On Mon, Oct 31, 2022 at 1:00 PM Tamar Christina via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi All,
>
> This patch series is to add recognition of pairwise operations (reductions)
> in match.pd such that we can benefit from them even at -O1 when the vectorizer
> isn't enabled.
>
> Ths use of these allow for a lot simpler codegen in AArch64 and allows us to
> avoid quite a lot of codegen warts.
>
> As an example a simple:
>
> typedef float v4sf __attribute__((vector_size (16)));
>
> float
> foo3 (v4sf x)
> {
> return x[1] + x[2];
> }
>
> currently generates:
>
> foo3:
> dup s1, v0.s[1]
> dup s0, v0.s[2]
> fadd s0, s1, s0
> ret
>
> while with this patch series now generates:
>
> foo3:
> ext v0.16b, v0.16b, v0.16b, #4
> faddp s0, v0.2s
> ret
>
> This patch will not perform the operation if the source is not a gimple
> register and leaves memory sources to the vectorizer as it's able to deal
> correctly with clobbers.
But the vectorizer should also be able to cope with the above. I don't think
we want to do this as part of general folding. Iff, then this belongs
in specific
points of the pass pipeline, no?
> The use of these instruction makes a significant difference in codegen quality
> for AArch64 and Arm.
>
> NOTE: The last entry in the series contains tests for all of the previous
> patches as it's a bit of an all or nothing thing.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
> and no issues.
>
> Ok for master?
>
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> * match.pd (adjacent_data_access_p): Import.
> Add new pattern for bitwise plus, min, max, fmax, fmin.
> * tree-cfg.cc (verify_gimple_call): Allow function arguments in IFNs.
> * tree.cc (adjacent_data_access_p): New.
> * tree.h (adjacent_data_access_p): New.
>
> --- inline copy of patch --
> diff --git a/gcc/match.pd b/gcc/match.pd
> index
> 2617d56091dfbd41ae49f980ee0af3757f5ec1cf..aecaa3520b36e770d11ea9a10eb18db23c0cd9f7
> 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -39,7 +39,8 @@ along with GCC; see the file COPYING3. If not see
> HONOR_NANS
> uniform_vector_p
> expand_vec_cmp_expr_p
> - bitmask_inv_cst_vector_p)
> + bitmask_inv_cst_vector_p
> + adjacent_data_access_p)
>
> /* Operator lists. */
> (define_operator_list tcc_comparison
> @@ -7195,6 +7196,47 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>
> /* Canonicalizations of BIT_FIELD_REFs. */
>
> +/* Canonicalize BIT_FIELD_REFS to pairwise operations. */
> +(for op (plus min max FMIN_ALL FMAX_ALL)
> + ifn (IFN_REDUC_PLUS IFN_REDUC_MIN IFN_REDUC_MAX
> + IFN_REDUC_FMIN IFN_REDUC_FMAX)
> + (simplify
> + (op @0 @1)
> + (if (INTEGRAL_TYPE_P (type) || SCALAR_FLOAT_TYPE_P (type))
> + (with { poly_uint64 nloc = 0;
> + tree src = adjacent_data_access_p (@0, @1, &nloc, true);
> + tree ntype = build_vector_type (type, 2);
> + tree size = TYPE_SIZE (ntype);
> + tree pos = build_int_cst (TREE_TYPE (size), nloc);
> + poly_uint64 _sz;
> + poly_uint64 _total; }
> + (if (src && is_gimple_reg (src) && ntype
> + && poly_int_tree_p (size, &_sz)
> + && poly_int_tree_p (TYPE_SIZE (TREE_TYPE (src)), &_total)
> + && known_ge (_total, _sz + nloc))
> + (ifn (BIT_FIELD_REF:ntype { src; } { size; } { pos; })))))))
> +
> +(for op (lt gt)
> + ifni (IFN_REDUC_MIN IFN_REDUC_MAX)
> + ifnf (IFN_REDUC_FMIN IFN_REDUC_FMAX)
> + (simplify
> + (cond (op @0 @1) @0 @1)
> + (if (INTEGRAL_TYPE_P (type) || SCALAR_FLOAT_TYPE_P (type))
> + (with { poly_uint64 nloc = 0;
> + tree src = adjacent_data_access_p (@0, @1, &nloc, false);
> + tree ntype = build_vector_type (type, 2);
> + tree size = TYPE_SIZE (ntype);
> + tree pos = build_int_cst (TREE_TYPE (size), nloc);
> + poly_uint64 _sz;
> + poly_uint64 _total; }
> + (if (src && is_gimple_reg (src) && ntype
> + && poly_int_tree_p (size, &_sz)
> + && poly_int_tree_p (TYPE_SIZE (TREE_TYPE (src)), &_total)
> + && known_ge (_total, _sz + nloc))
> + (if (SCALAR_FLOAT_MODE_P (TYPE_MODE (type)))
> + (ifnf (BIT_FIELD_REF:ntype { src; } { size; } { pos; }))
> + (ifni (BIT_FIELD_REF:ntype { src; } { size; } { pos; }))))))))
> +
> (simplify
> (BIT_FIELD_REF (BIT_FIELD_REF @0 @1 @2) @3 @4)
> (BIT_FIELD_REF @0 @3 { const_binop (PLUS_EXPR, bitsizetype, @2, @4); }))
> diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
> index
