1llc - LLVM static compiler
2==========================
3
4.. program:: llc
5
6SYNOPSIS
7--------
8
9:program:`llc` [*options*] [*filename*]
10
11DESCRIPTION
12-----------
13
14The :program:`llc` command compiles LLVM source inputs into assembly language
15for a specified architecture.  The assembly language output can then be passed
16through a native assembler and linker to generate a native executable.
17
18The choice of architecture for the output assembly code is automatically
19determined from the input file, unless the :option:`-march` option is used to
20override the default.
21
22OPTIONS
23-------
24
25If ``filename`` is "``-``" or omitted, :program:`llc` reads from standard input.
26Otherwise, it will from ``filename``.  Inputs can be in either the LLVM assembly
27language format (``.ll``) or the LLVM bitcode format (``.bc``).
28
29If the :option:`-o` option is omitted, then :program:`llc` will send its output
30to standard output if the input is from standard input.  If the :option:`-o`
31option specifies "``-``", then the output will also be sent to standard output.
32
33If no :option:`-o` option is specified and an input file other than "``-``" is
34specified, then :program:`llc` creates the output filename by taking the input
35filename, removing any existing ``.bc`` extension, and adding a ``.s`` suffix.
36
37Other :program:`llc` options are described below.
38
39End-user Options
40~~~~~~~~~~~~~~~~
41
42.. option:: -help
43
44 Print a summary of command line options.
45
46.. option:: -o <filename>
47
48 Use ``<filename>`` as the output filename. See the summary above for more
49 details.
50
51.. option:: -O=uint
52
53 Generate code at different optimization levels.  These correspond to the
54 ``-O0``, ``-O1``, ``-O2``, and ``-O3`` optimization levels used by
55 :program:`clang`.
56
57.. option:: -mtriple=<target triple>
58
59 Override the target triple specified in the input file with the specified
60 string.
61
62.. option:: -march=<arch>
63
64 Specify the architecture for which to generate assembly, overriding the target
65 encoded in the input file.  See the output of ``llc -help`` for a list of
66 valid architectures.  By default this is inferred from the target triple or
67 autodetected to the current architecture.
68
69.. option:: -mcpu=<cpuname>
70
71 Specify a specific chip in the current architecture to generate code for.
72 By default this is inferred from the target triple and autodetected to
73 the current architecture.  For a list of available CPUs, use:
74
75 .. code-block:: none
76
77   llvm-as < /dev/null | llc -march=xyz -mcpu=help
78
79.. option:: -filetype=<output file type>
80
81 Specify what kind of output ``llc`` should generated.  Options are: ``asm``
82 for textual assembly ( ``'.s'``), ``obj`` for native object files (``'.o'``)
83 and ``null`` for not emitting anything (for performance testing).
84
85 Note that not all targets support all options.
86
87.. option:: -mattr=a1,+a2,-a3,...
88
89 Override or control specific attributes of the target, such as whether SIMD
90 operations are enabled or not.  The default set of attributes is set by the
91 current CPU.  For a list of available attributes, use:
92
93 .. code-block:: none
94
95   llvm-as < /dev/null | llc -march=xyz -mattr=help
96
97.. option:: --frame-pointer
98
99 Specify effect of frame pointer elimination optimization (all,non-leaf,none).
100
101.. option:: --disable-excess-fp-precision
102
103 Disable optimizations that may produce excess precision for floating point.
104 Note that this option can dramatically slow down code on some systems
105 (e.g. X86).
106
107.. option:: --enable-no-infs-fp-math
108
109 Enable optimizations that assume no Inf values.
110
111.. option:: --enable-no-nans-fp-math
112
113 Enable optimizations that assume no NAN values.
114
115.. option:: --enable-unsafe-fp-math
116
117 Enable optimizations that make unsafe assumptions about IEEE math (e.g. that
118 addition is associative) or may not work for all input ranges.  These
119 optimizations allow the code generator to make use of some instructions which
120 would otherwise not be usable (such as ``fsin`` on X86).
121
122.. option:: --stats
123
124 Print statistics recorded by code-generation passes.
125
126.. option:: --time-passes
127
128 Record the amount of time needed for each pass and print a report to standard
129 error.
130
131.. option:: --load=<dso_path>
132
133 Dynamically load ``dso_path`` (a path to a dynamically shared object) that
134 implements an LLVM target.  This will permit the target name to be used with
135 the :option:`-march` option so that code can be generated for that target.
136
137.. option:: -meabi=[default|gnu|4|5]
138
139 Specify which EABI version should conform to.  Valid EABI versions are *gnu*,
140 *4* and *5*.  Default value (*default*) depends on the triple.
141
142.. option:: -stack-size-section
143
144 Emit the .stack_sizes section which contains stack size metadata. The section
145 contains an array of pairs of function symbol values (pointer size) and stack
146 sizes (unsigned LEB128). The stack size values only include the space allocated
147 in the function prologue. Functions with dynamic stack allocations are not
148 included.
149
150.. option:: -remarks-section
151
152 Emit the __remarks (MachO) section which contains metadata about remark
153 diagnostics.
154
155Tuning/Configuration Options
156~~~~~~~~~~~~~~~~~~~~~~~~~~~~
157
158.. option:: --print-machineinstrs
159
160 Print generated machine code between compilation phases (useful for debugging).
161
162.. option:: --regalloc=<allocator>
163
164 Specify the register allocator to use.
165 Valid register allocators are:
166
167 *basic*
168
169  Basic register allocator.
170
171 *fast*
172
173  Fast register allocator. It is the default for unoptimized code.
174
175 *greedy*
176
177  Greedy register allocator. It is the default for optimized code.
178
179 *pbqp*
180
181  Register allocator based on 'Partitioned Boolean Quadratic Programming'.
182
183.. option:: --spiller=<spiller>
184
185 Specify the spiller to use for register allocators that support it.  Currently
186 this option is used only by the linear scan register allocator.  The default
187 ``spiller`` is *local*.  Valid spillers are:
188
189 *simple*
190
191  Simple spiller
192
193 *local*
194
195  Local spiller
196
197Intel IA-32-specific Options
198~~~~~~~~~~~~~~~~~~~~~~~~~~~~
199
200.. option:: --x86-asm-syntax=[att|intel]
201
202 Specify whether to emit assembly code in AT&T syntax (the default) or Intel
203 syntax.
204
205EXIT STATUS
206-----------
207
208If :program:`llc` succeeds, it will exit with 0.  Otherwise, if an error
209occurs, it will exit with a non-zero value.
210
211SEE ALSO
212--------
213
214:manpage:`lli(1)`
215