I would start by looking at https://reviews.llvm.org/D32598, which adds a bunch of work we do up-front. I remember looking at this a while back and not being sure whether all of that work is relevant for osx, actually. (I'm specifically thinking of the SymbolFileDWARF::Index call, which is done unconditionally, but I think that index is unused if we have accelerator tables).
On Mon, 12 Mar 2018 at 21:59, Adrian Prantl via lldb-dev < lldb-dev@lists.llvm.org> wrote: > If this is a Mac I would recommend to build both lldbs in RelWithDebInfo > mode and then run them through Instruments and compare the traces. I'd be > very interested in learning what the cause for the slowdown is. > > -- adrian > > > On Mar 12, 2018, at 2:57 PM, Timothee Cour <timothee.co...@gmail.com> > wrote: > > > > after further inspection it turns out it's a performance regression > > between llvm 5 and llvm 6: > > > > $homebrew_D/Cellar/llvm/5.0.1/lldb -s test_lldb.txt -- prog > > 8 seconds > > $homebrew_D/Cellar/llvm/6.0.0/bin/lldb -s test_lldb.txt -- prog > > 40 seconds > > > > cat test_lldb.txt: > > ``` > > b FOO > > r > > bt > > q > > ``` > > > > prog is some binary I'm debugging. It's unfortunately hard to reduce. > > What are good ways to investigate this? > > > > > > > > On Mon, Mar 12, 2018 at 1:42 PM, Adrian Prantl <apra...@apple.com> > wrote: > >> Have you tried diff'ing your cmake invocation against the on used by > homebrew? > >> > >> -- adrian > >> > >>> On Mar 9, 2018, at 12:59 AM, Timothee Cour via lldb-dev < > lldb-dev@lists.llvm.org> wrote: > >>> > >>> while testing out https://github.com/llvm-mirror/lldb/pull/3 I noticed > >>> that when I compiled lldb from source (even un-modified from git HEAD) > >>> it was 5X slower than homebrew lldb or default lldb: > >>> > >>> I'm compiling lldb as follows: > >>> ``` > >>> git clone https://github.com/llvm-mirror/llvm.git > >>> cd llvm/tools > >>> git clone https://github.com/llvm-mirror/lldb > >>> ## also, patch in https://github.com/llvm-mirror/lldb/pull/3 > >>> git clone https://github.com/llvm-mirror/clang > >>> cd .. > >>> mkdir build > >>> cd build > >>> ccmake .. -G Ninja > >>> # here I set: CMAKE_BUILD_TYPE Release > >>> ninja all > >>> ``` > >>> > >>> I also tried setting `LLVM_ENABLE_ASSERTIONS OFF` but no difference > >>> > >>> > >>> commands.txt > >>> ``` > >>> b FOO > >>> r > >>> bt > >>> q > >>> ``` > >>> > >>> ./test is some program i have. > >>> > >>> ``` > >>> time lldb -s commands.txt -- ./test > >>> 8 seconds > >>> time ./build/bin/lldb -s commands.txt -- ./test > >>> 40 seconds > >>> ``` > >>> _______________________________________________ > >>> lldb-dev mailing list > >>> lldb-dev@lists.llvm.org > >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev > >> > > _______________________________________________ > lldb-dev mailing list > lldb-dev@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev >
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