=head1 NAME
-llvmc - The LLVM Compiler Driver (experimental)
+llvmc - The LLVM Compiler Driver (WIP)
=head1 SYNOPSIS
-B<llvmc> [I<options>] [I<filenames>...]
+B<llvmc> [I<options>] I<filenames...>
=head1 DESCRIPTION
B<llvmc> is a configurable driver for invoking other LLVM (and non-LLVM) tools
in order to compile, optimize and link software for multiple languages. For
those familiar with FSF's B<gcc> tool, it is very similar. Please note that
-B<llvmc> is considered an experimental tool. B<llvmc> has the following goals:
-
-=over
-
-=item * provide a single point of access to the LLVM tool set,
-
-=item * hide the complexities of the LLVM tools through a single interface,
-
-=item * make integration of existing non-LLVM tools simple,
-
-=item * extend the capabilities of minimal front ends, and
-
-=item * make the interface for compiling consistent for all languages.
-
-=back
-
-The tool itself does nothing with a user's program. It merely invokes other
-tools to get the compilation tasks done.
-
-The options supported by B<llvmc> generalize the compilation process and
-provide a consistent and simple interface for multiple programming languages.
-This makes it easier for developers to get their software compiled with LLVM.
-Without B<llvmc>, developers would need to understand how to invoke the
-front-end compiler, optimizer, assembler, and linker in order to compile their
-programs. B<llvmc>'s sole mission is to trivialize that process.
-
-=head2 Basic Operation
-
-B<llvmc> always takes the following basic actions:
-
-=over
-
-=item * Command line options and filenames are collected.
-
-The command line options provide the marching orders to B<llvmc> on what actions
-it should perform. This is the I<request> the user is making of B<llvmc> and it
-is interpreted first.
-
-=item * Configuration files are read.
-
-Based on the options and the suffixes of the filenames presented, a set of
-configuration files are read to configure the actions B<llvmc> will take.
-Configuration files are provided by either LLVM or the front end compiler tools
-that B<llvmc> invokes. Users generally don't need to be concerned with the
-contents of the configuration files.
-
-=item * Determine actions to take.
-
-The tool chain needed to complete the task is determined. This is the primary
-work of B<llvmc>. It breaks the request specified by the command line options
-into a set of basic actions to be done:
-
-=over
-
-=item * Pre-processing: gathering/filtering compiler input (optional).
-
-=item * Translation: source language to bytecode conversion.
-
-=item * Assembly: bytecode to native code conversion.
-
-=item * Optimization: conversion of bytecode to something that runs faster.
-
-=item * Linking: combining multiple bytecodes to produce executable program.
-
-=back
-
-=item * Execute actions.
-
-The actions determined previously are executed sequentially and then
-B<llvmc> terminates.
-
-=back
+B<llvmc> is considered an experimental tool.
=head1 OPTIONS
-=head2 Control Options
-
-Control options tell B<llvmc> what to do at a high level. The
-following control options are defined:
-
-=over
-
-=item B<-c> or B<--compile>
-
-This option specifies that the linking phase is not to be run. All
-previous phases, if applicable will run. This is generally how a given
-bytecode file is compiled and optimized for a source language module.
-
-=item B<-k> or B<--link> or default
-
-This option (or the lack of any control option) specifies that all stages
-of compilation, optimization, and linking should be attempted. Source files
-specified on the command line will be compiled and linked with objects and
-libraries also specified.
-
-=item B<-S>
-
-This option specifies that compilation should end in the creation of
-an LLVM assembly file that can be later converted to an LLVM object
-file.
-
-=item B<-E>
-
-This option specifies that no compilation or linking should be
-performed. Only pre-processing, if applicable to the language being
-compiled, is performed. For languages that support it, this will
-result in the output containing the raw input to the compiler.
-
-=back
-
-=head2 Optimization Options
-
-Optimization with B<llvmc> is based on goals and specified with
-the following -O options. The specific details of which
-optimizations run is controlled by the configuration files because
-each source language will have different needs.
-
-=over
-
-=item B<-O1> or B<-O0> (default, fast compilation)
-
-Only those optimizations that will hasten the compilation (mostly by reducing
-the output) are applied. In general these are extremely fast and simple
-optimizations that reduce emitted code size. The goal here is not to make the
-resulting program fast but to make the compilation fast. If not specified,
-this is the default level of optimization.
