%% -*- erlang-indent-level: 2 -*- %% %% %CopyrightBegin% %% %% Copyright Ericsson AB 2001-2009. All Rights Reserved. %% %% The contents of this file are subject to the Erlang Public License, %% Version 1.1, (the "License"); you may not use this file except in %% compliance with the License. You should have received a copy of the %% Erlang Public License along with this software. If not, it can be %% retrieved online at http://www.erlang.org/. %% %% Software distributed under the License is distributed on an "AS IS" %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See %% the License for the specific language governing rights and limitations %% under the License. %% %% %CopyrightEnd% %% %%----------------------------------------------------------------------- %% File : hipe_coalescing_regalloc.erl %% Authors : Andreas Wallin <d96awa@it.uu.se> %% Thorild Sel�n <d95ths@.it.uu.se> %% Ingemar �berg <d95ina@it.uu.se> %% Purpose : Play paintball with registers on a target machine. We win %% if they are all colored. This is an iterated coalescing %% register allocator. %% Created : 4 Mar 2000 %%----------------------------------------------------------------------- -module(hipe_coalescing_regalloc). -export([regalloc/5]). %%-ifndef(DEBUG). %%-define(DEBUG,true). %%-endif. -include("../main/hipe.hrl"). %%----------------------------------------------------------------------- %% Function: regalloc %% %% Description: Creates a K coloring for a function. %% Parameters: %% CFG -- A control flow graph %% SpillIndex -- Last index of spill variable %% SpillLimit -- Temporaries with numbers higher than this have %% infinite spill cost. %% Consider changing this to a set. %% Target -- The module containing the target-specific functions. %% %% Returns: %% Coloring -- A coloring for specified CFG %% SpillIndex0 -- A new spill index %%----------------------------------------------------------------------- regalloc(CFG, SpillIndex, SpillLimit, Target, _Options) -> %% Build interference graph ?debug_msg("Build IG\n", []), IG = hipe_ig:build(CFG, Target), %% io:format("IG: ~p\n", [IG]), ?debug_msg("Init\n", []), Num_Temps = Target:number_of_temporaries(CFG), ?debug_msg("Coalescing RA: num_temps = ~p~n", [Num_Temps]), Allocatable = Target:allocatable(), K = length(Allocatable), All_colors = colset_from_list(Allocatable), %% Add registers with their own coloring ?debug_msg("Moves\n", []), Move_sets = hipe_moves:new(IG), ?debug_msg("Build Worklist\n", []), Worklists = hipe_reg_worklists:new(IG, Target, CFG, Move_sets, K, Num_Temps), Alias = initAlias(Num_Temps), ?debug_msg("Do coloring\n~p~n", [Worklists]), {_IG0, Worklists0, _Moves0, Alias0} = do_coloring(IG, Worklists, Move_sets, Alias, K, SpillLimit, Target), %% io:format("SelStk0 ~w\n",[SelStk0]), ?debug_msg("Init node sets\n", []), Node_sets = hipe_node_sets:new(), %% io:format("NodeSet: ~w\n NonAlloc ~w\n",[Node_sets,Target:non_alloc(CFG)]), ?debug_msg("Default coloring\n", []), {Color0,Node_sets1} = defaultColoring(Target:all_precoloured(), initColor(Num_Temps), Node_sets, Target), ?debug_msg("Assign colors\n", []), {Color1,Node_sets2} = assignColors(hipe_reg_worklists:stack(Worklists0), Node_sets1, Color0, Alias0, All_colors, Target), %% io:format("color0:~w\nColor1:~w\nNodes:~w\nNodes2:~w\nNum_Temps:~w\n",[Color0,Color1,Node_sets,Node_sets2,Num_Temps]), ?debug_msg("Build mapping ~p\n", [Node_sets2]), Coloring = build_namelist(Node_sets2, SpillIndex, Alias0, Color1), ?debug_msg("Coloring ~p\n", [Coloring]), Coloring. %%---------------------------------------------------------------------- %% Function: do_coloring %% %% Description: Create a coloring. That is, play paintball. %% Parameters: %% IG -- An interference graph %% Worklists -- Worklists, that is simplify, spill and freeze %% Moves -- Moves sets, that is coalesced, constrained %% and so on. %% Alias -- Tells if two temporaries can have their value %% in the same register. %% K -- Want to create a K coloring. %% SpillLimit -- Try not to spill nodes that are above the spill limit. %% %% Returns: %% IG -- Updated interference graph %% Worklists -- Updated Worklists structure %% Moves -- Updated Moves structure %% Alias -- Updates Alias structure %% %%---------------------------------------------------------------------- do_coloring(IG, Worklists, Moves, Alias, K, SpillLimit, Target) -> Simplify = not(hipe_reg_worklists:is_empty_simplify(Worklists)), Coalesce = not(hipe_moves:is_empty_worklist(Moves)), Freeze = not(hipe_reg_worklists:is_empty_freeze(Worklists)), Spill = not(hipe_reg_worklists:is_empty_spill(Worklists)), if Simplify =:= true -> {IG0, Worklists0, Moves0} = simplify(hipe_reg_worklists:simplify(Worklists), IG, Worklists, Moves, K), do_coloring(IG0, Worklists0, Moves0, Alias, K, SpillLimit, Target); Coalesce =:= true -> {Moves0, IG0, Worklists0, Alias0} = coalesce(Moves, IG, Worklists, Alias, K, Target), do_coloring(IG0, Worklists0, Moves0, Alias0, K, SpillLimit, Target); Freeze =:= true -> {Worklists0,Moves0} = freeze(K, Worklists, Moves, IG, Alias), do_coloring(IG, Worklists0, Moves0, Alias, K, SpillLimit, Target); Spill =:= true -> {Worklists0, Moves0} = selectSpill(Worklists, Moves, IG, K, Alias, SpillLimit), do_coloring(IG, Worklists0, Moves0, Alias, K, SpillLimit, Target); true -> % Catchall case {IG, Worklists, Moves, Alias} end. %%---------------------------------------------------------------------- %% Function: adjacent %% %% Description: Adjacent nodes that's not coalesced, on the stack or %% precoloured. %% Parameters: %% Node -- Node that you want to adjacents of %% IG -- The interference graph %% %% Returns: %% A set with nodes/temporaries that are not coalesced, on the %% stack or precoloured. %%---------------------------------------------------------------------- adjacent(Node, IG, Worklists) -> Adjacent_edges = hipe_ig:node_adj_list(Node, IG), hipe_reg_worklists:non_stacked_or_coalesced_nodes(Adjacent_edges, Worklists). %%---------------------------------------------------------------------- %% Function: simplify %% %% Description: Simplify graph by removing nodes of low degree. This %% function simplifies all nodes it can at once. %% Parameters: %% [Node|Nodes] -- The simplify worklist %% IG -- The interference graph %% Worklists -- The worklists data-structure %% Moves -- The moves data-structure %% K -- Produce a K coloring %% %% Returns: %% IG -- An updated interference graph %% Worklists -- An updated worklists data-structure %% Moves -- An updated moves data-structure %%---------------------------------------------------------------------- simplify([], IG, Worklists, Moves, _K) -> {IG, Worklists, Moves}; simplify([Node|Nodes], IG, Worklists, Moves, K) -> Worklists0 = hipe_reg_worklists:remove_simplify(Node, Worklists), ?debug_msg("putting ~w on stack~n",[Node]), Adjacent = adjacent(Node, IG, Worklists0), Worklists01 = hipe_reg_worklists:push_stack(Node, Adjacent, Worklists0), {New_ig, Worklists1, New_moves} = decrement_degree(Adjacent, IG, Worklists01, Moves, K), simplify(Nodes, New_ig, Worklists1, New_moves, K). %%---------------------------------------------------------------------- %% Function: decrement_degree %% %% Description: Decrement the degree on a number of nodes/temporaries. %% Parameters: %% [Node|Nodes] -- Decrement degree on these nodes %% IG -- The interference graph %% Worklists -- The Worklists data structure %% Moves -- The Moves data structure. %% K -- We want to create a coloring with K colors %% %% Returns: %% IG -- An updated interference graph (the degrees) %% Worklists -- Updated Worklists. Changed if one degree goes %% down to K. %% Moves -- Updated Moves. Changed if a move related temporary %% gets degree K. %%---------------------------------------------------------------------- decrement_degree([], IG, Worklists, Moves, _K) -> {IG, Worklists, Moves}; decrement_degree([Node|Nodes], IG, Worklists, Moves, K) -> PrevDegree = hipe_ig:get_node_degree(Node, IG), IG0 = hipe_ig:dec_node_degree(Node, IG), if PrevDegree =:= K -> AdjList = hipe_ig:node_adj_list(Node, IG0), %% Ok since Node (a) is still in IG, and (b) cannot be adjacent to itself Moves00 = enable_moves_active_to_worklist(hipe_moves:node_movelist(Node, Moves), Moves), Moves0 = enable_moves(AdjList, Worklists, Moves00), Worklists0 = hipe_reg_worklists:remove_spill(Node, Worklists), case hipe_moves:move_related(Node, Moves0) of true -> Worklists1 = hipe_reg_worklists:add_freeze(Node, Worklists0), decrement_degree(Nodes, IG0, Worklists1, Moves0, K); _ -> Worklists1 = hipe_reg_worklists:add_simplify(Node, Worklists0), decrement_degree(Nodes, IG0, Worklists1, Moves0, K) end; true -> decrement_degree(Nodes, IG0, Worklists, Moves, K) end. %%---------------------------------------------------------------------- %% Function: