diff options
Diffstat (limited to 'contrib/llvm/tools/llvmc/doc')
| -rw-r--r-- | contrib/llvm/tools/llvmc/doc/LLVMC-Reference.rst | 832 | ||||
| -rw-r--r-- | contrib/llvm/tools/llvmc/doc/LLVMC-Tutorial.rst | 129 | ||||
| -rw-r--r-- | contrib/llvm/tools/llvmc/doc/Makefile | 33 | ||||
| -rw-r--r-- | contrib/llvm/tools/llvmc/doc/img/lines.gif | bin | 0 -> 91 bytes |
4 files changed, 994 insertions, 0 deletions
diff --git a/contrib/llvm/tools/llvmc/doc/LLVMC-Reference.rst b/contrib/llvm/tools/llvmc/doc/LLVMC-Reference.rst new file mode 100644 index 0000000..ca8500d --- /dev/null +++ b/contrib/llvm/tools/llvmc/doc/LLVMC-Reference.rst @@ -0,0 +1,832 @@ +=================================== +Customizing LLVMC: Reference Manual +=================================== +.. + This file was automatically generated by rst2html. + Please do not edit directly! + The ReST source lives in the directory 'tools/llvmc/doc'. + +.. contents:: + +.. raw:: html + + <div class="doc_author"> + <p>Written by <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a></p> + </div> + +Introduction +============ + +LLVMC is a generic compiler driver, designed to be customizable and +extensible. It plays the same role for LLVM as the ``gcc`` program +does for GCC - LLVMC's job is essentially to transform a set of input +files into a set of targets depending on configuration rules and user +options. What makes LLVMC different is that these transformation rules +are completely customizable - in fact, LLVMC knows nothing about the +specifics of transformation (even the command-line options are mostly +not hard-coded) and regards the transformation structure as an +abstract graph. The structure of this graph is completely determined +by plugins, which can be either statically or dynamically linked. This +makes it possible to easily adapt LLVMC for other purposes - for +example, as a build tool for game resources. + +Because LLVMC employs TableGen_ as its configuration language, you +need to be familiar with it to customize LLVMC. + +.. _TableGen: http://llvm.org/docs/TableGenFundamentals.html + + +Compiling with LLVMC +==================== + +LLVMC tries hard to be as compatible with ``gcc`` as possible, +although there are some small differences. Most of the time, however, +you shouldn't be able to notice them:: + + $ # This works as expected: + $ llvmc -O3 -Wall hello.cpp + $ ./a.out + hello + +One nice feature of LLVMC is that one doesn't have to distinguish between +different compilers for different languages (think ``g++`` vs. ``gcc``) - the +right toolchain is chosen automatically based on input language names (which +are, in turn, determined from file extensions). If you want to force files +ending with ".c" to compile as C++, use the ``-x`` option, just like you would +do it with ``gcc``:: + + $ # hello.c is really a C++ file + $ llvmc -x c++ hello.c + $ ./a.out + hello + +On the other hand, when using LLVMC as a linker to combine several C++ +object files you should provide the ``--linker`` option since it's +impossible for LLVMC to choose the right linker in that case:: + + $ llvmc -c hello.cpp + $ llvmc hello.o + [A lot of link-time errors skipped] + $ llvmc --linker=c++ hello.o + $ ./a.out + hello + +By default, LLVMC uses ``llvm-gcc`` to compile the source code. It is also +possible to choose the ``clang`` compiler with the ``-clang`` option. + + +Predefined options +================== + +LLVMC has some built-in options that can't be overridden in the +configuration libraries: + +* ``-o FILE`` - Output file name. + +* ``-x LANGUAGE`` - Specify the language of the following input files + until the next -x option. + +* ``-load PLUGIN_NAME`` - Load the specified plugin DLL. Example: + ``-load $LLVM_DIR/Release/lib/LLVMCSimple.so``. + +* ``-v`` - Enable verbose mode, i.e. print out all executed commands. + +* ``--save-temps`` - Write temporary files to the current directory and do not + delete them on exit. This option can also take an argument: the + ``--save-temps=obj`` switch will write files into the directory specified with + the ``-o`` option. The ``--save-temps=cwd`` and ``--save-temps`` switches are + both synonyms for the default behaviour. + +* ``--temp-dir DIRECTORY`` - Store temporary files in the given directory. This + directory is deleted on exit unless ``--save-temps`` is specified. If + ``--save-temps=obj`` is also specified, ``--temp-dir`` is given the + precedence. + +* ``--check-graph`` - Check the compilation for common errors like mismatched + output/input language names, multiple default edges and cycles. Because of + plugins, these checks can't be performed at compile-time. Exit with code zero + if no errors were found, and return the number of found errors + otherwise. Hidden option, useful