1llvm-diff - LLVM structural 'diff' 2================================== 3 4 5SYNOPSIS 6-------- 7 8 9**llvm-diff** [*options*] *module 1* *module 2* [*global name ...*] 10 11 12DESCRIPTION 13----------- 14 15 16**llvm-diff** compares the structure of two LLVM modules, primarily 17focusing on differences in function definitions. Insignificant 18differences, such as changes in the ordering of globals or in the 19names of local values, are ignored. 20 21An input module will be interpreted as an assembly file if its name 22ends in '.ll'; otherwise it will be read in as a bitcode file. 23 24If a list of global names is given, just the values with those names 25are compared; otherwise, all global values are compared, and 26diagnostics are produced for globals which only appear in one module 27or the other. 28 29**llvm-diff** compares two functions by comparing their basic blocks, 30beginning with the entry blocks. If the terminators seem to match, 31then the corresponding successors are compared; otherwise they are 32ignored. This algorithm is very sensitive to changes in control flow, 33which tend to stop any downstream changes from being detected. 34 35**llvm-diff** is intended as a debugging tool for writers of LLVM 36passes and frontends. It does not have a stable output format. 37 38 39EXIT STATUS 40----------- 41 42 43If **llvm-diff** finds no differences between the modules, it will exit 44with 0 and produce no output. Otherwise it will exit with a non-zero 45value. 46 47 48BUGS 49---- 50 51 52Many important differences, like changes in linkage or function 53attributes, are not diagnosed. 54 55Changes in memory behavior (for example, coalescing loads) can cause 56massive detected differences in blocks. 57