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authorBjörn Gustavsson <[email protected]>2018-08-27 06:02:59 +0200
committerBjörn Gustavsson <[email protected]>2018-09-12 14:19:04 +0200
commitd3551827cc0221437098c5afa492637072f8a771 (patch)
treee399324b146bf8e7b09c7dae69d6527c2d607e0b /lib/compiler/src
parente2a939dc4d23d75a0588722d0a08aef129b4c0be (diff)
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beam_ssa: Add normalize/1
Add normalize/1 to simplify optimizations.
Diffstat (limited to 'lib/compiler/src')
-rw-r--r--lib/compiler/src/beam_ssa.erl80
1 files changed, 79 insertions, 1 deletions
diff --git a/lib/compiler/src/beam_ssa.erl b/lib/compiler/src/beam_ssa.erl
index a2766a0501..548e73cf43 100644
--- a/lib/compiler/src/beam_ssa.erl
+++ b/lib/compiler/src/beam_ssa.erl
@@ -27,6 +27,7 @@
fold_instrs_rpo/4,
linearize/1,
mapfold_instrs_rpo/4,
+ normalize/1,
predecessors/1,
rename_vars/3,
rpo/1,rpo/2,
@@ -102,7 +103,7 @@
-type cg_prim_op() :: 'bs_get' | 'bs_match_string' | 'bs_restore' | 'bs_skip' |
'copy' | 'put_tuple_arity' | 'put_tuple_element'.
--import(lists, [foldl/3,mapfoldl/3,reverse/1]).
+-import(lists, [foldl/3,keyfind/3,mapfoldl/3,reverse/1]).
-spec add_anno(Key, Value, Construct) -> Construct when
Key :: atom(),
@@ -180,6 +181,69 @@ successors(#b_blk{last=Terminator}) ->
[]
end.
+%% normalize(Instr0) -> Instr.
+%% Normalize instructions to help optimizations.
+%%
+%% For commutative operators (such as '+' and 'or'), always
+%% place a variable operand before a literal operand.
+%%
+%% Normalize #b_br{} to one of the following forms:
+%%
+%% #b_br{b_literal{val=true},succ=Label,fail=Label}
+%% #b_br{b_var{},succ=Label1,fail=Label2} where Label1 =/= Label2
+%%
+%% Simplify a #b_switch{} with a literal argument to a #b_br{}.
+%%
+%% Simplify a #b_switch{} with a variable argument and an empty
+%% switch list to a #b_br{}.
+
+-spec normalize(b_set() | terminator()) ->
+ b_set() | terminator().
+
+normalize(#b_set{op={bif,Bif},args=Args}=Set) ->
+ case {is_commutative(Bif),Args} of
+ {false,_} ->
+ Set;
+ {true,[#b_literal{}=Lit,#b_var{}=Var]} ->
+ Set#b_set{args=[Var,Lit]};
+ {true,_} ->
+ Set
+ end;
+normalize(#b_set{}=Set) ->
+ Set;
+normalize(#b_br{}=Br) ->
+ case Br of
+ #b_br{bool=Bool,succ=Same,fail=Same} ->
+ case Bool of
+ #b_literal{val=true} ->
+ Br;
+ _ ->
+ Br#b_br{bool=#b_literal{val=true}}
+ end;
+ #b_br{bool=#b_literal{val=true},succ=Succ} ->
+ Br#b_br{fail=Succ};
+ #b_br{bool=#b_literal{val=false},fail=Fail} ->
+ Br#b_br{bool=#b_literal{val=true},succ=Fail};
+ #b_br{} ->
+ Br
+ end;
+normalize(#b_switch{arg=Arg,fail=Fail,list=List}=Sw) ->
+ case Arg of
+ #b_literal{} ->
+ case keyfind(Arg, 1, List) of
+ false ->
+ #b_br{bool=#b_literal{val=true},succ=Fail,fail=Fail};
+ {Arg,L} ->
+ #b_br{bool=#b_literal{val=true},succ=L,fail=L}
+ end;
+ #b_var{} when List =:= [] ->
+ #b_br{bool=#b_literal{val=true},succ=Fail,fail=Fail};
+ #b_var{} ->
+ Sw
+ end;
+normalize(#b_ret{}=Ret) ->
+ Ret.
+
-spec successors(label(), block_map()) -> [label()].
successors(L, Blocks) ->
@@ -424,6 +488,20 @@ used(_) -> [].
%%% Internal functions.
%%%
+is_commutative('and') -> true;
+is_commutative('or') -> true;
+is_commutative('xor') -> true;
+is_commutative('band') -> true;
+is_commutative('bor') -> true;
+is_commutative('bxor') -> true;
+is_commutative('+') -> true;
+is_commutative('*') -> true;
+is_commutative('=:=') -> true;
+is_commutative('==') -> true;
+is_commutative('=/=') -> true;
+is_commutative('/=') -> true;
+is_commutative(_) -> false.
+
def_used_1([#b_blk{is=Is,last=Last}|Bs], Preds, Def0, Used0) ->
{Def,Used1} = def_used_is(Is, Preds, Def0, Used0),
Used = gb_sets:union(gb_sets:from_list(used(Last)), Used1),