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Diffstat (limited to 'lib/hipe/regalloc/hipe_coalescing_regalloc.erl')
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1 files changed, 1029 insertions, 0 deletions
diff --git a/lib/hipe/regalloc/hipe_coalescing_regalloc.erl b/lib/hipe/regalloc/hipe_coalescing_regalloc.erl new file mode 100644 index 0000000000..5a4b017c71 --- /dev/null +++ b/lib/hipe/regalloc/hipe_coalescing_regalloc.erl @@ -0,0 +1,1029 @@ +%% -*- 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 <[email protected]> +%% Thorild Sel�n <[email protected]> +%% Ingemar �berg <[email protected]> +%% 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. |