Sorry for the slow response.
Tamar Christina <tamar.christ...@arm.com> writes:
> […]
> diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
> index
> 441d6cd28c4eaded7abd756164890dbcffd2f3b8..82123b96313e6783ea214b9259805d65c07d8858
> 100644
> --- a/gcc/tree-vect-patterns.c
> +++ b/gcc/tree-vect-patterns.c
> @@ -201,7 +201,8 @@ vect_get_external_def_edge (vec_info *vinfo, tree var)
> static bool
> vect_supportable_direct_optab_p (vec_info *vinfo, tree otype, tree_code code,
> tree itype, tree *vecotype_out,
> - tree *vecitype_out = NULL)
> + tree *vecitype_out = NULL,
> + enum optab_subtype subtype = optab_default)
> {
> tree vecitype = get_vectype_for_scalar_type (vinfo, itype);
> if (!vecitype)
> @@ -211,7 +212,7 @@ vect_supportable_direct_optab_p (vec_info *vinfo, tree
> otype, tree_code code,
> if (!vecotype)
> return false;
>
> - optab optab = optab_for_tree_code (code, vecitype, optab_default);
> + optab optab = optab_for_tree_code (code, vecitype, subtype);
> if (!optab)
> return false;
>
> @@ -487,10 +488,14 @@ vect_joust_widened_integer (tree type, bool shift_p,
> tree op,
> }
>
> /* Return true if the common supertype of NEW_TYPE and *COMMON_TYPE
> - is narrower than type, storing the supertype in *COMMON_TYPE if so. */
> + is narrower than type, storing the supertype in *COMMON_TYPE if so.
> + If UNPROM_TYPE then accept that *COMMON_TYPE and NEW_TYPE may be of
> + different signs but equal precision and that the resulting
> + multiplication of them be compatible with UNPROM_TYPE. */
>
> static bool
> -vect_joust_widened_type (tree type, tree new_type, tree *common_type)
> +vect_joust_widened_type (tree type, tree new_type, tree *common_type,
> + tree unprom_type = NULL)
> {
> if (types_compatible_p (*common_type, new_type))
> return true;
> @@ -514,7 +519,18 @@ vect_joust_widened_type (tree type, tree new_type, tree
> *common_type)
> unsigned int precision = MAX (TYPE_PRECISION (*common_type),
> TYPE_PRECISION (new_type));
> precision *= 2;
> - if (precision * 2 > TYPE_PRECISION (type))
> +
> + /* Check if the mismatch is only in the sign and if we have
> + UNPROM_TYPE then allow it if there is enough precision to
> + not lose any information during the conversion. */
> + if (unprom_type
> + && TYPE_SIGN (unprom_type) == SIGNED
> + && tree_nop_conversion_p (*common_type, new_type))
> + return true;
> +
> + /* The resulting application is unsigned, check if we have enough
> + precision to perform the operation. */
> + if (precision * 2 > TYPE_PRECISION (unprom_type ? unprom_type : type))
> return false;
>
> *common_type = build_nonstandard_integer_type (precision, false);
> @@ -532,6 +548,10 @@ vect_joust_widened_type (tree type, tree new_type, tree
> *common_type)
> to a type that (a) is narrower than the result of STMT_INFO and
> (b) can hold all leaf operand values.
>
> + If UNPROM_TYPE then allow that the signs of the operands
> + may differ in signs but not in precision and that the resulting type
> + of the operation on the operands is compatible with UNPROM_TYPE.
> +
> Return 0 if STMT_INFO isn't such a tree, or if no such COMMON_TYPE
> exists. */
>
> @@ -539,7 +559,8 @@ static unsigned int
> vect_widened_op_tree (vec_info *vinfo, stmt_vec_info stmt_info, tree_code
> code,
> tree_code widened_code, bool shift_p,
> unsigned int max_nops,
> - vect_unpromoted_value *unprom, tree *common_type)
> + vect_unpromoted_value *unprom, tree *common_type,
> + tree unprom_type = NULL)
> {
> /* Check for an integer operation with the right code. */
> gassign *assign = dyn_cast <gassign *> (stmt_info->stmt);
> @@ -600,7 +621,8 @@ vect_widened_op_tree (vec_info *vinfo, stmt_vec_info
> stmt_info, tree_code code,
> = vinfo->lookup_def (this_unprom->op);
> nops = vect_widened_op_tree (vinfo, def_stmt_info, code,
> widened_code, shift_p, max_nops,
> - this_unprom, common_type);
> + this_unprom, common_type,
> + unprom_type);
> if (nops == 0)
> return 0;
>
> @@ -617,7 +639,7 @@ vect_widened_op_tree (vec_info *vinfo, stmt_vec_info
> stmt_info, tree_code code,
> if (i == 0)
> *common_type = this_unprom->type;
> else if (!vect_joust_widened_type (type, this_unprom->type,
> - common_type))
> + common_type, unprom_type))
> return 0;
> }
> }
> @@ -799,12 +821,15 @@ vect_convert_input (vec_info *vinfo, stmt_vec_info
> stmt_info, tree type,
> }
>
> /* Invoke vect_convert_input for N elements of UNPROM and store the
> - result in the corresponding elements of RESULT. */
> + result in the corresponding elements of RESULT.
