[gentoo-dev] Re: check-reqs* vs CFLAGS=-g
On Thu, 1 Aug 2013 13:33:48 +0200 Michał Górny wrote: > What can we do to improve this? I'm not really happy to have LLVM > ebuild analyze CFLAGS to set proper space constraints. Maybe we should > make check-reqs-r1 automatically bump the constraints by some > statistical multiplier when it detects -g? The problem with that is there is no way to determine how much larger a -g build will be. It varies widely across GCC versions (eg. when var-tracking was added the size of debug info exploded, in some cases up to an order of magnitude), and different -g/-ggdb levels. All you can really do is warn people they may run out of space if they're using debugging options. -- Ryan Hillpsn: dirtyepic_sk gcc-porting/toolchain/wxwidgets @ gentoo.org 47C3 6D62 4864 0E49 8E9E 7F92 ED38 BD49 957A 8463 signature.asc Description: PGP signature
[gentoo-dev] Re: check-reqs* vs CFLAGS=-g
On Fri, 2 Aug 2013 13:47:10 +0100 Diego Elio Pettenò wrote: > On Fri, Aug 2, 2013 at 1:08 PM, Andreas K. Huettel > wrote: > > > I thought -O0 was generally discouraged, even for debugging?! > > > As Michał said, it all depends on what you want to debug. I would say that > for 90% of issues you *do not* want to use -O0. Your code might not even > compile (libav for instance used to rely heavily in the DCE pass being > executed, GCC disables DCE at -O0), and even if it, you're now given a > different program altogether, so if you're looking for a crash, it might > magically disappear (memory areas get cleared out at -O0 but they might be > re-used without clearing at any other -O level). If you're feeling adventurous you could try -Og -g with gcc 4.8. -- Ryan Hillpsn: dirtyepic_sk gcc-porting/toolchain/wxwidgets @ gentoo.org 47C3 6D62 4864 0E49 8E9E 7F92 ED38 BD49 957A 8463 signature.asc Description: PGP signature
Re: [gentoo-dev] Re: check-reqs* vs CFLAGS=-g
Unlikely you screwed up, -O0 makes bigger code than -O2 almost in every case; then -g annotates it. I'm expecting -ggdb to take some few GBs more. It'll be the same if not worse with almost all software, -g3 would make it even worse. Diego Elio Pettenò — Flameeyes flamee...@flameeyes.eu — http://blog.flameeyes.eu/ On Fri, Aug 2, 2013 at 9:05 AM, Michał Górny wrote: > Dnia 2013-08-02, o godz. 02:07:18 > Duncan <1i5t5.dun...@cox.net> napisał(a): > > > Michał Górny posted on Thu, 01 Aug 2013 13:33:48 +0200 as excerpted: > > > > > LLVM has peek build space consumption around: > > > > > > - 400-550M without clang (depending on targets), > > > - 950-1200M with clang, > > > - 16G with clang & USE=debug (assertions, checks). > > > > Ouch! > > > > Thanks for the heads-up. I didn't realize -g/debug added THAT much! For > > sure I'll have to keep that in mind if I ever decide to build llvm with > > debug... and the general rule in mind for building anything else with > > debug. > > Just to make it clear, USE=debug doesn't imply -g. It gets 16G with > -O2. Curious enough, -O0 -g gave me 14G but maybe I screwed something > up :). > > -- > Best regards, > Michał Górny >
Re: [gentoo-dev] Re: check-reqs* vs CFLAGS=-g
Dnia 2013-08-02, o godz. 02:07:18 Duncan <1i5t5.dun...@cox.net> napisał(a): > Michał Górny posted on Thu, 01 Aug 2013 13:33:48 +0200 as excerpted: > > > LLVM has peek build space consumption around: > > > > - 400-550M without clang (depending on targets), > > - 950-1200M with clang, > > - 16G with clang & USE=debug (assertions, checks). > > Ouch! > > Thanks for the heads-up. I didn't realize -g/debug added THAT much! For > sure I'll have to keep that in mind if I ever decide to build llvm with > debug... and the general rule in mind for building anything else with > debug. Just to make it clear, USE=debug doesn't imply -g. It gets 16G with -O2. Curious enough, -O0 -g gave me 14G but maybe I screwed something up :). -- Best regards, Michał Górny signature.asc Description: PGP signature
[gentoo-dev] Re: check-reqs* vs CFLAGS=-g
Michał Górny posted on Thu, 01 Aug 2013 13:33:48 +0200 as excerpted: > LLVM has peek build space consumption around: > > - 400-550M without clang (depending on targets), > - 950-1200M with clang, > - 16G with clang & USE=debug (assertions, checks). Ouch! Thanks for the heads-up. I didn't realize -g/debug added THAT much! For sure I'll have to keep that in mind if I ever decide to build llvm with debug... and the general rule in mind for building anything else with debug. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman
