Robin Dapp <rd...@linux.ibm.com> writes:
> Hi Kewen, Richard,
>
> thanks for the comments, I addressed them in the attached v4.
Sorry again for the slow review. I only have some very minor
comments left:
> Bootstrap and regtest are good as before.
>
> Regards
> Robin
>
> diff --git a/gcc/config/rs6000/vsx.md b/gcc/config/rs6000/vsx.md
> index bf033e31c1c..dc2756f83e9 100644
> --- a/gcc/config/rs6000/vsx.md
> +++ b/gcc/config/rs6000/vsx.md
> @@ -5637,7 +5637,8 @@
> (define_expand "len_load_v16qi"
> [(match_operand:V16QI 0 "vlogical_operand")
> (match_operand:V16QI 1 "memory_operand")
> - (match_operand:QI 2 "gpc_reg_operand")]
> + (match_operand:QI 2 "gpc_reg_operand")
> + (match_operand:QI 3 "zero_constant")]
> "TARGET_P9_VECTOR && TARGET_64BIT"
> {
> rtx mem = XEXP (operands[1], 0);
> @@ -5651,6 +5652,7 @@
> [(match_operand:V16QI 0 "memory_operand")
> (match_operand:V16QI 1 "vlogical_operand")
> (match_operand:QI 2 "gpc_reg_operand")
> + (match_operand:QI 3 "zero_constant")
> ]
> "TARGET_P9_VECTOR && TARGET_64BIT"
> {
> diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
> index 2b41cb7fb7b..8df61f578bd 100644
> --- a/gcc/doc/md.texi
> +++ b/gcc/doc/md.texi
> @@ -5213,7 +5213,10 @@ which must be a vector mode. Operand 2 has whichever
> integer mode the
> target prefers. If operand 2 exceeds the number of elements in mode
> @var{m}, the behavior is undefined. If the target prefers the length
> to be measured in bytes rather than elements, it should only implement
> -this pattern for vectors of @code{QI} elements.
> +this pattern for vectors of @code{QI} elements. Operand 3 specifies
> +a bias predicate that determines whether a length of zero is permitted
> +or not. If permitted, the predicate should only allow a zero immediate,
> +otherwise it should only allow an immediate value of -1.
I think it would be better to fold this into the existing documentation
a bit more:
--------------------------------------------------------------------------
Load (operand 2 - operand 3) elements from vector memory operand 1 into
vector register operand 0, setting the other elements of operand 0 to
undefined values. Operands 0 and 1 have mode @var{m}, which must be a
vector mode. Operand 2 has whichever integer mode the target prefers.
Operand 3 conceptually has mode @code{QI}.
Operand 2 can be a variable or a constant amount. Operand 3 specifies
a constant bias: it is either a constant 0 or a constant -1. The predicate
on operand 3 must only accept the bias values that the target actually
supports. GCC handles a bias of 0 more efficiently than a bias of -1.
If (operand 2 - operand 3) exceeds the number of elements in mode @var{m},
the behavior is undefined.
If the target prefers the length to be measured in bytes rather than
elements, it should only implement this pattern for vectors of @code{QI}
elements.
--------------------------------------------------------------------------
> @@ -5226,7 +5229,10 @@ a vector mode. Operand 2 has whichever integer mode
> the target prefers.
> If operand 2 exceeds the number of elements in mode @var{m}, the behavior
> is undefined. If the target prefers the length to be measured in bytes
> rather than elements, it should only implement this pattern for vectors
> -of @code{QI} elements.
> +of @code{QI} elements. Operand 3 specifies a bias predicate that
> +determines whether a length of zero is permitted or not. If permitted,
> +the predicate should only allow a zero constant, otherwise it should
> +only allow an immediate value of -1.
>
> This pattern is not allowed to @code{FAIL}.
Similarly here I think we should say:
--------------------------------------------------------------------------
Store (operand 2 - operand 3) vector elements from vector register
operand 1 into memory operand 0, leaving the other elements of operand 0
unchanged. Operands 0 and 1 have mode @var{m}, which must be a vector mode.
Operand 2 has whichever integer mode the target prefers. Operand 3
conceptually has mode @code{QI}.
Operand 2 can be a variable or a constant amount. Operand 3 specifies
a constant bias: it is either a constant 0 or a constant -1. The predicate
on operand 3 must only accept the bias values that the target actually
supports. GCC handles a bias of 0 more efficiently than a bias of -1.
If (operand 2 - operand 3) exceeds the number of elements in mode @var{m},
the behavior is undefined.
