re: kern/51322

[matthew green <mrg%eterna.com.au@localhost>]

The following reply was made to PR kern/51322; it has been noted by GNATS.

From: matthew green <mrg%eterna.com.au@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
    netbsd-bugs%netbsd.org@localhost, coypu%sdf.org@localhost
Subject: re: kern/51322
Date: Sun, 10 Jul 2016 01:49:30 +1000

 >  (when gdb says "optimized out", it doesn't mean that the value's not
 >  there, it means gdb doesn't know how to find it because it's e.g. in
 >  some scratch register and not in what gdb thinks of as a "variable")
 
 indeed.
 
 several times i've looked at this and GCC is usually failing to
 emit useful debug info.  when studying the asm, you can often
 find the value in a register.
 
 
 .mrg.