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authorBjörn Gustavsson <[email protected]>2019-01-29 07:34:11 +0100
committerGitHub <[email protected]>2019-01-29 07:34:11 +0100
commit2f296e1a44a8abfd3f5d35aa9c111eecaac3156d (patch)
tree5f28275abc4086f3d72542b3257e74e36987f7b5
parent5a38332a37eecc29a21fa2d83ba0b719f3a721d4 (diff)
parentacf96b6e024864b5dce41ef68725bb0228fe3100 (diff)
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Merge pull request #2112 from bjorng/bjorn/compiler/compilation-speed
Speed up the compiler when compiling the idna package
-rw-r--r--lib/compiler/src/beam_ssa_dead.erl47
-rw-r--r--lib/compiler/src/beam_ssa_opt.erl12
2 files changed, 47 insertions, 12 deletions
diff --git a/lib/compiler/src/beam_ssa_dead.erl b/lib/compiler/src/beam_ssa_dead.erl
index 067d9a6741..09b29025c6 100644
--- a/lib/compiler/src/beam_ssa_dead.erl
+++ b/lib/compiler/src/beam_ssa_dead.erl
@@ -181,9 +181,9 @@ shortcut_2(L, Bs0, UnsetVars0, St) ->
%% We have a potentially suitable br.
%% Now update the set of variables that will never
%% be set if this block will be skipped.
- UnsetVars1 = [V || #b_set{dst=V} <- Is],
- UnsetVars = ordsets:union(UnsetVars0,
- ordsets:from_list(UnsetVars1)),
+ SetInThisBlock = [V || #b_set{dst=V} <- Is],
+ UnsetVars = update_unset_vars(L, Br, SetInThisBlock,
+ UnsetVars0, St),
%% Continue checking whether this br is suitable.
shortcut_3(Br, Bs#{from:=L}, UnsetVars, St)
@@ -296,6 +296,37 @@ shortcut_3(Br, Bs, UnsetVars, #st{target=Target}=St) ->
end
end.
+update_unset_vars(L, Br, SetInThisBlock, UnsetVars, #st{skippable=Skippable}) ->
+ case is_map_key(L, Skippable) of
+ true ->
+ %% None of the variables used in this block are used in
+ %% the successors. We can speed up compilation by avoiding
+ %% adding variables to the UnsetVars if the presence of
+ %% those variable would not change the outcome of the
+ %% tests in is_br_safe/2.
+ case Br of
+ #b_br{bool=Bool} ->
+ case member(Bool, SetInThisBlock) of
+ true ->
+ %% Bool is a variable defined in this
+ %% block. It will change the outcome of
+ %% the `not member(V, UnsetVars)` check in
+ %% is_br_safe/2. The other variables
+ %% defined in this block will not.
+ ordsets:add_element(Bool, UnsetVars);
+ false ->
+ %% Bool is either a variable not defined
+ %% in this block or a literal. Adding it
+ %% to the UnsetVars set would not change
+ %% the outcome of the tests in
+ %% is_br_safe/2.
+ UnsetVars
+ end
+ end;
+ false ->
+ ordsets:union(UnsetVars, ordsets:from_list(SetInThisBlock))
+ end.
+
shortcut_two_way(#b_br{succ=Succ,fail=Fail}, Bs0, UnsetVars0, St) ->
case shortcut_2(Succ, Bs0, UnsetVars0, St#st{target=Fail}) of
{#b_br{bool=#b_literal{},succ=Fail},_,_}=Res ->
@@ -919,11 +950,11 @@ used_vars([{L,#b_blk{is=Is}=Blk}|Bs], UsedVars0, Skip0) ->
Used = used_vars_blk(Blk, Used0),
UsedVars = used_vars_phis(Is, L, Used, UsedVars0),
- %% combine_eqs/1 needs different variable usage
- %% information than shortcut_opt/1. The Skip
- %% map will have an entry for each block that
- %% can be skipped (does not bind any variable used
- %% in successor).
+ %% combine_eqs/1 needs different variable usage information than
+ %% shortcut_opt/1. The Skip map will have an entry for each block
+ %% that can be skipped (does not bind any variable used in
+ %% successor). This information is also useful for speeding up
+ %% shortcut_opt/1.
Defined0 = [Def || #b_set{dst=Def} <- Is],
Defined = ordsets:from_list(Defined0),
diff --git a/lib/compiler/src/beam_ssa_opt.erl b/lib/compiler/src/beam_ssa_opt.erl
index f99993522a..e528bb4dfb 100644
--- a/lib/compiler/src/beam_ssa_opt.erl
+++ b/lib/compiler/src/beam_ssa_opt.erl
@@ -1970,13 +1970,17 @@ verify_merge_is([#b_set{op=Op}|_]) ->
verify_merge_is(_) ->
ok.
-is_merge_allowed(_, _, #b_blk{is=[#b_set{op=peek_message}|_]}) ->
+is_merge_allowed(_, #b_blk{}, #b_blk{is=[#b_set{op=peek_message}|_]}) ->
false;
-is_merge_allowed(L, Blk0, #b_blk{}) ->
- case beam_ssa:successors(Blk0) of
+is_merge_allowed(L, #b_blk{last=#b_br{}}=Blk, #b_blk{}) ->
+ %% The predecessor block must have exactly one successor (L) for
+ %% the merge to be safe.
+ case beam_ssa:successors(Blk) of
[L] -> true;
[_|_] -> false
- end.
+ end;
+is_merge_allowed(_, #b_blk{last=#b_switch{}}, #b_blk{}) ->
+ false.
%%%
%%% When a tuple is matched, the pattern matching compiler generates a