On Fri, Nov 15, 2013 at 7:26 AM, Bob Wilson <bob.wilson at apple.com> wrote:> Hi Kostya, > > Thanks for the heads-up on this. I haven’t had a chance to look into the > details yet, but it looks like these patches may be breaking our > bootstrapped LTO build. Our buildbots have been failing all day, and we’re > still trying to figure out the problem. I’m going to speculatively revert > those changes, since they were the only patches on the buildbot blame list. > I will either reapply the changes or help debug the problem.How could this possibly affect your LTO build? The option is off by default. Do you have any details, logs, etc?> > —Bob > > On Nov 14, 2013, at 5:42 AM, Kostya Serebryany <kcc at google.com> wrote: > > Bob, Justin, > > I've just committed a poor man's coverage implementation that works with > asan. > http://llvm.org/viewvc/llvm-project?rev=194701&view=rev > http://llvm.org/viewvc/llvm-project?rev=194702&view=rev > It provides only function-level boolean coverage (i.e. no counters, just > "visited or not"), > but is very fast and very simple (no extra sections to the binary file, etc) > I've tried it for Chrome's content_shell (huge and heavy binary) and the > overhead > is negligible at both run-time and shutdown-time. > > We'll be evaluating this implementation and collecting usage stats. > Maybe we want to implement something simple like this in the Clang coverage. > > --kcc > >
Also, when are you planing to "reapply the changes or help debug"? On Fri, Nov 15, 2013 at 9:15 AM, Kostya Serebryany <kcc at google.com> wrote:> On Fri, Nov 15, 2013 at 7:26 AM, Bob Wilson <bob.wilson at apple.com> wrote: >> Hi Kostya, >> >> Thanks for the heads-up on this. I haven’t had a chance to look into the >> details yet, but it looks like these patches may be breaking our >> bootstrapped LTO build. Our buildbots have been failing all day, and we’re >> still trying to figure out the problem. I’m going to speculatively revert >> those changes, since they were the only patches on the buildbot blame list. >> I will either reapply the changes or help debug the problem. > > How could this possibly affect your LTO build? > The option is off by default. > Do you have any details, logs, etc? > >> >> —Bob >> >> On Nov 14, 2013, at 5:42 AM, Kostya Serebryany <kcc at google.com> wrote: >> >> Bob, Justin, >> >> I've just committed a poor man's coverage implementation that works with >> asan. >> http://llvm.org/viewvc/llvm-project?rev=194701&view=rev >> http://llvm.org/viewvc/llvm-project?rev=194702&view=rev >> It provides only function-level boolean coverage (i.e. no counters, just >> "visited or not"), >> but is very fast and very simple (no extra sections to the binary file, etc) >> I've tried it for Chrome's content_shell (huge and heavy binary) and the >> overhead >> is negligible at both run-time and shutdown-time. >> >> We'll be evaluating this implementation and collecting usage stats. >> Maybe we want to implement something simple like this in the Clang coverage. >> >> --kcc >> >>
I’m waiting to see if this fixes the buildbots. Unfortunately, because they were failing all day, there are a bunch of other regressions that have come up, and I’m still working through them. It takes quite a while to run a bootstrapped LTO clang build, so it will take a while longer. I don’t have any other useful information at this point, and I share your puzzlement about how your changes could possibly break the compiler. My only hypothesis is some sort of memory corruption. I will keep you posted. On Nov 14, 2013, at 9:22 PM, Kostya Serebryany <kcc at google.com> wrote:> Also, when are you planing to "reapply the changes or help debug"? > > On Fri, Nov 15, 2013 at 9:15 AM, Kostya Serebryany <kcc at google.com> wrote: >> On Fri, Nov 15, 2013 at 7:26 AM, Bob Wilson <bob.wilson at apple.com> wrote: >>> Hi Kostya, >>> >>> Thanks for the heads-up on this. I haven’t had a chance to look into the >>> details yet, but it looks like these patches may be breaking our >>> bootstrapped LTO build. Our buildbots have been failing all day, and we’re >>> still trying to figure out the problem. I’m going to speculatively revert >>> those changes, since they were the only patches on the buildbot blame list. >>> I will either reapply the changes or help debug the problem. >> >> How could this possibly affect your LTO build? >> The option is off by default. >> Do you have any details, logs, etc? >> >>> >>> —Bob >>> >>> On Nov 14, 2013, at 5:42 AM, Kostya Serebryany <kcc at google.com> wrote: >>> >>> Bob, Justin, >>> >>> I've just committed a poor man's coverage implementation that works with >>> asan. >>> http://llvm.org/viewvc/llvm-project?rev=194701&view=rev >>> http://llvm.org/viewvc/llvm-project?rev=194702&view=rev >>> It provides only function-level boolean coverage (i.e. no counters, just >>> "visited or not"), >>> but is very fast and very simple (no extra sections to the binary file, etc) >>> I've tried it for Chrome's content_shell (huge and heavy binary) and the >>> overhead >>> is negligible at both run-time and shutdown-time. >>> >>> We'll be evaluating this implementation and collecting usage stats. >>> Maybe we want to implement something simple like this in the Clang coverage. >>> >>> --kcc >>> >>>