1 | package B::Bblock;
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2 |
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3 | our $VERSION = '1.02_01';
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4 |
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5 | use Exporter ();
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6 | @ISA = "Exporter";
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7 | @EXPORT_OK = qw(find_leaders);
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8 |
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9 | use B qw(peekop walkoptree walkoptree_exec
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10 | main_root main_start svref_2object
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11 | OPf_SPECIAL OPf_STACKED );
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12 |
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13 | use B::Concise qw(concise_cv concise_main set_style_standard);
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14 | use strict;
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15 |
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16 | my $bblock;
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17 | my @bblock_ends;
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18 |
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19 | sub mark_leader {
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20 | my $op = shift;
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21 | if ($$op) {
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22 | $bblock->{$$op} = $op;
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23 | }
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24 | }
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25 |
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26 | sub remove_sortblock{
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27 | foreach (keys %$bblock){
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28 | my $leader=$$bblock{$_};
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29 | delete $$bblock{$_} if( $leader == 0);
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30 | }
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31 | }
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32 | sub find_leaders {
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33 | my ($root, $start) = @_;
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34 | $bblock = {};
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35 | mark_leader($start) if ( ref $start ne "B::NULL" );
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36 | walkoptree($root, "mark_if_leader") if ((ref $root) ne "B::NULL") ;
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37 | remove_sortblock();
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38 | return $bblock;
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39 | }
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40 |
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41 | # Debugging
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42 | sub walk_bblocks {
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43 | my ($root, $start) = @_;
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44 | my ($op, $lastop, $leader, $bb);
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45 | $bblock = {};
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46 | mark_leader($start);
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47 | walkoptree($root, "mark_if_leader");
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48 | my @leaders = values %$bblock;
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49 | while ($leader = shift @leaders) {
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50 | $lastop = $leader;
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51 | $op = $leader->next;
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52 | while ($$op && !exists($bblock->{$$op})) {
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53 | $bblock->{$$op} = $leader;
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54 | $lastop = $op;
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55 | $op = $op->next;
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56 | }
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57 | push(@bblock_ends, [$leader, $lastop]);
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58 | }
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59 | foreach $bb (@bblock_ends) {
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60 | ($leader, $lastop) = @$bb;
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61 | printf "%s .. %s\n", peekop($leader), peekop($lastop);
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62 | for ($op = $leader; $$op != $$lastop; $op = $op->next) {
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63 | printf " %s\n", peekop($op);
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64 | }
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65 | printf " %s\n", peekop($lastop);
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66 | }
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67 | }
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68 |
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69 | sub walk_bblocks_obj {
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70 | my $cvref = shift;
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71 | my $cv = svref_2object($cvref);
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72 | walk_bblocks($cv->ROOT, $cv->START);
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73 | }
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74 |
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75 | sub B::OP::mark_if_leader {}
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76 |
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77 | sub B::COP::mark_if_leader {
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78 | my $op = shift;
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79 | if ($op->label) {
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80 | mark_leader($op);
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81 | }
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82 | }
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83 |
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84 | sub B::LOOP::mark_if_leader {
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85 | my $op = shift;
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86 | mark_leader($op->next);
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87 | mark_leader($op->nextop);
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88 | mark_leader($op->redoop);
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89 | mark_leader($op->lastop->next);
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90 | }
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91 |
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92 | sub B::LOGOP::mark_if_leader {
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93 | my $op = shift;
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94 | my $opname = $op->name;
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95 | mark_leader($op->next);
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96 | if ($opname eq "entertry") {
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97 | mark_leader($op->other->next);
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98 | } else {
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99 | mark_leader($op->other);
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100 | }
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101 | }
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102 |
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103 | sub B::LISTOP::mark_if_leader {
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104 | my $op = shift;
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105 | my $first=$op->first;
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106 | $first=$first->next while ($first->name eq "null");
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107 | mark_leader($op->first) unless (exists( $bblock->{$$first}));
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108 | mark_leader($op->next);
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109 | if ($op->name eq "sort" and $op->flags & OPf_SPECIAL
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110 | and $op->flags & OPf_STACKED){
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111 | my $root=$op->first->sibling->first;
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112 | my $leader=$root->first;
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113 | $bblock->{$$leader} = 0;
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114 | }
