%% -*- erlang-indent-level: 2 -*-
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% ==========================================================================
%% Module : hipe_spillmin
%% Purpose : Driver module for minimizing the number of stack slots used
%% by a function. This is done using an algorithm for register
%% allocation. The implementation is target-independent and
%% requires a target-specific interface module as argument.
%% ==========================================================================
%% Exported functions (short description):
%%
%% stackalloc(CFG, StackSlots, SpillIndex, Options, TgtMod, TgtCtx,
%% TempMap) ->
%% {Coloring, NumberOfSpills}
%% Takes a CFG and the TempMap from register allocation and returns
%% a coloring of stack slots.
%% StackSlots should be a list of used stack slots, usually empty at
%% first call to function.
%% SpillIndex is the the first position we will spill to, usually 0.
%% TempMap is the TempMap from the register allocation
%%
%% The Coloring will be in the form of the "allocation datastructure"
%% described below, that is, a list of tuples on the form
%% {Name, {spill, SpillIndex}}
%% The NumberOfSpills is either 0 indicating no spill or the
%% SpillIndex of the last spilled register.
%%
%% mapmerge(Map, SpillMap) -> NewMap
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-module(hipe_spillmin).
-export([stackalloc/7, stackalloc/8, mapmerge/2]).
%%-define(DEBUG, 1).
-define(HIPE_INSTRUMENT_COMPILER, true).
%%---------------------------------------------------------------------------
-include("../main/hipe.hrl").
-include("../flow/cfg.hrl").
-type target_context() :: any().
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% stackalloc(CFG, StackSlots, SpillIndex, Options, Target, TempMap)
%% Calculates an allocation of stack slots using either a linear scan
%% or a graph coloring allocation algorithm.
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec stackalloc(#cfg{}, [_], non_neg_integer(),
comp_options(), module(), target_context(), hipe_temp_map()) ->
{hipe_spill_map(), non_neg_integer()}.
stackalloc(CFG, StackSlots, SpillIndex, Options, TgtMod, TgtCtx, TempMap) ->
Liveness = TgtMod:analyze(CFG,TgtCtx),
stackalloc(CFG, Liveness, StackSlots, SpillIndex, Options, TgtMod, TgtCtx, TempMap).
-spec stackalloc(#cfg{}, _, [_], non_neg_integer(),
comp_options(), module(), target_context(), hipe_temp_map()) ->
{hipe_spill_map(), non_neg_integer()}.
stackalloc(CFG, Liveness, StackSlots, SpillIndex, Options, TgtMod, TgtCtx,
TempMap) ->
case proplists:get_bool(spillmin_color, Options) of
false ->
?option_time(hipe_spillmin_scan:stackalloc(
CFG, Liveness, StackSlots, SpillIndex, Options, TgtMod,
TgtCtx, TempMap),
"Spill minimize, linear scan", Options);
true ->
?option_time(hipe_spillmin_color:stackalloc(
CFG, Liveness, StackSlots, SpillIndex, Options, TgtMod,
TgtCtx, TempMap),
"Spill minimize, graph coloring", Options)
end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% mapmerge(Map, SpillMap)
%%
%% stackalloc/6 will only return the subset of the tempmap that contains
%% the spilled temporaries. This function is used to merge the old
%% complete tempmap with the new spill information.
%% Map is the old map (a list of [{R0, C1}, {R1, C2}, ...]).
%% SpillMap is the new "spill" map.
%% !! Warning, the function does not work with the maps in another order !!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Combines the map with allocated spills with a map from the register
%% allocator
-spec mapmerge(hipe_map(), hipe_spill_map()) -> hipe_map().
mapmerge(TempMap, SpillMap) ->
mapmerge(TempMap, SpillMap, []).
mapmerge([], _, Ack) ->
lists:reverse(Ack);
mapmerge([{T1, _}|T1s], [{T2, C}|T2s], Ack) when T1 =:= T2 ->
mapmerge(T1s, T2s, [{T1, C}|Ack]);
mapmerge([{_, unknown}|T1s], T2s, Ack) ->
mapmerge(T1s, T2s, Ack);
mapmerge([T1|T1s], T2s, Ack) ->
mapmerge(T1s, T2s, [T1|Ack]).
