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authorBjörn Gustavsson <bjorn@erlang.org>2013-11-26 09:32:44 +0100
committerBjörn Gustavsson <bjorn@erlang.org>2014-01-20 12:22:42 +0100
commit48360023d2f5ae72df19f0095da55738f63800db (patch)
treedc8f7bf17ced4d9b2aebdfa505badcbce5645ad8 /lib/asn1
parent912b330733144ae37e7a4da1bfea5be2a46d7594 (diff)
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asn1ct_imm: Add the {set,{var,Src},{var,Dst}} instruction
The {assign,Dst,Src} instruction is difficult to cope with when doing advanced optimizations, since its source argument is a string which may contain any expression. Instead of changing how {assign,_,_} works, we will introduce new instructions that can be used instead of {assign,_}, and remove {assign,_,_} in a later commit when it is no longer used. The first new instruction we will introduce is: {set,{var,Src},{var,Dst}} It is useful for common sub-expression elemination among other things. For the moment, we will only allow a variable as a source argument, but we could extend it in the future to allow constants as well.
Diffstat (limited to 'lib/asn1')
-rw-r--r--lib/asn1/src/asn1ct_imm.erl8
1 files changed, 7 insertions, 1 deletions
diff --git a/lib/asn1/src/asn1ct_imm.erl b/lib/asn1/src/asn1ct_imm.erl
index 48d380bcbc..9089fdf983 100644
--- a/lib/asn1/src/asn1ct_imm.erl
+++ b/lib/asn1/src/asn1ct_imm.erl
@@ -978,6 +978,7 @@ is_nonbuilding({call,_,_,_,_}) -> true;
is_nonbuilding({call_gen,_,_,_,_,_,_}) -> true;
is_nonbuilding({'cond',_,_}) -> true;
is_nonbuilding({lc,_,_,_,_}) -> true;
+is_nonbuilding({set,_,_}) -> true;
is_nonbuilding({sub,_,_,_}) -> true;
is_nonbuilding({'try',_,_,_,_}) -> true;
is_nonbuilding(_) -> false.
@@ -1698,7 +1699,6 @@ enc_pre_cg_nonbuilding({'try',Try0,{P,Succ0},Else0,Dst}, StL) ->
{'try',Try,{P,Succ},Else,Dst};
enc_pre_cg_nonbuilding(Imm, _) -> Imm.
-
%%%
%%% Code generation for encoding.
%%%
@@ -1773,6 +1773,8 @@ enc_cg({sub,Src0,Int,Dst0}) ->
Src = mk_val(Src0),
Dst = mk_val(Dst0),
emit([Dst," = ",Src," - ",Int]);
+enc_cg({set,{var,Src},{var,Dst}}) ->
+ emit([Dst," = ",Src]);
enc_cg({'try',Try,{P,Succ},Else,Dst}) ->
emit([mk_val(Dst)," = try "]),
enc_cg(Try),
@@ -2053,6 +2055,8 @@ enc_opt_al({put_bits,_,N,[U]}=PutBits, Al) when is_integer(N), is_integer(Al) ->
{[PutBits],Al+N*U};
enc_opt_al({put_bits,_,binary,[U]}=PutBits, Al) when U rem 8 =:= 0 ->
{[PutBits],Al};
+enc_opt_al({set,_,_}=Imm, Al) ->
+ {[Imm],Al};
enc_opt_al({sub,_,_,_}=Imm, Al) ->
{[Imm],Al};
enc_opt_al({'try',_,_,_,_}=Imm, Al) ->
@@ -2138,6 +2142,8 @@ per_fixup([{lc,B,V,L}|T]) ->
[{lc,per_fixup(B),V,L}|per_fixup(T)];
per_fixup([{lc,B,V,L,Dst}|T]) ->
[{lc,per_fixup(B),V,L,Dst}|per_fixup(T)];
+per_fixup([{set,_,_}=H|T]) ->
+ [H|per_fixup(T)];
per_fixup([{sub,_,_,_}=H|T]) ->
[H|per_fixup(T)];
per_fixup([{'try',Try0,{P,Succ0},Else0,Dst}|T]) ->