Moore, Catherine <catherine_mo...@mentor.com> writes > Hi Matthew, > > > -----Original Message----- > > From: Matthew Fortune [mailto:matthew.fort...@imgtec.com] > > Sent: Tuesday, January 06, 2015 7:43 AM > > To: Moore, Catherine > > Cc: 'gcc-patches@gcc.gnu.org' (gcc-patches@gcc.gnu.org) > > Subject: [MIPS] Update the ZC constraint for MIPSR6 and use it > > > > Update the ZC constraint for MIPSR6 to allow it to be used as the > > memory operand for implementations of atomic operations. Also switch > > the internal implementation of atomic operations to use ZC instead of > ZR. > > > > This fix accurately describes the memory constraints for the LL and SC > > instructions. An offset can therefore be used to access a data item > > (ie. %lo (<var>)) rather than always having to load the address into a > > register. Tested for mips32r2, mips32r6 and micromips. > > > > gcc/ > > > > * config/mips/constraints.md (ZC): Add support for R6 LL/SC > > offsets. > > (ZD): Update to use ISA_HAS_PREF_LL_SC_9BIT. > > * config/mips/mips.h (ISA_HAS_PREFETCH_9BIT): Rename to... > > (ISA_HAS_PREF_LL_SC_9BIT): ... this. New macro. > > * config/mips/sync.md (sync_compare_and_swap<mode>): Use ZC > > instead of ZR for the memory operand of LL/SC. > > (compare_and_swap_12, sync_add<mode>): Likewise. > > (sync_<optab>_12, sync_old_<optab>_12): Likewise. > > (sync_new_<optab>_12, sync_nand_12): Likewise. > > (sync_old_nand_12, sync_new_nand_12): Likewise. > > (sync_sub<mode>, sync_old_add<mode>): Likewise. > > (sync_old_sub<mode>, sync_new_add<mode>): Likewise. > > (sync_new_sub<mode>, sync_<optab><mode>): Likewise. > > (sync_old_<optab><mode>, sync_new_<optab><mode>"): > > Likewise. > > (sync_nand<mode>, sync_old_nand<mode>): Likewise. > > (sync_new_nand<mode>, sync_lock_test_and_set<mode>): > > Likewise. > > (test_and_set_12, atomic_compare_and_swap<mode>): Likewise. > > (atomic_exchange<mode>_llsc, atomic_fetch_add<mode>_llsc): > > Likewise. > > * doc/md.texi (ZC): Update description. > > > > OK to commit? > > > > diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h index > > 9dad480..b608b17 100644 > > --- a/gcc/config/mips/mips.h > > +++ b/gcc/config/mips/mips.h > > @@ -1089,8 +1089,8 @@ struct mips_cpu_info { > > || mips_isa_rev >= 1) \ > > && !TARGET_MIPS16) > > > > -/* ISA has data prefetch with limited 9-bit displacement. */ > > -#define ISA_HAS_PREFETCH_9BIT (mips_isa_rev >= 6) > > +/* ISA has data prefetch, LL and SC with limited 9-bit displacement. > */ > > +#define ISA_HAS_PREF_LL_SC_9BIT (mips_isa_rev >= 6) > > > I'd like to see this described as something more general. Say: > ISA_HAS_9BIT_DISPLACEMENT. This patch is okay with that fixup.
I think I'm OK with changing that but it does leave us with a different issue of knowing which subset of instructions should check for 9-bit displacement. I.e. not all instructions only have a 9-bit displacement. A GCC 6 thing would be to look over all the ISA_HAS macros and perhaps do some general improvement in the framework we have there. I don't know exactly what I'd do but something a bit more table based seems sensible. Matthew