If the target prefers the length to be measured in bytes rather than
elements, it should only implement this pattern for vectors of @code{QI}
elements.
--------------------------------------------------------------------------
> diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
> index 8312d08aab2..d45f080c06f 100644
> --- a/gcc/internal-fn.c
> +++ b/gcc/internal-fn.c
> @@ -2696,9 +2696,9 @@ expand_call_mem_ref (tree type, gcall *stmt, int index)
> static void
> expand_partial_load_optab_fn (internal_fn, gcall *stmt, convert_optab optab)
> {
> - class expand_operand ops[3];
> - tree type, lhs, rhs, maskt;
> - rtx mem, target, mask;
> + class expand_operand ops[4];
> + tree type, lhs, rhs, maskt, biast;
> + rtx mem, target, mask, bias;
> insn_code icode;
>
> maskt = gimple_call_arg (stmt, 2);
> @@ -2723,11 +2723,20 @@ expand_partial_load_optab_fn (internal_fn, gcall
> *stmt, convert_optab optab)
> create_output_operand (&ops[0], target, TYPE_MODE (type));
> create_fixed_operand (&ops[1], mem);
> if (optab == len_load_optab)
> - create_convert_operand_from (&ops[2], mask, TYPE_MODE (TREE_TYPE
> (maskt)),
> - TYPE_UNSIGNED (TREE_TYPE (maskt)));
> + {
> + create_convert_operand_from (&ops[2], mask, TYPE_MODE (TREE_TYPE
> (maskt)),
> + TYPE_UNSIGNED (TREE_TYPE (maskt)));
> + biast = gimple_call_arg (stmt, 3);
> + bias = expand_normal (biast);
> + create_input_operand (&ops[3], bias, QImode);
> + expand_insn (icode, 4, ops);
> + }
> else
> + {
> create_input_operand (&ops[2], mask, TYPE_MODE (TREE_TYPE (maskt)));
> - expand_insn (icode, 3, ops);
> + expand_insn (icode, 3, ops);
> + }
> +
Formatting nit: the “else” body should be indented like the “then” body.
> if (!rtx_equal_p (target, ops[0].value))
> emit_move_insn (target, ops[0].value);
> }
> @@ -2741,9 +2750,9 @@ expand_partial_load_optab_fn (internal_fn, gcall *stmt,
> convert_optab optab)
> static void
> expand_partial_store_optab_fn (internal_fn, gcall *stmt, convert_optab optab)
> {
> - class expand_operand ops[3];
> - tree type, lhs, rhs, maskt;
> - rtx mem, reg, mask;
> + class expand_operand ops[4];
> + tree type, lhs, rhs, maskt, biast;
> + rtx mem, reg, mask, bias;
> insn_code icode;
>
> maskt = gimple_call_arg (stmt, 2);
> @@ -2766,11 +2775,19 @@ expand_partial_store_optab_fn (internal_fn, gcall
> *stmt, convert_optab optab)
> create_fixed_operand (&ops[0], mem);
> create_input_operand (&ops[1], reg, TYPE_MODE (type));
> if (optab == len_store_optab)
> - create_convert_operand_from (&ops[2], mask, TYPE_MODE (TREE_TYPE
> (maskt)),
> - TYPE_UNSIGNED (TREE_TYPE (maskt)));
> + {
> + create_convert_operand_from (&ops[2], mask, TYPE_MODE (TREE_TYPE
> (maskt)),
> + TYPE_UNSIGNED (TREE_TYPE (maskt)));
> + biast = gimple_call_arg (stmt, 4);
> + bias = expand_normal (biast);
> + create_input_operand (&ops[3], bias, QImode);
> + expand_insn (icode, 4, ops);
> + }
> else
> - create_input_operand (&ops[2], mask, TYPE_MODE (TREE_TYPE (maskt)));
> - expand_insn (icode, 3, ops);
> + {
> + create_input_operand (&ops[2], mask, TYPE_MODE (TREE_TYPE (maskt)));
> + expand_insn (icode, 3, ops);
> + }
> }
>
> #define expand_mask_store_optab_fn expand_partial_store_optab_fn
> @@ -4172,6 +4189,29 @@ internal_check_ptrs_fn_supported_p (internal_fn ifn,
> tree type,
> && insn_operand_matches (icode, 4, GEN_INT (align)));
> }
>
> +/* Return the supported bias for the len_load IFN. For now we only support
“for IFN, which is either IFN_LEN_LOAD or IFN_LEN_STORE.”
> + the biases of 0 and -1 (in case 0 is not an allowable length for
> len_load).
