https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108738
--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:6010189923908501ca5b02bd1f4aee05d2283118 commit r13-6439-g6010189923908501ca5b02bd1f4aee05d2283118 Author: Richard Biener <rguent...@suse.de> Date: Thu Mar 2 13:43:51 2023 +0100 target/108738 - limit STV chain discovery The following puts a hard limit on the inherently quadratic STV chain discovery. Without a limit for the compiler.i testcase in PR26854 we see at -O2 machine dep reorg : 574.45 ( 53%) with release checking while with the proposed limit it's machine dep reorg : 2.86 ( 1%) PR target/108738 * config/i386/i386.opt (--param x86-stv-max-visits): New param. * doc/invoke.texi (--param x86-stv-max-visits): Document it. * config/i386/i386-features.h (scalar_chain::max_visits): New. (scalar_chain::build): Add bitmap parameter, return boolean. (scalar_chain::add_insn): Likewise. (scalar_chain::analyze_register_chain): Likewise. * config/i386/i386-features.cc (scalar_chain::scalar_chain): Initialize max_visits. (scalar_chain::analyze_register_chain): When we exhaust max_visits, abort. Also abort when running into any disallowed insn. (scalar_chain::add_insn): Propagate abort. (scalar_chain::build): Likewise. When aborting amend the set of disallowed insn with the insns set. (convert_scalars_to_vector): Adjust. Do not convert aborted chains.