for debugging LLVMC plugins. + +* ``--view-graph`` - Show a graphical representation of the compilation graph + and exit. Requires that you have ``dot`` and ``gv`` programs installed. Hidden + option, useful for debugging LLVMC plugins. + +* ``--write-graph`` - Write a ``compilation-graph.dot`` file in the current + directory with the compilation graph description in Graphviz format (identical + to the file used by the ``--view-graph`` option). The ``-o`` option can be + used to set the output file name. Hidden option, useful for debugging LLVMC + plugins. + +* ``--help``, ``--help-hidden``, ``--version`` - These options have + their standard meaning. + +Compiling LLVMC plugins +======================= + +It's easiest to start working on your own LLVMC plugin by copying the +skeleton project which lives under ``$LLVMC_DIR/plugins/Simple``:: + + $ cd $LLVMC_DIR/plugins + $ cp -r Simple MyPlugin + $ cd MyPlugin + $ ls + Makefile PluginMain.cpp Simple.td + +As you can see, our basic plugin consists of only two files (not +counting the build script). ``Simple.td`` contains TableGen +description of the compilation graph; its format is documented in the +following sections. ``PluginMain.cpp`` is just a helper file used to +compile the auto-generated C++ code produced from TableGen source. It +can also contain hook definitions (see `below`__). + +__ hooks_ + +The first thing that you should do is to change the ``LLVMC_PLUGIN`` +variable in the ``Makefile`` to avoid conflicts (since this variable +is used to name the resulting library):: + + LLVMC_PLUGIN=MyPlugin + +It is also a good idea to rename ``Simple.td`` to something less +generic:: + + $ mv Simple.td MyPlugin.td + +To build your plugin as a dynamic library, just ``cd`` to its source +directory and run ``make``. The resulting file will be called +``plugin_llvmc_$(LLVMC_PLUGIN).$(DLL_EXTENSION)`` (in our case, +``plugin_llvmc_MyPlugin.so``). This library can be then loaded in with the +``-load`` option. Example:: + + $ cd $LLVMC_DIR/plugins/Simple + $ make + $ llvmc -load $LLVM_DIR/Release/lib/plugin_llvmc_Simple.so + +Compiling standalone LLVMC-based drivers +======================================== + +By default, the ``llvmc`` executable consists of a driver core plus several +statically linked plugins (``Base`` and ``Clang`` at the moment). You can +produce a standalone LLVMC-based driver executable by linking the core with your +own plugins. The recommended way to do this is by starting with the provided +``Skeleton`` example (``$LLVMC_DIR/example/Skeleton``):: + + $ cd $LLVMC_DIR/example/ + $ cp -r Skeleton mydriver + $ cd mydriver + $ vim Makefile + [...] + $ make + +If you're compiling LLVM with different source and object directories, then you +must perform the following additional steps before running ``make``:: + + # LLVMC_SRC_DIR = $LLVM_SRC_DIR/tools/llvmc/ + # LLVMC_OBJ_DIR = $LLVM_OBJ_DIR/tools/llvmc/ + $ cp $LLVMC_SRC_DIR/example/mydriver/Makefile \ + $LLVMC_OBJ_DIR/example/mydriver/ + $ cd $LLVMC_OBJ_DIR/example/mydriver + $ make + +Another way to do the same thing is by using the following command:: + + $ cd $LLVMC_DIR + $ make LLVMC_BUILTIN_PLUGINS=MyPlugin LLVMC_BASED_DRIVER_NAME=mydriver + +This works with both srcdir == objdir and srcdir != objdir, but assumes that the +plugin source directory was placed under ``$LLVMC_DIR/plugins``. + +Sometimes, you will want a 'bare-bones' version of LLVMC that has no +built-in plugins. It can be compiled with the following command:: + + $ cd $LLVMC_DIR + $ make LLVMC_BUILTIN_PLUGINS="" + + +Customizing LLVMC: the compilation graph +======================================== + +Each TableGen configuration file should include the common +definitions:: + + include "llvm/CompilerDriver/Common.td" + +Internally, LLVMC stores information about possible source +transformations in form of a graph. Nodes in this graph represent +tools, and edges between two nodes represent a transformation path. A +special "root" node is used to mark entry points for the +transformations. LLVMC also assigns a weight to each edge (more on +this later) to choose between several alternative edges. + +The definition of the compilation graph (see file +``plugins/Base/Base.td`` for an example) is just a list of edges:: + + def CompilationGraph : CompilationGraph<[ + Edge<"root", "llvm_gcc_c">, + Edge<"root", "llvm_gcc_assembler">, + ... + + Edge<"llvm_gcc_c", "llc">, + Edge<"llvm_gcc_cpp", "llc">, + ... + + OptionalEdge<"llvm_gcc_c", "opt", (case (switch_on "opt"), + (inc_weight))>, + OptionalEdge<"llvm_gcc_cpp", "opt", (case (switch_on "opt"), + (inc_weight))>, + ... + + OptionalEdge<"llvm_gcc_assembler", "llvm_gcc_cpp_linker", + (case (input_languages_contain "c++"), (inc_weight), + (or (parameter_equals "linker", "g++"), + (parameter_equals "linker", "c++")), (inc_weight))>, + ... + + ]>; + +As you can see, the edges can be either default or optional, where +optional edges are differentiated by an additional ``case`` expression +used to calculate the weight of this edge. Notice also that we refer +to tools via their names (as strings). This makes it possible to add +edges to an existing compilation graph in plugins without having to +know about all tool definitions used in the graph. + +The default edges are assigned a weight of 1, and optional edges get a +weight of 0 + 2*N where N is the number of tests that evaluated to +true in the ``case`` expression. It is also possible to provide an +integer parameter to ``inc_weight`` and ``dec_weight`` - in this case, +the weight is increased (or decreased) by the provided value instead +of the default 2. It is also possible to change the default weight of +an optional edge by using the ``default`` clause of the ``case`` +construct. + +When passing an input file through the graph, LLVMC picks the edge +with the maximum weight. To avoid ambiguity, there should be only one +default edge between two nodes (with the exception of the root node, +which gets a special treatment - there you are allowed to specify one +default edge *per language*). + +When multiple plugins are loaded, their compilation graphs are merged +together. Since multiple edges that have the same end nodes are not +allowed (i.e. the graph is not a multigraph), an edge defined in +several plugins will be replaced by the definition from the plugin +that was loaded last. Plugin load order can be controlled by using the +plugin priority feature described above. + +To get a visual representation of the compilation graph (useful for +debugging), run ``llvmc --view-graph``. You will need ``dot`` and +``gsview`` installed for this to work properly. + +Describing options +================== + +Command-line options that the plugin supports are defined by using an +``OptionList``:: + + def Options : OptionList<[ + (switch_option "E", (help "Help string")), + (alias_option "quiet", "q") + ... + ]>; + +As you can see, the option list is just a list of DAGs, where each DAG +is an option description consisting of the option name and some +properties. A plugin can define more than one option list (they are +all merged together in the end), which can be handy if one wants to +separate option groups syntactically. + +* Possible option types: + + - ``switch_option`` - a simple boolean switch without arguments, for example + ``-O2`` or ``-time``. At most one occurrence is allowed. + + - ``parameter_option`` - option that takes one argument, for example + ``-std=c99``. It is also allowed to use spaces instead of the equality + sign: ``-std c99``. At most one occurrence is allowed. + + - ``parameter_list_option`` - same as the above, but more than one option + occurence is allowed. + + - ``prefix_option`` - same as the parameter_option, but the option name and + argument do not have to be separated. Example: ``-ofile``. This can be also + specified as ``-o file``; however, ``-o=file`` will be parsed incorrectly + (``=file`` will be interpreted as option value). At most one occurrence is + allowed. + + - ``prefix_list_option`` - same as the above, but more than one occurence of + the option is allowed; example: ``-lm -lpthread``. + + - ``alias_option`` - a special option type for creating aliases. Unlike other + option types, aliases are not allowed to have any properties besides the + aliased option name. Usage example: ``(alias_option "preprocess", "E")`` + + +* Possible option properties: + + - ``help`` - help string associated with this option. Used for ``--help`` + output. + + - ``required`` - this option must be specified exactly once (or, in case of + the list options without the ``multi_val`` property, at least + once). Incompatible with ``optional`` and ``one_or_more``. + + - ``optional`` - the option can be specified either zero times or exactly + once. The default for switch options. Useful only for list options in + conjunction with ``multi_val``. Incompatible with ``required``, + ``zero_or_more`` and ``one_or_more``. + + - ``one_or_more`` - the option must be specified at least once. Can be useful + to allow switch options be both obligatory and be specified multiple + times. For list options is useful only in conjunction with ``multi_val``; + for ordinary it is synonymous with ``required``. Incompatible with + ``required``, ``optional`` and ``zero_or_more``. + + - ``zero_or_more`` - the option can be specified zero or more times. Useful + to allow a single switch option to be specified more than + once. Incompatible with ``required``, ``optional`` and ``one_or_more``. + + - ``hidden`` - the