-
-=item B<-O2> (basic optimization)
-
-This level of optimization specifies a balance between generating good code
-that will execute reasonably quickly and not spending too much time optimizing
-the code to get there. For example, this level of optimization may include
-things like global common subexpression elimination, aggressive dead code
-elimination, and scalar replication.
+=head2 Built-in Options
-=item B<-O3> (aggressive optimization)
-
-This level of optimization aggressively optimizes each set of files compiled
-together. However, no link-time inter-procedural optimization is performed.
-This level implies all the optimizations of the B<-O1> and B<-O2> optimization
-levels, and should also provide loop optimizations and compile time
-inter-procedural optimizations. Essentially, this level tries to do as much
-as it can with the input it is given but doesn't do any link time IPO.
-
-=item B<-O4> (link time optimization)
-
-In addition to the previous three levels of optimization, this level of
-optimization aggressively optimizes each program at link time. It employs
-basic analysis and basic link-time inter-procedural optimizations,
-considering the program as a whole.
-
-=item B<-O5> (aggressive link time optimization)
-
-This is the same as B<-O4> except it employs aggressive analyses and
-aggressive inter-procedural optimization.
-
-=item B<-O6> (profile guided optimization: not implemented)
-
-This is the same as B<-O5> except that it employs profile-guided
-re-optimization of the program after it has executed. Note that this implies
-a single level of re-optimization based on runtime profile analysis. Once
-the re-optimization has completed, the profiling instrumentation is
-removed and final optimizations are employed.
-
-=item B<-O7> (lifelong optimization: not implemented)
-
-This is the same as B<-O5> and similar to B<-O6> except that re-optimization
-is performed through the life of the program. That is, each run will update
-the profile by which future re-optimizations are directed.
-
-=back
-
-=head2 Input Options
+LLVMC has some built-in options that can't be overridden in the
+configuration libraries.
=over
-=item B<-l> I<LIBRARY>
+=item B<-o> I<filename>
-This option instructs B<llvmc> to locate a library named I<LIBRARY> and search
-it for unresolved symbols when linking the program.
+Output file name.
-=item B<-L> F<path>
+=item B<-x> I<language>
-This option instructs B<llvmc> to add F<path> to the list of places in which
-the linker will
+Specify the language of the following input files until the next B<-x>
+option.
-=item B<-x> I<LANGUAGE>
+=item B<-load> I<plugin_name>
-This option instructs B<llvmc> to regard the following input files as
-containing programs in the language I<LANGUAGE>. Normally, input file languages
-are identified by their suffix but this option will override that default
-behavior. The B<-x> option stays in effect until the end of the options or
-a new B<-x> option is encountered.
+Load the specified plugin DLL. Example:
+S<-load $LLVM_DIR/Release/lib/LLVMCSimple.so>.
-=back
+=item B<-v> or B<--verbose>
-=head2 Output Options
+Enable verbose mode, i.e. print out all executed commands.
-=over
+=item B<--check-graph>
-=item B<-m>I<arch>
+Check the compilation for common errors like mismatched output/input language
+names, multiple default edges and cycles. Because of plugins, these checks can't
+be performed at compile-time. Exit with code zero if no errors were found, and
+return the number of found errors otherwise. Hidden option, useful for debugging
+LLVMC plugins.
-This option selects the back end code generator to use. The I<arch> portion
-of the option names the back end to use.
+=item B<--view-graph>
-=item B<--native>
+Show a graphical representation of the compilation graph and exit. Requires that
+you have I<dot> and I<gv> programs installed. Hidden option, useful for
+debugging LLVMC plugins.
-Normally, B<llvmc> produces bytecode files at most stages of compilation.
-With this option, B<llvmc> will arrange for native object files to be
-generated with the B<-c> option, native assembly files to be generated
-with the B<-S> option, and native executables to be generated with the
-B<--link> option. In the case of the B<-E> option, the output will not
-differ as there is no I<native> version of pre-processed output.
+=item B<--write-graph>
-=item B<-o> F<filename>
+Write a I<compilation-graph.dot> file in the current directory with the
+compilation graph description in Graphviz format (identical to the file used by
+the B<--view-graph> option). The B<-o> option can be used to set the output file
+name. Hidden option, useful for debugging LLVMC plugins.
