[llvm-symbolizer] Unhide and document the "-output-style" option

With the latest changes, the option gets useful for users of
llvm-symbolizer, not only for the upcoming llvm-addr2line.

Differential Revision: https://reviews.llvm.org/D60816

llvm-svn: 358748
diff --git a/llvm/docs/CommandGuide/llvm-symbolizer.rst b/llvm/docs/CommandGuide/llvm-symbolizer.rst
index b794f56..4dd6d9b 100644
--- a/llvm/docs/CommandGuide/llvm-symbolizer.rst
+++ b/llvm/docs/CommandGuide/llvm-symbolizer.rst
@@ -128,6 +128,37 @@
  Add the specified offset to object file addresses when performing lookups. This
  can be used to perform lookups as if the object were relocated by the offset.
 
+.. option:: -output-style=<LLVM|GNU>
+
+  Specify the preferred output style. Defaults to ``LLVM``. When the output
+  style is set to ``GNU``, the tool follows the style of GNU's **addr2line**.
+  The differences from the ``LLVM`` style are:
+  
+  * Does not print column of a source code location.
+
+  * Does not add an empty line after the report for an address.
+
+  * Does not replace the name of an inlined function with the name of the
+    topmost caller when inlined frames are not shown and ``-use-symbol-table``
+    is on.
+
+  .. code-block:: console
+
+    $ llvm-symbolizer -p -e=addr.exe 0x40054d 0x400568
+    inc at /tmp/x.c:3:3
+     (inlined by) main at /tmp/x.c:14:0
+
+    main at /tmp/x.c:14:3
+
+    $ llvm-symbolizer --output-style=LLVM -p -i=0 -e=addr.exe 0x40054d 0x400568
+    main at /tmp/x.c:3:3
+
+    main at /tmp/x.c:14:3
+
+    $ llvm-symbolizer --output-style=GNU -p -i=0 -e=addr.exe 0x40054d 0x400568
+    inc at /tmp/x.c:3
+    main at /tmp/x.c:14
+
 EXIT STATUS
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