…or len_store
> + If none of the biases match what the backend provides, return
> + VECT_PARTIAL_BIAS_UNSUPPORTED. */
> +
> +signed char
> +internal_len_load_store_bias (internal_fn ifn, machine_mode mode)
> +{
> + optab optab = direct_internal_fn_optab (ifn);
> + insn_code icode = direct_optab_handler (optab, mode);
> +
> + if (icode != CODE_FOR_nothing)
> + {
> + /* For now we only support biases of 0 or -1. Try both of them. */
> + if (insn_operand_matches (icode, 3, GEN_INT (0)))
> + return 0;
> + if (insn_operand_matches (icode, 3, GEN_INT (-1)))
> + return -1;
> + }
> +
> + return VECT_PARTIAL_BIAS_UNSUPPORTED;
> +}
> +
> /* Expand STMT as though it were a call to internal function FN. */
>
> void
> diff --git a/gcc/internal-fn.h b/gcc/internal-fn.h
> index 19d0f849a5a..d46aa4ebf33 100644
> --- a/gcc/internal-fn.h
> +++ b/gcc/internal-fn.h
> @@ -227,6 +227,10 @@ extern bool internal_gather_scatter_fn_supported_p
> (internal_fn, tree,
> tree, tree, int);
> extern bool internal_check_ptrs_fn_supported_p (internal_fn, tree,
> poly_uint64, unsigned int);
> +#define VECT_PARTIAL_BIAS_UNSUPPORTED 127
> +
> +extern signed char internal_len_load_store_bias (internal_fn ifn,
> + machine_mode);
>
> extern void expand_addsub_overflow (location_t, tree_code, tree, tree, tree,
> bool, bool, bool, bool, tree *);
> diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
> index a94490373c3..c4a6492b50d 100644
> --- a/gcc/tree-ssa-math-opts.c
> +++ b/gcc/tree-ssa-math-opts.c
> @@ -2723,16 +2723,7 @@ convert_mult_to_widen (gimple *stmt,
> gimple_stmt_iterator *gsi)
> from_unsigned1 = from_unsigned2 = false;
> }
> else
> - {
> - /* Expand can synthesize smul_widen_optab if the target
> - supports umul_widen_optab. */
> - op = umul_widen_optab;
> - handler = find_widening_optab_handler_and_mode (op, to_mode,
> - from_mode,
> - &actual_mode);
> - if (handler == CODE_FOR_nothing)
> - return false;
> - }
> + return false;
This part looks unrelated.
> }
>
> /* Ensure that the inputs to the handler are in the correct precison
> diff --git a/gcc/tree-vect-loop-manip.c b/gcc/tree-vect-loop-manip.c
> index 4988c93fdb6..4fd078d535a 100644
> --- a/gcc/tree-vect-loop-manip.c
> +++ b/gcc/tree-vect-loop-manip.c
> @@ -421,6 +421,7 @@ vect_maybe_permute_loop_masks (gimple_seq *seq,
> rgroup_controls *dest_rgm,
> static tree
> vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo,
> gimple_seq *preheader_seq,
> + gimple_seq *header_seq,
> gimple_stmt_iterator loop_cond_gsi,
> rgroup_controls *rgc, tree niters,
> tree niters_skip, bool might_wrap_p)
> @@ -664,6 +665,19 @@ vect_set_loop_controls_directly (class loop *loop,
> loop_vec_info loop_vinfo,
>
> vect_set_loop_control (loop, ctrl, init_ctrl, next_ctrl);
> }
> +
> + int partial_load_bias = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
> + if (partial_load_bias != 0)
> + {
> + tree adjusted_len = rgc->bias_adjusted_ctrl;
> + gassign *minus = gimple_build_assign (adjusted_len, MINUS_EXPR,
> + rgc->controls[0],
> + build_int_cst
> + (TREE_TYPE (rgc->controls[0]),
> + -partial_load_bias));
It would be more canonical to use PLUS_EXPR and not negate the bias.
MINUS_EXPR of a constant gets converted to PLUS_EXPR of the negative.
