diff options
| -rw-r--r-- | lib/compiler/src/beam_block.erl | 35 | ||||
| -rw-r--r-- | lib/compiler/test/receive_SUITE.erl | 25 |
2 files changed, 44 insertions, 16 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl index 9c6f835ab0..c45874597a 100644 --- a/lib/compiler/src/beam_block.erl +++ b/lib/compiler/src/beam_block.erl @@ -36,12 +36,13 @@ function({function,Name,Arity,CLabel,Is0}, Lc0) -> %% Collect basic blocks and optimize them. Is2 = blockify(Is1), - Is3 = beam_utils:live_opt(Is2), - Is4 = opt_blocks(Is3), - Is5 = beam_utils:delete_live_annos(Is4), + Is3 = move_allocates(Is2), + Is4 = beam_utils:live_opt(Is3), + Is5 = opt_blocks(Is4), + Is6 = beam_utils:delete_live_annos(Is5), %% Optimize bit syntax. - {Is,Lc} = bsm_opt(Is5, Lc0), + {Is,Lc} = bsm_opt(Is6, Lc0), %% Done. {{function,Name,Arity,CLabel,Is},Lc} @@ -156,11 +157,7 @@ opt_blocks([I|Is]) -> opt_blocks([]) -> []. opt_block(Is0) -> - %% We explicitly move any allocate instruction upwards before optimising - %% moves, to avoid any potential problems with the calculation of live - %% registers. - Is1 = move_allocates(Is0), - Is = find_fixpoint(fun opt/1, Is1), + Is = find_fixpoint(fun opt/1, Is0), opt_alloc(Is). find_fixpoint(OptFun, Is0) -> @@ -170,11 +167,21 @@ find_fixpoint(OptFun, Is0) -> end. %% move_allocates(Is0) -> Is -%% Move allocates upwards in the instruction stream, in the hope of -%% getting more possibilities for optimizing away moves later. - -move_allocates(Is) -> - move_allocates_1(reverse(Is), []). +%% Move allocate instructions upwards in the instruction stream, 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. + +move_allocates([{block,Bl0}|Is]) -> + Bl = move_allocates_1(reverse(Bl0), []), + [{block,Bl}|move_allocates(Is)]; +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), diff --git a/lib/compiler/test/receive_SUITE.erl b/lib/compiler/test/receive_SUITE.erl index fca3f0387b..2a592dd669 100644 --- a/lib/compiler/test/receive_SUITE.erl +++ b/lib/compiler/test/receive_SUITE.erl @@ -21,7 +21,7 @@ -module(receive_SUITE). -export([all/1,init_per_testcase/2,fin_per_testcase/2, - recv/1,coverage/1,otp_7980/1,ref_opt/1]). + recv/1,coverage/1,otp_7980/1,ref_opt/1,export/1]). -include("test_server.hrl"). @@ -36,7 +36,7 @@ fin_per_testcase(_Case, Config) -> all(suite) -> test_lib:recompile(?MODULE), - [recv,coverage,otp_7980,ref_opt]. + [recv,coverage,otp_7980,ref_opt,export]. -record(state, {ena = true}). @@ -205,4 +205,25 @@ collect_recv_opt_instrs(Code) -> end] || {function,_,_,_,Is} <- Code], lists:append(L). +export(Config) when is_list(Config) -> + Ref = make_ref(), + ?line self() ! {result,Ref,42}, + ?line 42 = export_1(Ref), + ?line {error,timeout} = export_1(Ref), + ok. + +export_1(Reference) -> + id(Reference), + receive + {result,Reference,Result} -> + Result + after 1 -> + Result = {error,timeout} + end, + %% Result ({x,1}) is used, but not the return value ({x,0}) + %% of the receive. Used to be incorrectly optimized + %% by beam_block. + id({build,self()}), + Result. + id(I) -> I. |