aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/src/beam_jump.erl
diff options
context:
space:
mode:
Diffstat (limited to 'lib/compiler/src/beam_jump.erl')
-rw-r--r--lib/compiler/src/beam_jump.erl125
1 files changed, 44 insertions, 81 deletions
diff --git a/lib/compiler/src/beam_jump.erl b/lib/compiler/src/beam_jump.erl
index db67d24514..b05d01b2a1 100644
--- a/lib/compiler/src/beam_jump.erl
+++ b/lib/compiler/src/beam_jump.erl
@@ -20,7 +20,7 @@
-module(beam_jump).
--export([module/2,module_labels/1,
+-export([module/2,
is_unreachable_after/1,is_exit_instruction/1,
remove_unused_labels/1,is_label_used_in/2]).
@@ -46,10 +46,13 @@
%%% such as a jump that never transfers control to the instruction
%%% following it.
%%%
-%%% (2) case_end, if_end, and badmatch, and function calls that cause an
-%%% exit (such as calls to exit/1) are moved to the end of the function.
-%%% The purpose is to allow further optimizations at the place from
-%%% which the code was moved.
+%%% (2) Short sequences starting with a label and ending in case_end, if_end,
+%%% and badmatch, and function calls that cause an exit (such as calls
+%%% to exit/1) are moved to the end of the function, but only if the
+%%% the block is not entered via a fallthrough. The purpose of this move
+%%% is to allow further optimizations at the place from which the
+%%% code was moved (a jump around the block could be replaced with a
+%%% fallthrough).
%%%
%%% (3) Any unreachable code is removed. Unreachable code is code
%%% after jump, call_last and other instructions which never
@@ -130,13 +133,6 @@ module({Mod,Exp,Attr,Fs0,Lc}, _Opt) ->
Fs = [function(F) || F <- Fs0],
{ok,{Mod,Exp,Attr,Fs,Lc}}.
-module_labels({Mod,Exp,Attr,Fs,Lc}) ->
- {Mod,Exp,Attr,[function_labels(F) || F <- Fs],Lc}.
-
-function_labels({function,Name,Arity,CLabel,Asm0}) ->
- Asm = remove_unused_labels(Asm0),
- {function,Name,Arity,CLabel,Asm}.
-
%% function(Function) -> Function'
%% Optimize jumps and branches.
%%
@@ -232,6 +228,9 @@ extract_seq_1([{line,_}=Line|Is], Acc) ->
extract_seq_1(Is, [Line|Acc]);
extract_seq_1([{label,_},{func_info,_,_,_}|_], _) ->
no;
+extract_seq_1([{label,Lbl},{jump,{f,Lbl}}|_], _) ->
+ %% Don't move a sequence which have a fallthrough entering it.
+ no;
extract_seq_1([{label,_}=Lbl|Is], Acc) ->
{yes,[Lbl|Acc],Is};
extract_seq_1(_, _) -> no.
@@ -260,43 +259,39 @@ find_fixpoint(OptFun, Is0) ->
Is -> find_fixpoint(OptFun, Is)
end.
-opt([{test,Test0,{f,Lnum}=Lbl,Ops}=I|Is0], Acc, St) ->
- case Is0 of
- [{jump,{f,Lnum}}|Is] ->
- %% We have
- %% Test Label Ops
- %% jump Label
- %% The test instruction is definitely not needed.
- %% The jump instruction is not needed if there is
- %% a definition of Label following the jump instruction.
- case is_label_defined(Is, Lnum) of
- false ->
- %% The jump instruction is still needed.
- opt(Is0, [I|Acc], label_used(Lbl, St));
- true ->
- %% Neither the test nor the jump are needed.
- opt(Is, Acc, St)
- end;
- [{jump,To}|Is] ->
- case is_label_defined(Is, Lnum) of
- false ->
+opt([{test,_,{f,L}=Lbl,_}=I|[{jump,{f,L}}|_]=Is], Acc, St) ->
+ %% We have
+ %% Test Label Ops
+ %% jump Label
+ %% The test instruction is not needed if the test is pure
+ %% (it modifies neither registers nor bit syntax state).
+ case beam_utils:is_pure_test(I) of
+ false ->
+ %% Test is not pure; we must keep it.
+ opt(Is, [I|Acc], label_used(Lbl, St));
+ true ->
+ %% The test is pure and its failure label is the same
+ %% as in the jump that follows -- thus it is not needed.
+ opt(Is, Acc, St)
+ end;
+opt([{test,Test0,{f,L}=Lbl,Ops}=I|[{jump,To}|Is]=Is0], Acc, St) ->
+ case is_label_defined(Is, L) of
+ false ->
+ opt(Is0, [I|Acc], label_used(Lbl, St));
+ true ->
+ case invert_test(Test0) of
+ not_possible ->
opt(Is0, [I|Acc], label_used(Lbl, St));
- true ->
- case invert_test(Test0) of
- not_possible ->
- opt(Is0, [I|Acc], label_used(Lbl, St));
- Test ->
- opt([{test,Test,To,Ops}|Is], Acc, St)
- end
- end;
- _Other ->
- opt(Is0, [I|Acc], label_used(Lbl, St))
+ Test ->
+ %% Invert the test and remove the jump.
