Re: [PATCH, rs6000 8/9] enable gimple folding for vec_xl, vec_xst

[Richard Biener <richard dot guenther at gmail dot com>]

On Thu, May 31, 2018 at 9:59 PM Will Schmidt <will_schmidt@vnet.ibm.com> wrote:
>
> Hi,
>   Add support for gimple folding for unaligned vector loads and stores.
> testcases posted separately in this thread.
>
> Regtest completed across variety of systems, P6,P7,P8,P9.
>
> OK for trunk?
> Thanks,
> -Will
>
> [gcc]
>
> 2018-05-31 Will Schmidt <will_schmidt@vnet.ibm.com>
>
>         * config/rs6000/rs6000.c: (rs6000_builtin_valid_without_lhs) Add vec_xst
>         variants to the list.  (rs6000_gimple_fold_builtin) Add support for
>         folding unaligned vector loads and stores.
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index d62abdf..54b7de2 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -15360,10 +15360,16 @@ rs6000_builtin_valid_without_lhs (enum rs6000_builtins fn_code)
>      case ALTIVEC_BUILTIN_STVX_V8HI:
>      case ALTIVEC_BUILTIN_STVX_V4SI:
>      case ALTIVEC_BUILTIN_STVX_V4SF:
>      case ALTIVEC_BUILTIN_STVX_V2DI:
>      case ALTIVEC_BUILTIN_STVX_V2DF:
> +    case VSX_BUILTIN_STXVW4X_V16QI:
> +    case VSX_BUILTIN_STXVW4X_V8HI:
> +    case VSX_BUILTIN_STXVW4X_V4SF:
> +    case VSX_BUILTIN_STXVW4X_V4SI:
> +    case VSX_BUILTIN_STXVD2X_V2DF:
> +    case VSX_BUILTIN_STXVD2X_V2DI:
>        return true;
>      default:
>        return false;
>      }
>  }
> @@ -15869,10 +15875,77 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
>         gimple_set_location (g, loc);
>         gsi_replace (gsi, g, true);
>         return true;
>        }
>
> +    /* unaligned Vector loads.  */
> +    case VSX_BUILTIN_LXVW4X_V16QI:
> +    case VSX_BUILTIN_LXVW4X_V8HI:
> +    case VSX_BUILTIN_LXVW4X_V4SF:
> +    case VSX_BUILTIN_LXVW4X_V4SI:
> +    case VSX_BUILTIN_LXVD2X_V2DF:
> +    case VSX_BUILTIN_LXVD2X_V2DI:
> +      {
> +        arg0 = gimple_call_arg (stmt, 0);  // offset
> +        arg1 = gimple_call_arg (stmt, 1);  // address
> +        lhs = gimple_call_lhs (stmt);
> +        location_t loc = gimple_location (stmt);
> +        /* Since arg1 may be cast to a different type, just use ptr_type_node
> +           here instead of trying to enforce TBAA on pointer types.  */
> +        tree arg1_type = ptr_type_node;
> +        tree lhs_type = TREE_TYPE (lhs);
> +        /* POINTER_PLUS_EXPR wants the offset to be of type 'sizetype'.  Create
> +           the tree using the value from arg0.  The resulting type will match
> +           the type of arg1.  */
> +        gimple_seq stmts = NULL;
> +        tree temp_offset = gimple_convert (&stmts, loc, sizetype, arg0);
> +        tree temp_addr = gimple_build (&stmts, loc, POINTER_PLUS_EXPR,
> +                                      arg1_type, arg1, temp_offset);
> +        gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
> +        /* Use the build2 helper to set up the mem_ref.  The MEM_REF could also
> +           take an offset, but since we've already incorporated the offset
> +           above, here we just pass in a zero.  */
> +        gimple *g;
> +        g = gimple_build_assign (lhs, build2 (MEM_REF, lhs_type, temp_addr,
> +                                               build_int_cst (arg1_type, 0)));

So in GIMPLE the type of the MEM_REF specifies the alignment so my question
is what type does the lhs usually have here?  I'd simply guess V4SF, etc.?  In
this case you are missing a

  tree ltype = build_aligned_type (lhs_type, desired-alignment);

and use that ltype for building the MEM_REF.  I suppose in this case the known
alignment is either BITS_PER_UNIT or element alignment (thus
TYPE_ALIGN (TREE_TYPE (lhs_type)))?

Or is the type of the load the element types?

Richard.

> +        gimple_set_location (g, loc);
> +        gsi_replace (gsi, g, true);
> +        return true;
> +      }
> +
> +    /* unaligned Vector stores.  */
> +    case VSX_BUILTIN_STXVW4X_V16QI:
> +    case VSX_BUILTIN_STXVW4X_V8HI:
> +    case VSX_BUILTIN_STXVW4X_V4SF:
> +    case VSX_BUILTIN_STXVW4X_V4SI:
> +    case VSX_BUILTIN_STXVD2X_V2DF:
> +    case VSX_BUILTIN_STXVD2X_V2DI:
> +      {
> +        arg0 = gimple_call_arg (stmt, 0); /* Value to be stored.  */
> +        arg1 = gimple_call_arg (stmt, 1); /* Offset.  */
> +        tree arg2 = gimple_call_arg (stmt, 2); /* Store-to address.  */
> +        location_t loc = gimple_location (stmt);
> +        tree arg0_type = TREE_TYPE (arg0);
> +        /* Use ptr_type_node (no TBAA) for the arg2_type.  */
> +        tree arg2_type = ptr_type_node;
> +        /* POINTER_PLUS_EXPR wants the offset to be of type 'sizetype'.  Create
> +           the tree using the value from arg0.  The resulting type will match
> +           the type of arg2.  */
> +        gimple_seq stmts = NULL;
> +        tree temp_offset = gimple_convert (&stmts, loc, sizetype, arg1);
> +        tree temp_addr = gimple_build (&stmts, loc, POINTER_PLUS_EXPR,
> +                                      arg2_type, arg2, temp_offset);
> +        /* Mask off any lower bits from the address.  */
> +        gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
> +        gimple *g;
> +        g = gimple_build_assign (build2 (MEM_REF, arg0_type, temp_addr,
> +                                          build_int_cst (arg2_type, 0)), arg0);
> +        gimple_set_location (g, loc);
> +        gsi_replace (gsi, g, true);
> +        return true;
> +      }
> +
>      /* Vector Fused multiply-add (fma).  */
>      case ALTIVEC_BUILTIN_VMADDFP:
>      case VSX_BUILTIN_XVMADDDP:
>      case ALTIVEC_BUILTIN_VMLADDUHM:
>        {
>
>