Merge branch 'bjorn/compiler/yreg-init'

* bjorn/compiler/yreg-init:
  beam_validator: Verify Y registers in exception-causing instructions
  Correct beam_utils:is_killed/3 (again)

3 files changed, 19 insertions, 11 deletions

diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index 1ddad30328..f57a7af1ab 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -377,7 +377,7 @@ check_liveness(R, [{test,_,{f,Fail},As}|Is], St0) ->
 		{killed,St1} ->
 		    check_liveness(R, Is, St1);
 		{exit_not_used,St1} ->
-		    check_liveness(R, Is, St1);
+		    not_used(check_liveness(R, Is, St1));
 		{not_used,St1} ->
 		    not_used(check_liveness(R, Is, St1));
 		{used,_}=Used ->
@@ -395,14 +395,14 @@ check_liveness(R, [{select,_,_,Fail,Branches}|_], St) ->
     check_liveness_everywhere(R, [Fail|Branches], St);
 check_liveness(R, [{jump,{f,F}}|_], St) ->
     check_liveness_at(R, F, St);
-check_liveness(R, [{case_end,Used}|_], St) -> 
-    check_liveness_ret(R, Used, St);
+check_liveness(R, [{case_end,Used}|_], St) ->
+    check_liveness_exit(R, Used, St);
 check_liveness(R, [{try_case_end,Used}|_], St) ->
-    check_liveness_ret(R, Used, St);
+    check_liveness_exit(R, Used, St);
 check_liveness(R, [{badmatch,Used}|_], St) ->
-    check_liveness_ret(R, Used, St);
-check_liveness(_, [if_end|_], St) ->
-    {killed,St};
+    check_liveness_exit(R, Used, St);
+check_liveness(R, [if_end|_], St) ->
+    check_liveness_exit(R, ignore, St);
 check_liveness(R, [{func_info,_,_,Ar}|_], St) ->
     case R of
 	{x,X} when X < Ar -> {used,St};
@@ -658,8 +658,9 @@ check_liveness_at(R, Lbl, #live{lbl=Ll,res=ResMemorized}=St0) ->
 not_used({used,_}=Res) -> Res;
 not_used({_,St}) -> {not_used,St}.
 
-check_liveness_ret(R, R, St) -> {used,St};
-check_liveness_ret(_, _, St) -> {killed,St}.
+check_liveness_exit(R, R, St) -> {used,St};
+check_liveness_exit({x,_}, _, St) -> {killed,St};
+check_liveness_exit({y,_}, _, St) -> {exit_not_used,St}.
 
 %% check_liveness_block(Reg, [Instruction], State) ->
 %%     {killed | not_used | used | alloc_used | transparent,State'}
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index 962f17d83c..86aa12e19b 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -267,13 +267,17 @@ valfun_1(_I, #vst{current=none}=Vst) ->
     Vst;
 valfun_1({badmatch,Src}, Vst) ->
     assert_term(Src, Vst),
+    verify_y_init(Vst),
     kill_state(Vst);
 valfun_1({case_end,Src}, Vst) ->
     assert_term(Src, Vst),
+    verify_y_init(Vst),
     kill_state(Vst);
 valfun_1(if_end, Vst) ->
+    verify_y_init(Vst),
     kill_state(Vst);
 valfun_1({try_case_end,Src}, Vst) ->
+    verify_y_init(Vst),
     assert_term(Src, Vst),
     kill_state(Vst);
 %% Instructions that can not cause exceptions
@@ -375,6 +379,9 @@ valfun_1({call_ext,Live,Func}=I, Vst) ->
     case return_type(Func, Vst) of
 	exception ->
 	    verify_live(Live, Vst),
+            %% The stack will be scanned, so Y registers
+            %% must be initialized.
+            verify_y_init(Vst),
 	    kill_state(Vst);
 	_ ->
 	    valfun_2(I, Vst)
diff --git a/lib/compiler/test/beam_validator_SUITE.erl b/lib/compiler/test/beam_validator_SUITE.erl
index 3af71559ae..41f2957dc1 100644
--- a/lib/compiler/test/beam_validator_SUITE.erl
+++ b/lib/compiler/test/beam_validator_SUITE.erl
@@ -157,8 +157,8 @@ call_last(Config) when is_list(Config) ->
 merge_undefined(Config) when is_list(Config) ->
     Errors = do_val(merge_undefined, Config),
     [{{t,handle_call,2},
-      {{call_ext,2,{extfunc,debug,filter,2}},
-       22,
+      {{call_ext,1,{extfunc,erlang,exit,1}},
+       10,
        {uninitialized_reg,{y,0}}}}] = Errors,
     ok.