aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/src
diff options
context:
space:
mode:
Diffstat (limited to 'lib/compiler/src')
-rw-r--r--lib/compiler/src/beam_block.erl98
-rw-r--r--lib/compiler/src/compile.erl20
2 files changed, 76 insertions, 42 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index 85d332c56e..ec41925beb 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -159,14 +159,43 @@ find_fixpoint(OptFun, Is0) ->
end.
%% move_allocates(Is0) -> Is
-%% Move allocate instructions upwards in the instruction stream, in the
-%% hope of getting more possibilities for optimizing away moves later.
+%% Move allocate instructions upwards in the instruction stream
+%% (within the same block), in the hope of getting more possibilities
+%% for optimizing away moves later.
%%
-%% NOTE: Moving allocation instructions is only safe because it is done
-%% immediately after code generation so that we KNOW that if {x,X} is
-%% initialized, all x registers with lower numbers are also initialized.
-%% That assumption may not be true after other optimizations, such as
-%% the beam_utils:live_opt/1 optimization.
+%% For example, we can transform the following instructions:
+%%
+%% get_tuple_element x(1) Element => x(2)
+%% allocate_zero StackSize 3 %% x(0), x(1), x(2) are live
+%%
+%% to the following instructions:
+%%
+%% allocate_zero StackSize 2 %% x(0) and x(1) are live
+%% get_tuple_element x(1) Element => x(2)
+%%
+%% NOTE: Since the beam_reorder pass has been run, it is no longer
+%% safe to assume that if x(N) is initialized, then all lower-numbered
+%% x registers are also initialized.
+%%
+%% For example, in general it is not safe to transform the following
+%% instructions:
+%%
+%% get_tuple_element x(0) Element => x(1)
+%% allocate_zero StackSize 3 %x(0), x(1), x(2) are live
+%%
+%% to the following instructions:
+%%
+%% allocate_zero StackSize 3
+%% get_tuple_element x(0) Element => x(1)
+%%
+%% The transformation is safe if and only if x(1) has been
+%% initialized previously. Unfortunately, beam_reorder may have moved
+%% a get_tuple_element instruction so that x(1) is not always
+%% initialized when this code is reached. To find whether or not x(1)
+%% is initialized, we would need to analyze all code preceding these
+%% two instructions (across branches). Since we currently don't have
+%% any practical mechanism for doing that, we will have to
+%% conservatively assume that the transformation is unsafe.
move_allocates([{block,Bl0}|Is]) ->
Bl = move_allocates_1(reverse(Bl0), []),
@@ -175,27 +204,19 @@ move_allocates([I|Is]) ->
[I|move_allocates(Is)];
move_allocates([]) -> [].
-move_allocates_1([{set,[],[],{alloc,_,_}=Alloc}|Is0], Acc0) ->
- {Is,Acc} = move_allocates_2(Alloc, Is0, Acc0),
- move_allocates_1(Is, Acc);
+move_allocates_1([I|Is], [{set,[],[],{alloc,Live0,Info}}|Acc]=Acc0) ->
+ case {alloc_may_pass(I),alloc_live_regs(I, Live0)} of
+ {false,_} ->
+ move_allocates_1(Is, [I|Acc0]);
+ {true,not_possible} ->
+ move_allocates_1(Is, [I|Acc0]);
+ {true,Live} when is_integer(Live) ->
+ A = {set,[],[],{alloc,Live,Info}},
+ move_allocates_1(Is, [A,I|Acc])
+ end;
move_allocates_1([I|Is], Acc) ->
move_allocates_1(Is, [I|Acc]);
-move_allocates_1([], Is) -> Is.
-
-move_allocates_2({alloc,Live,Info}, [{set,[],[],{alloc,Live0,Info0}}|Is], Acc) ->
- Live = Live0, % Assertion.
- Alloc = {alloc,Live,combine_alloc(Info0, Info)},
- move_allocates_2(Alloc, Is, Acc);
-move_allocates_2({alloc,Live,Info}=Alloc0, [I|Is]=Is0, Acc) ->
- case alloc_may_pass(I) of
- false ->
- {Is0,[{set,[],[],Alloc0}|Acc]};
- true ->
- Alloc = {alloc,alloc_live_regs(I, Live),Info},
- move_allocates_2(Alloc, Is, [I|Acc])
- end;
-move_allocates_2(Alloc, [], Acc) ->
- {[],[{set,[],[],Alloc}|Acc]}.
+move_allocates_1([], Acc) -> Acc.
alloc_may_pass({set,_,_,{alloc,_,_}}) -> false;
alloc_may_pass({set,_,_,{set_tuple_element,_}}) -> false;
@@ -204,9 +225,6 @@ alloc_may_pass({set,_,_,put_list}) -> false;
alloc_may_pass({set,_,_,put}) -> false;
alloc_may_pass({set,_,_,_}) -> true.
-combine_alloc({_,Ns,Nh1,Init}, {_,nostack,Nh2,[]}) ->
- {zero,Ns,beam_utils:combine_heap_needs(Nh1, Nh2),Init}.
-
%% opt([Instruction]) -> [Instruction]
%% Optimize the instruction stream inside a basic block.