description of this option will not appear in + the ``--help`` output (but will appear in the ``--help-hidden`` + output). + + - ``really_hidden`` - the option will not be mentioned in any help + output. + + - ``comma_separated`` - Indicates that any commas specified for an option's + value should be used to split the value up into multiple values for the + option. This property is valid only for list options. In conjunction with + ``forward_value`` can be used to implement option forwarding in style of + gcc's ``-Wa,``. + + - ``multi_val n`` - this option takes *n* arguments (can be useful in some + special cases). Usage example: ``(parameter_list_option "foo", (multi_val + 3))``; the command-line syntax is '-foo a b c'. Only list options can have + this attribute; you can, however, use the ``one_or_more``, ``optional`` + and ``required`` properties. + + - ``init`` - this option has a default value, either a string (if it is a + parameter), or a boolean (if it is a switch; as in C++, boolean constants + are called ``true`` and ``false``). List options can't have ``init`` + attribute. + Usage examples: ``(switch_option "foo", (init true))``; ``(prefix_option + "bar", (init "baz"))``. + + - ``extern`` - this option is defined in some other plugin, see `below`__. + + __ extern_ + +.. _extern: + +External options +---------------- + +Sometimes, when linking several plugins together, one plugin needs to +access options defined in some other plugin. Because of the way +options are implemented, such options must be marked as +``extern``. This is what the ``extern`` option property is +for. Example:: + + ... + (switch_option "E", (extern)) + ... + +If an external option has additional attributes besides 'extern', they are +ignored. See also the section on plugin `priorities`__. + +__ priorities_ + +.. _case: + +Conditional evaluation +====================== + +The 'case' construct is the main means by which programmability is +achieved in LLVMC. It can be used to calculate edge weights, program +actions and modify the shell commands to be executed. The 'case' +expression is designed after the similarly-named construct in +functional languages and takes the form ``(case (test_1), statement_1, +(test_2), statement_2, ... (test_N), statement_N)``. The statements +are evaluated only if the corresponding tests evaluate to true. + +Examples:: + + // Edge weight calculation + + // Increases edge weight by 5 if "-A" is provided on the + // command-line, and by 5 more if "-B" is also provided. + (case + (switch_on "A"), (inc_weight 5), + (switch_on "B"), (inc_weight 5)) + + + // Tool command line specification + + // Evaluates to "cmdline1" if the option "-A" is provided on the + // command line; to "cmdline2" if "-B" is provided; + // otherwise to "cmdline3". + + (case + (switch_on "A"), "cmdline1", + (switch_on "B"), "cmdline2", + (default), "cmdline3") + +Note the slight difference in 'case' expression handling in contexts +of edge weights and command line specification - in the second example +the value of the ``"B"`` switch is never checked when switch ``"A"`` is +enabled, and the whole expression always evaluates to ``"cmdline1"`` in +that case. + +Case expressions can also be nested, i.e. the following is legal:: + + (case (switch_on "E"), (case (switch_on "o"), ..., (default), ...) + (default), ...) + +You should, however, try to avoid doing that because it hurts +readability. It is usually better to split tool descriptions and/or +use TableGen inheritance instead. + +* Possible tests are: + + - ``switch_on`` - Returns true if a given command-line switch is provided by + the user. Can be given a list as argument, in that case ``(switch_on ["foo", + "bar", "baz"])`` is equivalent to ``(and (switch_on "foo"), (switch_on + "bar"), (switch_on "baz"))``. + Example: ``(switch_on "opt")``. + + - ``any_switch_on`` - Given a list of switch options, returns true if any of + the switches is turned on. + Example: ``(any_switch_on ["foo", "bar", "baz"])`` is equivalent to ``(or + (switch_on "foo"), (switch_on "bar"), (switch_on "baz"))``. + + - ``parameter_equals`` - Returns true if a command-line parameter equals + a given value. + Example: ``(parameter_equals "W", "all")``. + + - ``element_in_list`` - Returns true if a command-line parameter + list contains a given value. + Example: ``(element_in_list "l", "pthread")``. + + - ``input_languages_contain`` - Returns true if a given language + belongs to the current input language set. + Example: ``(input_languages_contain "c++")``. + + - ``in_language`` - Evaluates to true if the input file language is equal to + the argument. At the moment works only with ``cmd_line`` and ``actions`` (on + non-join nodes). + Example: ``(in_language "c++")``. + + - ``not_empty`` - Returns