> + gimple_seq_add_stmt (header_seq, minus);
> + }
> +
> return next_ctrl;
> }
>
> @@ -744,6 +758,7 @@ vect_set_loop_condition_partial_vectors (class loop *loop,
> /* Set up all controls for this group. */
> test_ctrl = vect_set_loop_controls_directly (loop, loop_vinfo,
> &preheader_seq,
> + &header_seq,
> loop_cond_gsi, rgc,
> niters, niters_skip,
> might_wrap_p);
> diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
> index e94356d76e9..8eb1726b4f5 100644
> --- a/gcc/tree-vect-loop.c
> +++ b/gcc/tree-vect-loop.c
> @@ -1163,6 +1163,31 @@ vect_verify_loop_lens (loop_vec_info loop_vinfo)
> if (LOOP_VINFO_LENS (loop_vinfo).is_empty ())
> return false;
>
> + machine_mode len_load_mode = get_len_load_store_mode
> + (loop_vinfo->vector_mode, true).require ();
> + machine_mode len_store_mode = get_len_load_store_mode
> + (loop_vinfo->vector_mode, false).require ();
> +
> + signed char partial_load_bias = internal_len_load_store_bias
> + (IFN_LEN_LOAD, len_load_mode);
> +
> + signed char partial_store_bias = internal_len_load_store_bias
> + (IFN_LEN_STORE, len_store_mode);
> +
> + gcc_assert (partial_load_bias == partial_store_bias);
> +
> + if (partial_load_bias == VECT_PARTIAL_BIAS_UNSUPPORTED)
> + return false;
> +
> + /* If the backend requires a bias of -1 for LEN_LOAD, we must not emit
> + len_loads with a length of zero. In order to avoid that we prohibit
> + more than one loop length here. */
> + if (partial_load_bias == -1
> + && LOOP_VINFO_LENS (loop_vinfo).length () > 1)
> + return false;
Nit: return is indented two spaces too far.
> +
> + LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo) = partial_load_bias;
> +
> unsigned int max_nitems_per_iter = 1;
> unsigned int i;
> rgroup_controls *rgl;
> @@ -4125,6 +4150,8 @@ vect_estimate_min_profitable_iters (loop_vec_info
> loop_vinfo,
> here. */
>
> bool niters_known_p = LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo);
> + signed char partial_load_store_bias
> + = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
> bool need_iterate_p
> = (!LOOP_VINFO_EPILOGUE_P (loop_vinfo)
> && !vect_known_niters_smaller_than_vf (loop_vinfo));
> @@ -4157,6 +4184,11 @@ vect_estimate_min_profitable_iters (loop_vec_info
> loop_vinfo,
> for each since start index is zero. */
> prologue_stmts += num_vectors;
>
> + /* If we have a non-zero partial load bias, we need one MINUS
Becomes PLUS after the change above.
> + to adjust the load length. */
> + if (partial_load_store_bias != 0)
> + body_stmts += 1;
> +
> /* Each may need two MINs and one MINUS to update lengths in body
> for next iteration. */
> if (need_iterate_p)
> @@ -9226,6 +9258,11 @@ vect_get_loop_len (loop_vec_info loop_vinfo,
> vec_loop_lens *lens,
> {
> rgroup_controls *rgl = &(*lens)[nvectors - 1];
>
> + signed char partial_load_store_bias =
> + LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
> +
> + bool use_bias_adjusted_len = partial_load_store_bias != 0;
> +
> /* Populate the rgroup's len array, if this is the first time we've
> used it. */
> if (rgl->controls.is_empty ())
> @@ -9235,6 +9272,15 @@ vect_get_loop_len (loop_vec_info loop_vinfo,
> vec_loop_lens *lens,
> {
> tree len_type = LOOP_VINFO_RGROUP_COMPARE_TYPE (loop_vinfo);
> gcc_assert (len_type != NULL_TREE);
> +
> + if (i == 0 && use_bias_adjusted_len)
> + {
> + tree adjusted_len =
> + make_temp_ssa_name (len_type, NULL, "adjusted_loop_len");
> + SSA_NAME_DEF_STMT (adjusted_len) = gimple_build_nop ();
> + rgl->bias_adjusted_ctrl = adjusted_len;
> + }
> +
Think it would be better to make it:
if (use_bias_adjusted_len)
{
gcc_assert (i == 0);
But do we need to do this? Code should only care about the final value,
so I didn't think we would need to keep the intermediate unbiased length
alongside the biased one. (Or maybe we do. My memory is a bit rusty,
sorry.)
> tree len = make_temp_ssa_name (len_type, NULL, "loop_len");
>
> /* Provide a dummy definition until the real one is available. */
> @@ -9243,7 +9289,10 @@ vect_get_loop_len (loop_vec_info loop_vinfo,
> vec_loop_lens *lens,
> }
> }
>
> - return rgl->controls[index];
> + if (use_bias_adjusted_len)
> + return rgl->bias_adjusted_ctrl;
> + else
> + return rgl->controls[index];
> }
>
> /* Scale profiling counters by estimation for LOOP which is vectorized
> diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
> index 17849b575b7..006f4c31217 100644
> --- a/gcc/tree-vect-stmts.c
> +++ b/gcc/tree-vect-stmts.c
> @@ -8289,9 +8289,16 @@ vectorizable_store (vec_info *vinfo,
> gsi);
> vec_oprnd = var;
> }
> +
> + /* Check which bias value to use. */
> + signed char biasval = internal_len_load_store_bias
> + (IFN_LEN_STORE, new_vmode);
I think we talked earlier about asserting that the biases agree
with the one chosen by vect_verify_loop_lens.
