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