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7546bed590
Massive check in. This changes the "-fast" flag to "-O#" in llc. If you want to use the old behavior, the flag is -O0. This change allows for finer-grained control over which optimizations are run at different -O levels. Most of this work was pretty mechanical. The majority of the fixes came from verifying that a "fast" variable wasn't used anymore. The JIT still uses a "Fast" flag. I'll change the JIT with a follow-up patch. llvm-svn: 70343
198 lines
4.9 KiB
Plaintext
198 lines
4.9 KiB
Plaintext
=pod
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=head1 NAME
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llc - LLVM static compiler
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=head1 SYNOPSIS
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B<llc> [I<options>] [I<filename>]
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=head1 DESCRIPTION
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The B<llc> command compiles LLVM bitcode into assembly language for a
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specified architecture. The assembly language output can then be passed through
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a native assembler and linker to generate a native executable.
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The choice of architecture for the output assembly code is automatically
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determined from the input bitcode file, unless the B<-march> option is used to
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override the default.
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=head1 OPTIONS
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If I<filename> is - or omitted, B<llc> reads LLVM bitcode from standard input.
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Otherwise, it will read LLVM bitcode from I<filename>.
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If the B<-o> option is omitted, then B<llc> will send its output to standard
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output if the input is from standard input. If the B<-o> option specifies -,
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then the output will also be sent to standard output.
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If no B<-o> option is specified and an input file other than - is specified,
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then B<llc> creates the output filename by taking the input filename,
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removing any existing F<.bc> extension, and adding a F<.s> suffix.
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Other B<llc> options are as follows:
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=head2 End-user Options
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=over
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=item B<--help>
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Print a summary of command line options.
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=item B<-O>=I<uint>
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Generate code at different optimization levels. These correspond to the I<-O0>,
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I<-O1>, I<-O2>, I<-O3>, and I<-O4> optimization levels used by B<llvm-gcc> and
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B<clang>.
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=item B<-f>
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Overwrite output files. By default, B<llc> will refuse to overwrite
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an output file which already exists.
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=item B<-mtriple>=I<target triple>
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Override the target triple specified in the input bitcode file with the
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specified string.
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=item B<-march>=I<arch>
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Specify the architecture for which to generate assembly, overriding the target
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encoded in the bitcode file. See the output of B<llc --help> for a list of
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valid architectures. By default this is inferred from the target triple or
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autodetected to the current architecture.
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=item B<-mcpu>=I<cpuname>
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Specify a specific chip in the current architecture to generate code for.
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By default this is inferred from the target triple and autodetected to
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the current architecture. For a list of available CPUs, use:
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B<llvm-as E<lt> /dev/null | llc -march=xyz -mcpu=help>
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=item B<-mattr>=I<a1,+a2,-a3,...>
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Override or control specific attributes of the target, such as whether SIMD
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operations are enabled or not. The default set of attributes is set by the
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current CPU. For a list of available attributes, use:
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B<llvm-as E<lt> /dev/null | llc -march=xyz -mattr=help>
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=item B<--disable-fp-elim>
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Disable frame pointer elimination optimization.
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=item B<--disable-excess-fp-precision>
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Disable optimizations that may produce excess precision for floating point.
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Note that this option can dramatically slow down code on some systems
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(e.g. X86).
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=item B<--enable-unsafe-fp-math>
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Enable optimizations that make unsafe assumptions about IEEE math (e.g. that
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addition is associative) or may not work for all input ranges. These
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optimizations allow the code generator to make use of some instructions which
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would otherwise not be usable (such as fsin on X86).
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=item B<--enable-correct-eh-support>
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Instruct the B<lowerinvoke> pass to insert code for correct exception handling
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support. This is expensive and is by default omitted for efficiency.
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=item B<--stats>
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Print statistics recorded by code-generation passes.
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=item B<--time-passes>
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Record the amount of time needed for each pass and print a report to standard
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error.
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=item B<--load>=F<dso_path>
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Dynamically load F<dso_path> (a path to a dynamically shared object) that
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implements an LLVM target. This will permit the target name to be used with the
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B<-march> option so that code can be generated for that target.
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=back
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=head2 Tuning/Configuration Options
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=over
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=item B<--print-machineinstrs>
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Print generated machine code between compilation phases (useful for debugging).
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=item B<--regalloc>=I<allocator>
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Specify the register allocator to use. The default I<allocator> is I<local>.
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Valid register allocators are:
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=over
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=item I<simple>
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Very simple "always spill" register allocator
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=item I<local>
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Local register allocator
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=item I<linearscan>
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Linear scan global register allocator
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=item I<iterativescan>
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Iterative scan global register allocator
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=back
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=item B<--spiller>=I<spiller>
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Specify the spiller to use for register allocators that support it. Currently
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this option is used only by the linear scan register allocator. The default
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I<spiller> is I<local>. Valid spillers are:
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=over
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=item I<simple>
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Simple spiller
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=item I<local>
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Local spiller
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=back
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=back
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=head2 Intel IA-32-specific Options
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=over
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=item B<--x86-asm-syntax=att|intel>
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Specify whether to emit assembly code in AT&T syntax (the default) or intel
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syntax.
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=back
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=head1 EXIT STATUS
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If B<llc> succeeds, it will exit with 0. Otherwise, if an error occurs,
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it will exit with a non-zero value.
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=head1 SEE ALSO
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L<lli|lli>
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=head1 AUTHORS
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Maintained by the LLVM Team (L<http://llvm.org>).
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=cut
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