-Specify the output file name. The contents of the file depend on other
-options.
+=item B<--save-temps>
-=back
+Write temporary files to the current directory and do not delete them on
+exit. This option can also take an argument: the I<--save-temps=obj> switch will
+write files into the directory specified with the I<-o> option. The
+I<--save-temps=cwd> and I<--save-temps> switches are both synonyms for the
+default behaviour.
-=head2 Information Options
+=item B<--temp-dir> I<directory>
-=over
+Store temporary files in the given directory. This directory is deleted on exit
+unless I<--save-temps> is specified. If I<--save-temps=obj> is also specified,
+I<--temp-dir> is given the precedence.
-=item B<-n> or B<--no-op>
+=item B<-help>
-This option tells B<llvmc> to do everything but actually execute the
-resulting tools. In combination with the B<-v> option, this causes B<llvmc>
-to merely print out what it would have done.
+Print a summary of command-line options and exit.
-=item B<-v> or B<--verbose>
+=item B<-help-hidden>
-This option will cause B<llvmc> to print out (on standard output) each of the
-actions it takes to accomplish the objective. The output will immediately
-precede the invocation of other tools.
+Print a summary of command-line options and exit. Print help even for
+options intended for developers.
-=item B<--stats>
+=item B<--version>
-Print all statistics gathered during the compilation to the standard error.
-Note that this option is merely passed through to the sub-tools to do with
-as they please.
+Print version information and exit.
-=item B<--time-passes>
+=item B<@>I<file>
-Record the amount of time needed for each optimization pass and print it
-to standard error. Like B<--stats> this option is just passed through to
-the sub-tools to do with as they please.
+Read command-line options from I<file>. The options read are inserted
+in place of the original @I<file> option. If I<file> does not exist, or
+cannot be read, then the option will be treated literally, and not
+removed.
-=item B<--time-programs>
+Options in I<file> are separated by whitespace. A whitespace character
+may be included in an option by surrounding the entire option in
+either single or double quotes. Any character (including a backslash)
+may be included by prefixing the character to be included with a
+backslash. The file may itself contain additional @I<file> options;
+any such options will be processed recursively.
-Record the amount of time each program (compilation tool) takes and print
-it to the standard error.
=back
-=head2 Language Specific Options
-
-=over
-
-=item B<-T,pre>=I<options>
-
-Pass an arbitrary option to the pre-processor.
-
-=item B<-T,opt>=I<options>
-
-Pass an arbitrary option to the optimizer.
-
-=item B<-T,lnk>=I<options>
-
-Pass an arbitrary option to the linker.
-
-=item B<-T,asm>=I<options>
-Pass an arbitrary option to the code generator.
-
-=back
+=head2 Control Options
-=head2 C/C++ Specific Options
+By default, LLVMC is built with some standard configuration libraries
+that define the following options:
=over
-=item B<-I>F<path>
-
-This option is just passed through to a C or C++ front end compiler to tell it
-where include files can be found.
-
-=item B<-D>F<symbol>
-
-This option is just passed through to a C or C++ front end compiler to tell it
-to define a symbol.
-
-=back
+=item B<-clang>
-=head2 Miscellaneous Options
+Use Clang instead of llvm-gcc.
-=over
+=item B<-opt>
-=item B<--help>
+Enable optimization passes with B<opt>. To pass options to the B<opt> program
+use the B<-Wo,> option.
-Print a summary of command line options.
+=item B<-I> I<directory>
-=item B<--version>
+Add a directory to the header file search path.
-This option will cause B<llvmc> to print out its version number and terminate.
+=item B<-L> I<directory>
-=back
+Add I<directory> to the library search path.
-=head2 Advanced Options
+=item B<-F> I<directory>
-You better know what you're doing if you use these options. Improper use
-of these options can produce drastically wrong results.
+Add I<directory> to the framework search path.
-=over
+=item B<-l>I<name>
-=item B<--config-dir> F<dirname>
-
-This option tells B<llvmc> to read configuration data from the I<directory>
-named F<dirname>. Data from such directories will be read in the order
-specified on the command line after all other standard configuration files have
-been read. This allows users or groups of users to conveniently create
-their own configuration directories in addition to the standard ones to which
-they may not have write access.
