Launch GDB, debugging regexp.test:

$ gdb regexp.test
GNU gdb (GDB) 7.2-gg8
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv  3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
Type "show copying" and "show warranty" for licensing/warranty details.
This GDB was configured as "x86_64-linux".

Reading symbols from  /home/user/go/src/regexp/regexp.test...
done.
Loading Go Runtime support.
(gdb)
If for some reason GDB still can't find that directory or that script, you can load it by hand by telling gdb (assuming you have the go sources in ~/go/):

(gdb) source ~/go/src/runtime/runtime-gdb.py
Loading Go Runtime support.
To help GDB find the Go runtime sources and the accompanying support script, pass your $GOROOT with the '-d' flag:

$ gdb regexp.test -d $GOROOT

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