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- llvm-diff - LLVM structural 'diff'
- ==================================
- SYNOPSIS
- --------
- **llvm-diff** [*options*] *module 1* *module 2* [*global name ...*]
- DESCRIPTION
- -----------
- **llvm-diff** compares the structure of two LLVM modules, primarily
- focusing on differences in function definitions. Insignificant
- differences, such as changes in the ordering of globals or in the
- names of local values, are ignored.
- An input module will be interpreted as an assembly file if its name
- ends in '.ll'; otherwise it will be read in as a bitcode file.
- If a list of global names is given, just the values with those names
- are compared; otherwise, all global values are compared, and
- diagnostics are produced for globals which only appear in one module
- or the other.
- **llvm-diff** compares two functions by comparing their basic blocks,
- beginning with the entry blocks. If the terminators seem to match,
- then the corresponding successors are compared; otherwise they are
- ignored. This algorithm is very sensitive to changes in control flow,
- which tend to stop any downstream changes from being detected.
- **llvm-diff** is intended as a debugging tool for writers of LLVM
- passes and frontends. It does not have a stable output format.
- EXIT STATUS
- -----------
- If **llvm-diff** finds no differences between the modules, it will exit
- with 0 and produce no output. Otherwise it will exit with a non-zero
- value.
- BUGS
- ----
- Many important differences, like changes in linkage or function
- attributes, are not diagnosed.
- Changes in memory behavior (for example, coalescing loads) can cause
- massive detected differences in blocks.
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