/usr/bin/wasm-reduce

================================================================================
wasm-reduce INFILE

Reduce a wasm file to a smaller one with the same behavior on a given command.

Typical usage:

  wasm-reduce orig.wasm '--command=bash a.sh' --test t.wasm --working w.wasm

The original file orig.wasm is where we begin. We then repeatedly test a small
reduction of it by writing that modification to the 'test file' (specified by
'--test'), and we run the command, in this example 'bash a.sh'. That command
should use the test file (and not the original file or any other one). Whenever
the reduction works, we write that new smaller file to the 'working file'
(specified by '--working'). The reduction 'works' if it correctly preserves the
behavior of the command on the original input, specifically, that it has the
same stdout and the result return code. Each time reduction works we continue to
reduce from that point (and each time it fails, we go back and try something
else).

As mentioned above, the command should run on the test file. That is, the first
thing that wasm-reduce does on the example above is, effectively,

  cp orig.wasm t.wasm
  bash a.sh

In other words, it copies the original to the test file, and runs the command.
Whatever the command does, we will preserve as we copy progressively smaller
files to t.wasm. As we make progress, the smallest file will be written to
the working file, w.wasm, and when reduction is done you will find the final
result there.

Comparison to creduce:

1. creduce requires the command to return 0. wasm-reduce is often used to reduce
   crashes, which have non-zero return codes, so it is natural to allow any
   return code. As mentioned above, we preserve the return code as we reduce.
2. creduce ignores stdout. wasm-reduce preserves stdout as it reduces, as part
   of the principle of preserving the original behavior of the command (if your
   stdout varies in uninteresting ways, your command can be a script that runs
   the real command and captures stdout to /dev/null, or filters it).
3. creduce tramples the original input file as it reduces. wasm-reduce never
   modifies the input (to avoid mistakes that cause data loss). Instead,
   when reductions work we write to the 'working file' as mentioned above, and
   the final reduction will be there.
4. creduce runs the command in a temp directory. That is safer in general, but
   it is not how the original command ran, and in particular forces additional
   work if you have multiple files (which, for wasm-reduce, is common, e.g. if
   the testcase is a combination of JavaScript and wasm). wasm-reduce runs the
   command in the current directory (of course, your command can be a script
   that changes directory to anywhere else).

More documentation can be found at

  https://github.com/WebAssembly/binaryen/wiki/Fuzzing#reducing

================================================================================


wasm-reduce options:
--------------------

  --command,-cmd                       The command to run on the test, that we
                                       want to reduce while keeping the
                                       command's output identical. We look at
                                       the command's return code and stdout here
                                       (TODO: stderr), and we reduce while
                                       keeping those unchanged.

  --test,-t                            Test file (this will be written to test,
                                       the given command should read it when we
                                       call it)

  --working,-w                         Working file (this will contain the
                                       current good state while doing temporary
                                       computations, and will contain the final
                                       best result at the end)

  --binaries,-b                        binaryen binaries location (bin/
                                       directory)

  --text,-S                            Emit intermediate files as text, instead
                                       of binary (also make sure the test and
                                       working files have a .wat or .wast
                                       suffix)

  --denan                              Avoid nans when reducing

  --verbose,-v                         Verbose output mode

  --debugInfo,-g                       Keep debug info in binaries

  --force,-f                           Force the reduction attempt, ignoring
                                       problems that imply it is unlikely to
                                       succeed

  --timeout,-to                        A timeout to apply to each execution of
                                       the command, in seconds (default: 2)

  --extra-flags,-ef                    Extra commandline flags to pass to
                                       wasm-opt while reducing. (default:
                                       --enable-all)

  --save-all-working,-saw              Save all intermediate working files, as
                                       $WORKING.0, .1, .2 etc


Tool options:
-------------

  --mvp-features,-mvp                  Disable all non-MVP features

  --all-features,-all                  Enable all features

  --detect-features                    (deprecated - this flag does nothing)

  --quiet,-q                           Emit less verbose output and hide trivial
                                       warnings.

  --experimental-poppy                 Parse wast files as Poppy IR for testing
                                       purposes.

  --emit-module-names                  Emit module names, even if not emitting
                                       the rest of the names section.