> 91ec33c80a41e1e0cc6224e137dd42144724a168..b19710392940cf469de52d006603ae1e3deb6b76
> 100644
> --- a/gcc/tree-cfg.cc
> +++ b/gcc/tree-cfg.cc
> @@ -3492,6 +3492,7 @@ verify_gimple_call (gcall *stmt)
> {
> tree arg = gimple_call_arg (stmt, i);
> if ((is_gimple_reg_type (TREE_TYPE (arg))
> + && !is_gimple_variable (arg)
> && !is_gimple_val (arg))
> || (!is_gimple_reg_type (TREE_TYPE (arg))
> && !is_gimple_lvalue (arg)))
> diff --git a/gcc/tree.h b/gcc/tree.h
> index
> e6564aaccb7b69cd938ff60b6121aec41b7e8a59..8f8a9660c9e0605eb516de194640b8c1b531b798
> 100644
> --- a/gcc/tree.h
> +++ b/gcc/tree.h
> @@ -5006,6 +5006,11 @@ extern bool integer_pow2p (const_tree);
>
> extern tree bitmask_inv_cst_vector_p (tree);
>
> +/* TRUE if the two operands represent adjacent access of data such that a
> + pairwise operation can be used. */
> +
> +extern tree adjacent_data_access_p (tree, tree, poly_uint64*, bool);
> +
> /* integer_nonzerop (tree x) is nonzero if X is an integer constant
> with a nonzero value. */
>
> diff --git a/gcc/tree.cc b/gcc/tree.cc
> index
> 007c9325b17076f474e6681c49966c59cf6b91c7..5315af38a1ead89ca5f75dc4b19de9841e29d311
> 100644
> --- a/gcc/tree.cc
> +++ b/gcc/tree.cc
> @@ -10457,6 +10457,90 @@ bitmask_inv_cst_vector_p (tree t)
> return builder.build ();
> }
>
> +/* Returns base address if the two operands represent adjacent access of data
> + such that a pairwise operation can be used. OP1 must be a lower subpart
> + than OP2. If POS is not NULL then on return if a value is returned POS
> + will indicate the position of the lower address. If COMMUTATIVE_P then
> + the operation is also tried by flipping op1 and op2. */
> +
> +tree adjacent_data_access_p (tree op1, tree op2, poly_uint64 *pos,
> + bool commutative_p)
> +{
> + gcc_assert (op1);
> + gcc_assert (op2);
> + if (TREE_CODE (op1) != TREE_CODE (op2)
> + || TREE_TYPE (op1) != TREE_TYPE (op2))
> + return NULL;
> +
> + tree type = TREE_TYPE (op1);
> + gimple *stmt1 = NULL, *stmt2 = NULL;
> + unsigned int bits = GET_MODE_BITSIZE (GET_MODE_INNER (TYPE_MODE (type)));
> +
> + if (TREE_CODE (op1) == BIT_FIELD_REF
> + && operand_equal_p (TREE_OPERAND (op1, 0), TREE_OPERAND (op2, 0), 0)
> + && operand_equal_p (TREE_OPERAND (op1, 1), TREE_OPERAND (op2, 1), 0)
> + && known_eq (bit_field_size (op1), bits))
> + {
> + poly_uint64 offset1 = bit_field_offset (op1);
> + poly_uint64 offset2 = bit_field_offset (op2);
> + if (known_eq (offset2 - offset1, bits))
> + {
> + if (pos)
> + *pos = offset1;
> + return TREE_OPERAND (op1, 0);
> + }
> + else if (commutative_p && known_eq (offset1 - offset2, bits))
> + {
> + if (pos)
> + *pos = offset2;
> + return TREE_OPERAND (op1, 0);
> + }
> + }
> + else if (TREE_CODE (op1) == ARRAY_REF
> + && operand_equal_p (get_base_address (op1), get_base_address
> (op2)))
> + {
> + wide_int size1 = wi::to_wide (array_ref_element_size (op1));
> + wide_int size2 = wi::to_wide (array_ref_element_size (op2));
> + if (wi::ne_p (size1, size2) || wi::ne_p (size1, bits / 8)
> + || !tree_fits_poly_uint64_p (TREE_OPERAND (op1, 1))
> + || !tree_fits_poly_uint64_p (TREE_OPERAND (op2, 1)))
> + return NULL;
> +
> + poly_uint64 offset1 = tree_to_poly_uint64 (TREE_OPERAND (op1, 1));
> + poly_uint64 offset2 = tree_to_poly_uint64 (TREE_OPERAND (op2, 1));
> + if (known_eq (offset2 - offset1, 1UL))
> + {
> + if (pos)
> + *pos = offset1 * bits;
> + return TREE_OPERAND (op1, 0);
> + }
> + else if (commutative_p && known_eq (offset1 - offset2, 1UL))
> + {
> + if (pos)
> + *pos = offset2 * bits;
> + return TREE_OPERAND (op1, 0);
> + }
> + }
> + else if (TREE_CODE (op1) == SSA_NAME
> + && (stmt1 = SSA_NAME_DEF_STMT (op1)) != NULL
> + && (stmt2 = SSA_NAME_DEF_STMT (op2)) != NULL
> + && is_gimple_assign (stmt1)
> + && is_gimple_assign (stmt2))
> + {
> + if (gimple_assign_rhs_code (stmt1) != ARRAY_REF
> + && gimple_assign_rhs_code (stmt1) != BIT_FIELD_REF
> + && gimple_assign_rhs_code (stmt2) != ARRAY_REF
> + && gimple_assign_rhs_code (stmt2) != BIT_FIELD_REF)
> + return NULL;
> +
> + return adjacent_data_access_p (gimple_assign_rhs1 (stmt1),
> + gimple_assign_rhs1 (stmt2), pos,
> + commutative_p);
> + }
> +
> + return NULL;
> +}
> +
> /* If VECTOR_CST T has a single nonzero element, return the index of that
> element, otherwise return -1. */
>
>
>
>
>
> --