true if a given option (which should be either a + parameter or a parameter list) is set by the user. Like ``switch_on``, can + be also given a list as argument. + Example: ``(not_empty "o")``. + + - ``any_not_empty`` - Returns true if ``not_empty`` returns true for any of + the options in the list. + Example: ``(any_not_empty ["foo", "bar", "baz"])`` is equivalent to ``(or + (not_empty "foo"), (not_empty "bar"), (not_empty "baz"))``. + + - ``empty`` - The opposite of ``not_empty``. Equivalent to ``(not (not_empty + X))``. Provided for convenience. Can be given a list as argument. + + - ``any_not_empty`` - Returns true if ``not_empty`` returns true for any of + the options in the list. + Example: ``(any_empty ["foo", "bar", "baz"])`` is equivalent to ``(not (and + (not_empty "foo"), (not_empty "bar"), (not_empty "baz")))``. + + - ``single_input_file`` - Returns true if there was only one input file + provided on the command-line. Used without arguments: + ``(single_input_file)``. + + - ``multiple_input_files`` - Equivalent to ``(not (single_input_file))`` (the + case of zero input files is considered an error). + + - ``default`` - Always evaluates to true. Should always be the last + test in the ``case`` expression. + + - ``and`` - A standard binary logical combinator that returns true iff all of + its arguments return true. Used like this: ``(and (test1), (test2), + ... (testN))``. Nesting of ``and`` and ``or`` is allowed, but not + encouraged. + + - ``or`` - A binary logical combinator that returns true iff any of its + arguments returns true. Example: ``(or (test1), (test2), ... (testN))``. + + - ``not`` - Standard unary logical combinator that negates its + argument. Example: ``(not (or (test1), (test2), ... (testN)))``. + + + +Writing a tool description +========================== + +As was said earlier, nodes in the compilation graph represent tools, +which are described separately. A tool definition looks like this +(taken from the ``include/llvm/CompilerDriver/Tools.td`` file):: + + def llvm_gcc_cpp : Tool<[ + (in_language "c++"), + (out_language "llvm-assembler"), + (output_suffix "bc"), + (cmd_line "llvm-g++ -c $INFILE -o $OUTFILE -emit-llvm"), + (sink) + ]>; + +This defines a new tool called ``llvm_gcc_cpp``, which is an alias for +``llvm-g++``. As you can see, a tool definition is just a list of +properties; most of them should be self-explanatory. The ``sink`` +property means that this tool should be passed all command-line +options that aren't mentioned in the option list. + +The complete list of all currently implemented tool properties follows. + +* Possible tool properties: + + - ``in_language`` - input language name. Can be either a string or a + list, in case the tool supports multiple input languages. + + - ``out_language`` - output language name. Multiple output languages are not + allowed. + + - ``output_suffix`` - output file suffix. Can also be changed + dynamically, see documentation on actions. + + - ``cmd_line`` - the actual command used to run the tool. You can + use ``$INFILE`` and ``$OUTFILE`` variables, output redirection + with ``>``, hook invocations (``$CALL``), environment variables + (via ``$ENV``) and the ``case`` construct. + + - ``join`` - this tool is a "join node" in the graph, i.e. it gets a + list of input files and joins them together. Used for linkers. + + - ``sink`` - all command-line options that are not handled by other + tools are passed to this tool. + + - ``actions`` - A single big ``case`` expression that specifies how + this tool reacts on command-line options (described in more detail + `below`__). + +__ actions_ + +.. _actions: + +Actions +------- + +A tool often needs to react to command-line options, and this is +precisely what the ``actions`` property is for. The next example +illustrates this feature:: + + def llvm_gcc_linker : Tool<[ + (in_language "object-code"), + (out_language "executable"), + (output_suffix "out"), + (cmd_line "llvm-gcc $INFILE -o $OUTFILE"), + (join), + (actions (case (not_empty "L"), (forward "L"), + (not_empty "l"), (forward "l"), + (not_empty "dummy"), + [(append_cmd "-dummy1"), (append_cmd "-dummy2")]) + ]>; + +The ``actions`` tool property is implemented on top of the omnipresent +``case`` expression. It associates one or more different *actions* +with given conditions - in the example, the actions are ``forward``, +which forwards a given option unchanged, and ``append_cmd``, which +appends a given string to the tool execution command. Multiple actions +can be associated with a single condition by using a list of actions +(used in the example to append some dummy options). The same ``case`` +construct can also be used in the ``cmd_line`` property to modify the +tool command line. + +The "join" property used in the example means that this tool behaves +like a linker. + +The list of all possible actions follows. + +* Possible actions: + + - ``append_cmd`` - Append a string to the tool invocation command. + Example: ``(case (switch_on "pthread"), (append_cmd "-lpthread"))``. + + - ``error`` - Exit with error. + Example: ``(error "Mixing -c and -S is not allowed!")