GCC的参数-ftree-vectorizer-verbose=n

This option controls the amount of debugging output the vectorizer prints. This information is written to standard error, unless ‘-fdump-tree-all’ or ‘-fdump-tree-vect’ is specified, in which case it is output to the usual dump listing file, ‘.vect’.

For n=0 no diagnostic information is reported.

If n=1the vectorizer reports each loop that got vectorized, and the total number of loops that got vectorized.

If n=2 the vectorizer also reports non-vectorized loops that passed the first analysis phase (vect analyze loop form) - i.e. countable,inner-most, single-bb, single-entry/exit loops. This is the same verbosity level that ‘-fdump-tree-vect-stats’ uses. Higher verbosity levels mean either more information dumped for each reported loop, or same amount of informationreported for more loops:

if n=3, vectorizer cost model informationis reported.

If n=4, alignment related information is added to the reports.

If n=5, data-references related information (e.g. memory dependences, memory access-patterns) is added to the reports.

If n=6, the vectorizer reports also nonvectorized inner-most loops that did not pass the first analysis phase (i.e., may not be countable, or may have complicated control-flow).

If n=7, the vectorizer reports also non-vectorized nested loops.

If n=8, SLP related information is added to the reports.

For n=9, all the information the vectorizer generates during its analysis and transformation is reported. This is the same verbosity level that ‘-fdump-tree-vect-details’ uses.