1 | (* Pasted from Pottier's PP compiler *) |
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2 | |
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3 | (** This module implements a data structure for interference graphs. |
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4 | It provides functions that help construct, transform and inspect |
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5 | interference graphs. *) |
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6 | |
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7 | (* Interference graphs record two kinds of edges: interference edges |
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8 | (``these two vertices cannot receive the same color'') and |
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9 | preference edges (``these two vertices should preferably receive |
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10 | the same color''). Furthermore, each kind of edge can relate either |
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11 | two pseudo-registers or one pseudo-register and one hardware |
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12 | register. Thus, an interference graph keeps track of four kinds of |
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13 | relationships. |
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14 | |
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15 | This module automatically maintains the invariant that two vertices |
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16 | [x] and [y] cannot be related by both an interference edge and a |
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17 | preference edge. When such a situation appears (for instance, |
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18 | because of coalescing), the preference edge is automatically |
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19 | removed. *) |
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20 | |
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21 | type graph |
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22 | |
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23 | (* The vertices of an interference graph initially correspond to |
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24 | pseudo-registers. However, interference graphs support coalescing, |
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25 | which means that a new graph can be constructed by coalescing two |
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26 | vertices in an existing graph. As a result, in general, the vertices |
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27 | of an interference graph correspond to sets of pseudo-registers. *) |
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28 | |
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29 | (* ------------------------------------------------------------------------- *) |
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30 | |
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31 | (* Operations over vertices: sets of vertices, maps over vertices. *) |
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32 | |
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33 | module Vertex : sig |
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34 | |
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35 | type t |
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36 | |
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37 | (* The usual operations on sets, see [Set.S] in Objective Caml's |
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38 | documentation. *) |
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39 | |
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40 | module Set : Set.S with type elt = t |
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41 | |
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42 | (* The usual operations on maps, see [Map.S] in Objective Caml's |
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43 | documentation. One slight difference is that [find] expects |
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44 | the key to be present in the map -- it will fail otherwise. *) |
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45 | |
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46 | module Map : Map.S with type key = t |
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47 | |
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48 | end |
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49 | |
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50 | (* ------------------------------------------------------------------------- *) |
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51 | |
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52 | (* Building interference graphs. *) |
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53 | |
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54 | (* [create regs] creates an interference graph whose vertices are |
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55 | the pseudo-registers [regs] and that does not have any edges. *) |
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56 | |
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57 | val create: Register.Set.t -> graph |
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58 | |
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59 | (* [mki graph regs1 regs2] adds interference edges between all pairs |
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60 | of (pseudo- or hardware) registers [r1] and [r2], where [r1] ranges |
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61 | over [regs1], [r2] ranges over [regs2], and [r1] and [r2] are |
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62 | distinct. *) |
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63 | |
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64 | val mki: graph -> |
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65 | Register.Set.t * I8051.RegisterSet.t -> |
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66 | Register.Set.t * I8051.RegisterSet.t -> |
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67 | graph |
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68 | |
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69 | (* [mkiph graph regs hwregs] adds interference edges between all pairs |
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70 | of a pseudo-register [r] and a hardware register [hwr], where [r] |
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71 | ranges over [regs] and [hwr] ranges over [hwregs]. *) |
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72 | |
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73 | val mkiph: graph -> Register.Set.t -> I8051.RegisterSet.t -> graph |
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74 | |
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75 | (* [mkppp graph r1 r2] adds a preference edge between the |
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76 | pseudo-registers [r1] and [r2]. *) |
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77 | |
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78 | val mkppp: graph -> Register.t -> Register.t -> graph |
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79 | |
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80 | (* [mkpph graph r h] adds a preference edge between the |
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81 | pseudo-register [r] and the hardware register [h]. *) |
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82 | |
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83 | val mkpph: graph -> Register.t -> I8051.register -> graph |
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84 | |
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85 | (* ------------------------------------------------------------------------- *) |
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86 | |
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87 | (* Transforming interference graphs. *) |
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88 | |
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89 | (* [coalesce graph v1 v2] is a new graph where the vertices [v1] and |
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90 | [v2] are coalesced. [v1] and [v2] must not interfere. The new |
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91 | coalesced vertex is known under the name [v2]. *) |
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92 | |
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93 | val coalesce: graph -> Vertex.t -> Vertex.t -> graph |
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94 | |
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95 | (* [coalesceh graph v h] coalesces the vertex [v] with the hardware register |
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96 | [h]. This produces a new graph where [v] no longer exists and all edges |
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97 | leading to [v] are replaced with edges leading to [h]. *) |
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98 | |
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99 | val coalesceh: graph -> Vertex.t -> I8051.register -> graph |
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100 | |
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101 | (* [remove graph v] is a new graph where vertex [v] is removed. *) |
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102 | |
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103 | val remove: graph -> Vertex.t -> graph |
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104 | |
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105 | (* [freeze graph x] is a new graph where all preference edges carried |
