1 llc - LLVM static compiler 2 ========================== 3 4 SYNOPSIS 5 -------- 6 7 :program:`llc` [*options*] [*filename*] 8 9 DESCRIPTION 10 ----------- 11 12 The :program:`llc` command compiles LLVM source inputs into assembly language 13 for a specified architecture. The assembly language output can then be passed 14 through a native assembler and linker to generate a native executable. 15 16 The choice of architecture for the output assembly code is automatically 17 determined from the input file, unless the :option:`-march` option is used to 18 override the default. 19 20 OPTIONS 21 ------- 22 23 If ``filename`` is "``-``" or omitted, :program:`llc` reads from standard input. 24 Otherwise, it will from ``filename``. Inputs can be in either the LLVM assembly 25 language format (``.ll``) or the LLVM bitcode format (``.bc``). 26 27 If the :option:`-o` option is omitted, then :program:`llc` will send its output 28 to standard output if the input is from standard input. If the :option:`-o` 29 option specifies "``-``", then the output will also be sent to standard output. 30 31 If no :option:`-o` option is specified and an input file other than "``-``" is 32 specified, then :program:`llc` creates the output filename by taking the input 33 filename, removing any existing ``.bc`` extension, and adding a ``.s`` suffix. 34 35 Other :program:`llc` options are described below. 36 37 End-user Options 38 ~~~~~~~~~~~~~~~~ 39 40 .. option:: -help 41 42 Print a summary of command line options. 43 44 .. option:: -O=uint 45 46 Generate code at different optimization levels. These correspond to the 47 ``-O0``, ``-O1``, ``-O2``, and ``-O3`` optimization levels used by 48 :program:`clang`. 49 50 .. option:: -mtriple=<target triple> 51 52 Override the target triple specified in the input file with the specified 53 string. 54 55 .. option:: -march=<arch> 56 57 Specify the architecture for which to generate assembly, overriding the target 58 encoded in the input file. See the output of ``llc -help`` for a list of 59 valid architectures. By default this is inferred from the target triple or 60 autodetected to the current architecture. 61 62 .. option:: -mcpu=<cpuname> 63 64 Specify a specific chip in the current architecture to generate code for. 65 By default this is inferred from the target triple and autodetected to 66 the current architecture. For a list of available CPUs, use: 67 68 .. code-block:: none 69 70 llvm-as < /dev/null | llc -march=xyz -mcpu=help 71 72 .. option:: -filetype=<output file type> 73 74 Specify what kind of output ``llc`` should generated. Options are: ``asm`` 75 for textual assembly ( ``'.s'``), ``obj`` for native object files (``'.o'``) 76 and ``null`` for not emitting anything (for performance testing). 77 78 Note that not all targets support all options. 79 80 .. option:: -mattr=a1,+a2,-a3,... 81 82 Override or control specific attributes of the target, such as whether SIMD 83 operations are enabled or not. The default set of attributes is set by the 84 current CPU. For a list of available attributes, use: 85 86 .. code-block:: none 87 88 llvm-as < /dev/null | llc -march=xyz -mattr=help 89 90 .. option:: --disable-fp-elim 91 92 Disable frame pointer elimination optimization. 93 94 .. option:: --disable-excess-fp-precision 95 96 Disable optimizations that may produce excess precision for floating point. 97 Note that this option can dramatically slow down code on some systems 98 (e.g. X86). 99 100 .. option:: --enable-no-infs-fp-math 101 102 Enable optimizations that assume no Inf values. 103 104 .. option:: --enable-no-nans-fp-math 105 106 Enable optimizations that assume no NAN values. 107 108 .. option:: --enable-unsafe-fp-math 109 110 Enable optimizations that make unsafe assumptions about IEEE math (e.g. that 111 addition is associative) or may not work for all input ranges. These 112 optimizations allow the code generator to make use of some instructions which 113 would otherwise not be usable (such as ``fsin`` on X86). 114 115 .. option:: --stats 116 117 Print statistics recorded by code-generation passes. 118 119 .. option:: --time-passes 120 121 Record the amount of time needed for each pass and print a report to standard 122 error. 123 124 .. option:: --load=<dso_path> 125 126 Dynamically load ``dso_path`` (a path to a dynamically shared object) that 127 implements an LLVM target. This will permit the target name to be used with 128 the :option:`-march` option so that code can be generated for that target. 129 130 Tuning/Configuration Options 131 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 132 133 .. option:: --print-machineinstrs 134 135 Print generated machine code between compilation phases (useful for debugging). 136 137 .. option:: --regalloc=<allocator> 138 139 Specify the register allocator to use. 140 Valid register allocators are: 141 142 *basic* 143 144 Basic register allocator. 145 146 *fast* 147 148 Fast register allocator. It is the default for unoptimized code. 149 150 *greedy* 151 152 Greedy register allocator. It is the default for optimized code. 153 154 *pbqp* 155 156 Register allocator based on 'Partitioned Boolean Quadratic Programming'. 157 158 .. option:: --spiller=<spiller> 159 160 Specify the spiller to use for register allocators that support it. Currently 161 this option is used only by the linear scan register allocator. The default 162 ``spiller`` is *local*. Valid spillers are: 163 164 *simple* 165 166 Simple spiller 167 168 *local* 169 170 Local spiller 171 172 Intel IA-32-specific Options 173 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 174 175 .. option:: --x86-asm-syntax=[att|intel] 176 177 Specify whether to emit assembly code in AT&T syntax (the default) or Intel 178 syntax. 179 180 EXIT STATUS 181 ----------- 182 183 If :program:`llc` succeeds, it will exit with 0. Otherwise, if an error 184 occurs, it will exit with a non-zero value. 185 186 SEE ALSO 187 -------- 188 189 lli 190 191
