The patch for this was committed to trunk as 267562 (see below). Is this also ok for backport to 8?
Thanks, Aaron On 12/20/18 5:44 PM, Segher Boessenkool wrote: > On Thu, Dec 20, 2018 at 05:34:54PM -0600, Aaron Sawdey wrote: >> On 12/20/18 3:51 AM, Segher Boessenkool wrote: >>> On Wed, Dec 19, 2018 at 01:53:05PM -0600, Aaron Sawdey wrote: >>>> Because of POWER9 dd2.1 issues with certain unaligned vsx instructions >>>> to cache inhibited memory, here is a patch that keeps memmove (and memcpy) >>>> inline expansion from doing unaligned vector or using vector load/store >>>> other than lvx/stvx. More description of the issue is here: >>>> >>>> https://patchwork.ozlabs.org/patch/814059/ >>>> >>>> OK for trunk if bootstrap/regtest ok? >>> >>> Okay, but see below. >>> >> [snip] >>> >>> This is extraordinarily clumsy :-) Maybe something like: >>> >>> static rtx >>> gen_lvx_v4si_move (rtx dest, rtx src) >>> { >>> gcc_assert (!(MEM_P (dest) && MEM_P (src)); >>> gcc_assert (GET_MODE (dest) == V4SImode && GET_MODE (src) == V4SImode); >>> if (MEM_P (dest)) >>> return gen_altivec_stvx_v4si_internal (dest, src); >>> else if (MEM_P (src)) >>> return gen_altivec_lvx_v4si_internal (dest, src); >>> else >>> gcc_unreachable (); >>> } >>> >>> (Or do you allow VOIDmode for src as well?) Anyway, at least get rid of >>> the useless extra variable. >> >> I think this should be better: > > The gcc_unreachable at the end catches the non-mem to non-mem case. > >> static rtx >> gen_lvx_v4si_move (rtx dest, rtx src) >> { >> gcc_assert ((MEM_P (dest) && !MEM_P (src)) || (MEM_P (src) && >> !MEM_P(dest))); > > But if you prefer this, how about > > { > gcc_assert (MEM_P (dest) ^ MEM_P (src)); > gcc_assert (GET_MODE (dest) == V4SImode && GET_MODE (src) == V4SImode); > > if (MEM_P (dest)) > return gen_altivec_stvx_v4si_internal (dest, src); > else > return gen_altivec_lvx_v4si_internal (dest, src); > } > > :-) > > > Segher > 2019-01-03 Aaron Sawdey <acsaw...@linux.ibm.com> * config/rs6000/rs6000-string.c (expand_block_move): Don't use unaligned vsx and avoid lxvd2x/stxvd2x. (gen_lvx_v4si_move): New function. Index: gcc/config/rs6000/rs6000-string.c =================================================================== --- gcc/config/rs6000/rs6000-string.c (revision 267299) +++ gcc/config/rs6000/rs6000-string.c (working copy) @@ -2669,6 +2669,25 @@ return true; } +/* Generate loads and stores for a move of v4si mode using lvx/stvx. + This uses altivec_{l,st}vx_<mode>_internal which use unspecs to + keep combine from changing what instruction gets used. + + DEST is the destination for the data. + SRC is the source of the data for the move. */ + +static rtx +gen_lvx_v4si_move (rtx dest, rtx src) +{ + gcc_assert (MEM_P (dest) ^ MEM_P (src)); + gcc_assert (GET_MODE (dest) == V4SImode && GET_MODE (src) == V4SImode); + + if (MEM_P (dest)) + return gen_altivec_stvx_v4si_internal (dest, src); + else + return gen_altivec_lvx_v4si_internal (dest, src); +} + /* Expand a block move operation, and return 1 if successful. Return 0 if we should let the compiler generate normal code. @@ -2721,11 +2740,11 @@ /* Altivec first, since it will be faster than a string move when it applies, and usually not significantly larger. */ - if (TARGET_ALTIVEC && bytes >= 16 && (TARGET_EFFICIENT_UNALIGNED_VSX || align >= 128)) + if (TARGET_ALTIVEC && bytes >= 16 && align >= 128) { move_bytes = 16; mode = V4SImode; - gen_func.mov = gen_movv4si; + gen_func.mov = gen_lvx_v4si_move; } else if (bytes >= 8 && TARGET_POWERPC64 && (align >= 64 || !STRICT_ALIGNMENT)) -- Aaron Sawdey, Ph.D. acsaw...@linux.vnet.ibm.com 050-2/C113 (507) 253-7520 home: 507/263-0782 IBM Linux Technology Center - PPC Toolchain