``. + + - ``warning`` - Print a warning. + Example: ``(warning "Specifying both -O1 and -O2 is meaningless!")``. + + - ``forward`` - Forward the option unchanged. + Example: ``(forward "Wall")``. + + - ``forward_as`` - Change the option's name, but forward the argument + unchanged. + Example: ``(forward_as "O0", "--disable-optimization")``. + + - ``forward_value`` - Forward only option's value. Cannot be used with switch + options (since they don't have values), but works fine with lists. + Example: ``(forward_value "Wa,")``. + + - ``forward_transformed_value`` - As above, but applies a hook to the + option's value before forwarding (see `below`__). When + ``forward_transformed_value`` is applied to a list + option, the hook must have signature + ``std::string hooks::HookName (const std::vector<std::string>&)``. + Example: ``(forward_transformed_value "m", "ConvertToMAttr")``. + + __ hooks_ + + - ``output_suffix`` - Modify the output suffix of this tool. + Example: ``(output_suffix "i")``. + + - ``stop_compilation`` - Stop compilation after this tool processes its + input. Used without arguments. + Example: ``(stop_compilation)``. + + +Language map +============ + +If you are adding support for a new language to LLVMC, you'll need to +modify the language map, which defines mappings from file extensions +to language names. It is used to choose the proper toolchain(s) for a +given input file set. Language map definition looks like this:: + + def LanguageMap : LanguageMap< + [LangToSuffixes<"c++", ["cc", "cp", "cxx", "cpp", "CPP", "c++", "C"]>, + LangToSuffixes<"c", ["c"]>, + ... + ]>; + +For example, without those definitions the following command wouldn't work:: + + $ llvmc hello.cpp + llvmc: Unknown suffix: cpp + +The language map entries are needed only for the tools that are linked from the +root node. Since a tool can't have multiple output languages, for inner nodes of +the graph the input and output languages should match. This is enforced at +compile-time. + +Option preprocessor +=================== + +It is sometimes useful to run error-checking code before processing the +compilation graph. For example, if optimization options "-O1" and "-O2" are +implemented as switches, we might want to output a warning if the user invokes +the driver with both of these options enabled. + +The ``OptionPreprocessor`` feature is reserved specially for these +occasions. Example (adapted from the built-in Base plugin):: + + + def Preprocess : OptionPreprocessor< + (case (not (any_switch_on ["O0", "O1", "O2", "O3"])), + (set_option "O2"), + (and (switch_on "O3"), (any_switch_on ["O0", "O1", "O2"])), + (unset_option ["O0", "O1", "O2"]), + (and (switch_on "O2"), (any_switch_on ["O0", "O1"])), + (unset_option ["O0", "O1"]), + (and (switch_on "O1"), (switch_on "O0")), + (unset_option "O0")) + >; + +Here, ``OptionPreprocessor`` is used to unset all spurious ``-O`` options so +that they are not forwarded to the compiler. If no optimization options are +specified, ``-O2`` is enabled. + +``OptionPreprocessor`` is basically a single big ``case`` expression, which is +evaluated only once right after the plugin is loaded. The only allowed actions +in ``OptionPreprocessor`` are ``error``, ``warning``, and two special actions: +``unset_option`` and ``set_option``. As their names suggest, they can be used to +set or unset a given option. To set an option with ``set_option``, use the +two-argument form: ``(set_option "parameter", VALUE)``. Here, ``VALUE`` can be +either a string, a string list, or a boolean constant. + +For convenience, ``set_option`` and ``unset_option`` also work on lists. That +is, instead of ``[(unset_option "A"), (unset_option "B")]`` you can use +``(unset_option ["A", "B"])``. Obviously, ``(set_option ["A", "B"])`` is valid +only if both ``A`` and ``B`` are switches. + + +More advanced topics +==================== + +.. _hooks: + +Hooks and environment variables +------------------------------- + +Normally, LLVMC executes programs from the system ``PATH``. Sometimes, +this is not sufficient: for example, we may want to specify tool paths +or names in the configuration file. This can be easily achieved via +the hooks mechanism. To write your own hooks, just add their +definitions to the ``PluginMain.cpp`` or drop a ``.cpp`` file into the +your plugin directory. Hooks should live in the ``hooks`` namespace +and have the signature ``std::string hooks::MyHookName ([const char* +Arg0 [ const char* Arg2 [, ...]]])