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106 | by [x] are removed. *) |
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107 | |
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108 | val freeze: graph -> Vertex.t -> graph |
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109 | |
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110 | (* [restrict graph p] is a new graph where only those vertices that |
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111 | satisfy predicate [p] are kept. *) |
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112 | |
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113 | val restrict: graph -> (Vertex.t -> bool) -> graph |
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114 | |
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115 | (* [droph graph] is a new graph where all information concerning hardware |
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116 | registers has been dropped. *) |
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117 | |
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118 | val droph: graph -> graph |
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119 | |
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120 | (* ------------------------------------------------------------------------- *) |
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121 | |
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122 | (* Inspecting interference graphs. *) |
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123 | |
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124 | (* [lookup graph r] returns the graph vertex associated with |
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125 | pseudo-register [r]. *) |
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126 | |
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127 | val lookup: graph -> Register.t -> Vertex.t |
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128 | |
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129 | (* Conversely, [registers graph v] returns the set of pseudo-registers |
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130 | associated with vertex [v]. *) |
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131 | |
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132 | val registers: graph -> Vertex.t -> Register.Set.t |
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133 | |
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134 | (* [degree graph v] is the degree of the vertex [v], that is, the number |
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135 | of vertices and hardware registers that [v] interferes with. *) |
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136 | |
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137 | val degree: graph -> Vertex.t -> int |
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138 | |
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139 | (* [lowest graph] returns [Some (v, d)], where the vertex [v] has |
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140 | minimum degree [d], or returns [None] if the graph is empty. *) |
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141 | |
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142 | val lowest: graph -> (Vertex.t * int) option |
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143 | |
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144 | (* [lowest_non_move_related graph] returns [Some (v, d)], where the |
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145 | vertex [v] has minimum degree [d] among the vertices that are not |
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146 | move-related, or returns [None] if all vertices are move-related. A |
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147 | vertex is move-related if it carries a preference edge. *) |
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148 | |
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149 | val lowest_non_move_related: graph -> (Vertex.t * int) option |
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150 | |
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151 | (* [minimum f graph] returns a vertex [v] such that the value of [f x] |
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152 | is minimal. The values returned by [f] are compared using Objective |
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153 | Caml's generic comparison operator [<]. If the graph is empty, |
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154 | [None] is returned. *) |
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155 | |
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156 | val minimum: (Vertex.t -> 'a) -> graph -> Vertex.t option |
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157 | |
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158 | (* [fold f graph accu] folds over all vertices. *) |
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159 | |
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160 | val fold: (Vertex.t -> 'a -> 'a) -> graph -> 'a -> 'a |
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161 | |
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162 | (* [ipp graph v] is the set of vertices that the vertex [v] interferes |
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163 | with. *) |
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164 | |
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165 | val ipp: graph -> Vertex.t -> Vertex.Set.t |
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166 | |
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167 | (* [iph graph v] is the set of hardware registers that the vertex [v] |
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168 | interferes with. *) |
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169 | |
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170 | val iph: graph -> Vertex.t -> I8051.RegisterSet.t |
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171 | |
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172 | (* [ppp graph v] is the set of vertices that should preferably be |
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173 | assigned the same color as the vertex [v]. *) |
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174 | |
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175 | val ppp: graph -> Vertex.t -> Vertex.Set.t |
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176 | |
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177 | (* [pph graph v] is the set of hardware registers that [v] should |
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178 | preferably be assigned. *) |
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179 | |
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180 | val pph: graph -> Vertex.t -> I8051.RegisterSet.t |
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181 | |
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182 | (* [pppick graph p] returns an arbitrary preference edge that |
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183 | satisfies the predicate [p], if the graph contains one. *) |
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184 | |
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185 | type ppedge = |
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186 | Vertex.t * Vertex.t |
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187 | |
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188 | val pppick: graph -> (ppedge -> bool) -> ppedge option |
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189 | |
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190 | (* [phpick graph p] returns an arbitrary preference edge that |
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191 | satisfies the predicate [p], if the graph contains one. *) |
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192 | |
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193 | type phedge = |
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194 | Vertex.t * I8051.register |
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195 | |
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196 | val phpick: graph -> (phedge -> bool) -> phedge option |
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197 | |
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198 | (* ------------------------------------------------------------------------- *) |
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199 | |
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200 | (* Displaying interference graphs. *) |
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201 | |
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202 | (* [print_vertex graph v] produces a string representation of the |
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203 | vertex [v]. *) |
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204 | |
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205 | val print_vertex: graph -> Vertex.t -> string |
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206 | |
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207 | (* [print f graph] prints a representation of the interference graph |
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208 | [graph] in [dot] format to the output channel [f]. Interference |
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209 | edges are drawn as plain lines; preference edges are drawn as |
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210 | dotted lines. *) |
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211 | |
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212 | val print: out_channel -> graph -> unit |
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213 | |
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