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authorMichał Muskała <[email protected]>2017-11-23 21:27:40 +0100
committerMichał Muskała <[email protected]>2017-11-23 21:27:40 +0100
commit1cbc6a430d18d80a0b5e6ad0f7f1010d5394056a (patch)
tree9b53b78a1955d3d15e1258df57c615afea262efc
parent9556949af97553ad99133d2198b8d92c18de98c7 (diff)
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Place move S x0 instructions at the end of blocks
The loader has a lot of fused instructions that include move S x0. Placing them at the end of blocks makes it possible to take advantage of this optimization more frequently.
-rw-r--r--lib/compiler/src/beam_block.erl11
1 files changed, 10 insertions, 1 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index 6543e05e20..c640af224d 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -219,11 +219,20 @@ alloc_may_pass({set,_,_,{set_tuple_element,_}}) -> false;
alloc_may_pass({set,_,_,put_list}) -> false;
alloc_may_pass({set,_,_,put}) -> false;
alloc_may_pass({set,_,_,_}) -> true.
-
+
%% opt([Instruction]) -> [Instruction]
%% Optimize the instruction stream inside a basic block.
opt([{set,[X],[X],move}|Is]) -> opt(Is);
+opt([{set,[X],_,move},{set,[X],_,move}=I|Is]) ->
+ opt([I|Is]);
+opt([{set,[{x,0}],[S1],move}=I1,{set,[D2],[{x,0}],move}|Is]) ->
+ opt([I1,{set,[D2],[S1],move}|Is]);
+opt([{set,[{x,0}],[S1],move}=I1,{set,[D2],[S2],move}|Is0]) when S1 =/= D2 ->
+ %% Place move S x0 at the end of move sequences so that
+ %% loader can merge with the following instruction
+ {Ds,Is} = opt_moves([D2], Is0),
+ [{set,Ds,[S2],move}|opt([I1|Is])];
opt([{set,_,_,{line,_}}=Line1,
{set,[D1],[{integer,Idx1},Reg],{bif,element,{f,0}}}=I1,
{set,_,_,{line,_}}=Line2,