%% -*- 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.
