Qt5 has predefined optimization flags depending if you're building for
size, for debug etc. These flags are defined in
mkspecs/common/gcc-base.conf:
QMAKE_CFLAGS_OPTIMIZE = -O2
QMAKE_CFLAGS_OPTIMIZE_FULL = -O3
QMAKE_CFLAGS_OPTIMIZE_DEBUG = -Og
QMAKE_CFLAGS_OPTIMIZE_SIZE = -Os
Then, in common/features/default_post.prf, they add those flags to
QMAKE_CFLAGS_RELEASE/QMAKE_CXXFLAGS_RELEASE depending on various build
options (optimize_size, optimize_full, optimize_debug):
optimize_size {
!isEmpty(QMAKE_CFLAGS_OPTIMIZE):!isEmpty(QMAKE_CFLAGS_OPTIMIZE_SIZE) {
QMAKE_CFLAGS_RELEASE -= $$QMAKE_CFLAGS_OPTIMIZE
QMAKE_CXXFLAGS_RELEASE -= $$QMAKE_CFLAGS_OPTIMIZE
QMAKE_CFLAGS_RELEASE += $$QMAKE_CFLAGS_OPTIMIZE_SIZE
QMAKE_CXXFLAGS_RELEASE += $$QMAKE_CFLAGS_OPTIMIZE_SIZE
}
} else: optimize_full {
!isEmpty(QMAKE_CFLAGS_OPTIMIZE):!isEmpty(QMAKE_CFLAGS_OPTIMIZE_FULL) {
QMAKE_CFLAGS_RELEASE -= $$QMAKE_CFLAGS_OPTIMIZE
QMAKE_CXXFLAGS_RELEASE -= $$QMAKE_CFLAGS_OPTIMIZE
QMAKE_CFLAGS_RELEASE += $$QMAKE_CFLAGS_OPTIMIZE_FULL
QMAKE_CXXFLAGS_RELEASE += $$QMAKE_CFLAGS_OPTIMIZE_FULL
}
}
Since this default_post.prf is included *after* our qmake.conf file,
these flags override our optimizations flags, which is not good.
However, our qmake.conf file is included *after* gcc-base.conf, so we
can simply reset those variables to have the empty value, and our
optimization flags will be used.
Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
[Thomas: completely change the approach, by simply resetting the
QMAKE_CFLAGS_OPTIMIZE_* variables in qmake.conf]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
# modifications to gcc-base.conf
QMAKE_CFLAGS += $${BR_COMPILER_CFLAGS}
QMAKE_CXXFLAGS += $${BR_COMPILER_CXXFLAGS}
+QMAKE_CFLAGS_OPTIMIZE =
+QMAKE_CFLAGS_OPTIMIZE_DEBUG =
+QMAKE_CFLAGS_OPTIMIZE_FULL =
+QMAKE_CFLAGS_OPTIMIZE_SIZE =
CONFIG += nostrip
QMAKE_LIBS += -lrt -lpthread -ldl