[llvm] Fix usage docstring.
Usage:
- $ extract_passes_from_llvm_source_tree /path/to/llvm/source/root
+ $ python extract_passes_from_llvm_source_tree.py /path/to/llvm-project/llvm
Optionally accepts a list of specific files to examine:
- $ extract_passes_from_llvm_source_tree /path/to/llvm/source/root /path/to/llvm/source/file
+ $ python extract_passes_from_llvm_source_tree.py \
+ /path/to/llvm-project/llvm /path/to/llvm/source/file
Implementation notes
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