-O3 is passed even for CMAKE_BUILD_TYPE=Debug

Question

-O3 is passed even for CMAKE_BUILD_TYPE=Debug

danlipsa opened this issue a year ago · comments

Dan Lipsa commented a year ago

Both -g and -O3 are passed for debug build. That makes debugging difficult.

Dan Lipsa · Answer 1 · Tue Sep 05 2023 23:16:35 GMT+0800 (China Standard Time)

@burlen Any ideas here? Thanks!

Burlen Loring · Answer 2 · Wed Sep 06 2023 02:31:14 GMT+0800 (China Standard Time)

When configuring SENSEI for Debug build -O3 is not present.

However, note that if you first configure SENSEI for a Release build, then later try to change to a Debug build, you will need to start fresh or modify your CMakeCache.txt manually since CMake will not reconfigure cached variables including CXX_FLAGS. This is not a bug in SENSEI but rather a feature of CMake.

Burlen Loring · Answer 3 · Wed Sep 06 2023 02:33:11 GMT+0800 (China Standard Time)

Here are how the flags are set for a Debug build:

$ rm -rfI ./*; cmake -DCMAKE_BUILD_TYPE=Debug ..; grep CXX_FLAGS CMakeCache.txt
...
CMAKE_CXX_FLAGS:STRING=-fPIC -std=c++17 -Wall -Wextra -fvisibility=hidden
CMAKE_CXX_FLAGS_DEBUG:STRING=-g
CMAKE_CXX_FLAGS_MINSIZEREL:STRING=-Os -DNDEBUG
CMAKE_CXX_FLAGS_RELEASE:STRING=-O3 -DNDEBUG
CMAKE_CXX_FLAGS_RELWITHDEBINFO:STRING=-O2 -g -DNDEBUG

Burlen Loring · Answer 4 · Wed Sep 06 2023 02:49:43 GMT+0800 (China Standard Time)

After looking at our code, it may be the case that we could move the optimization related flags from CXX_FLAGS to CXX_FLAGS_RELEASE making the reconfigure unnecessary.