[llvm-commits] [llvm] r130090 - in /llvm/trunk/tools/llvmc/doc: LLVMC-Reference.rst LLVMC-Tutorial.rst
Mikhail Glushenkov
foldr at codedgers.com
Sun Apr 24 07:17:32 PDT 2011
Author: foldr
Date: Sun Apr 24 09:17:32 2011
New Revision: 130090
URL: http://llvm.org/viewvc/llvm-project?rev=130090&view=rev
Log:
Remove all references to plugins from the LLVMC docs.
Modified:
llvm/trunk/tools/llvmc/doc/LLVMC-Reference.rst
llvm/trunk/tools/llvmc/doc/LLVMC-Tutorial.rst
Modified: llvm/trunk/tools/llvmc/doc/LLVMC-Reference.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvmc/doc/LLVMC-Reference.rst?rev=130090&r1=130089&r2=130090&view=diff
==============================================================================
--- llvm/trunk/tools/llvmc/doc/LLVMC-Reference.rst (original)
+++ llvm/trunk/tools/llvmc/doc/LLVMC-Reference.rst Sun Apr 24 09:17:32 2011
@@ -18,17 +18,16 @@
============
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.
+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 described in
+high-level TableGen code, from which an efficient C++ representation is
+automatically derived. This makes it possible to 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.
@@ -36,8 +35,8 @@
.. _TableGen: http://llvm.org/docs/TableGenFundamentals.html
-Compiling with LLVMC
-====================
+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,
@@ -78,17 +77,13 @@
Predefined options
==================
-LLVMC has some built-in options that can't be overridden in the
-configuration libraries:
+LLVMC has some built-in options that can't be overridden in the TableGen code:
* ``-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 $LLVM_DIR/Release/lib/LLVMCSimple.so``.
-
* ``-v`` - Enable verbose mode, i.e. print out all executed commands.
* ``--save-temps`` - Write temporary files to the current directory and do not
@@ -103,124 +98,90 @@
precedence.
* ``--check-graph`` - Check the compilation for common errors like mismatched
- output/input language names, multiple default edges and cycles. Because of
- plugins, these checks can't be performed at compile-time. Exit with code zero
- if no errors were found, and return the number of found errors
- otherwise. Hidden option, useful for debugging LLVMC plugins.
+ output/input language names, multiple default edges and cycles. Exit with code
+ zero if no errors were found, and return the number of found errors
+ otherwise. Hidden option, useful for debugging.
* ``--view-graph`` - Show a graphical representation of the compilation graph
and exit. Requires that you have ``dot`` and ``gv`` programs installed. Hidden
- option, useful for debugging LLVMC plugins.
+ option, useful for debugging.
* ``--write-graph`` - Write a ``compilation-graph.dot`` file in the current
directory with the compilation graph description in Graphviz format (identical
to the file used by the ``--view-graph`` option). The ``-o`` option can be
- used to set the output file name. Hidden option, useful for debugging LLVMC
- plugins.
+ used to set the output file name. Hidden option, useful for debugging.
* ``--help``, ``--help-hidden``, ``--version`` - These options have
their standard meaning.
-Compiling LLVMC plugins
-=======================
+Compiling LLVMC-based drivers
+=============================
-It's easiest to start working on your own LLVMC plugin by copying the
-skeleton project which lives under ``$LLVMC_DIR/plugins/Simple``::
+It's easiest to start working on your own LLVMC driver by copying the skeleton
+project which lives under ``$LLVMC_DIR/examples/Skeleton``::
- $ cd $LLVMC_DIR/plugins
- $ cp -r Simple MyPlugin
- $ cd MyPlugin
+ $ cd $LLVMC_DIR/examples
+ $ cp -r Skeleton MyDriver
+ $ cd MyDriver
$ ls
- Makefile PluginMain.cpp Simple.td
+ AutoGenerated.td Hooks.cpp Main.cpp Makefile
-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`__).
+As you can see, our basic driver consists of only three files (not counting the
+build script). ``AutoGenerated.td`` contains TableGen description of the
+compilation graph; its format is documented in the following
+sections. ``Hooks.cpp`` is an empty file that should be used for hook
+definitions (see `below`__). ``Main.cpp`` is just a helper used to compile the
+auto-generated C++ code produced from TableGen source.
__ 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)::
+The first thing that you should do is to change the ``LLVMC_BASED_DRIVER``
+variable in the ``Makefile``::
- LLVMC_PLUGIN=MyPlugin
+ LLVMC_BASED_DRIVER=MyDriver
-It is also a good idea to rename ``Simple.td`` to something less
-generic::
+It can also be a good idea to put your TableGen code into a file with a less
+generic name::
- $ mv Simple.td MyPlugin.td
+ $ touch MyDriver.td
+ $ vim AutoGenerated.td
+ [...]
