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Diffstat (limited to 'tools/llvm-config/find-cycles.pl')
| -rw-r--r-- | tools/llvm-config/find-cycles.pl | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/tools/llvm-config/find-cycles.pl b/tools/llvm-config/find-cycles.pl new file mode 100644 index 0000000000..5cbf5b4b27 --- /dev/null +++ b/tools/llvm-config/find-cycles.pl @@ -0,0 +1,170 @@ +#!/usr/bin/perl +# +# Program: find-cycles.pl +# +# Synopsis: Given a list of possibly cyclic dependencies, merge all the +# cycles. This makes it possible to topologically sort the +# dependencies between different parts of LLVM. +# +# Syntax: find-cycles.pl < LibDeps.txt > FinalLibDeps.txt +# +# Input: cycmem1: cycmem2 dep1 dep2 +# cycmem2: cycmem1 dep3 dep4 +# boring: dep4 +# +# Output: cycmem1 cycmem2: dep1 dep2 dep3 dep4 +# boring: dep4 +# +# This file was written by Eric Kidd, and is placed into the public domain. +# + +use 5.006; +use strict; +use warnings; + +my %DEPS; +my @CYCLES; +sub find_all_cycles; + +# Read our dependency information. +while (<>) { + chomp; + my ($module, $dependency_str) = /^\s*([^:]+):\s*(.*)\s*$/; + die "Malformed data: $_" unless defined $dependency_str; + my @dependencies = split(/ /, $dependency_str); + $DEPS{$module} = \@dependencies; +} + +# Partition our raw dependencies into sets of cyclically-connected nodes. +find_all_cycles(); + +# Print out the finished cycles, with their dependencies. +my @output; +my $cycles_found = 0; +foreach my $cycle (@CYCLES) { + my @modules = sort keys %{$cycle}; + + # Merge the dependencies of all modules in this cycle. + my %dependencies; + foreach my $module (@modules) { + @dependencies{@{$DEPS{$module}}} = 1; + } + + # Prune the known cyclic dependencies. + foreach my $module (@modules) { + delete $dependencies{$module}; + } + + # Warn about possible linker problems. + my @archives = grep(/\.a$/, @modules); + if (@archives > 1) { + $cycles_found = $cycles_found + 1; + print STDERR "find-cycles.pl: Circular dependency between *.a files:\n"; + print STDERR "find-cycles.pl: ", join(' ', @archives), "\n"; + push @modules, @archives; # WORKAROUND: Duplicate *.a files. Ick. + } elsif (@modules > 1) { + $cycles_found = $cycles_found + 1; + print STDERR "find-cycles.pl: Circular dependency between *.o files:\n"; + print STDERR "find-cycles.pl: ", join(' ', @modules), "\n"; + push @modules, @modules; # WORKAROUND: Duplicate *.o files. Ick. + } + + # Add to our output. (@modules is already as sorted as we need it to be.) + push @output, (join(' ', @modules) . ': ' . + join(' ', sort keys %dependencies) . "\n"); +} +print sort @output; + +exit $cycles_found; + +#========================================================================== +# Depedency Cycle Support +#========================================================================== +# For now, we have cycles in our dependency graph. Ideally, each cycle +# would be collapsed down to a single *.a file, saving us all this work. +# +# To understand this code, you'll need a working knowledge of Perl 5, +# and possibly some quality time with 'man perlref'. + +my %SEEN; +my %CYCLES; +sub find_cycles ($@); +sub found_cycles ($@); + +sub find_all_cycles { + # Find all multi-item cycles. + my @modules = sort keys %DEPS; + foreach my $module (@modules) { find_cycles($module); } + + # Build fake one-item "cycles" for the remaining modules, so we can + # treat them uniformly. + foreach my $module (@modules) { + unless (defined $CYCLES{$module}) { + my %cycle = ($module, 1); + $CYCLES{$module} = \%cycle; + } + } + + # Find all our unique cycles. We have to do this the hard way because + # we apparently can't store hash references as hash keys without making + # 'strict refs' sad. + my %seen; + foreach my $cycle (values %CYCLES) { + unless ($seen{$cycle}) { + $seen{$cycle} = 1; + push @CYCLES, $cycle; + } + } +} + +# Walk through our graph depth-first (keeping a trail in @path), and report +# any cycles we find. +sub find_cycles ($@) { + my ($module, @path) = @_; + if (str_in_list($module, @path)) { + found_cycle($module, @path); + } else { + return if defined $SEEN{$module}; + $SEEN{$module} = 1; + foreach my $dep (@{$DEPS{$module}}) { + find_cycles($dep, @path, $module); + } + } +} + +# Give a cycle, attempt to merge it with pre-existing cycle data. +sub found_cycle ($@) { + my ($module, @path) = @_; + + # Pop any modules which aren't part of our cycle. + while ($path[0] ne $module) { shift @path; } + #print join("->", @path, $module) . "\n"; + + # Collect the modules in our cycle into a hash. + my %cycle; + foreach my $item (@path) { + $cycle{$item} = 1; + if (defined $CYCLES{$item}) { + # Looks like we intersect with an existing cycle, so merge + # all those in, too. + foreach my $old_item (keys %{$CYCLES{$item}}) { + $cycle{$old_item} = 1; + } + } + } + + # Update our global cycle table. + my $cycle_ref = \%cycle; + foreach my $item (keys %cycle) { + $CYCLES{$item} = $cycle_ref; + } + #print join(":", sort keys %cycle) . "\n"; +} + +sub str_in_list ($@) { + my ($str, @list) = @_; + foreach my $item (@list) { + return 1 if ($item eq $str); + } + return 0; +} |