[lldb-dev] lldb compiled from source 5X slower than homebrew or default lldb
Timothee Cour via lldb-dev
lldb-dev at lists.llvm.org
Mon Mar 12 14:57:19 PDT 2018
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
$homebrew_D/Cellar/llvm/6.0.0/bin/lldb -s test_lldb.txt -- prog
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 <aprantl at 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 at 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
>> b FOO
>> ./test is some program i have.
>> time lldb -s commands.txt -- ./test
>> 8 seconds
>> time ./build/bin/lldb -s commands.txt -- ./test
>> 40 seconds
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