On Wed, 24 Mar 2021, Stam Markianos-Wright wrote: > Hi all, > > This patch resolves bug: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96974 > > This is achieved by forcing a re-calculation of *stmt_vectype_out if an > incompatible combination of TYPE_VECTOR_SUBPARTS is detected, but with an > extra introduced max_nunits ceiling. > > I am not 100% sure if this is the best way to go about fixing this, because > this is my first look at the vectorizer and I lack knowledge of the wider > context, so do let me know if you see a better way to do this! > > I have added the previously ICE-ing reproducer as a new test. > > This is compiled as "g++ -Ofast -march=armv8.2-a+sve -fdisable-tree-fre4" for > GCC11 and "g++ -Ofast -march=armv8.2-a+sve" for GCC10. > > (the non-fdisable-tree-fre4 version has gone latent on GCC11) > > Bootstrapped and reg-tested on aarch64-linux-gnu. > Also reg-tested on aarch64-none-elf.
I don't think this is going to work well given uses will expect a vector type that's consistent here. I think giving up is for the moment the best choice, thus replacing the assert with vectorization failure. In the end we shouldn't require those nunits vectypes to be separately computed - we compute the vector type of the defs anyway and in case they're invariant the vectorizable_* function either can deal with the type mix or not anyway. That said, the goal should be to simplify things here. Richard. > > gcc/ChangeLog: > > * tree-vect-stmts.c (get_vectype_for_scalar_type): Add new > parameter to core function and add new function overload. > (vect_get_vector_types_for_stmt): Add re-calculation logic. > > gcc/testsuite/ChangeLog: > > * g++.target/aarch64/sve/pr96974.C: New test. > -- Richard Biener <rguent...@suse.de> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