-
-=back
+Link in the library libI<name>.[bc | a | so]. This library should
+be a bitcode library.
+=item B<-framework> I<name>
-=head2 Unimplemented Options
+Link in the library libI<name>.[bc | a | so]. This library should
+be a bitcode library.
-The options below are not currently implemented in B<llvmc> but will be
-eventually. They are documented here as "future design".
+=item B<-emit-llvm>
-=over
+Output LLVM bitcode (with B<-c>) or assembly (with B<-S>) instead of native
+object (or assembly). If B<-emit-llvm> is given without either B<-c> or B<-S>
+it has no effect.
-=item B<--show-config> I<[suffixes...]>
+=item B<-Wa>
-When this option is given, the only action taken by B<llvmc> is to show its
-final configuration state in the form of a configuration file. No compilation
-tasks will be conducted when this option is given; processing will stop once
-the configuration has been printed. The optional (comma separated) list of
-suffixes controls what is printed. Without any suffixes, the configuration
-for all languages is printed. With suffixes, only the languages pertaining
-to those file suffixes will be printed. The configuration information is
-printed after all command line options and configuration files have been
-read and processed. This allows the user to verify that the correct
-configuration data has been read by B<llvmc>.
+Pass options to assembler.
-=item B<--config> :I<section>:I<name>=I<value>
+=item B<-Wl>
-This option instructs B<llvmc> to accept I<value> as the value for configuration
-item I<name> in the section named I<section>. This is a quick way to override
-a configuration item on the command line without resorting to changing the
-configuration files.
+Pass options to linker.
-=item B<--config-only-from> F<dirname>
+=item B<-Wo>
-This option tells B<llvmc> to skip the normal processing of configuration
-files and only configure from the contents of the F<dirname> directory. Multiple
-B<--config-only-from> options may be given in which case the directories are
-read in the order given on the command line.
+Pass options to opt.
-=item B<--emit-raw-code>
+=item B<-Wllc>
-No optimization is done whatsoever. The compilers invoked by B<llvmc> with
-this option given will be instructed to produce raw, unoptimized code. This
-option is useful only to front end language developers and therefore does not
-participate in the list of B<-O> options. This is distinctly different from
-the B<-O0> option (a synonym for B<-O1>) because those optimizations will
-reduce code size to make compilation faster. With B<--emit-raw-code>, only
-the full raw code produced by the compiler will be generated.
+Pass options to llc (code generator).
=back
-
=head1 EXIT STATUS
-If B<llvmc> succeeds, it will exit with 0. Otherwise, if an error
-occurs, it will exit with a non-zero value and no compilation actions
-will be taken. If one of the compilation tools returns a non-zero
-status, pending actions will be discarded and B<llvmc> will return the
-same result code as the failing compilation tool.
-
-=head1 DEFICIENCIES
-
-B<llvmc> is considered an experimental LLVM tool because it has these
-deficiencies:
-
-=over
-
-=item Insufficient support for native linking
-
-Because B<llvm-ld> doesn't handle native linking, neither can B<llvmc>
-
-=item Poor configuration support
-
-The support for configuring new languages, etc. is weak. There are many
-command line configurations that cannot be achieved with the current
-support. Furthermore the grammar is cumbersome for configuration files.
-Please see L<http://llvm.org/PR686> for further details.
-
-=item Does not handle target specific configurations
-
-This is one of the major deficiencies, also addressed in
-L<http://llvm.org/PR686>
-
-=back
+If B<llvmc> succeeds, it will exit with code 0. Otherwise, if an
+error occurs, it will exit with a non-zero value. If one of the
+compilation tools returns a non-zero status, pending actions will be
+discarded and B<llvmc> will return the same result code as the failing
+compilation tool.
=head1 SEE ALSO
-L<llvm-as|llvm-as>, L<llvm-dis|llvm-dis>, L<llc|llc>, L<llvm-link|llvm-link>
+L<llvm-gcc|llvmgcc>, L<llvm-g++|llvmgxx>, L<llvm-as|llvm-as>,
+L<llvm-dis|llvm-dis>, L<llc|llc>, L<llvm-link|llvm-link>
=head1 AUTHORS
projects / oota-llvm.git / blobdiff