| llc - LLVM static compiler |
| ========================== |
| |
| SYNOPSIS |
| -------- |
| |
| :program:`llc` [*options*] [*filename*] |
| |
| DESCRIPTION |
| ----------- |
| |
| The :program:`llc` command compiles LLVM source inputs into assembly language |
| for a specified architecture. The assembly language output can then be passed |
| through a native assembler and linker to generate a native executable. |
| |
| The choice of architecture for the output assembly code is automatically |
| determined from the input file, unless the :option:`-march` option is used to |
| override the default. |
| |
| OPTIONS |
| ------- |
| |
| If ``filename`` is "``-``" or omitted, :program:`llc` reads from standard input. |
| Otherwise, it will from ``filename``. Inputs can be in either the LLVM assembly |
| language format (``.ll``) or the LLVM bitcode format (``.bc``). |
| |
| If the :option:`-o` option is omitted, then :program:`llc` will send its output |
| to standard output if the input is from standard input. If the :option:`-o` |
| option specifies "``-``", then the output will also be sent to standard output. |
| |
| If no :option:`-o` option is specified and an input file other than "``-``" is |
| specified, then :program:`llc` creates the output filename by taking the input |
| filename, removing any existing ``.bc`` extension, and adding a ``.s`` suffix. |
| |
| Other :program:`llc` options are described below. |
| |
| End-user Options |
| ~~~~~~~~~~~~~~~~ |
| |
| .. option:: -help |
| |
| Print a summary of command line options. |
| |
| .. option:: -O=uint |
| |
| Generate code at different optimization levels. These correspond to the |
| ``-O0``, ``-O1``, ``-O2``, and ``-O3`` optimization levels used by |
| :program:`clang`. |
| |
| .. option:: -mtriple=<target triple> |
| |
| Override the target triple specified in the input file with the specified |
| string. |
| |
| .. option:: -march=<arch> |
| |
| Specify the architecture for which to generate assembly, overriding the target |
| encoded in the input 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: |
| |
| .. code-block:: none |
| |
| llvm-as < /dev/null | llc -march=xyz -mcpu=help |
| |
| .. option:: -filetype=<output file type> |
| |
| Specify what kind of output ``llc`` should generated. Options are: ``asm`` |
| for textual assembly ( ``'.s'``), ``obj`` for native object files (``'.o'``) |
| and ``null`` for not emitting anything (for performance testing). |
| |
| Note that not all targets support all options. |
| |
| .. 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: |
| |
| .. code-block:: none |
| |
| llvm-as < /dev/null | llc -march=xyz -mattr=help |
| |
| .. option:: --frame-pointer |
| |
| Specify effect of frame pointer elimination optimization (all,non-leaf,none). |
| |
| .. option:: --disable-excess-fp-precision |
| |
| Disable optimizations that may produce excess precision for floating point. |
| Note that this option can dramatically slow down code on some systems |
| (e.g. X86). |
| |
| .. 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 |
| |
| Enable optimizations that make unsafe assumptions about IEEE math (e.g. that |
| addition is associative) or may not work for all input ranges. These |
| optimizations allow the code generator to make use of some instructions which |
| would otherwise not be usable (such as ``fsin`` on X86). |
| |
| .. option:: --stats |
| |
| Print statistics recorded by code-generation passes. |
| |
| .. option:: --time-passes |
| |
| Record the amount of time needed for each pass and print a report to standard |
| error. |
| |
| .. option:: --load=<dso_path> |
| |
| Dynamically load ``dso_path`` (a path to a dynamically shared object) that |
| implements an LLVM target. This will permit the target name to be used with |
| the :option:`-march` option so that code can be generated for that target. |
| |
| .. option:: -meabi=[default|gnu|4|5] |
| |
| Specify which EABI version should conform to. Valid EABI versions are *gnu*, |
| *4* and *5*. Default value (*default*) depends on the triple. |
| |
| .. option:: -stack-size-section |
| |
| Emit the .stack_sizes section which contains stack size metadata. The section |
| contains an array of pairs of function symbol values (pointer size) and stack |
| sizes (unsigned LEB128). The stack size values only include the space allocated |
| in the function prologue. Functions with dynamic stack allocations are not |
| included. |
| |
| .. option:: -remarks-section |
| |
| Emit the .remarks (ELF) / __remarks (MachO) section which contains metadata |
| about remark diagnostics. |
| |
| Tuning/Configuration Options |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: --print-machineinstrs |
| |
| Print generated machine code between compilation phases (useful for debugging). |
| |
| .. option:: --regalloc=<allocator> |
| |
| Specify the register allocator to use. |
| Valid register allocators are: |
| |
| *basic* |
| |
| Basic register allocator. |
| |
| *fast* |
| |
| Fast register allocator. It is the default for unoptimized code. |
| |
| *greedy* |
| |
| Greedy register allocator. It is the default for optimized code. |
| |
| *pbqp* |
| |
| Register allocator based on 'Partitioned Boolean Quadratic Programming'. |
| |
| .. option:: --spiller=<spiller> |
| |
| Specify the spiller to use for register allocators that support it. Currently |
| this option is used only by the linear scan register allocator. The default |
| ``spiller`` is *local*. Valid spillers are: |
| |
| *simple* |
| |
| Simple spiller |
| |
| *local* |
| |
| Local spiller |
| |
| Intel IA-32-specific Options |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| .. option:: --x86-asm-syntax=[att|intel] |
| |
| Specify whether to emit assembly code in AT&T syntax (the default) or Intel |
| syntax. |
| |
| EXIT STATUS |
| ----------- |
| |
| If :program:`llc` succeeds, it will exit with 0. Otherwise, if an error |
| occurs, it will exit with a non-zero value. |
| |
| SEE ALSO |
| -------- |
| |
| lli |
| |