1LLC(1) LLVM LLC(1)
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6 llc - LLVM static compiler
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9 llc [options] [filename]
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12 The llc command compiles LLVM source inputs into assembly language for
13 a specified architecture. The assembly language output can then be
14 passed through a native assembler and linker to generate a native exe‐
15 cutable.
16 The choice of architecture for the output assembly code is automati‐
18 cally determined from the input file, unless the -march option is used
19 to override the default.
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22 If filename is "-" or omitted, llc reads from standard input. Other‐
23 wise, it will from filename. Inputs can be in either the LLVM assembly
24 language format (.ll) or the LLVM bitcode format (.bc).
25 If the -o option is omitted, then llc will send its output to standard
27 output if the input is from standard input. If the -o option specifies
28 "-", then the output will also be sent to standard output.
29 If no -o option is specified and an input file other than "-" is speci‐
31 fied, then llc creates the output filename by taking the input file‐
32 name, removing any existing .bc extension, and adding a .s suffix.
33 Other llc options are described below.
35 End-user Options
37 -help Print a summary of command line options.
38 -O=uint
40 Generate code at different optimization levels. These corre‐
41 spond to the -O0, -O1, -O2, and -O3 optimization levels used by
42 clang.
43 -mtriple=<target triple>
45 Override the target triple specified in the input file with the
46 specified string.
47 -march=<arch>
49 Specify the architecture for which to generate assembly, over‐
50 riding the target encoded in the input file. See the output of
51 llc -help for a list of valid architectures. By default this is
52 inferred from the target triple or autodetected to the current
53 architecture.
54 -mcpu=<cpuname>
56 Specify a specific chip in the current architecture to generate
57 code for. By default this is inferred from the target triple
58 and autodetected to the current architecture. For a list of
59 available CPUs, use:
60 llvm-as < /dev/null | llc -march=xyz -mcpu=help
62 -filetype=<output file type>
64 Specify what kind of output llc should generated. Options are:
65 asm for textual assembly ( '.s'), obj for native object files
66 ('.o') and null for not emitting anything (for performance test‐
67 ing).
68 Note that not all targets support all options.
70 -mattr=a1,+a2,-a3,...
72 Override or control specific attributes of the target, such as
73 whether SIMD operations are enabled or not. The default set of
74 attributes is set by the current CPU. For a list of available
75 attributes, use:
76 llvm-as < /dev/null | llc -march=xyz -mattr=help
78 --disable-fp-elim
80 Disable frame pointer elimination optimization.
81 --disable-excess-fp-precision
83 Disable optimizations that may produce excess precision for
84 floating point. Note that this option can dramatically slow
85 down code on some systems (e.g. X86).
86 --enable-no-infs-fp-math
88 Enable optimizations that assume no Inf values.
89 --enable-no-nans-fp-math
91 Enable optimizations that assume no NAN values.
92 --enable-unsafe-fp-math
94 Enable optimizations that make unsafe assumptions about IEEE
95 math (e.g. that addition is associative) or may not work for all
96 input ranges. These optimizations allow the code generator to
97 make use of some instructions which would otherwise not be us‐
98 able (such as fsin on X86).
99 --stats
101 Print statistics recorded by code-generation passes.
102 --time-passes
104 Record the amount of time needed for each pass and print a re‐
105 port to standard error.
106 --load=<dso_path>
108 Dynamically load dso_path (a path to a dynamically shared ob‐
109 ject) that implements an LLVM target. This will permit the tar‐
110 get name to be used with the -march option so that code can be
111 generated for that target.
112 -meabi=[default|gnu|4|5]
114 Specify which EABI version should conform to. Valid EABI ver‐
115 sions are gnu, 4 and 5. Default value (default) depends on the
116 triple.
117 -stack-size-section
119 Emit the .stack_sizes section which contains stack size meta‐
120 data. The section contains an array of pairs of function symbol
121 values (pointer size) and stack sizes (unsigned LEB128). The
122 stack size values only include the space allocated in the func‐
123 tion prologue. Functions with dynamic stack allocations are not
124 included.
125 Tuning/Configuration Options
127 --print-machineinstrs
128 Print generated machine code between compilation phases (useful
129 for debugging).
130 --regalloc=<allocator>
132 Specify the register allocator to use. Valid register alloca‐
133 tors are:
134 basic
136 Basic register allocator.
137 fast
139 Fast register allocator. It is the default for unoptimized
140 code.
141 greedy
143 Greedy register allocator. It is the default for optimized
144 code.
145 pbqp
147 Register allocator based on 'Partitioned Boolean Quadratic
148 Programming'.
149 --spiller=<spiller>
151 Specify the spiller to use for register allocators that support
152 it. Currently this option is used only by the linear scan reg‐
153 ister allocator. The default spiller is local. Valid spillers
154 are:
155 simple
157 Simple spiller
158 local
160 Local spiller
161 Intel IA-32-specific Options
163 --x86-asm-syntax=[att|intel]
164 Specify whether to emit assembly code in AT&T syntax (the de‐
165 fault) or Intel syntax.
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168 If llc succeeds, it will exit with 0. Otherwise, if an error occurs,
169 it will exit with a non-zero value.
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172 lli
173
175 Maintained by The LLVM Team (http://llvm.org/).
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178 2003-2023, LLVM Project
1797 2023-07-20 LLC(1)