This is probably going back on an earlier decision, sorry, but I think
we should either do that or (simpler) just use
LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo). We'll then ICE later
if the target doesn't accept the bias.
> +
> + tree bias = build_int_cst (intQI_type_node, biasval);
> gcall *call
> - = gimple_build_call_internal (IFN_LEN_STORE, 4, dataref_ptr,
> - ptr, final_len, vec_oprnd);
> + = gimple_build_call_internal (IFN_LEN_STORE, 5, dataref_ptr,
> + ptr, final_len, vec_oprnd,
> + bias);
> gimple_call_set_nothrow (call, true);
> vect_finish_stmt_generation (vinfo, stmt_info, call, gsi);
> new_stmt = call;
> @@ -9588,22 +9595,30 @@ vectorizable_load (vec_info *vinfo,
> vec_num * j + i);
> tree ptr = build_int_cst (ref_type,
> align * BITS_PER_UNIT);
> +
> + machine_mode vmode = TYPE_MODE (vectype);
> + opt_machine_mode new_ovmode
> + = get_len_load_store_mode (vmode, true);
> + machine_mode new_vmode = new_ovmode.require ();
> + tree qi_type = unsigned_intQI_type_node;
> +
> + /* Check which bias value to use. */
> + signed char biasval = internal_len_load_store_bias
> + (IFN_LEN_LOAD, new_vmode);
Same here.
Thanks,
Richard
> +
> + tree bias = build_int_cst (intQI_type_node, biasval);
> +
> gcall *call
> - = gimple_build_call_internal (IFN_LEN_LOAD, 3,
> + = gimple_build_call_internal (IFN_LEN_LOAD, 4,
> dataref_ptr, ptr,
> - final_len);
> + final_len, bias);
> gimple_call_set_nothrow (call, true);
> new_stmt = call;
> data_ref = NULL_TREE;
>
> /* Need conversion if it's wrapped with VnQI. */
> - machine_mode vmode = TYPE_MODE (vectype);
> - opt_machine_mode new_ovmode
> - = get_len_load_store_mode (vmode, true);
> - machine_mode new_vmode = new_ovmode.require ();
> if (vmode != new_vmode)
> {
> - tree qi_type = unsigned_intQI_type_node;
> tree new_vtype
> = build_vector_type_for_mode (qi_type, new_vmode);
> tree var = vect_get_new_ssa_name (new_vtype,
> diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
> index c4c5678e7f1..75fdfa31405 100644
> --- a/gcc/tree-vectorizer.h
> +++ b/gcc/tree-vectorizer.h
> @@ -544,6 +544,10 @@ struct rgroup_controls {
>
> /* A vector of nV controls, in iteration order. */
> vec<tree> controls;
> +
> + /* In case of len_load and len_store with a bias there is only one
> + rgroup. This holds the adjusted loop length for the this rgroup. */
> + tree bias_adjusted_ctrl;
> };
>
> typedef auto_vec<rgroup_controls> vec_loop_masks;
> @@ -749,6 +753,11 @@ public:
> epilogue of loop. */
> bool epil_using_partial_vectors_p;
>
> + /* The bias for len_load and len_store. For now, only 0 and -1 are
> + supported. -1 must be used when a backend does not support
> + len_load/len_store with a length of zero. */
> + signed char partial_load_store_bias;
> +
> /* When we have grouped data accesses with gaps, we may introduce invalid
> memory accesses. We peel the last iteration of the loop to prevent
> this. */
> @@ -814,6 +823,7 @@ public:
> #define LOOP_VINFO_USING_PARTIAL_VECTORS_P(L) (L)->using_partial_vectors_p
> #define LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P(L)
> \
> (L)->epil_using_partial_vectors_p
> +#define LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS(L) (L)->partial_load_store_bias
> #define LOOP_VINFO_VECT_FACTOR(L) (L)->vectorization_factor
> #define LOOP_VINFO_MAX_VECT_FACTOR(L) (L)->max_vectorization_factor
> #define LOOP_VINFO_MASKS(L) (L)->masks