> +
> + If ALLOW_SHORT_SIGN_MISMATCH then don't convert the types if they only
> + differ by sign. */
>
> static void
> vect_convert_inputs (vec_info *vinfo, stmt_vec_info stmt_info, unsigned int
> n,
> tree *result, tree type, vect_unpromoted_value *unprom,
> - tree vectype)
> + tree vectype, bool allow_short_sign_mismatch = false)
> {
> for (unsigned int i = 0; i < n; ++i)
> {
> @@ -812,8 +837,12 @@ vect_convert_inputs (vec_info *vinfo, stmt_vec_info
> stmt_info, unsigned int n,
> for (j = 0; j < i; ++j)
> if (unprom[j].op == unprom[i].op)
> break;
> +
> if (j < i)
> result[i] = result[j];
> + else if (allow_short_sign_mismatch
> + && tree_nop_conversion_p (type, unprom[i].type))
> + result[i] = unprom[i].op;
> else
> result[i] = vect_convert_input (vinfo, stmt_info,
> type, &unprom[i], vectype);
> @@ -888,21 +917,24 @@ vect_reassociating_reduction_p (vec_info *vinfo,
>
> Try to find the following pattern:
>
> - type x_t, y_t;
> + type1a x_t
> + type1b y_t;
> TYPE1 prod;
> TYPE2 sum = init;
> loop:
> sum_0 = phi <init, sum_1>
> S1 x_t = ...
> S2 y_t = ...
> - S3 x_T = (TYPE1) x_t;
> - S4 y_T = (TYPE1) y_t;
> + S3 x_T = (TYPE3) x_t;
> + S4 y_T = (TYPE4) y_t;
> S5 prod = x_T * y_T;
> [S6 prod = (TYPE2) prod; #optional]
> S7 sum_1 = prod + sum_0;
>
> - where 'TYPE1' is exactly double the size of type 'type', and 'TYPE2' is
> the
> - same size of 'TYPE1' or bigger. This is a special case of a reduction
> + where 'TYPE1' is exactly double the size of type 'type1a' and 'type1b',
> + the sign of 'TYPE1' must be one of 'type1a' or 'type1b' but the sign of
> + 'type1a' and 'type1b' can differ. 'TYPE2' is the same size of 'TYPE1' or
> + bigger and must be the same sign. This is a special case of a reduction
> computation.
What are TYPE3 and TYPE4 in the above? AFAICT the x_T and y_T casts
should still be to TYPE1, since the types of x_T and y_T need to agree.
The sign of TYPE2 shouldn't matter, since TYPE2 is only used for
the addition.
> @@ -939,15 +971,16 @@ vect_recog_dot_prod_pattern (vec_info *vinfo,
>
> /* Look for the following pattern
> DX = (TYPE1) X;
> - DY = (TYPE1) Y;
> + DY = (TYPE2) Y;
> DPROD = DX * DY;
> - DDPROD = (TYPE2) DPROD;
> + DDPROD = (TYPE3) DPROD;
> sum_1 = DDPROD + sum_0;
> In which
> - DX is double the size of X
> - DY is double the size of Y
> - DX, DY, DPROD all have the same type but the sign
> - between DX, DY and DPROD can differ.
> + between DX, DY and DPROD can differ. The sign of DPROD
> + is one of the signs of DX or DY.
> - sum is the same size of DPROD or bigger
> - sum has been recognized as a reduction variable.
These changes don't look right: DY has to be the same type as DX.
(What's different with usdot is that X and Y can be different signs.)
> @@ -986,20 +1019,29 @@ vect_recog_dot_prod_pattern (vec_info *vinfo,
> inside the loop (in case we are analyzing an outer-loop). */
> vect_unpromoted_value unprom0[2];
> if (!vect_widened_op_tree (vinfo, mult_vinfo, MULT_EXPR, WIDEN_MULT_EXPR,
> - false, 2, unprom0, &half_type))
> + false, 2, unprom0, &half_type,
> + TREE_TYPE (unprom_mult.op)))
> return NULL;
>
> + /* Check to see if there is a sign change happening in the operands of the
> + multiplication and pick the appropriate optab subtype. */
> + enum optab_subtype subtype;
> + if (TYPE_SIGN (unprom0[0].type) == TYPE_SIGN (unprom0[1].type))
> + subtype = optab_default;
> + else
> + subtype = optab_vector_mixed_sign;
> +
Doesn't this check the signs of the uncast operands? What really matters
is how things stand after the result of the (possible) casts to half_type.
E.g.:
signed short x;
unsigned char y;
int z;
z = (int) x * (int) y + z;
is an sdot operation with half_type signed short, rather than a usdot
operation.
How about instead passing a optab_subtype* to vect_widened_op_tree, in
place of the unprom_mult.op type? When this optab_subtype* is nonnull,
the joust operation is allowed to fail as long as:
tree_nop_conversion_p (this_unprom->type, common_type)
is true. vect_widened_op_tree would set the optab_subtype to
optab_vector_mixed_sign to indicate this case.
We should make sure that we handle:
unsigned short x;
signed char y;
int z;
z = (int) x * (int) y + z;
correctly though: this should be a usdot operation in which y
is cast to signed short. I'm not sure whether the patch would
insert the needed cast.
Thanks,
Richard
> vect_pattern_detected ("vect_recog_dot_prod_pattern", last_stmt);
>
> tree half_vectype;
> if (!vect_supportable_direct_optab_p (vinfo, type, DOT_PROD_EXPR,
> half_type,
> - type_out, &half_vectype))
> + type_out, &half_vectype, subtype))
> return NULL;
>
> /* Get the inputs in the appropriate types. */
> tree mult_oprnd[2];
> vect_convert_inputs (vinfo, stmt_vinfo, 2, mult_oprnd, half_type,
> - unprom0, half_vectype);
> + unprom0, half_vectype, true);
>
> var = vect_recog_temp_ssa_var (type, NULL);
> pattern_stmt = gimple_build_assign (var, DOT_PROD_EXPR,
