Re: [PATCH 0/9] Add UBSan to the build

[Tom Tromey <tom at tromey dot com>]

>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:

Pedro> I think this is a good idea.  On enabling this by default on devel
Pedro> builds, do you have a sense of CPU/memory overhead this introduces?

I have no idea about the CPU.  It doesn't seem notably slower to me but
I am not sure I would really notice.

I don't think -fsanitize=undefined has notable memory overhead.  I
believe it just introduces checks at spots where undefined behavior
might be possible.

It does increase the size of gdb:

size before:

   text	   data	    bss	    dec	    hex	filename
23070184	2372034	 323664	25765882	18927fa	gdb

size after:

   text	   data	    bss	    dec	    hex	filename
26879230	9135154	 324688	36339072	22a7d80	gdb


I think this isn't so important because it's only for development mode
and because it can be turned off if need be.

Though, let's not oversell it -- UB sanitization didn't catch anything
very important.  Address sanitizer, on the other hand, did; and if I can
fix that last bug I would like to give -fsanitize=address the same
treatment as was done here.

Tom