Merge branch 'bjorn/raise'

* bjorn/raise:
  Remove unreachable code after 'raise' instructions
  Simplify the raise instruction to reduce code size

7 files changed, 41 insertions, 45 deletions

diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index 09a41f2b56..d648a2f23c 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -3360,48 +3360,18 @@ do {						\
      goto do_schedule;
  }
 
- OpCase(raise_ss): {
-     /* This was not done very well in R10-0; then, we passed the tag in
-	the first argument and hoped that the existing c_p->ftrace was
-	still correct. But the ftrace-object already includes the tag
-	(or rather, the freason). Now, we pass the original ftrace in
-	the first argument. We also handle atom tags in the first
-	argument for backwards compatibility.
-     */
-     Eterm raise_val1;
-     Eterm raise_val2;
-     GetArg2(0, raise_val1, raise_val2);
-     c_p->fvalue = raise_val2;
-     if (c_p->freason == EXC_NULL) {
-       /* a safety check for the R10-0 case; should not happen */
-       c_p->ftrace = NIL;
-       c_p->freason = EXC_ERROR;
-     }
-     /* for R10-0 code, keep existing c_p->ftrace and hope it's correct */
-     switch (raise_val1) {
-     case am_throw:
-       c_p->freason = EXC_THROWN & ~EXF_SAVETRACE;
-       break;
-     case am_error:
-       c_p->freason = EXC_ERROR & ~EXF_SAVETRACE;
-       break;
-     case am_exit:
-       c_p->freason = EXC_EXIT & ~EXF_SAVETRACE;
-       break;
-     default:
-       {/* R10-1 and later
-	   XXX note: should do sanity check on given trace if it can be
-	   passed from a user! Currently only expecting generated calls.
-	*/
-	 struct StackTrace *s;
-	 c_p->ftrace = raise_val1;
-	 s = get_trace_from_exc(raise_val1);
-	 if (s == NULL) {
-	   c_p->freason = EXC_ERROR;
-	 } else {
-	   c_p->freason = PRIMARY_EXCEPTION(s->freason);
-	 }
-       }
+ OpCase(i_raise): {
+     Eterm raise_trace = x(2);
+     Eterm raise_value = x(1);
+     struct StackTrace *s;
+
+     c_p->fvalue = raise_value;
+     c_p->ftrace = raise_trace;
+     s = get_trace_from_exc(raise_trace);
+     if (s == NULL) {
+	 c_p->freason = EXC_ERROR;
+     } else {
+	 c_p->freason = PRIMARY_EXCEPTION(s->freason);
      }
      goto find_func_info;
  }
diff --git a/erts/emulator/beam/ops.tab b/erts/emulator/beam/ops.tab
index 15f27835a8..96a3a72bb5 100644
--- a/erts/emulator/beam/ops.tab
+++ b/erts/emulator/beam/ops.tab
@@ -251,7 +251,14 @@ case_end x
 badmatch x
 
 if_end
-raise s s
+
+# Operands for raise/2 are almost always in x(2) and x(1).
+# Optimize for that case.
+raise x==2 x==1 => i_raise
+raise Trace=y Value=y => move Trace x=2 | move Value x=1 | i_raise
+raise Trace Value => move Trace x=3 | move Value x=1 | move x=3 x=2 | i_raise
+
+i_raise
 
 # Internal now, but could be useful to make known to the compiler.
 badarg j
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index d1052303e0..429b1aa010 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -88,7 +88,9 @@ collect_block([I|Is]=Is0, Acc) ->
     case collect(I) of
 	error -> {reverse(Acc),Is0};
 	Instr -> collect_block(Is, [Instr|Acc])
-    end.
+    end;
+collect_block([], Acc) ->
+    {reverse(Acc),[]}.
 
