES:%=%.erl)
+NO_MOD_OPT_MODULES= $(NO_MOD_OPT:%=%_no_module_opt_SUITE)
+NO_MOD_OPT_ERL_FILES= $(NO_MOD_OPT_MODULES:%=%.erl)
 
 ERL_FILES= $(MODULES:%=%.erl)
 CORE_FILES= $(CORE_MODULES:%=%.core)
@@ -142,7 +146,7 @@ EBIN = .
 # ----------------------------------------------------
 
 make_emakefile: $(NO_OPT_ERL_FILES) $(POST_OPT_ERL_FILES) \
-  $(INLINE_ERL_FILES) $(R21_ERL_FILES)
+  $(INLINE_ERL_FILES) $(R21_ERL_FILES) $(NO_MOD_OPT_ERL_FILES)
 	$(ERL_TOP)/make/make_emakefile $(ERL_COMPILE_FLAGS) -o$(EBIN) $(MODULES) \
 	> $(EMAKEFILE)
 	$(ERL_TOP)/make/make_emakefile +no_copt +no_postopt \
@@ -154,6 +158,8 @@ make_emakefile: $(NO_OPT_ERL_FILES) $(POST_OPT_ERL_FILES) \
 	-o$(EBIN) $(INLINE_MODULES) >> $(EMAKEFILE)
 	$(ERL_TOP)/make/make_emakefile +r21 $(ERL_COMPILE_FLAGS) \
 	-o$(EBIN) $(R21_MODULES) >> $(EMAKEFILE)
+	$(ERL_TOP)/make/make_emakefile +no_module_opt $(ERL_COMPILE_FLAGS) \
+	-o$(EBIN) $(NO_MOD_OPT_MODULES) >> $(EMAKEFILE)
 	$(ERL_TOP)/make/make_emakefile +from_core $(ERL_COMPILE_FLAGS) \
 	-o$(EBIN) $(CORE_MODULES) >> $(EMAKEFILE)
 
@@ -183,6 +189,9 @@ docs:
 %_r21_SUITE.erl: %_SUITE.erl
 	sed -e 's;-module($(basename $<));-module($(basename $@));' $< > $@
 
+%_no_module_opt_SUITE.erl: %_SUITE.erl
+	sed -e 's;-module($(basename $<));-module($(basename $@));' $< > $@
+
 # ----------------------------------------------------
 # Release Target
 # ---------------------------------------------------- 
@@ -195,7 +204,8 @@ release_tests_spec: make_emakefile
 	$(INSTALL_DATA) compiler.spec compiler.cover \
 		$(EMAKEFILE) $(ERL_FILES) "$(RELSYSDIR)"
 	$(INSTALL_DATA) $(NO_OPT_ERL_FILES) $(POST_OPT_ERL_FILES) \
-		$(INLINE_ERL_FILES) $(R21_ERL_FILES) "$(RELSYSDIR)"
+		$(INLINE_ERL_FILES) $(R21_ERL_FILES) \
+		$(NO_MOD_OPT_ERL_FILES) "$(RELSYSDIR)"
 	$(INSTALL_DATA) $(CORE_FILES) "$(RELSYSDIR)"
 	for file in $(ERL_DUMMY_FILES); do \
 	    module=`basename $$file .erl`; \
diff --git a/lib/compiler/test/apply_SUITE.erl b/lib/compiler/test/apply_SUITE.erl
index 0f82a56fb7..2ee518b1a0 100644
--- a/lib/compiler/test/apply_SUITE.erl
+++ b/lib/compiler/test/apply_SUITE.erl
@@ -73,6 +73,7 @@ mfa(Config) when is_list(Config) ->
     {'EXIT',_} = (catch ?APPLY2(Mod, (id(bazzzzzz)), a, b)),
     {'EXIT',_} = (catch ?APPLY2({}, baz, a, b)),
     {'EXIT',_} = (catch ?APPLY2(?MODULE, [], a, b)),
+    {'EXIT',_} = (catch bad_literal_call(1)),
 
     ok = apply(Mod, foo, id([])),
     {[a,b|c]} = apply(Mod, bar, id([[a,b|c]])),
@@ -92,6 +93,13 @@ mfa(Config) when is_list(Config) ->
 
     apply(Mod, foo, []).
 
+%% The single call to this function with a literal argument caused type
+%% optimization to swap out the 'mod' field of a #b_remote{}, which was
+%% mishandled during code generation as it assumed that the module would always
+%% be an atom.
+bad_literal_call(I) ->
+    I:foo().
+
 foo() ->
     ok.
 
diff --git a/lib/compiler/test/compile_SUITE.erl b/lib/compiler/test/compile_SUITE.erl
index c17d63cd60..7452466666 100644
--- a/lib/compiler/test/compile_SUITE.erl
+++ b/lib/compiler/test/compile_SUITE.erl
@@ -1249,7 +1249,8 @@ do_opt_guards_fun([]) -> [].
 is_exception(guard_SUITE, {'-complex_not/1-fun-4-',1}) -> true;
 is_exception(guard_SUITE, {'-complex_not/1-fun-5-',1}) -> true;
 is_exception(guard_SUITE, {bad_guards,1}) -> true;
-is_exception(guard_SUITE, {nested_not_2b,4}) -> true;
+is_exception(guard_SUITE, {nested_not_2b,6}) -> true; %% w/o type optimization
+is_exception(guard_SUITE, {nested_not_2b,2}) -> true; %% with type optimization
 is_exception(_, _) -> false.
 
