IMPALA-11110: Switch debug builds to use -Og

GCC's -Og applies optimizations that are compatible with
being debuggable. It is similar to -O1 and results
in a modest speed-up. This modifies the default debug
build to use -Og, so it is now more akin to a fastdebug
mode.

Even though -Og is intended to preserve debuggability,
optimization always impacts debuggability and -Og is
no exception. To enable the old behavior, this adds
a DEBUG_NOOPT build mode that retains the old
non-optimized behavior. Using the -debug_noopt flag
with buildall.sh enables this behavior.

Change-Id: Ie06c149c8181c90572b8668bd01dfd26c0a5971e
Reviewed-on: http://gerrit.cloudera.org:8080/18200
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Reviewed-by: Laszlo Gaal (Cloudera) <laszlo.gaal@cloudera.com>
Reviewed-by: Csaba Ringhofer <csringhofer@cloudera.com>

be/CMakeLists.txt

@@ -96,7 +96,8 @@ SET(CXX_CLANG_FLAGS "${CXX_CLANG_FLAGS} -DCALLONCEHACK")
 #   -gdwarf-4: Set the appropriate DWARF version. Later versions of DWARF have better
 #    support for newer C++ language features and better compression, but require newer
 #    versions of GDB. DWARF 4 requires GDB 7.0 or above.
-SET(CXX_GCC_FLAGS "-g -Wno-unused-local-typedefs -gdwarf-4")
+#   -Wno-maybe-unitialized: Do not warn for variables that might be uninitialized
+SET(CXX_GCC_FLAGS "-g -Wno-unused-local-typedefs -gdwarf-4 -Wno-maybe-uninitialized")
 if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 7.0)
   # We need to add additional arguments for GCC 7+. We go down this branch if building
   # with a non-GCC compiler of version 7+, but in that case CXX_GCC_FLAGS is not used,
@@ -109,15 +110,23 @@ if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 7.0)
 endif()
 
 # compiler flags for different build types (run 'cmake -DCMAKE_BUILD_TYPE=<type> .')
-# For CMAKE_BUILD_TYPE=Debug
+# For CMAKE_BUILD_TYPE=DEBUG_NOOPT
 #   -ggdb: Enable gdb debugging
+# For CMAKE_BUILD_TYPE=Debug
+#   (Same as CMAKE_BUILD_TYPE=DEBUG_NOOPT) +
+#   -Og: Enable basic optimizations
 # For CMAKE_BUILD_TYPE=Release
 #   -O3: Enable all compiler optimizations
 #   -DNDEBUG: Turn off dchecks/asserts/debug only code.
-SET(CXX_FLAGS_DEBUG "${CXX_GCC_FLAGS} -ggdb")
+SET(CXX_FLAGS_DEBUG_NOOPT "${CXX_GCC_FLAGS} -ggdb")
 # -Werror: compile warnings should be errors when using the toolchain compiler.
 #   Enabled for DEBUG, ASAN, TSAN and UBSAN builds which are built pre-commit.
-SET(CXX_FLAGS_DEBUG "${CXX_FLAGS_DEBUG} -Werror")
+SET(CXX_FLAGS_DEBUG_NOOPT "${CXX_FLAGS_DEBUG_NOOPT} -Werror")
+# The legacy debug mode built without optimizations, as optimizations can interfere with
+# debuggability. The DEBUG_NOOPT mode maintains this old behavior, while the default
+# Debug mode now applies basic optimizations (-Og) to speed up test runs.
+SET(CXX_FLAGS_DEBUG "${CXX_FLAGS_DEBUG_NOOPT} -Og")
+
 SET(CXX_FLAGS_RELEASE "${CXX_GCC_FLAGS} -O3 -DNDEBUG")
 SET(CXX_FLAGS_ADDRESS_SANITIZER
   "${CXX_CLANG_FLAGS} -Werror -O1 -g -fsanitize=address -fno-omit-frame-pointer -DADDRESS_SANITIZER")
@@ -165,6 +174,8 @@ SET(CXX_FLAGS_TIDY "${CXX_FLAGS_TIDY} -fno-color-diagnostics")
 # Set compile flags based on the build type.
 if ("${CMAKE_BUILD_TYPE}" STREQUAL "DEBUG")
   SET(CMAKE_CXX_FLAGS ${CXX_FLAGS_DEBUG})
+elseif ("${CMAKE_BUILD_TYPE}" STREQUAL "DEBUG_NOOPT")
+  SET(CMAKE_CXX_FLAGS ${CXX_FLAGS_DEBUG_NOOPT})
 elseif ("${CMAKE_BUILD_TYPE}" STREQUAL "RELEASE")
   SET(CMAKE_CXX_FLAGS ${CXX_FLAGS_RELEASE})
 elseif ("${CMAKE_BUILD_TYPE}" STREQUAL "ADDRESS_SANITIZER")

buildall.sh

@@ -75,6 +75,7 @@ BUILD_UBSAN=0
 BUILD_UBSAN_FULL=0
 BUILD_TSAN=0
 BUILD_TSAN_FULL=0
+BUILD_DEBUG_NOOPT=0
 BUILD_SHARED_LIBS=0
 # Export MAKE_CMD so it is visible in scripts that invoke make, e.g. copy-udfs-udas.sh
 export MAKE_CMD=make
@@ -148,6 +149,9 @@ do
     -full_tsan)
       BUILD_TSAN_FULL=1
       ;;
+    -debug_noopt)
+      BUILD_DEBUG_NOOPT=1
+      ;;
     -testpairwise)
       EXPLORATION_STRATEGY=pairwise
       ;;
@@ -226,6 +230,10 @@ do
       echo "[-full_ubsan] : Undefined behavior sanitizer build, including code generated"\
            "by cross-compilation to LLVM IR. Much slower queries than plain -ubsan"\
            "[Default: False]"
+      echo "[-debug_noopt] : Debug build without optimizations applied. The regular"\
+           "debug build applies basic optimizations, but even these optimizations may"\
+           "impact debuggability, so this is an option to omit the optimizations."\
+           "[Default: False]"
       echo "[-skiptests] : Skips execution of all tests"
       echo "[-notests] : Skips building and execution of all tests"
       echo "[-start_minicluster] : Start test cluster including Impala and all"\
@@ -325,6 +333,10 @@ if [[ ${BUILD_TSAN_FULL} -eq 1 ]]; then
   CMAKE_BUILD_TYPE_LIST+=(TSAN_FULL)
   export TSAN_FULL=1
 fi
+if [[ ${BUILD_DEBUG_NOOPT} -eq 1 ]]; then
+  CMAKE_BUILD_TYPE_LIST+=(DEBUG_NOOPT)
+  export DEBUG_NOOPT=1
+fi
 if [[ -n "${CMAKE_BUILD_TYPE_LIST:+1}" ]]; then
   if [[ ${#CMAKE_BUILD_TYPE_LIST[@]} -gt 1 ]]; then
     echo "ERROR: more than one CMake build type defined: ${CMAKE_BUILD_TYPE_LIST[@]}"