gcc -O3 -fopt-info-missed=missed.all
outputs missed optimization report from all the passes into missed.all.
As another example,
gcc -O3 -fopt-info-inline-optimized-missed=inline.txt
will output information about missed optimizations as well as optimized locations from all the inlining passes into inline.txt.
If the filename is provided, then the dumps from all the applicable optimizations are concatenated into the filename. Otherwise the dump is output onto stderr. If options is omitted, it defaults to all-all, which means dump all available optimization info from all the passes. In the following example, all optimization info is output on to stderr.
gcc -O3 -fopt-info
Note that -fopt-info-vec-missed behaves the same as -fopt-info-missed-vec.
As another example, consider
gcc -fopt-info-vec-missed=vec.miss -fopt-info-loop-optimized=loop.opt
Here the two output file names vec.miss and loop.opt are in conflict since only one output file is allowed. In this case, only the first option takes effect and the subsequent options are ignored. Thus only the vec.miss is produced which containts dumps from the vectorizer about missed opportunities.