``. They can be used from the +``cmd_line`` tool property:: + + (cmd_line "$CALL(MyHook)/path/to/file -o $CALL(AnotherHook)") + +To pass arguments to hooks, use the following syntax:: + + (cmd_line "$CALL(MyHook, 'Arg1', 'Arg2', 'Arg # 3')/path/to/file -o1 -o2") + +It is also possible to use environment variables in the same manner:: + + (cmd_line "$ENV(VAR1)/path/to/file -o $ENV(VAR2)") + +To change the command line string based on user-provided options use +the ``case`` expression (documented `above`__):: + + (cmd_line + (case + (switch_on "E"), + "llvm-g++ -E -x c $INFILE -o $OUTFILE", + (default), + "llvm-g++ -c -x c $INFILE -o $OUTFILE -emit-llvm")) + +__ case_ + +.. _priorities: + +How plugins are loaded +---------------------- + +It is possible for LLVMC plugins to depend on each other. For example, +one can create edges between nodes defined in some other plugin. To +make this work, however, that plugin should be loaded first. To +achieve this, the concept of plugin priority was introduced. By +default, every plugin has priority zero; to specify the priority +explicitly, put the following line in your plugin's TableGen file:: + + def Priority : PluginPriority<$PRIORITY_VALUE>; + # Where PRIORITY_VALUE is some integer > 0 + +Plugins are loaded in order of their (increasing) priority, starting +with 0. Therefore, the plugin with the highest priority value will be +loaded last. + +Debugging +--------- + +When writing LLVMC plugins, it can be useful to get a visual view of +the resulting compilation graph. This can be achieved via the command +line option ``--view-graph``. This command assumes that Graphviz_ and +Ghostview_ are installed. There is also a ``--write-graph`` option that +creates a Graphviz source file (``compilation-graph.dot``) in the +current directory. + +Another useful ``llvmc`` option is ``--check-graph``. It checks the +compilation graph for common errors like mismatched output/input +language names, multiple default edges and cycles. These checks can't +be performed at compile-time because the plugins can load code +dynamically. When invoked with ``--check-graph``, ``llvmc`` doesn't +perform any compilation tasks and returns the number of encountered +errors as its status code. + +.. _Graphviz: http://www.graphviz.org/ +.. _Ghostview: http://pages.cs.wisc.edu/~ghost/ + +Conditioning on the executable name +----------------------------------- + +For now, the executable name (the value passed to the driver in ``argv[0]``) is +accessible only in the C++ code (i.e. hooks). Use the following code:: + + namespace llvmc { + extern const char* ProgramName; + } + + namespace hooks { + + std::string MyHook() { + //... + if (strcmp(ProgramName, "mydriver") == 0) { + //... + + } + + } // end namespace hooks + +In general, you're encouraged not to make the behaviour dependent on the +executable file name, and use command-line switches instead. See for example how +the ``Base`` plugin behaves when it needs to choose the correct linker options +(think ``g++`` vs. ``gcc``). + +.. raw:: html + + <hr /> + <address> + <a href="http://jigsaw.w3.org/css-validator/check/referer"> + <img src="http://jigsaw.w3.org/css-validator/images/vcss-blue" + alt="Valid CSS" /></a> + <a href="http://validator.w3.org/check?uri=referer"> + <img src="http://www.w3.org/Icons/valid-xhtml10-blue" + alt="Valid XHTML 1.0 Transitional"/></a> + + <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a><br /> + <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br /> + + Last modified: $Date: 2008-12-11 11:34:48 -0600 (Thu, 11 Dec 2008) $ + </address> diff --git a/contrib/llvm/tools/llvmc/doc/LLVMC-Tutorial.rst b/contrib/llvm/tools/llvmc/doc/LLVMC-Tutorial.rst new file mode 100644 index 0000000..e7e8f08 --- /dev/null +++ b/contrib/llvm/tools/llvmc/doc/LLVMC-Tutorial.rst @@ -0,0 +1,129 @@ +====================== +Tutorial - Using LLVMC +====================== +.. + This file was automatically generated by rst2html. + Please do not edit directly! + The ReST source lives in the directory 'tools/llvmc/doc'. + +.. contents:: + +.. raw:: html + + <div class="doc_author"> + <p>Written by <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a></p> + </div> + +Introduction +============ + +LLVMC is a generic compiler driver, which plays the same role for LLVM +as the ``gcc`` program does for GCC - the difference being that LLVMC +is designed to be more adaptable and easier to customize. Most of +LLVMC functionality is implemented via plugins, which can be loaded +dynamically or compiled in. This tutorial describes the basic usage +and configuration of LLVMC. + + +Compiling with LLVMC +==================== + +In