[Mesa-dev] [PATCH mesa v2] nouveau: codegen: combineLd/St do not combine indirect loads

[Ilia Mirkin]

Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>

On Fri, Apr 22, 2016 at 7:07 AM, Hans de Goede <hdegoede at redhat.com> wrote:
> combineLd/St would combine, i.e. :
>
> st  u32 # g[$r2+0x0] $r2
> st  u32 # g[$r2+0x4] $r3
>
> into:
>
> st  u64 # g[$r2+0x0] $r2d
>
> But this is only valid if r2 contains an 8 byte aligned address,
> which is not guaranteed for compute shaders
>
> This commit checks for src0 dim 0 not being indirect when combining
> loads / stores as combining indirect loads / stores may break alignment
> rules.
>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---
> Changes in v2:
> -Only check for indirect loads/stores in the compute case
> ---
>  src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> index 6ec5fa5..9ce062e 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> @@ -2216,6 +2216,9 @@ MemoryOpt::combineLd(Record *rec, Instruction *ld)
>     if (((size == 0x8) && (MIN2(offLd, offRc) & 0x7)) ||
>         ((size == 0xc) && (MIN2(offLd, offRc) & 0xf)))
>        return false;
> +   // for compute indirect loads are not guaranteed to be aligned
> +   if (prog->getType() == Program::TYPE_COMPUTE && rec->rel[0])
> +      return false;
>
>     assert(sizeRc + sizeLd <= 16 && offRc != offLd);
>
> @@ -2268,8 +2271,12 @@ MemoryOpt::combineSt(Record *rec, Instruction *st)
>     if (!prog->getTarget()->
>         isAccessSupported(st->getSrc(0)->reg.file, typeOfSize(size)))
>        return false;
> +   // no unaligned stores
>     if (size == 8 && MIN2(offRc, offSt) & 0x7)
>        return false;
> +   // for compute indirect stores are not guaranteed to be aligned
> +   if (prog->getType() == Program::TYPE_COMPUTE && rec->rel[0])
> +      return false;
>
>     st->takeExtraSources(0, extra); // save predicate and indirect address
>
> --
> 2.7.3
>