mapleFU commented on code in PR #15022:
URL: https://github.com/apache/arrow/pull/15022#discussion_r1104026087
##########
cpp/cmake_modules/SetupCxxFlags.cmake:
##########
@@ -604,76 +604,42 @@ endif()
# For all builds:
# For CMAKE_BUILD_TYPE=Debug
# -ggdb: Enable gdb debugging
-# For CMAKE_BUILD_TYPE=FastDebug
-# Same as Debug, except with some optimizations on.
# For CMAKE_BUILD_TYPE=Release
-# -O2: Enable all compiler optimizations
+# -O2 (not -O3): Enable compiler optimizations
# Debug symbols are stripped for reduced binary size.
# For CMAKE_BUILD_TYPE=RelWithDebInfo
# Same as Release, except with debug symbols enabled.
if(NOT MSVC)
- string(REPLACE "-O3" "" CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}")
- string(REPLACE "-O3" "" CMAKE_CXX_FLAGS_RELWITHDEBINFO
- "${CMAKE_CXX_FLAGS_RELWITHDEBINFO}")
-
- set(RELEASE_FLAGS "-O2 -DNDEBUG")
+ set(C_RELEASE_FLAGS "")
+ if(CMAKE_C_FLAGS_RELEASE MATCHES "-O3")
+ string(APPEND C_RELEASE_FLAGS " -O2")
Review Comment:
Thanks, the code and comment here is clear. I just want to make clear why we
we O2, because when compiling I found the argument is "-O3 -NDEBUG -O2", which
make me confused.
I'll try some benchmark under x86, if I got benefits when enabling O3, I'd
like to add a flag here.
##########
cpp/cmake_modules/SetupCxxFlags.cmake:
##########
@@ -604,76 +604,42 @@ endif()
# For all builds:
# For CMAKE_BUILD_TYPE=Debug
# -ggdb: Enable gdb debugging
-# For CMAKE_BUILD_TYPE=FastDebug
-# Same as Debug, except with some optimizations on.
# For CMAKE_BUILD_TYPE=Release
-# -O2: Enable all compiler optimizations
+# -O2 (not -O3): Enable compiler optimizations
# Debug symbols are stripped for reduced binary size.
# For CMAKE_BUILD_TYPE=RelWithDebInfo
# Same as Release, except with debug symbols enabled.
if(NOT MSVC)
- string(REPLACE "-O3" "" CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}")
- string(REPLACE "-O3" "" CMAKE_CXX_FLAGS_RELWITHDEBINFO
- "${CMAKE_CXX_FLAGS_RELWITHDEBINFO}")
-
- set(RELEASE_FLAGS "-O2 -DNDEBUG")
+ set(C_RELEASE_FLAGS "")
+ if(CMAKE_C_FLAGS_RELEASE MATCHES "-O3")
+ string(APPEND C_RELEASE_FLAGS " -O2")
Review Comment:
Thanks, the code and comment here is clear. I just want to make clear why we
we O2, because when compiling I found the argument is "-O3 -NDEBUG -O2", which
makes me confused.
I'll try some benchmark under x86, if I got benefits when enabling O3, I'd
like to add a flag here.
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