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115 | }
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116 |
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117 | sub B::PMOP::mark_if_leader {
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118 | my $op = shift;
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119 | if ($op->name ne "pushre") {
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120 | my $replroot = $op->pmreplroot;
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121 | if ($$replroot) {
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122 | mark_leader($replroot);
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123 | mark_leader($op->next);
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124 | mark_leader($op->pmreplstart);
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125 | }
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126 | }
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127 | }
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128 |
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129 | # PMOP stuff omitted
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130 |
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131 | sub compile {
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132 | my @options = @_;
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133 | B::clearsym();
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134 | if (@options) {
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135 | return sub {
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136 | my $objname;
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137 | foreach $objname (@options) {
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138 | $objname = "main::$objname" unless $objname =~ /::/;
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139 | eval "walk_bblocks_obj(\\&$objname)";
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140 | die "walk_bblocks_obj(\\&$objname) failed: $@" if $@;
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141 | print "-------\n";
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142 | set_style_standard("terse");
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143 | eval "concise_cv('exec', \\&$objname)";
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144 | die "concise_cv('exec', \\&$objname) failed: $@" if $@;
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145 | }
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146 | }
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147 | } else {
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148 | return sub {
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149 | walk_bblocks(main_root, main_start);
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150 | print "-------\n";
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151 | set_style_standard("terse");
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152 | concise_main("exec");
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153 | };
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154 | }
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155 | }
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156 |
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157 | # Basic block leaders:
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158 | # Any COP (pp_nextstate) with a non-NULL label
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159 | # [The op after a pp_enter] Omit
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160 | # [The op after a pp_entersub. Don't count this one.]
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161 | # The ops pointed at by nextop, redoop and lastop->op_next of a LOOP
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162 | # The ops pointed at by op_next and op_other of a LOGOP, except
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163 | # for pp_entertry which has op_next and op_other->op_next
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164 | # The op pointed at by op_pmreplstart of a PMOP
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165 | # The op pointed at by op_other->op_pmreplstart of pp_substcont?
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166 | # [The op after a pp_return] Omit
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167 |
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168 | 1;
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169 |
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170 | __END__
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171 |
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172 | =head1 NAME
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173 |
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174 | B::Bblock - Walk basic blocks
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175 |
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176 | =head1 SYNOPSIS
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177 |
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178 | # External interface
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179 | perl -MO=Bblock[,OPTIONS] foo.pl
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180 |
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181 | # Programmatic API
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182 | use B::Bblock qw(find_leaders);
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183 | my $leaders = find_leaders($root_op, $start_op);
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184 |
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185 | =head1 DESCRIPTION
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186 |
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187 | This module is used by the B::CC back end. It walks "basic blocks".
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188 | A basic block is a series of operations which is known to execute from
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189 | start to finish, with no possibility of branching or halting.
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190 |
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191 | It can be used either stand alone or from inside another program.
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192 |
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193 | =for _private
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194 | Somebody who understands the stand-alone options document them, please.
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195 |
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196 | =head2 Functions
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197 |
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198 | =over 4
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199 |
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200 | =item B<find_leaders>
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201 |
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202 | my $leaders = find_leaders($root_op, $start_op);
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203 |
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204 | Given the root of the op tree and an op from which to start
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205 | processing, it will return a hash ref representing all the ops which
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206 | start a block.
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207 |
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208 | =for _private
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209 | The above description may be somewhat wrong.
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210 |
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211 | The values of %$leaders are the op objects themselves. Keys are $$op
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212 | addresses.
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213 |
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214 | =for _private
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215 | Above cribbed from B::CC's comments. What's a $$op address?
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216 |
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217 | =back
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218 |
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219 |
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220 | =head1 AUTHOR
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221 |
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222 | Malcolm Beattie, C<[email protected]>
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223 |
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224 | =cut
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