enable_moves %% %% Description: Make (move-related) nodes that are not yet considered for %% coalescing, ready for possible coalescing. %% %% Parameters: %% [Node|Nodes] -- A list of move nodes %% Moves -- The moves data-structure %% %% Returns: %% An updated moves data-structure %%---------------------------------------------------------------------- enable_moves([], _Worklists, Moves) -> Moves; enable_moves([Node|Nodes], Worklists, Moves) -> case hipe_reg_worklists:member_stack_or_coalesced(Node, Worklists) of true -> enable_moves(Nodes, Worklists, Moves); _ -> %% moveList[n] suffices since we're checking for activeMoves membership Node_moves = hipe_moves:node_movelist(Node, Moves), New_moves = enable_moves_active_to_worklist(Node_moves, Moves), enable_moves(Nodes, Worklists, New_moves) end. %%---------------------------------------------------------------------- %% Function: enable_moves_active_to_worklist %% %% Description: Make (move-related) nodes that are not yet considered for %% coalescing, ready for possible coalescing. %% %% Parameters: %% [Node|Nodes] -- A list of move nodes %% Moves -- The moves data structure %% %% Returns: %% An updated moves data structure %%---------------------------------------------------------------------- enable_moves_active_to_worklist([], Moves) -> Moves; enable_moves_active_to_worklist([Node|Nodes], Moves) -> NewMoves = case hipe_moves:member_active(Node, Moves) of true -> hipe_moves:add_worklist(Node, hipe_moves:remove_active(Node, Moves)); _ -> Moves end, enable_moves_active_to_worklist(Nodes, NewMoves). %% Build the namelists, these functions are fast hacks, they use knowledge %% about data representation that they shouldn't know, bad abstraction. build_namelist(NodeSets, Index, Alias, Color) -> ?debug_msg("Building mapping\n",[]), ?debug_msg("Vector to list\n",[]), AliasList = build_alias_list(aliasToList(Alias), 0, %% The first temporary has index 0 []), %% Accumulator ?debug_msg("Alias list:~p\n",[AliasList]), ?debug_msg("Coalesced\n",[]), NL1 = build_coalescedlist(AliasList, Color, Alias, []), ?debug_msg("Coalesced list:~p\n",[NL1]), ?debug_msg("Regs\n",[]), NL2 = build_reglist(hipe_node_sets:colored(NodeSets), Color, NL1), ?debug_msg("Regs list:~p\n",[NL2]), ?debug_msg("Spills\n",[]), build_spillist(hipe_node_sets:spilled(NodeSets), Index, NL2). build_spillist([], Index, List) -> {List,Index}; build_spillist([Node|Nodes], Index, List) -> ?debug_msg("[~p]: Spill ~p to ~p\n", [?MODULE,Node,Index]), build_spillist(Nodes, Index+1, [{Node,{spill,Index}}|List]). build_coalescedlist([], _Color, _Alias, List) -> List; build_coalescedlist([Node|Ns], Color, Alias, List) when is_integer(Node) -> ?debug_msg("Alias of ~p is ~p~n", [Node, getAlias(Node,Alias)]), AC = getColor(getAlias(Node, Alias), Color), build_coalescedlist(Ns, Color, Alias, [{Node,{reg,AC}}|List]). build_reglist([], _Color, List) -> List; build_reglist([Node|Ns], Color, List) -> build_reglist(Ns, Color, [{Node,{reg,getColor(Node,Color)}}|List]). build_alias_list([], _I, List) -> List; build_alias_list([Alias|Aliases], I, List) when is_integer(Alias) -> build_alias_list(Aliases, I+1, [I|List]); build_alias_list([_Alias|Aliases], I, List) -> build_alias_list(Aliases, I+1, List). %%---------------------------------------------------------------------- %% Function: assignColors %% %% Description: Tries to assign colors to nodes in a stack. %% Parameters: %% Stack -- The SelectStack built by the Select function, %% this stack contains tuples in the form {Node,Edges} %% where Node is the Node number and Edges is an ordset %% containing the numbers of all the adjacent nodes. %% NodeSets -- This is a record containing all the different node %% sets that are used in the register allocator. %% Alias -- This is a mapping from nodes to nodes, if a node has %% been coalesced this mapping shows the alias for that %% node. %% AllColors -- This is an ordset containing all the available colors %% %% Target -- The module containing the target-specific functions. %% %% Returns: %% Color -- A mapping from nodes to their respective color. %% NodeSets -- The updated node sets. %%---------------------------------------------------------------------- assignColors(Stack, NodeSets, Color, Alias, AllColors, Target) -> case Stack of [] -> {Color,NodeSets}; [{Node,Edges}|Stack1] -> ?debug_msg("Coloring Node: ~p~n",[Node]), ?IF_DEBUG(lists:foreach(fun (_E) -> ?msg(" Edge ~w-><~w>->~w~n", begin A = getAlias(_E,Alias), [_E,A,getColor(A,Color)] end) end, Edges), []), %% When debugging, check that Node isn't precoloured. OkColors = findOkColors(Edges, AllColors, Color, Alias), case colset_is_empty(OkColors) of true -> % Spill case NodeSets1 = hipe_node_sets:add_spilled(Node, NodeSets), assignColors(Stack1, NodeSets1, Color, Alias, AllColors, Target); false -> % Colour case Col = colset_smallest(OkColors), NodeSets1 = hipe_node_sets:add_colored(Node, NodeSets), Color1 = setColor(Node, Target:physical_name(Col), Color), assignColors(Stack1, NodeSets1, Color1, Alias, AllColors, Target) end end. %%--------------------------------------------------------------------- %% Function: defaultColoring %% %% Description: Make the default coloring %% Parameters: %% Regs -- The list of registers to be default colored %% Color -- The color mapping that shall be changed %% NodeSets -- The node sets that shall be updated %% Target -- The module containing the target-specific functions. %% %% Returns: %% NewColor -- The updated color mapping %% NewNodeSets -- The updated node sets %%--------------------------------------------------------------------- defaultColoring([], Color, NodeSets, _Target) -> {Color,NodeSets}; defaultColoring([Reg|Regs], Color, NodeSets, Target) -> Color1 = setColor(Reg,Target:physical_name(Reg), Color), NodeSets1 = hipe_node_sets:add_colored(Reg, NodeSets), defaultColoring(Regs, Color1, NodeSets1, Target). %% Find the colors that are OK for a node with certain edges. findOkColors(Edges, AllColors, Color, Alias) -> find(Edges, AllColors, Color, Alias). %% Find all the colors of the nodes in the list [Node|Nodes] and remove them %% from the set OkColors, when the list is empty, return OkColors. find([], OkColors, _Color, _Alias) -> OkColors; find([Node0|Nodes], OkColors, Color, Alias) -> Node = getAlias(Node0, Alias), case getColor(Node, Color) of [] -> find(Nodes, OkColors, Color, Alias); Col -> OkColors1 = colset_del_element(Col, OkColors), find(Nodes, OkColors1, Color, Alias) end. %%% %%% ColSet -- ADT for the set of available colours while %%% assigning colours. %%% -ifdef(notdef). % old ordsets-based implementation colset_from_list(Allocatable) -> ordsets:from_list(Allocatable). colset_del_element(Colour, ColSet) -> ordsets:del_element(Colour, ColSet). colset_is_empty(ColSet) -> case ColSet of [] -> true; [_|_] -> false end. colset_smallest([Colour|_]) -> Colour. -endif. -ifdef(notdef). % new gb_sets-based implementation colset_from_list(Allocatable) -> gb_sets:from_list(Allocatable). colset_del_element(Colour, ColSet) -> %% Must use gb_sets:delete_any/2 since gb_sets:del_element/2 %% fails if the element isn't present. Bummer. gb_sets:delete_any(Colour, ColSet). colset_is_empty(ColSet) -> gb_sets:is_empty(ColSet). colset_smallest(ColSet) -> gb_sets:smallest(ColSet). -endif. %%-ifdef(notdef). % new bitmask-based implementation colset_from_list(Allocatable) -> colset_from_list(Allocatable, 0). colset_from_list([], ColSet) -> ColSet; colset_from_list([Colour|Allocatable], ColSet) -> colset_from_list(Allocatable, ColSet bor (1 bsl Colour)). colset_del_element(Colour, ColSet) -> ColSet band bnot(1 bsl Colour). colset_is_empty(0) -> true; colset_is_empty(_) -> false. colset_smallest(ColSet) -> bitN_log2(ColSet band -ColSet, 0). bitN_log2(BitN, ShiftN) -> if BitN > 16#ffff -> bitN_log2(BitN bsr 16, ShiftN + 16); true -> ShiftN + hweight16(BitN - 1) end. hweight16(W) -> Res1 = ( W band 16#5555) + (( W bsr 1) band 16#5555), Res2 = (Res1 band 16#3333) + ((Res1 bsr 2) band 16#3333), Res3 = (Res2 band 16#0F0F) + ((Res2 bsr 4) band 16#0F0F), (Res3 band 16#00FF) + ((Res3 bsr 8) band 16#00FF). %%-endif. %%% %%% Colour ADT providing a partial mapping from nodes to colours. %%% initColor(NrNodes) -> {colmap, hipe_bifs:array(NrNodes, [])}. getColor(Node, {colmap, ColMap}) -> hipe_bifs:array_sub(ColMap, Node). setColor(Node, Colour, {colmap, ColMap} = Col) -> hipe_bifs:array_update(ColMap, Node, Colour), Col. %%% %%% Alias ADT providing a partial mapping from nodes to nodes. %%% initAlias(NrNodes) -> {alias, hipe_bifs:array(NrNodes, [])}. getAlias(Node, {alias, AliasMap} = Alias) -> case hipe_bifs:array_sub(AliasMap, Node) of [] -> Node; AliasNode -> getAlias(AliasNode, Alias) end. setAlias(Node, AliasNode, {alias, AliasMap} = Alias) -> hipe_bifs:array_update(AliasMap, Node, AliasNode), Alias. aliasToList({alias,AliasMap}) -> aliasToList(AliasMap, hipe_bifs:array_length(AliasMap), []). aliasToList(AliasMap, I1, Tail) -> I0 = I1 - 1, if I0 >= 0 -> aliasToList(AliasMap, I0, [hipe_bifs:array_sub(AliasMap, I0)|Tail]); true -> Tail end. %%---------------------------------------------------------------------- %% Function: coalesce %% %% Description: Coalesces nodes in worklist %% Parameters: %% Moves -- Current move information %% IG -- Interference graph %% Worklists -- Current worklists %% Alias -- Current aliases for temporaries %% K -- Number of registers %% %% Returns: %% {Moves, IG, Worklists, Alias} %% (Updated versions of above structures, after coalescing) %%---------------------------------------------------------------------- coalesce(Moves, IG, Worklists, Alias, K, Target) -> case hipe_moves:worklist_get_and_remove(Moves) of {[],Moves0} -> %% Moves marked for removal from worklistMoves by FreezeMoves() %% are removed by worklist_get_and_remove(). This case is unlikely, %% but can occur if only stale moves remain in worklistMoves. {Moves0,IG,Worklists,Alias}; {Move,Moves0} -> {Dest,Source} = hipe_moves:get_move(Move, Moves0), ?debug_msg("Testing nodes ~p and ~p for coalescing~n",[Dest,Source]), Alias_src = getAlias(Source, Alias), Alias_dst = getAlias(Dest, Alias), {U,V} = case Target:is_precoloured(Alias_dst) of true -> {Alias_dst, Alias_src}; false -> {Alias_src, Alias_dst} end, %% When debugging, check that neither V nor U is on the stack. if U =:= V -> Moves1 = Moves0, % drop coalesced move Move Worklists1 = add_worklist(Worklists, U, K, Moves1, IG, Target), {Moves1, IG, Worklists1, Alias}; true -> case (Target:is_precoloured(V) orelse hipe_ig:nodes_are_adjacent(U, V, IG)) of true -> Moves1 = Moves0, % drop constrained move Move Worklists1 = add_worklist(Worklists, U, K, Moves1, IG, Target), Worklists2 = add_worklist(Worklists1, V, K, Moves1, IG, Target), {Moves1, IG, Worklists2, Alias}; false -> case (case Target:is_precoloured(U) of true -> AdjV = hipe_ig:node_adj_list(V, IG), all_adjacent_ok(AdjV, U, Worklists, IG, K, Target); false -> AdjV = hipe_ig:node_adj_list(V, IG), AdjU = hipe_ig:node_adj_list(U, IG), conservative(AdjU, AdjV, U, Worklists, IG, K) end) of true -> Moves1 = Moves0, % drop coalesced move Move {IG1,Worklists1,Moves2,Alias1} = combine(U, V, IG, Worklists, Moves1, Alias, K, Target), Worklists2 = add_worklist(Worklists1, U, K, Moves2, IG1, Target), {Moves2, IG1, Worklists2, Alias1}; false -> Moves1 = hipe_moves:add_active(Move, Moves0), {Moves1, IG, Worklists, Alias} end end end end. %%---------------------------------------------------------------------- %% Function: add_worklist %% %% Description: Builds new worklists where U is transferred from freeze %% to simplify, if possible %% %% Parameters: %% Worklists -- Current worklists %% U -- Node to operate on %% K -- Number of registers %% Moves -- Current move information %% IG -- Interference graph %% Target -- The containing the target-specific functions %% %% Returns: %% Worklists (updated) %%---------------------------------------------------------------------- add_worklist(Worklists, U, K, Moves, IG, Target) -> case (not(Target:is_precoloured(U)) andalso not(hipe_moves:move_related(U, Moves)) andalso (hipe_ig:is_trivially_colourable(U, K, IG))) of true -> hipe_reg_worklists:transfer_freeze_simplify(U, Worklists); false -> Worklists end. %%---------------------------------------------------------------------- %% Function: combine %% %% Description: Combines two nodes into one (used when coalescing) %% %% Parameters: %% U -- First node to operate on %% V -- Second node to operate on %% IG -- Interference graph %% Worklists -- Current worklists %% Moves -- Current move information %% Alias -- Current aliases for temporaries %% K -- Number of registers %% %% Returns: %% {IG, Worklists, Moves, Alias} (updated) %%---------------------------------------------------------------------- combine(U, V, IG, Worklists, Moves, Alias, K, Target) -> Worklists1 = case hipe_reg_worklists:member_freeze(V, Worklists) of true -> hipe_reg_worklists:remove_freeze(V, Worklists); false -> hipe_reg_worklists:remove_spill(V, Worklists) end, Worklists11 = hipe_reg_worklists:add_coalesced(V, Worklists1), ?debug_msg("Coalescing ~p and ~p to ~p~n",[V,U,U]), Alias1 = setAlias(V, U, Alias), %% Typo in published algorithm: s/nodeMoves/moveList/g to fix. %% XXX: moveList[u] \union moveList[v] OR NodeMoves(u) \union NodeMoves(v) ??? %% XXX: NodeMoves() is correct, but unnecessarily strict. The ordsets:union %% constrains NodeMoves() to return an ordset. Moves1 = hipe_moves:update_movelist(U, ordsets:union(hipe_moves:node_moves(U, Moves), hipe_moves:node_moves(V, Moves)), Moves), %% Missing in published algorithm. From Tiger book Errata. Moves2 = enable_moves_active_to_worklist(hipe_moves:node_movelist(V, Moves1), Moves1), AdjV = hipe_ig:node_adj_list(V, IG), {IG1, Worklists2, Moves3} = combine_edges(AdjV, U, IG, Worklists11, Moves2, K, Target), New_worklists = case (not(hipe_ig:is_trivially_colourable(U, K, IG1)) andalso hipe_reg_worklists:member_freeze(U, Worklists2)) of true -> hipe_reg_worklists:transfer_freeze_spill(U, Worklists2); false -> Worklists2 end, {IG1, New_worklists, Moves3, Alias1}. %%---------------------------------------------------------------------- %% Function: combine_edges %% %% Description: For each node in a list, make an edge between that node %% and node U, and decrement its degree by 1 %% (Used when two nodes are coalesced, to connect all nodes %% adjacent to one node to the other node) %% %% Parameters: %% [T|Ts] -- List of nodes to make edges to %% U -- Node to make edges from %% IG -- Interference graph %% Worklists -- Current worklists %% Moves -- Current move information %% K -- Number of registers %% %% Returns: %% {IG, Worklists, Moves} (updated) %%---------------------------------------------------------------------- combine_edges([], _U, IG, Worklists, Moves, _K, _Target) -> {IG, Worklists, Moves}; combine_edges([T|Ts], U, IG, Worklists, Moves, K, Target) -> case hipe_reg_worklists:member_stack_or_coalesced(T, Worklists) of true -> combine_edges(Ts, U, IG, Worklists, Moves, K, Target); _ -> %% XXX: The issue below occurs because the T->V edge isn't removed. %% This causes adjList[T] to contain stale entries, to possibly grow %% (if T isn't already adjacent to U), and degree[T] to possibly %% increase (again, if T isn't already adjacent to U). %% The decrement_degree() call repairs degree[T] but not adjList[T]. %% It would be better to physically replace T->V with T->U, and only %% decrement_degree(T) if T->U already existed. %% %% add_edge() may change a low-degree move-related node to be of %% significant degree. In this case the node belongs in the spill %% worklist, and that's where decrement_degree() expects to find it. %% This issue is not covered in the published algorithm. OldDegree = hipe_ig:get_node_degree(T, IG), IG1 = hipe_ig:add_edge(T, U, IG, Target), NewDegree = hipe_ig:get_node_degree(T, IG1), Worklists0 = if NewDegree =:= K, OldDegree =:= K-1 -> %% io:format("~w:combine_edges(): repairing worklist membership for node ~w\n", [?MODULE,T]), %% The node T must be on the freeze worklist: %% 1. Since we're coalescing, the simplify worklist must have been %% empty when combine_edges() started. %% 2. decrement_degree() may put the node T back on the simplify %% worklist, but that occurs after the worklists repair step. %% 3. There are no duplicates among the edges. Worklists00 = hipe_reg_worklists:remove_freeze(T, Worklists), hipe_reg_worklists:add_spill(T, Worklists00); true -> Worklists end, {IG2, Worklists1, Moves1} = decrement_degree([T], IG1, Worklists0, Moves, K), combine_edges(Ts, U, IG2, Worklists1, Moves1, K, Target) end. %%---------------------------------------------------------------------- %% Function: ok %% %% Description: Checks if a node T is suitable to coalesce with R %% %% Parameters: %% T -- Node to test %% R -- Other node to test %% IG -- Interference graph %% K -- Number of registers %% Target -- The module containing the target-specific functions %% %% Returns: %% true iff coalescing is OK %%---------------------------------------------------------------------- ok(T, R, IG, K, Target) -> ((hipe_ig:is_trivially_colourable(T, K, IG)) orelse Target:is_precoloured(T) orelse hipe_ig:nodes_are_adjacent(T, R, IG)). %%---------------------------------------------------------------------- %% Function: all_ok %% %% Description: True iff, for every T in the list, OK(T,U) %% %% Parameters: %% [T|Ts] -- Nodes