docs/CommandGuide/lli.rst

lli - directly execute programs from LLVM bitcode
=================================================

SYNOPSIS
--------

:program:`lli` [*options*] [*filename*] [*program args*]

DESCRIPTION
-----------

:program:`lli` directly executes programs in LLVM bitcode format.  It takes a program
in LLVM bitcode format and executes it using a just-in-time compiler or an
interpreter.

:program:`lli` is *not* an emulator. It will not execute IR of different architectures
and it can only interpret (or JIT-compile) for the host architecture.

The JIT compiler takes the same arguments as other tools, like :program:`llc`,
but they don't necessarily work for the interpreter.

If `filename` is not specified, then :program:`lli` reads the LLVM bitcode for the
program from standard input.

The optional *args* specified on the command line are passed to the program as
arguments.

GENERAL OPTIONS
---------------

.. option:: -fake-argv0=executable

 Override the ``argv[0]`` value passed into the executing program.

.. option:: -force-interpreter={false,true}

 If set to true, use the interpreter even if a just-in-time compiler is available
 for this architecture. Defaults to false.

.. option:: -help

 Print a summary of command line options.

.. option:: -load=pluginfilename

 Causes :program:`lli` to load the plugin (shared object) named *pluginfilename* and use
 it for optimization.

.. option:: -stats

 Print statistics from the code-generation passes. This is only meaningful for
 the just-in-time compiler, at present.

.. option:: -time-passes

 Record the amount of time needed for each code-generation pass and print it to
 standard error.

.. option:: -version

 Print out the version of :program:`lli` and exit without doing anything else.

TARGET OPTIONS
--------------

.. option:: -mtriple=target triple

 Override the target triple specified in the input bitcode file with the
 specified string.  This may result in a crash if you pick an
 architecture which is not compatible with the current system.

.. option:: -march=arch

 Specify the architecture for which to generate assembly, overriding the target
 encoded in the bitcode file.  See the output of **llc -help** for a list of
 valid architectures.  By default this is inferred from the target triple or
 autodetected to the current architecture.

.. option:: -mcpu=cpuname

 Specify a specific chip in the current architecture to generate code for.
 By default this is inferred from the target triple and autodetected to
 the current architecture.  For a list of available CPUs, use:
 **llvm-as < /dev/null | llc -march=xyz -mcpu=help**

.. option:: -mattr=a1,+a2,-a3,...

 Override or control specific attributes of the target, such as whether SIMD
 operations are enabled or not.  The default set of attributes is set by the
 current CPU.  For a list of available attributes, use:
 **llvm-as < /dev/null | llc -march=xyz -mattr=help**

FLOATING POINT OPTIONS
----------------------

.. option:: -disable-excess-fp-precision

 Disable optimizations that may increase floating point precision.

.. option:: -enable-no-infs-fp-math

 Enable optimizations that assume no Inf values.

.. option:: -enable-no-nans-fp-math

 Enable optimizations that assume no NAN values.

.. option:: -enable-unsafe-fp-math

 Causes :program:`lli` to enable optimizations that may decrease floating point
 precision.

.. option:: -soft-float

 Causes :program:`lli` to generate software floating point library calls instead of
 equivalent hardware instructions.

CODE GENERATION OPTIONS
-----------------------

.. option:: -code-model=model

 Choose the code model from:

 .. code-block:: text

      default: Target default code model
      tiny: Tiny code model
      small: Small code model
      kernel: Kernel code model
      medium: Medium code model
      large: Large code model

.. option:: -disable-post-RA-scheduler

 Disable scheduling after register allocation.

.. option:: -disable-spill-fusing

 Disable fusing of spill code into instructions.

.. option:: -jit-enable-eh

 Exception handling should be enabled in the just-in-time compiler.

.. option:: -join-liveintervals

 Coalesce copies (default=true).

.. option:: -nozero-initialized-in-bss

  Don't place zero-initialized symbols into the BSS section.

.. option:: -pre-RA-sched=scheduler

 Instruction schedulers available (before register allocation):

 .. code-block:: text

      =default: Best scheduler for the target
      =none: No scheduling: breadth first sequencing
      =simple: Simple two pass scheduling: minimize critical path and maximize processor utilization
      =simple-noitin: Simple two pass scheduling: Same as simple except using generic latency
      =list-burr: Bottom-up register reduction list scheduling
      =list-tdrr: Top-down register reduction list scheduling
      =list-td: Top-down list scheduler -print-machineinstrs - Print generated machine code

.. option:: -regalloc=allocator

 Register allocator to use (default=linearscan)

 .. code-block:: text

      =bigblock: Big-block register allocator
      =linearscan: linear scan register allocator =local -   local register allocator
      =simple: simple register allocator

.. option:: -relocation-model=model

 Choose relocation model from:

 .. code-block:: text

      =default: Target default relocation model
      =static: Non-relocatable code =pic -   Fully relocatable, position independent code
      =dynamic-no-pic: Relocatable external references, non-relocatable code

.. option:: -spiller

 Spiller to use (default=local)

 .. code-block:: text

      =simple: simple spiller
      =local: local spiller

.. option:: -x86-asm-syntax=syntax

 Choose style of code to emit from X86 backend:

 .. code-block:: text

      =att: Emit AT&T-style assembly
      =intel: Emit Intel-style assembly

EXIT STATUS
-----------

If :program:`lli` fails to load the program, it will exit with an exit code of 1.
Otherwise, it will return the exit code of the program it executes.

SEE ALSO
--------

:program:`llc`