> This patch adds a workaround to the Sparc backend for the LEON3FT > store-store errata. It is enabled when using the -mfix-ut699, > -mfix-ut700, or -mfix-gr712rc flag.
Let's forget -mfix-gr712rc for now, -mfix-ut700 is enough I think. > The workaround inserts NOP instructions to prevent the following two > instruction sequences from being generated: > > std -> stb/sth/st/std > stb/sth/st -> any single non-store/load instruction -> stb/sth/st/std > > The __FIX_B2BST define can be used to only enable workarounds in assembly > code when the flag is used. I'm not thrilled with this, it's undocumented, the other workaround don't have it and I don't think that we really need it. > See GRLIB-TN-0009, "LEON3FT Stale Cache Entry After Store with Data Tag > Parity Error", for more information. > > gcc/ChangeLog: > > 2017-06-21 Daniel Cederman <ceder...@gaisler.com> > > * config/sparc/sparc.c (sparc_do_work_around_errata): Insert NOP > instructions to prevent sequences that can trigger the store-store > errata for certain LEON3FT processors. > (sparc_option_override): -mfix-ut699, -mfix-ut700, and > -mfix-gr712rc enables the errata workaround. > * config/sparc/sparc-c.c (sparc_target_macros): Define __FIX_B2BST > when errata workaround is enabled. > * config/sparc/sparc.md: Prevent stores in delay slot. > * config/sparc/sparc.opt: Add -mfix-ut700 and -mfix-gr712rc flag. > * doc/invoke.texi: Document -mfix-ut700 and -mfix-gr712rc flag. OK for mainline and 7 branch modulo the above two remarks. -- Eric Botcazou
