[XRay][docs] Document xray_mode and log registration API.

This marks certain flags in XRay as deprecated (in particular,
`xray_naive_log=` and `xray_fdr_log=`), and recommends the use of the
`xray_mode=` flag.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319763 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dean Michael Berris 2017-12-05 12:43:12 +00:00
parent b8aa60d240
commit f5f5294ad8
2 changed files with 24 additions and 6 deletions

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@ -143,15 +143,25 @@ variable, where we list down the options and their defaults below.
| | | | instrumentation points |
| | | | before main. |
+-------------------+-----------------+---------------+------------------------+
| xray_naive_log | ``bool`` | ``false`` | Whether to install |
| | | | the naive log |
| | | | implementation. |
| xray_mode | ``const char*`` | ``""`` | Default mode to |
| | | | install and initialize |
| | | | before ``main``. |
+-------------------+-----------------+---------------+------------------------+
| xray_logfile_base | ``const char*`` | ``xray-log.`` | Filename base for the |
| | | | XRay logfile. |
+-------------------+-----------------+---------------+------------------------+
| xray_fdr_log | ``bool`` | ``false`` | Whether to install the |
| | | | Flight Data Recorder |
| xray_naive_log | ``bool`` | ``false`` | **DEPRECATED:** Use |
| | | | xray_mode=xray-basic |
| | | | instead. Whether to |
| | | | install the basic log |
| | | | the naive log |
| | | | implementation. |
+-------------------+-----------------+---------------+------------------------+
| xray_fdr_log | ``bool`` | ``false`` | **DEPRECATED:** Use |
| | | | xray_mode=xray-fdr |
| | | | instead. Whether to |
| | | | install the Flight |
| | | | Data Recorder |
| | | | (FDR) mode. |
+-------------------+-----------------+---------------+------------------------+
@ -241,6 +251,14 @@ following API:
- ``__xray_set_log_impl(...)``: This function takes a struct of type
``XRayLogImpl``, which is defined in ``xray/xray_log_interface.h``, part of
the XRay compiler-rt installation.
- ``__xray_log_register_mode(...)``: Register a logging implementation against
a string Mode. The implementation is an instance of ``XRayLogImpl`` defined
in ``xray/xray_log_interface.h``.
- ``__xray_log_select_mode(...)``: Select the mode to install, associated with
a string Mode. Only implementations registered with
``__xray_log_register_mode(...)`` can be chosen with this function. When
successful, has the same effects as calling ``__xray_set_log_impl(...)`` with
the registered logging implementation.
- ``__xray_log_init(...)``: This function allows for initializing and
re-initializing an installed logging implementation. See
``xray/xray_log_interface.h`` for details, part of the XRay compiler-rt

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@ -60,7 +60,7 @@ to enable XRay at application start. To do this, XRay checks the
$ ./bin/llc input.ll
# We need to set the XRAY_OPTIONS to enable some features.
$ XRAY_OPTIONS="patch_premain=true xray_naive_log=true" ./bin/llc input.ll
$ XRAY_OPTIONS="patch_premain=true xray_mode=xray-basic" ./bin/llc input.ll
==69819==XRay: Log file in 'xray-log.llc.m35qPB'
At this point we now have an XRay trace we can start analysing.