+ include "MyDriver.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 $LLVM_DIR/Release/lib/plugin_llvmc_Simple.so
+If you have more than one TableGen source file, they all should be included from
+``AutoGenerated.td``, since this file is used by the build system to generate
+C++ code.
-Compiling standalone LLVMC-based drivers
-========================================
-
-By default, the ``llvmc`` executable consists of a driver core plus several
-statically linked plugins (``Base`` and ``Clang`` at the moment). You can
-produce a standalone LLVMC-based driver executable by linking the core with your
-own plugins. The recommended way to do this is by starting with the provided
-``Skeleton`` example (``$LLVMC_DIR/example/Skeleton``)::
-
- $ cd $LLVMC_DIR/example/
- $ cp -r Skeleton mydriver
- $ cd mydriver
- $ vim Makefile
- [...]
- $ make
+To build your driver, just ``cd`` to its source directory and run ``make``. The
+resulting executable will be put into ``$LLVM_OBJ_DIR/$(BuildMode)/bin``.
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
+ $ mkdir $LLVMC_OBJ_DIR/examples/MyDriver/
+ $ cp $LLVMC_SRC_DIR/examples/MyDriver/Makefile \
+ $LLVMC_OBJ_DIR/examples/MyDriver/
+ $ cd $LLVMC_OBJ_DIR/examples/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::
+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.
+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::
+The definition of the compilation graph (see file ``llvmc/src/Base.td`` for an
+example) is just a list of edges::
def CompilationGraph : CompilationGraph<[
Edge<"root", "llvm_gcc_c">,
@@ -245,43 +206,37 @@
]>;
-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``
+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
+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. Default weight of an
+optional edge can be changed 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.
+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 compilation graphs are defined, they are merged together. Multiple
+edges with the same end nodes are not allowed (i.e. the graph is not a
+multigraph), and will lead to a compile-time error.
+
+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
+Command-line options supported by the driver are defined by using an
``OptionList``::
def Options : OptionList<[
@@ -290,11 +245,10 @@
...
]>;
-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.
+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. More than
+one option list can be defined (they are all merged together in the end), which
+can be handy if one wants to separate option groups syntactically.
* Possible option types:
@@ -380,42 +334,17 @@
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.
+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::
@@ -439,20 +368,19 @@
(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.
+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.
+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:
@@ -526,72 +454,75 @@
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)::
+As was said earlier, nodes in the compilation graph represent tools, which are
+described separately. A tool definition looks like this (taken from the
+``llvmc/src/Base.td`` file)::
def llvm_gcc_cpp : Tool<[
(in_language "c++"),
(out_language "llvm-assembler"),
(output_suffix "bc"),
- (cmd_line "llvm-g++ -c $INFILE -o $OUTFILE -emit-llvm"),
+ (command "llvm-g++ -c -emit-llvm"),
(sink)
]>;
This defines a new tool called ``llvm_gcc_cpp``, which is an alias for
-``llvm-g++``. As you can see, a tool definition is just a list of
-properties; most of them should be self-explanatory. The ``sink``
-property means that this tool should be passed all command-line
-options that aren't mentioned in the option list.
+``llvm-g++``. As you can see, a tool definition is just a list of properties;
+most of them should be self-explanatory. The ``sink`` property means that this
+tool should be passed all command-line options that aren't mentioned in the
+option list.
The complete list of all currently implemented tool properties follows.
* Possible tool properties:
- ``in_language`` - input language name. Can be given multiple arguments, in
- case the tool supports multiple input languages.
+ case the tool supports multiple input languages. Used for typechecking and
+ mapping file extensions to tools.
- ``out_language`` - output language name. Multiple output languages are
- allowed.
+ allowed. Used for typechecking the compilation graph.
- - ``output_suffix`` - output file suffix. Can also be changed
- dynamically, see documentation on actions.
+ - ``output_suffix`` - output file suffix. Can also be changed dynamically, see
+ documentation on `actions`__.
- - ``cmd_line`` - the actual command used to run the tool. You can
- use ``$INFILE`` and ``$OUTFILE`` variables, output redirection
- with ``>``, hook invocations (``$CALL``), environment variables
+__ actions_
+
+ - ``command`` - the actual command used to run the tool. You can use 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.
+ - ``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.
+ - ``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`` - A single big ``case`` expression that specifies how this tool
+ reacts on command-line options (described in more detail `below`__).
__ actions_
+ - ``out_file_option``, ``in_file_option`` - Options appended to the
+ ``command`` string to designate output and input files. Default values are
+ ``"-o"`` and ``""``, respectively.
+
.. _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::
+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"),
+ (command "llvm-gcc"),
(join),
(actions (case (not_empty "L"), (forward "L"),
(not_empty "l"), (forward "l"),
@@ -599,18 +530,17 @@
[(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 ``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 "join" property used in the example means that this tool behaves like a
+linker.
The list of all possible actions follows.
@@ -656,10 +586,10 @@
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::
+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"]>,
@@ -673,9 +603,7 @@
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.