 collect({allocate,N,R})      -> {set,[],[],{alloc,R,{nozero,N,0,[]}}};
 collect({allocate_zero,N,R}) -> {set,[],[],{alloc,R,{zero,N,0,[]}}};
diff --git a/lib/compiler/src/beam_split.erl b/lib/compiler/src/beam_split.erl
index bb1c0e23a9..7b7f0a0f80 100644
--- a/lib/compiler/src/beam_split.erl
+++ b/lib/compiler/src/beam_split.erl
@@ -47,6 +47,8 @@ split_block([{set,[R],[_,_,_]=As,{bif,is_record,{f,Lbl}}}|Is], Bl, Acc) ->
     split_block(Is, [], [{bif,is_record,{f,Lbl},As,R}|make_block(Bl, Acc)]);
 split_block([{set,[R],As,{bif,N,{f,Lbl}=Fail}}|Is], Bl, Acc) when Lbl =/= 0 ->
     split_block(Is, [], [{bif,N,Fail,As,R}|make_block(Bl, Acc)]);
+split_block([{set,[R],As,{bif,raise,{f,_}=Fail}}|Is], Bl, Acc) ->
+    split_block(Is, [], [{bif,raise,Fail,As,R}|make_block(Bl, Acc)]);
 split_block([{set,[R],As,{alloc,Live,{gc_bif,N,{f,Lbl}=Fail}}}|Is], Bl, Acc)
   when Lbl =/= 0 ->
     split_block(Is, [], [{gc_bif,N,Fail,Live,As,R}|make_block(Bl, Acc)]);
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index fd38fc0095..1c052789fd 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -509,6 +509,9 @@ valfun_4({bif,element,{f,Fail},[Pos,Tuple],Dst}, Vst0) ->
     TupleType = upgrade_tuple_type({tuple,[get_tuple_size(PosType)]}, TupleType0),
     Vst = set_type(TupleType, Tuple, Vst1),
     set_type_reg(term, Dst, Vst);
+valfun_4({bif,raise,{f,0},Src,_Dst}, Vst) ->
+    validate_src(Src, Vst),
+    kill_state(Vst);
 valfun_4({bif,Op,{f,Fail},Src,Dst}, Vst0) ->
     validate_src(Src, Vst0),
     Vst = branch_state(Fail, Vst0),
diff --git a/lib/compiler/src/beam_z.erl b/lib/compiler/src/beam_z.erl
index 8381578b68..e44423d257 100644
--- a/lib/compiler/src/beam_z.erl
+++ b/lib/compiler/src/beam_z.erl
@@ -24,6 +24,8 @@
 
 -export([module/2]).
 
+-import(lists, [dropwhile/2]).
+
 module({Mod,Exp,Attr,Fs0,Lc}, _Opt) ->
     Fs = [function(F) || F <- Fs0],
     {ok,{Mod,Exp,Attr,Fs,Lc}}.
@@ -51,6 +53,16 @@ undo_renames([{call,A,F},return|Is]) ->
     [{call_only,A,F}|undo_renames(Is)];
 undo_renames([{call_ext,A,F},return|Is]) ->
     [{call_ext_only,A,F}|undo_renames(Is)];
+undo_renames([{bif,raise,_,_,_}=I|Is0]) ->
+    %% A minor optimization. Done here because:
+    %%  (1) beam_jump may move or share 'raise' instructions, and that
+    %%      may confuse beam_validator.
+    %%  (2) beam_trim cannot do its optimization if the 'deallocate'
+    %%      instruction after 'raise' has been removed.
+    Is = dropwhile(fun({label,_}) -> false;
+		      (_) -> true
+		   end, Is0),
+    [I|undo_renames(Is)];
 undo_renames([I|Is]) ->
     [undo_rename(I)|undo_renames(Is)];
 undo_renames([]) -> [].
diff --git a/lib/compiler/test/beam_validator_SUITE.erl b/lib/compiler/test/beam_validator_SUITE.erl
index d27512b6eb..b3fb091f46 100644
--- a/lib/compiler/test/beam_validator_SUITE.erl
+++ b/lib/compiler/test/beam_validator_SUITE.erl
@@ -312,7 +312,7 @@ state_after_fault_in_catch(Config) when is_list(Config) ->
 no_exception_in_catch(Config) when is_list(Config) ->
     Errors = do_val(no_exception_in_catch, Config),
     [{{no_exception_in_catch,nested_of_1,4},
-      {{move,{x,3},{x,0}},88,{uninitialized_reg,{x,3}}}}] = Errors,
+      {{move,{x,3},{x,0}},87,{uninitialized_reg,{x,3}}}}] = Errors,
     ok.
 
 undef_label(Config) when is_list(Config) ->