general, LLVMC tries to be command-line compatible with ``gcc`` as +much as possible, so most of the familiar options work:: + + $ llvmc -O3 -Wall hello.cpp + $ ./a.out + hello + +This will invoke ``llvm-g++`` under the hood (you can see which +commands are executed by using the ``-v`` option). For further help on +command-line LLVMC usage, refer to the ``llvmc --help`` output. + + +Using LLVMC to generate toolchain drivers +========================================= + +LLVMC plugins are written mostly using TableGen_, so you need to +be familiar with it to get anything done. + +.. _TableGen: http://llvm.org/docs/TableGenFundamentals.html + +Start by compiling ``example/Simple``, which is a primitive wrapper for +``gcc``:: + + $ cd $LLVM_DIR/tools/llvmc + $ cp -r example/Simple plugins/Simple + + # NB: A less verbose way to compile standalone LLVMC-based drivers is + # described in the reference manual. + + $ make LLVMC_BASED_DRIVER_NAME=mygcc LLVMC_BUILTIN_PLUGINS=Simple + $ cat > hello.c + [...] + $ mygcc hello.c + $ ./hello.out + Hello + +Here we link our plugin with the LLVMC core statically to form an executable +file called ``mygcc``. It is also possible to build our plugin as a dynamic +library to be loaded by the ``llvmc`` executable (or any other LLVMC-based +standalone driver); this is described in the reference manual. + +Contents of the file ``Simple.td`` look like this:: + + // Include common definitions + include "llvm/CompilerDriver/Common.td" + + // Tool descriptions + def gcc : Tool< + [(in_language "c"), + (out_language "executable"), + (output_suffix "out"), + (cmd_line "gcc $INFILE -o $OUTFILE"), + (sink) + ]>; + + // Language map + def LanguageMap : LanguageMap<[LangToSuffixes<"c", ["c"]>]>; + + // Compilation graph + def CompilationGraph : CompilationGraph<[Edge<"root", "gcc">]>; + +As you can see, this file consists of three parts: tool descriptions, +language map, and the compilation graph definition. + +At the heart of LLVMC is the idea of a compilation graph: vertices in +this graph are tools, and edges represent a transformation path +between two tools (for example, assembly source produced by the +compiler can be transformed into executable code by an assembler). The +compilation graph is basically a list of edges; a special node named +``root`` is used to mark graph entry points. + +Tool descriptions are represented as property lists: most properties +in the example above should be self-explanatory; the ``sink`` property +means that all options lacking an explicit description should be +forwarded to this tool. + +The ``LanguageMap`` associates a language name with a list of suffixes +and is used for deciding which toolchain corresponds to a given input +file. + +To learn more about LLVMC customization, refer to the reference +manual and plugin source code in the ``plugins`` directory. + +.. raw:: html + + <hr /> + <address> + <a href="http://jigsaw.w3.org/css-validator/check/referer"> + <img src="http://jigsaw.w3.org/css-validator/images/vcss-blue" + alt="Valid CSS" /></a> + <a href="http://validator.w3.org/check?uri=referer"> + <img src="http://www.w3.org/Icons/valid-xhtml10-blue" + alt="Valid XHTML 1.0 Transitional"/></a> + + <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a><br /> + <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br /> + + Last modified: $Date: 2008-12-11 11:34:48 -0600 (Thu, 11 Dec 2008) $ + </address> diff --git a/contrib/llvm/tools/llvmc/doc/Makefile b/contrib/llvm/tools/llvmc/doc/Makefile new file mode 100644 index 0000000..ef98767 --- /dev/null +++ b/contrib/llvm/tools/llvmc/doc/Makefile @@ -0,0 +1,33 @@ +##===- tools/llvmc/doc/Makefile ----------------------------*- Makefile -*-===## +# +# The LLVM Compiler Infrastructure +# +# This file is distributed under the University of Illinois Open Source +# License. See LICENSE.TXT for details. +# +##===----------------------------------------------------------------------===## + +LEVEL=../../.. + +ifneq (,$(strip $(wildcard $(LEVEL)/Makefile.config))) +include $(LEVEL)/Makefile.config +else +CP=cp +RM=rm +endif + +DOC_DIR=../../../docs +RST2HTML=rst2html --stylesheet=llvm.css --link-stylesheet + +all : LLVMC-Reference.html LLVMC-Tutorial.html + $(CP) LLVMC-Reference.html $(DOC_DIR)/CompilerDriver.html + $(CP) LLVMC-Tutorial.html $(DOC_DIR)/CompilerDriverTutorial.html + +LLVMC-Tutorial.html : LLVMC-Tutorial.rst + $(RST2HTML) $< $@ + +LLVMC-Reference.html : LLVMC-Reference.rst + $(RST2HTML) $< $@ + +clean : + $(RM) LLVMC-Tutorial.html LLVMC-Reference.html diff --git a/contrib/llvm/tools/llvmc/doc/img/lines.gif b/contrib/llvm/tools/llvmc/doc/img/lines.gif Binary files differnew file mode 100644 index 0000000..88f491e --- /dev/null +++ b/contrib/llvm/tools/llvmc/doc/img/lines.gif |
