1=pod 2 3=head1 NAME 4 5llvm-diff - LLVM structural 'diff' 6 7=head1 SYNOPSIS 8 9B<llvm-diff> [I<options>] I<module 1> I<module 2> [I<global name ...>] 10 11=head1 DESCRIPTION 12 13B<llvm-diff> compares the structure of two LLVM modules, primarily 14focusing on differences in function definitions. Insignificant 15differences, such as changes in the ordering of globals or in the 16names of local values, are ignored. 17 18An input module will be interpreted as an assembly file if its name 19ends in '.ll'; otherwise it will be read in as a bitcode file. 20 21If a list of global names is given, just the values with those names 22are compared; otherwise, all global values are compared, and 23diagnostics are produced for globals which only appear in one module 24or the other. 25 26B<llvm-diff> compares two functions by comparing their basic blocks, 27beginning with the entry blocks. If the terminators seem to match, 28then the corresponding successors are compared; otherwise they are 29ignored. This algorithm is very sensitive to changes in control flow, 30which tend to stop any downstream changes from being detected. 31 32B<llvm-diff> is intended as a debugging tool for writers of LLVM 33passes and frontends. It does not have a stable output format. 34 35=head1 EXIT STATUS 36 37If B<llvm-diff> finds no differences between the modules, it will exit 38with 0 and produce no output. Otherwise it will exit with a non-zero 39value. 40 41=head1 BUGS 42 43Many important differences, like changes in linkage or function 44attributes, are not diagnosed. 45 46Changes in memory behavior (for example, coalescing loads) can cause 47massive detected differences in blocks. 48 49=head1 AUTHORS 50 51Maintained by the LLVM Team (L<http://llvm.org/>). 52 53=cut 54