 sys_pre_attributes(Config) ->
diff --git a/lib/compiler/test/float_SUITE.erl b/lib/compiler/test/float_SUITE.erl
index 012810aba2..831e8279aa 100644
--- a/lib/compiler/test/float_SUITE.erl
+++ b/lib/compiler/test/float_SUITE.erl
@@ -20,7 +20,8 @@
 -module(float_SUITE).
 -export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
 	 init_per_group/2,end_per_group/2,
-	 pending/1,bif_calls/1,math_functions/1,mixed_float_and_int/1]).
+	 pending/1,bif_calls/1,math_functions/1,mixed_float_and_int/1,
+         subtract_number_type/1]).
 
 -include_lib("common_test/include/ct.hrl").
 
@@ -28,7 +29,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
     [pending, bif_calls, math_functions,
-     mixed_float_and_int].
+     mixed_float_and_int, subtract_number_type].
 
 groups() -> 
     [].
@@ -176,5 +177,15 @@ mixed_float_and_int(Config) when is_list(Config) ->
 pc(Cov, NotCov, X) ->
     round(Cov/(Cov+NotCov)*100) + 42 + 2.0*X.
 
+subtract_number_type(Config) when is_list(Config) ->
+    120 = fact(5).
+
+fact(N) ->
+    fact(N, 1).
+
+fact(0, P) -> P;
+fact(1, P) -> P;
+fact(N, P) -> fact(N-1, P*N).
+
 id(I) -> I.
 
diff --git a/lib/compiler/test/receive_SUITE.erl b/lib/compiler/test/receive_SUITE.erl
index 4219768d6f..12108445f0 100644
--- a/lib/compiler/test/receive_SUITE.erl
+++ b/lib/compiler/test/receive_SUITE.erl
@@ -25,7 +25,7 @@
 	 init_per_group/2,end_per_group/2,
 	 init_per_testcase/2,end_per_testcase/2,
 	 export/1,recv/1,coverage/1,otp_7980/1,ref_opt/1,
-	 wait/1,recv_in_try/1,double_recv/1]).
+	 wait/1,recv_in_try/1,double_recv/1,receive_var_zero/1]).
 
 -include_lib("common_test/include/ct.hrl").
 
@@ -45,7 +45,7 @@ all() ->
 groups() -> 
     [{p,test_lib:parallel(),
       [recv,coverage,otp_7980,ref_opt,export,wait,
-       recv_in_try,double_recv]}].
+       recv_in_try,double_recv,receive_var_zero]}].
 
 
 init_per_suite(Config) ->
@@ -378,4 +378,27 @@ do_double_recv(_, Msg) ->
             error
     end.
 
+%% Test 'after Z', when Z =:= 0 been propagated as an immediate by the type
+%% optimization pass.
+receive_var_zero(Config) when is_list(Config) ->
+    self() ! x,
+    self() ! y,
+    Z = zero(),
+    timeout = receive
+                  z -> ok
+              after Z -> timeout
+              end,
+    timeout = receive
+              after Z -> timeout
+              end,
+    self() ! w,
+    receive
+	x -> ok;
+	Other ->
+	    ct:fail({bad_message,Other})
+    end.
+
+zero() -> 0.
+
+
 id(I) -> I.
diff --git a/lib/compiler/test/test_lib.erl b/lib/compiler/test/test_lib.erl
index 4502f5b68a..26149e11e6 100644
--- a/lib/compiler/test/test_lib.erl
+++ b/lib/compiler/test/test_lib.erl
@@ -81,6 +81,8 @@ opt_opts(Mod) ->
                     (no_put_tuple2) -> true;
                     (no_bsm3) -> true;
                     (no_bsm_opt) -> true;
+                    (no_module_opt) -> true;
+                    (no_type_opt) -> true;
 		    (_) -> false
 		 end, Opts).
 
@@ -93,8 +95,9 @@ get_data_dir(Config) ->
     Opts = [{return,list}],
     Data1 = re:replace(Data0, "_no_opt_SUITE", "_SUITE", Opts),
     Data2 = re:replace(Data1, "_post_opt_SUITE", "_SUITE", Opts),
-    Data = re:replace(Data2, "_inline_SUITE", "_SUITE", Opts),
-    re:replace(Data, "_r21_SUITE", "_SUITE", Opts).
+    Data3 = re:replace(Data2, "_inline_SUITE", "_SUITE", Opts),
+    Data4 = re:replace(Data3, "_r21_SUITE", "_SUITE", Opts),
+    re:replace(Data4, "_no_module_opt_SUITE", "_SUITE", Opts).
 
 is_cloned_mod(Mod) ->
     is_cloned_mod_1(atom_to_list(Mod)).
@@ -105,6 +108,7 @@ is_cloned_mod_1("no_opt_SUITE") -> true;
 is_cloned_mod_1("post_opt_SUITE") -> true;
 is_cloned_mod_1("inline_SUITE") -> true;
 is_cloned_mod_1("21_SUITE") -> true;
+is_cloned_mod_1("no_module_opt_SUITE") -> true;
 is_cloned_mod_1([_|T]) -> is_cloned_mod_1(T);
 is_cloned_mod_1([]) -> false.