The current documentation doesn't explain what the option is for, or
how one might use it. The attached patch expands the documentation a
bit to try to explain this.
Tested with a make doc, and verifying that the gcc.info file looks OK.
And tested by verifying that the option works the way I think it does..
OK?
Jim
2017-10-25 Jim Wilson <wil...@tuliptree.org>
gcc/
* doc/invoke.texi (-fdebug-prefix-map): Expand documentation.
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 254023)
+++ gcc/doc/invoke.texi (working copy)
@@ -6981,7 +6981,12 @@ link processing time. Merging is enabled by defau
@item -fdebug-prefix-map=@var{old}=@var{new}
@opindex fdebug-prefix-map
When compiling files in directory @file{@var{old}}, record debugging
-information describing them as in @file{@var{new}} instead.
+information describing them as in @file{@var{new}} instead. This can be
+used to replace a build time path with an install time path in the debug info.
+It can also be used to change an absolute path to a relative path by using
+@file{.} for @var{new}. This can give more reproducible builds, which are
+location independent, but may require an extra command to tell gdb where to
+find the source files.
@item -fvar-tracking
@opindex fvar-tracking
