From 0d3be61f3a4b5aa3437d08603ea7565432e3a07b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 2 Mar 2015 16:22:06 +0100 Subject: v3_codegen: Teach the put_map_* instructions to reuse source registers The put_map_assoc and put_map_exact instructions in the run-time system will support that the target register is the same as one of the source registers. Teach the code generator to take advantage of that. The disadvantages of not reusing register when possible is that the garbage collector may retain dead terms longer than necessary. --- lib/compiler/src/v3_codegen.erl | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'lib/compiler/src') diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl index 8c1a0c08ac..cbe50b93b0 100644 --- a/lib/compiler/src/v3_codegen.erl +++ b/lib/compiler/src/v3_codegen.erl @@ -1523,9 +1523,11 @@ set_cg([{var,R}], {map,Op,Map,[{map_pair,{var,_}=K,V}]}, Le, Vdb, Bef, List = [cg_reg_arg(K,Int0),cg_reg_arg(V,Int0)], Live = max_reg(Bef#sr.reg), - Int1 = Int0#sr{reg=put_reg(R, Int0#sr.reg)}, - Aft = clear_dead(Int1, Le#l.i, Vdb), - Target = fetch_reg(R, Int1#sr.reg), + + %% The target register can reuse one of the source registers. + Aft0 = clear_dead(Int0, Le#l.i, Vdb), + Aft = Aft0#sr{reg=put_reg(R, Aft0#sr.reg)}, + Target = fetch_reg(R, Aft#sr.reg), I = case Op of assoc -> put_map_assoc; @@ -1557,9 +1559,11 @@ set_cg([{var,R}], {map,Op,Map,Es}, Le, Vdb, Bef, List = flatmap(fun({K,V}) -> [K,cg_reg_arg(V,Int0)] end, Pairs), Live = max_reg(Bef#sr.reg), - Int1 = Int0#sr{reg=put_reg(R, Int0#sr.reg)}, - Aft = clear_dead(Int1, Le#l.i, Vdb), - Target = fetch_reg(R, Int1#sr.reg), + + %% The target register can reuse one of the source registers. + Aft0 = clear_dead(Int0, Le#l.i, Vdb), + Aft = Aft0#sr{reg=put_reg(R, Aft0#sr.reg)}, + Target = fetch_reg(R, Aft#sr.reg), I = case Op of assoc -> put_map_assoc; -- cgit v1.2.3