NAME¶
llc - LLVM static compiler
SYNOPSIS¶
llc [
options] [
filename]
DESCRIPTION¶
The
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
-march option is used to
override the default.
OPTIONS¶
If
filename is - or omitted,
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
-o option is omitted, then
llc will send its output to
standard output if the input is from standard input. If the
-o option
specifies -, then the output will also be sent to standard output.
If no
-o option is specified and an input file other than - is specified,
then
llc creates the output filename by taking the input filename,
removing any existing
.bc extension, and adding a
.s suffix.
Other
llc options are as follows:
End-user Options¶
- -help
- Print a summary of command line options.
- -O=uint
- Generate code at different optimization levels. These
correspond to the -O0, -O1, -O2, -O3, and
-O4 optimization levels used by llvm-gcc and
clang.
- -mtriple=target triple
- Override the target triple specified in the input file with
the specified string.
- -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.
- -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
- -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
- --disable-fp-elim
- Disable frame pointer elimination optimization.
- --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).
- --enable-no-infs-fp-math
- Enable optimizations that assume no Inf values.
- --enable-no-nans-fp-math
- Enable optimizations that assume no NAN values.
- --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).
- --enable-correct-eh-support
- Instruct the lowerinvoke pass to insert code for
correct exception handling support. This is expensive and is by default
omitted for efficiency.
- --stats
- Print statistics recorded by code-generation passes.
- --time-passes
- Record the amount of time needed for each pass and print a
report to standard error.
- --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 -march option so that code can be
generated for that target.
Tuning/Configuration Options¶
- --print-machineinstrs
- Print generated machine code between compilation phases
(useful for debugging).
- --regalloc=allocator
- Specify the register allocator to use. The default
allocator is local. Valid register allocators are:
- simple
- Very simple "always spill" register
allocator
- local
- Local register allocator
- linearscan
- Linear scan global register allocator
- iterativescan
- Iterative scan global register allocator
- --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¶
- --x86-asm-syntax=att|intel
- Specify whether to emit assembly code in AT&T syntax
(the default) or intel syntax.
EXIT STATUS¶
If
llc succeeds, it will exit with 0. Otherwise, if an error occurs, it
will exit with a non-zero value.
SEE ALSO¶
lli
AUTHORS¶
Maintained by the LLVM Team (<
http://llvm.org/>).