to test %% U -- Node to test for coalescing %% IG -- Interference graph %% K -- Number of registers %% Target -- The module containing the target-specific functions %% %% Returns: %% true iff coalescing is OK for all nodes in the list %%---------------------------------------------------------------------- all_adjacent_ok([], _U, _Worklists, _IG, _K, _Target) -> true; all_adjacent_ok([T|Ts], U, Worklists, IG, K, Target) -> case hipe_reg_worklists:member_stack_or_coalesced(T, Worklists) of true -> all_adjacent_ok(Ts, U, Worklists, IG, K, Target); _ -> %% 'andalso' does not preserve tail-recursion case ok(T, U, IG, K, Target) of true -> all_adjacent_ok(Ts, U, Worklists, IG, K, Target); false -> false end end. %%---------------------------------------------------------------------- %% Function: conservative %% %% Description: Checks if nodes can be safely coalesced according to %% the Briggs' conservative coalescing heuristic %% %% Parameters: %% Nodes -- Adjacent nodes %% IG -- Interference graph %% K -- Number of registers %% %% Returns: %% true iff coalescing is safe %%---------------------------------------------------------------------- conservative(AdjU, AdjV, U, Worklists, IG, K) -> conservative_countU(AdjU, AdjV, U, Worklists, IG, K, 0). %%---------------------------------------------------------------------- %% Function: conservative_count %% %% Description: Counts degrees for conservative (Briggs' heuristic) %% %% Parameters: %% Nodes -- (Remaining) adjacent nodes %% IG -- Interference graph %% K -- Number of registers %% Cnt -- Accumulator for counting %% %% Returns: %% Final value of accumulator %%---------------------------------------------------------------------- conservative_countU([], AdjV, U, Worklists, IG, K, Cnt) -> conservative_countV(AdjV, U, Worklists, IG, K, Cnt); conservative_countU([Node|AdjU], AdjV, U, Worklists, IG, K, Cnt) -> case hipe_reg_worklists:member_stack_or_coalesced(Node, Worklists) of true -> conservative_countU(AdjU, AdjV, U, Worklists, IG, K, Cnt); _ -> case hipe_ig:is_trivially_colourable(Node, K, IG) of true -> conservative_countU(AdjU, AdjV, U, Worklists, IG, K, Cnt); _ -> Cnt1 = Cnt + 1, if Cnt1 < K -> conservative_countU(AdjU, AdjV, U, Worklists, IG, K, Cnt1); true -> false end end end. conservative_countV([], _U, _Worklists, _IG, _K, _Cnt) -> true; conservative_countV([Node|AdjV], U, Worklists, IG, K, Cnt) -> case hipe_reg_worklists:member_stack_or_coalesced(Node, Worklists) of true -> conservative_countV(AdjV, U, Worklists, IG, K, Cnt); _ -> case hipe_ig:nodes_are_adjacent(Node, U, IG) of true -> conservative_countV(AdjV, U, Worklists, IG, K, Cnt); _ -> case hipe_ig:is_trivially_colourable(Node, K, IG) of true -> conservative_countV(AdjV, U, Worklists, IG, K, Cnt); _ -> Cnt1 = Cnt + 1, if Cnt1 < K -> conservative_countV(AdjV, U, Worklists, IG, K, Cnt1); true -> false end end end end. %%--------------------------------------------------------------------- %% Function: selectSpill %% %% Description: Select the node to spill and spill it %% Parameters: %% WorkLists -- A datatype containing the different worklists %% Moves -- A datatype containing the move sets %% IG -- The interference graph %% K -- The number of available registers %% Alias -- The alias mapping %% SpillLimit -- Try not to spill any nodes above the spill limit %% %% Returns: %% WorkLists -- The updated worklists %% Moves -- The updated moves %%--------------------------------------------------------------------- selectSpill(WorkLists, Moves, IG, K, Alias, SpillLimit) -> [CAR|CDR] = hipe_reg_worklists:spill(WorkLists), SpillCost = getCost(CAR, IG, SpillLimit), M = findCheapest(CDR, IG, SpillCost, CAR, SpillLimit), WorkLists1 = hipe_reg_worklists:remove_spill(M, WorkLists), %% The published algorithm adds M to the simplify worklist %% before the freezeMoves() call. That breaks the worklist %% invariants, which is why the order is switched here. {WorkLists2,Moves1} = freezeMoves(M, K, WorkLists1, Moves, IG, Alias), WorkLists3 = hipe_reg_worklists:add_simplify(M, WorkLists2), {WorkLists3,Moves1}. %% Find the node that is cheapest to spill findCheapest([], _IG, _Cost, Cheapest, _SpillLimit) -> Cheapest; findCheapest([Node|Nodes], IG, Cost, Cheapest, SpillLimit) -> ThisCost = getCost(Node, IG, SpillLimit), case ThisCost < Cost of true -> findCheapest(Nodes, IG, ThisCost, Node, SpillLimit); false -> findCheapest(Nodes, IG, Cost, Cheapest, SpillLimit) end. %% Get the cost for spilling a certain node, node numbers above the spill %% limit are extremely expensive. getCost(Node, IG, SpillLimit) -> case Node > SpillLimit of true -> inf; false -> hipe_ig:node_spill_cost(Node, IG) end. %%---------------------------------------------------------------------- %% Function: freeze %% %% Description: When both simplifying and coalescing is impossible we %% rather freezes a node in stead of spilling, this function %% selects a node for freezing (it just picks the first one in %% the list) %% %% Parameters: %% K -- The number of available registers %% WorkLists -- A datatype containing the different worklists %% Moves -- A datatype containing the different movelists %% IG -- Interference graph %% Alias -- An alias mapping, shows the alias of all coalesced %% nodes %% %% Returns: %% WorkLists -- The updated worklists %% Moves -- The updated movelists %%---------------------------------------------------------------------- freeze(K, WorkLists, Moves, IG, Alias) -> [U|_] = hipe_reg_worklists:freeze(WorkLists), % Smarter routine? ?debug_msg("freezing node ~p~n", [U]), WorkLists0 = hipe_reg_worklists:remove_freeze(U, WorkLists), %% The published algorithm adds U to the simplify worklist %% before the freezeMoves() call. That breaks the worklist %% invariants, which is why the order is switched here. {WorkLists1,Moves1} = freezeMoves(U,K,WorkLists0,Moves,IG,Alias), WorkLists2 = hipe_reg_worklists:add_simplify(U, WorkLists1), {WorkLists2,Moves1}. %%---------------------------------------------------------------------- %% Function: freezeMoves %% %% Description: Make all move related interferences for a certain node %% into ordinary interference arcs. %% %% Parameters: %% U -- The node we want to freeze %% K -- The number of available registers %% WorkLists -- A datatype containing the different worklists %% Moves -- A datatype containing the different movelists %% IG -- Interference graph %% Alias -- An alias mapping, shows the alias of all coalesced %% nodes %% %% Returns: %% WorkLists -- The updated worklists %% Moves -- The updated movelists %%---------------------------------------------------------------------- freezeMoves(U, K, WorkLists, Moves, IG, Alias) -> Nodes = hipe_moves:node_moves(U, Moves), freezeEm(U, Nodes, K, WorkLists, Moves, IG, Alias). %% Find what the other value in a copy instruction is, return false if %% the instruction isn't a move with the first argument in it. moves(U, Move, Alias, Moves) -> {X,Y} = hipe_moves:get_move(Move, Moves), %% The old code (which followed the published algorithm) did %% not follow aliases before looking for "the other" node. %% This caused moves() to skip some moves, making some nodes %% still move-related after freezeMoves(). These move-related %% nodes were then added to the simplify worklist (by freeze() %% or selectSpill()), breaking the worklist invariants. Nodes %% already simplified appeared in coalesce(), were re-added to %% the simplify worklist by add_worklist(), simplified again, %% and coloured multiple times by assignColors(). Ouch! X1 = getAlias(X, Alias), Y1 = getAlias(Y, Alias), if U =:= X1 -> Y1; U =:= Y1 -> X1; true -> exit({?MODULE,moves}) % XXX: shouldn't happen end. freezeEm(_U, [], _K, WorkLists, Moves, _IG, _Alias) -> {WorkLists,Moves}; freezeEm(U,[M|Ms], K, WorkLists, Moves, IG, Alias) -> V = moves(U, M, Alias, Moves), {WorkLists2,Moves2} = freezeEm2(U, V, M, K, WorkLists, Moves, IG, Alias), freezeEm(U, Ms, K, WorkLists2, Moves2, IG, Alias). freezeEm2(U, V, M, K, WorkLists, Moves, IG, Alias) -> case hipe_moves:member_active(M, Moves) of true -> Moves1 = hipe_moves:remove_active(M, Moves), freezeEm3(U, V, M, K, WorkLists, Moves1, IG, Alias); false -> Moves1 = hipe_moves:remove_worklist(M, Moves), freezeEm3(U, V, M, K, WorkLists, Moves1, IG, Alias) end. freezeEm3(_U, V, _M, K, WorkLists, Moves, IG, _Alias) -> Moves1 = Moves, % drop frozen move M V1 = V, % getAlias(V,Alias), %% "not MoveRelated(v)" is cheaper than "NodeMoves(v) = {}" case ((not hipe_moves:move_related(V1, Moves1)) andalso hipe_ig:is_trivially_colourable(V1, K, IG)) of true -> ?debug_msg("freezing move to ~p~n", [V]), Worklists1 = hipe_reg_worklists:transfer_freeze_simplify(V1, WorkLists), {Worklists1, Moves1}; false -> {WorkLists, Moves1} end.