  --enable-sign-ext                    Enable sign extension operations

  --disable-sign-ext                   Disable sign extension operations

  --enable-threads                     Enable atomic operations

  --disable-threads                    Disable atomic operations

  --enable-mutable-globals             Enable mutable globals

  --disable-mutable-globals            Disable mutable globals

  --enable-nontrapping-float-to-int    Enable nontrapping float-to-int
                                       operations

  --disable-nontrapping-float-to-int   Disable nontrapping float-to-int
                                       operations

  --enable-simd                        Enable SIMD operations and types

  --disable-simd                       Disable SIMD operations and types

  --enable-bulk-memory                 Enable bulk memory operations

  --disable-bulk-memory                Disable bulk memory operations

  --enable-bulk-memory-opt             Enable memory.copy and memory.fill

  --disable-bulk-memory-opt            Disable memory.copy and memory.fill

  --enable-call-indirect-overlong      Enable LEB encoding of call-indirect
                                       (Ignored for compatibility as it has no
                                       effect on Binaryen)

  --disable-call-indirect-overlong     Disable LEB encoding of call-indirect
                                       (Ignored for compatibility as it has no
                                       effect on Binaryen)

  --enable-exception-handling          Enable exception handling operations

  --disable-exception-handling         Disable exception handling operations

  --enable-tail-call                   Enable tail call operations

  --disable-tail-call                  Disable tail call operations

  --enable-reference-types             Enable reference types

  --disable-reference-types            Disable reference types

  --enable-multivalue                  Enable multivalue functions

  --disable-multivalue                 Disable multivalue functions

  --enable-gc                          Enable garbage collection

  --disable-gc                         Disable garbage collection

  --enable-memory64                    Enable memory64

  --disable-memory64                   Disable memory64

  --enable-relaxed-simd                Enable relaxed SIMD

  --disable-relaxed-simd               Disable relaxed SIMD

  --enable-extended-const              Enable extended const expressions

  --disable-extended-const             Disable extended const expressions

  --enable-strings                     Enable strings

  --disable-strings                    Disable strings

  --enable-multimemory                 Enable multimemory

  --disable-multimemory                Disable multimemory

  --enable-stack-switching             Enable stack switching

  --disable-stack-switching            Disable stack switching

  --enable-shared-everything           Enable shared-everything threads

  --disable-shared-everything          Disable shared-everything threads

  --enable-fp16                        Enable float 16 operations

  --disable-fp16                       Disable float 16 operations

  --enable-custom-descriptors          Enable custom descriptors (RTTs) and
                                       exact references

  --disable-custom-descriptors         Disable custom descriptors (RTTs) and
                                       exact references

  --enable-multibyte                   Enable multibyte array loads and stores

  --disable-multibyte                  Disable multibyte array loads and stores

  --enable-acquire-release-atomics     Enable acquire/release atomic memory
                                       operations

  --disable-acquire-release-atomics    Disable acquire/release atomic memory
                                       operations

  --enable-custom-page-sizes           Enable custom page sizes

  --disable-custom-page-sizes          Disable custom page sizes

  --enable-wide-arithmetic             Enable wide arithmetic

  --disable-wide-arithmetic            Disable wide arithmetic

  --enable-compact-imports             Enable compact import section

  --disable-compact-imports            Disable compact import section

  --enable-relaxed-atomics             Enable relaxed atomic memory operations

  --disable-relaxed-atomics            Disable relaxed atomic memory operations

  --enable-typed-function-references   Deprecated compatibility flag

  --disable-typed-function-references  Deprecated compatibility flag

  --no-validation,-n                   Disables validation, assumes inputs are
                                       correct

  --pass-arg,-pa                       An argument passed along to optimization
                                       passes being run. Must be in the form
                                       KEY@VALUE.  If KEY is the name of a pass
                                       then it applies to the closest instance
                                       of that pass before us. If KEY is not the
                                       name of a pass then it is a global option
                                       that applies to all pass instances that
                                       read it.

  --closed-world,-cw                   Assume code outside of the module does
                                       not inspect or interact with GC and
                                       function references, even if they are
                                       passed out. The outside may hold on to
                                       them and pass them back in, but not
                                       inspect their contents or call them.

  --preserve-type-order                Preserve the order of types from the
                                       input (useful for debugging and testing)

  --generate-stack-ir                  generate StackIR during writing

  --optimize-stack-ir                  optimize StackIR during writing

  --print-stack-ir                     print StackIR during writing


General options:
----------------

  --version                            Output version information and exit

  --help,-h                            Show this help message and exit

  --debug,-d                           Print debug information to stderr