+ opt([{test,Test,To,Ops}|Is], Acc, St)
+ end
end;
+opt([{test,_,{f,_}=Lbl,_}=I|Is], Acc, St) ->
+ opt(Is, [I|Acc], label_used(Lbl, St));
opt([{test,_,{f,_}=Lbl,_,_,_}=I|Is], Acc, St) ->
opt(Is, [I|Acc], label_used(Lbl, St));
-opt([{select_val,_R,Fail,{list,Vls}}=I|Is], Acc, St) ->
- skip_unreachable(Is, [I|Acc], label_used([Fail|Vls], St));
-opt([{select_tuple_arity,_R,Fail,{list,Vls}}=I|Is], Acc, St) ->
+opt([{select,_,_R,Fail,Vls}=I|Is], Acc, St) ->
skip_unreachable(Is, [I|Acc], label_used([Fail|Vls], St));
opt([{label,L}=I|Is], Acc, #st{entry=L}=St) ->
%% NEVER move the entry label.
@@ -412,14 +407,8 @@ is_label_used(L, St) ->
is_unreachable_after({func_info,_M,_F,_A}) -> true;
is_unreachable_after(return) -> true;
-is_unreachable_after({call_ext_last,_Ar,_ExtFunc,_D}) -> true;
-is_unreachable_after({call_ext_only,_Ar,_ExtFunc}) -> true;
-is_unreachable_after({call_last,_Ar,_Lbl,_D}) -> true;
-is_unreachable_after({call_only,_Ar,_Lbl}) -> true;
-is_unreachable_after({apply_last,_Ar,_N}) -> true;
is_unreachable_after({jump,_Lbl}) -> true;
-is_unreachable_after({select_val,_R,_Lbl,_Cases}) -> true;
-is_unreachable_after({select_tuple_arity,_R,_Lbl,_Cases}) -> true;
+is_unreachable_after({select,_What,_R,_Lbl,_Cases}) -> true;
is_unreachable_after({loop_rec_end,_}) -> true;
is_unreachable_after({wait,_}) -> true;
is_unreachable_after(I) -> is_exit_instruction(I).
@@ -430,10 +419,6 @@ is_unreachable_after(I) -> is_exit_instruction(I).
is_exit_instruction({call_ext,_,{extfunc,M,F,A}}) ->
erl_bifs:is_exit_bif(M, F, A);
-is_exit_instruction({call_ext_last,_,{extfunc,M,F,A},_}) ->
- erl_bifs:is_exit_bif(M, F, A);
-is_exit_instruction({call_ext_only,_,{extfunc,M,F,A}}) ->
- erl_bifs:is_exit_bif(M, F, A);
is_exit_instruction(if_end) -> true;
is_exit_instruction({case_end,_}) -> true;
is_exit_instruction({try_case_end,_}) -> true;
@@ -516,9 +501,7 @@ ulbl({test,_,Fail,_}, Used) ->
mark_used(Fail, Used);
ulbl({test,_,Fail,_,_,_}, Used) ->
mark_used(Fail, Used);
-ulbl({select_val,_,Fail,{list,Vls}}, Used) ->
- mark_used_list(Vls, mark_used(Fail, Used));
-ulbl({select_tuple_arity,_,Fail,{list,Vls}}, Used) ->
+ulbl({select,_,_,Fail,Vls}, Used) ->
mark_used_list(Vls, mark_used(Fail, Used));
ulbl({'try',_,Lbl}, Used) ->
mark_used(Lbl, Used);
@@ -538,29 +521,9 @@ ulbl({bif,_Name,Lbl,_As,_R}, Used) ->
mark_used(Lbl, Used);
ulbl({gc_bif,_Name,Lbl,_Live,_As,_R}, Used) ->
mark_used(Lbl, Used);
-ulbl({bs_init2,Lbl,_,_,_,_,_}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_init_bits,Lbl,_,_,_,_,_}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_put_integer,Lbl,_Bits,_Unit,_Fl,_Val}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_put_float,Lbl,_Bits,_Unit,_Fl,_Val}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_put_binary,Lbl,_Bits,_Unit,_Fl,_Val}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_put_utf8,Lbl,_Fl,_Val}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_put_utf16,Lbl,_Fl,_Val}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_put_utf32,Lbl,_Fl,_Val}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_add,Lbl,_,_}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_append,Lbl,_,_,_,_,_,_,_}, Used) ->
- mark_used(Lbl, Used);
-ulbl({bs_utf8_size,Lbl,_,_}, Used) ->
+ulbl({bs_init,Lbl,_,_,_,_}, Used) ->
mark_used(Lbl, Used);
-ulbl({bs_utf16_size,Lbl,_,_}, Used) ->
+ulbl({bs_put,Lbl,_,_}, Used) ->
mark_used(Lbl, Used);
ulbl(_, Used) -> Used.
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-03 07:00:54 +0000