[Git][ghc/ghc][wip/con-info] Start of documentation

[Matthew Pickering]

Matthew Pickering pushed to branch wip/con-info at Glasgow Haskell Compiler / GHC


Commits:
fb288e29 by Matthew Pickering at 2020-11-04T08:22:41+00:00
Start of documentation

- - - - -


1 changed file:

- docs/users_guide/debug-info.rst


Changes:

=====================================
docs/users_guide/debug-info.rst
=====================================
@@ -331,3 +331,54 @@ Further Reading
 For more information about the debug information produced by GHC see
 Peter Wortmann's PhD thesis, `*Profiling Optimized Haskell: Causal
 Analysis and Implementation* <http://etheses.whiterose.ac.uk/8321/>`__.
+
+
+Direct Mapping
+==============
+
+In addition to the DWARF debug information, which can be used by many
+standard tools, using the ``-finfo-table-map`` flag
+
+
+.. ghc-flag:: -finfo-table-map
+    :shortdesc: Embed a lookup table in the generated binary which
+                maps the address of an info table to the source position
+                the closure originated from.
+    :type: dynamic
+    :category: debugging
+
+    :since: 9.2
+
+    This flag enables the generation of a table which maps the address of
+    an info table to an approximate source position of where that
+    info table statically originated from.
+
+.. ghc-flag:: -fdistinct-constructor-tables
+    :shortdesc: Generate a fresh info table for each usage
+                of a data constructor.
+    :type: dynamic
+    :category: debugging
+
+    :since: 9.2
+
+    For every usage of a data constructor in the source program
+    a new info table will be created. This is useful for debugging
+    as if each usage has a unique info table then the info table map
+    and profiling modes can distinguish the allocation sites of
+    a data constructor.
+
+
+
+Querying the Info Table Map
+---------------------------
+
+If it is generated then the info table map can be used
+in two ways.
+
+1. The ``whereFrom`` function can be used to determine the source
+   position which we think a specific closure was created.
+2. The complete mapping is also dumped into the eventlog.
+
+If you are using gdb then you can use the ``lookupIPE`` function
+directly in order to find any information which is known
+about the info table for a specific closure.



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/fb288e2950e3644cf4978aab6d8a3c7f2722d0ae

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/fb288e2950e3644cf4978aab6d8a3c7f2722d0ae
You're receiving this email because of your account on gitlab.haskell.org.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-commits/attachments/20201104/07006e6f/attachment-0001.html>