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Diffstat (limited to 'tools/llvmc/doc/LLVMC-Reference.rst')
| -rw-r--r-- | tools/llvmc/doc/LLVMC-Reference.rst | 46 |
1 files changed, 28 insertions, 18 deletions
diff --git a/tools/llvmc/doc/LLVMC-Reference.rst b/tools/llvmc/doc/LLVMC-Reference.rst index 4d80a2a..dfe3898 100644 --- a/tools/llvmc/doc/LLVMC-Reference.rst +++ b/tools/llvmc/doc/LLVMC-Reference.rst @@ -656,10 +656,10 @@ For example, without those definitions the following command wouldn't work:: $ llvmc hello.cpp llvmc: Unknown suffix: cpp -The language map entries should be added only for tools that are -linked with the root node. Since tools are not allowed to have -multiple output languages, for nodes "inside" the graph the input and -output languages should match. This is enforced at compile-time. +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 =================== @@ -672,24 +672,34 @@ 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 (and (switch_on "O3"), (any_switch_on ["O0", "O1", "O2"])), - [(unset_option ["O0", "O1", "O2"]), - (warning "Multiple -O options specified, defaulted to -O3.")], - (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 optimization options -(so that they are not forwarded to the compiler). + 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 a special action -``unset_option``, which, as the name suggests, unsets a given option. For -convenience, ``unset_option`` also works on lists. +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 |