@@ -393,10 +411,19 @@ eliminate_use_of_from_reg([I]=Is, From, _To, Acc) ->
%% opt_alloc(Instructions) -> Instructions'
%% Optimises all allocate instructions.
+opt_alloc([{set,[],[],{alloc,Live0,Info0}},
+ {set,[],[],{alloc,Live,Info}}|Is]) ->
+ Live = Live0, %Assertion.
+ Alloc = combine_alloc(Info0, Info),
+ I = {set,[],[],{alloc,Live,Alloc}},
+ opt_alloc([I|Is]);
opt_alloc([{set,[],[],{alloc,R,{_,Ns,Nh,[]}}}|Is]) ->
[{set,[],[],opt_alloc(Is, Ns, Nh, R)}|Is];
opt_alloc([I|Is]) -> [I|opt_alloc(Is)];
opt_alloc([]) -> [].
+
+combine_alloc({_,Ns,Nh1,Init}, {_,nostack,Nh2,[]}) ->
+ {zero,Ns,beam_utils:combine_heap_needs(Nh1, Nh2),Init}.
%% opt_alloc(Instructions, FrameSize, HeapNeed, LivingRegs) -> [Instr]
%% Generates the optimal sequence of instructions for
@@ -445,13 +472,14 @@ count_ones(Bits, Acc) ->
alloc_live_regs({set,Ds,Ss,_}, Regs0) ->
Rset = x_live(Ss, x_dead(Ds, (1 bsl Regs0)-1)),
- live_regs(Rset).
+ live_regs(0, Rset).
-live_regs(Regs) ->
- live_regs_1(0, Regs).
-
-live_regs_1(N, 0) -> N;
-live_regs_1(N, Regs) -> live_regs_1(N+1, Regs bsr 1).
+live_regs(N, 0) ->
+ N;
+live_regs(N, Regs) when Regs band 1 =:= 1 ->
+ live_regs(N+1, Regs bsr 1);
+live_regs(_, _) ->
+ not_possible.
x_dead([{x,N}|Rs], Regs) -> x_dead(Rs, Regs band (bnot (1 bsl N)));
x_dead([_|Rs], Regs) -> x_dead(Rs, Regs);
diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index 82ff8a95f3..e951a25e04 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -43,6 +43,10 @@
-type abstract_code() :: [erl_parse:abstract_form()].
+%% Internal representations used for 'from_asm' and 'from_beam' compilation can
+%% also be valid, but have no relevant types defined.
+-type forms() :: abstract_code() | cerl:c_module().
+
-type option() :: atom() | {atom(), term()} | {'d', atom(), term()}.
-type err_info() :: {erl_anno:line() | 'none',
@@ -88,7 +92,7 @@ file(File, Opt) ->
forms(Forms) -> forms(Forms, ?DEFAULT_OPTIONS).
--spec forms(abstract_code(), [option()] | option()) -> comp_ret().
+-spec forms(forms(), [option()] | option()) -> comp_ret().
forms(Forms, Opts) when is_list(Opts) ->
do_compile({forms,Forms}, [binary|Opts++env_default_opts()]);
@@ -116,7 +120,7 @@ noenv_file(File, Opts) when is_list(Opts) ->
noenv_file(File, Opt) ->
noenv_file(File, [Opt|?DEFAULT_OPTIONS]).
--spec noenv_forms(abstract_code(), [option()] | option()) -> comp_ret().
+-spec noenv_forms(forms(), [option()] | option()) -> comp_ret().
noenv_forms(Forms, Opts) when is_list(Opts) ->
do_compile({forms,Forms}, [binary|Opts]);
@@ -236,6 +240,8 @@ format_error({epp,E}) ->
epp:format_error(E);
format_error(write_error) ->
"error writing file";
+format_error({write_error, Error}) ->
+ io_lib:format("error writing file: ~ts", [file:format_error(Error)]);
format_error({rename,From,To,Error}) ->
io_lib:format("failed to rename ~ts to ~ts: ~ts",
[From,To,file:format_error(Error)]);
@@ -1206,7 +1212,7 @@ makedep_output(#compile{code=Code,options=Opts,ofile=Ofile}=St) ->
end,
{ok,St}
catch
- exit:_ ->
+ error:_ ->
%% Couldn't write to output Makefile.
Err = {St#compile.ifile,[{none,?MODULE,write_error}]},
{error,St#compile{errors=St#compile.errors++[Err]}}
@@ -1479,8 +1485,8 @@ save_binary_1(St) ->
end,
{error,St#compile{errors=St#compile.errors ++ Es}}
end;
- {error,_Error} ->
- Es = [{Tfile,[{none,compile,write_error}]}],
+ {error,Error} ->
+ Es = [{Tfile,[{none,compile,{write_error,Error}}]}],
{error,St#compile{errors=St#compile.errors ++ Es}}
end.
@@ -1628,8 +1634,8 @@ listing(LFun, Ext, St) ->
LFun(Lf, Code),
ok = file:close(Lf),
{ok,St};
- {error,_Error} ->
- Es = [{Lfile,[{none,compile,write_error}]}],
+ {error,Error} ->
+ Es = [{Lfile,[{none,compile,{write_error,Error}}]}],
{error,St#compile{errors=St#compile.errors ++ Es}}
end.
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-07 03:48:01 +0000