Hi, I am trying to get information about various flags that are enabled/disabled at each optimization levels. I am using gcc-5.1 compiler and for getting flag information, I used the command "gcc -Q (-O0 or -O1 or -O2 or -O3 or -Ofast) --help=optimizers". --CUT-- [root@udp03279771uds result]# gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/root/work/GCC_Team/apawar/install/gcc0501/libexec/gcc/x86_64-unknown-linux-gnu/5.1.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../../gcc-5.1.0/configure --enable-bootstrap --enable-languages=all --prefix=/root/work/GCC_Team/apawar/install/gcc0501 Thread model: posix gcc version 5.1.0 (GCC) [root@udp03279771uds result]# gcc -Q -Ofast --help=optimizers | grep lrs -ftree-lrs [disabled] [root@udp03279771uds result]# gcc -Q -Ofast --help=optimizers | grep vectori -ftree-loop-vectorize [enabled] -ftree-slp-vectorize [enabled] -ftree-vectorize [disabled] [root@udp03279771uds result]# gcc -Q -O3 --help=optimizers | grep fvar\-tracking -fvar-tracking [enabled] -fvar-tracking-assignments [enabled] -fvar-tracking-assignments-toggle [disabled] -fvar-tracking-uninit [disabled] --CUT-- Can someone please clarify the following questions: 1. -fvar-tracking-uninit, -free-lrs are shown as disabled. I searched in "gcc" internals and not able to find any description about these options. Please help me how to find the information about these. 2. -ftree-vectorize is shown as disabled in O3 and Ofast. Should this be updated as enabled? Regards, Amit
