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The script is based on an example provided by Tim Northover (https://github.com/TNorthover).
138 lines
3.7 KiB
ReStructuredText
138 lines
3.7 KiB
ReStructuredText
llvm-reduce - LLVM automatic testcase reducer.
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==============================================
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.. program:: llvm-reduce
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SYNOPSIS
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--------
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:program:`llvm-reduce` [*options*] [*input...*]
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DESCRIPTION
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-----------
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The :program:`llvm-reduce` tool project that can be used for reducing the size of LLVM test cases.
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It works by removing redundant or unnecessary code from LLVM test cases while still preserving
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their ability to detect bugs.
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If ``input`` is "``-``", :program:`llvm-reduce` reads from standard
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input. Otherwise, it will read from the specified ``filenames``.
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LLVM-Reduce is a useful tool for reducing the size and
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complexity of LLVM test cases, making it easier to identify and debug issues in
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the LLVM compiler infrastructure.
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GENERIC OPTIONS
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---------------
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.. option:: --help
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Display available options (--help-hidden for more).
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.. option:: --abort-on-invalid-reduction
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Abort if any reduction results in invalid IR
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.. option::--delta-passes=<string>
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Delta passes to run, separated by commas. By default, run all delta passes.
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.. option:: --in-place
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WARNING: This option will replace your input file with the reduced version!
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.. option:: --ir-passes=<string>
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A textual description of the pass pipeline, same as what's passed to `opt -passes`.
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.. option:: -j <uint>
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Maximum number of threads to use to process chunks. Set to 1 to disable parallelism.
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.. option:: --max-pass-iterations=<int>
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Maximum number of times to run the full set of delta passes (default=5).
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.. option:: --mtriple=<string>
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Set the target triple.
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.. option:: --preserve-debug-environment
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Don't disable features used for crash debugging (crash reports, llvm-symbolizer and core dumps)
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.. option:: --print-delta-passes
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Print list of delta passes, passable to --delta-passes as a comma separated liste.
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.. option:: --skip-delta-passes=<string>
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Delta passes to not run, separated by commas. By default, run all delta passes.
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.. option:: --starting-granularity-level=<uint>
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Number of times to divide chunks prior to first test.
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Note : Granularity refers to the level of detail at which the reduction process operates.
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A lower granularity means that the reduction process operates at a more coarse-grained level,
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while a higher granularity means that it operates at a more fine-grained level.
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.. option:: --test=<string>
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Name of the interesting-ness test to be run.
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.. option:: --test-arg=<string>
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Arguments passed onto the interesting-ness test.
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.. option:: --verbose
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Print extra debugging information.
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.. option:: --write-tmp-files-as-bitcode
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Always write temporary files as bitcode instead of textual IR.
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.. option:: -x={ir|mir}
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Input language as ir or mir.
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EXIT STATUS
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------------
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:program:`llvm-reduce` returns 0 under normal operation. It returns a non-zero
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exit code if there were any errors.
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EXAMPLE
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-------
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:program:`llvm-reduce` can be used to simplify a test that causes a
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compiler crash.
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For example, let's assume that `opt` is crashing on the IR file
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`test.ll` with error message `Assertion failed at line 1234 of
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WhateverFile.cpp`, when running at `-O2`.
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The test case of `test.ll` can be reduced by invoking the following
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command:
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.. code-block:: bash
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$(LLVM_BUILD_FOLDER)/bin/llvm-reduce --test=script.sh <path to>/test.ll
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The shell script passed to the option `test` consists of the
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following:
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.. code-block:: bash
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$(LLVM_BUILD_FOLDER)/bin/opt -O2 -disable-output $1 \
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|& grep "Assertion failed at line 1234 of WhateverFile.cpp"
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(In this script, `grep` exits with 0 if it finds the string and that
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becomes the whole script's status.)
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This example can be generalized to other tools that process IR files,
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for example `llc`.
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