+root node. A tool can have multiple output languages.
Option preprocessor
===================
@@ -686,7 +614,7 @@
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)::
+occasions. Example (adapted from ``llvm/src/Base.td.in``)::
def Preprocess : OptionPreprocessor<
@@ -705,7 +633,7 @@
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
+evaluated only once right after the driver is started. 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
@@ -726,30 +654,28 @@
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::
+Normally, LLVMC searches for programs in 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 achieved via the hooks mechanism. To write your
+own hooks, add their definitions to the ``Hooks.cpp`` or drop a ``.cpp`` file
+into your driver 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 ``command`` tool property::
- (cmd_line "$CALL(MyHook)/path/to/file -o $CALL(AnotherHook)")
+ (command "$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")
+ (command "$CALL(MyHook, 'Arg1', 'Arg2', 'Arg # 3')/path/to/file -o1 -o2")
It is also possible to use environment variables in the same manner::
- (cmd_line "$ENV(VAR1)/path/to/file -o $ENV(VAR2)")
+ (command "$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
+ (command
(case
(switch_on "E"),
"llvm-g++ -E -x c $INFILE -o $OUTFILE",
@@ -758,42 +684,21 @@
__ case_
-.. _priorities:
-
-How plugins are loaded
-----------------------
-
-It is possible for LLVMC plugins to depend on each other. For example,
-one can create edges between nodes defined in some other plugin. To
-make this work, however, that plugin should be loaded first. To
-achieve this, the concept of plugin priority was introduced. By
-default, every plugin has priority zero; to specify the priority
-explicitly, put the following line in your plugin's TableGen file::
-
- def Priority : PluginPriority<$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.
+When writing LLVMC-based drivers, 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`` (which 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. When invoked with ``--check-graph``, ``llvmc`` doesn't
+perform any compilation tasks and returns the number of encountered errors as
+its status code. In the future, these checks will be performed at compile-time
+and this option will disappear.
.. _Graphviz: http://www.graphviz.org/
.. _Ghostview: http://pages.cs.wisc.edu/~ghost/
@@ -821,7 +726,7 @@
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
+the ``llvmc`` program behaves when it needs to choose the correct linker options
(think ``g++`` vs. ``gcc``).
.. raw:: html
Modified: llvm/trunk/tools/llvmc/doc/LLVMC-Tutorial.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvmc/doc/LLVMC-Tutorial.rst?rev=130090&r1=130089&r2=130090&view=diff
==============================================================================
--- llvm/trunk/tools/llvmc/doc/LLVMC-Tutorial.rst (original)
+++ llvm/trunk/tools/llvmc/doc/LLVMC-Tutorial.rst Sun Apr 24 09:17:32 2011
@@ -17,59 +17,54 @@
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.
+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 high-level TableGen code, from which a corresponding C++ source
+file is automatically generated. This tutorial describes the basic usage and
+configuration of LLVMC.
-Compiling with LLVMC
-====================
+Using the ``llvmc`` program
+===========================
-In general, LLVMC tries to be command-line compatible with ``gcc`` as
-much as possible, so most of the familiar options work::
+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.
+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.
+LLVMC-based drivers 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
+ $ cd $LLVM_OBJ_DIR/tools/examples/Simple
+ $ make
$ cat > hello.c
- [...]
- $ mygcc hello.c
+ #include <stdio.h>
+ int main() { printf("Hello\n"); }
+ $ $LLVM_BIN_DIR/Simple -v hello.c
+ gcc hello.c -o hello.out
$ ./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::
+We have thus produced a simple driver called, appropriately, ``Simple``, from
+the input TableGen file ``Simple.td``. The ``llvmc`` program itself is generated
+using a similar process (see ``llvmc/src``). Contents of the file ``Simple.td``
+look like this::
// Include common definitions
include "llvm/CompilerDriver/Common.td"
@@ -79,37 +74,40 @@
[(in_language "c"),
(out_language "executable"),
(output_suffix "out"),
- (cmd_line "gcc $INFILE -o $OUTFILE"),
- (sink)
+ (command "gcc"),
+ (sink),
+
+ // -o is what is used by default, out_file_option here is included for
+ // instructive purposes.
+ (out_file_option "-o")
]>;
// Language map
- def LanguageMap : LanguageMap<[LangToSuffixes<"c", ["c"]>]>;
+ def LanguageMap : LanguageMap<[(lang_to_suffixes "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.
+ def CompilationGraph : CompilationGraph<[(edge "root", "gcc")]>;
-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.
+As you can see, this file consists of three parts: tool descriptions, language
+map, and the compilation graph definition.
-To learn more about LLVMC customization, refer to the reference
-manual and plugin source code in the ``plugins`` directory.
+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 writing your own drivers with LLVMC, refer to the reference
+manual and examples in the ``examples`` directory. Of a particular interest is
+the ``Skeleton`` example, which can serve as a template for your LLVMC-based
+drivers.
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