On Wed, 9 Aug 2023, juzhe.zh...@rivai.ai wrote:
> From: Ju-Zhe Zhong <juzhe.zh...@rivai.ai>
>
> Hi, this patch is adding loop len control on extract_last autovectorization.
>
> Consider this following case:
>
> #include <stdint.h>
>
> #define EXTRACT_LAST(TYPE) \
> TYPE __attribute__ ((noinline, noclone)) \
> test_##TYPE (TYPE *x, int n, TYPE value) \
> { \
> TYPE last; \
> for (int j = 0; j < n; ++j) \
> { \
> last = x[j]; \
> x[j] = last * value; \
> } \
> return last; \
> }
>
> #define TEST_ALL(T) \
> T (uint8_t) \
>
> TEST_ALL (EXTRACT_LAST)
>
> ARM SVE IR:
>
> Preheader:
> max_mask_34 = .WHILE_ULT (0, bnd.5_6, { 0, ... });
>
> Loop:
> ...
> # loop_mask_22 = PHI <next_mask_35(4), max_mask_34(3)>
> ...
> vect_last_12.8_23 = .MASK_LOAD (_7, 8B, loop_mask_22);
> vect__4.9_27 = vect_last_12.8_23 * vect_cst__26;
> .MASK_STORE (_7, 8B, loop_mask_22, vect__4.9_27);
> ...
> next_mask_35 = .WHILE_ULT (_1, bnd.5_6, { 0, ... });
> ...
>
> Epilogue:
> _25 = .EXTRACT_LAST (loop_mask_22, vect_last_12.8_23);
>
> For RVV since we prefer len in loop control, after this patch for RVV:
>
> Loop:
> ...
> loop_len_22 = SELECT_VL;
> vect_last_12.8_23 = .MASK_LOAD (_7, 8B, loop_len_22);
> vect__4.9_27 = vect_last_12.8_23 * vect_cst__26;
> .MASK_STORE (_7, 8B, loop_len_22, vect__4.9_27);
> ...
>
> Epilogue:
> _25 = .EXTRACT_LAST (loop_len_22, vect_last_12.8_23);
>
> This patch didn't add a new pattern for length loop control of extract_last.
> Instead we reuse current extract_last.
>
> Here is the code:
>
> Step 1 - Enable length and record length for extract_last:
>
> + machine_mode vec_mode = TYPE_MODE (vectype);
> + if (get_len_load_store_mode (vec_mode, true).exists (&vec_mode))
> + vect_record_loop_len (loop_vinfo,
> + &LOOP_VINFO_LENS (loop_vinfo), 1,
> + vectype, 1);
> + else
> + vect_record_loop_mask (loop_vinfo,
> + &LOOP_VINFO_MASKS (loop_vinfo), 1,
> + vectype, NULL);
>
> We use 'get_len_load_store_mode' to check whether targets support loop len
> control or not.
> If yes, record a loop len.
>
> Step 2 - Build EXTRACT_LAST with len:
>
> - tree mask = vect_get_loop_mask (loop_vinfo, gsi,
> - &LOOP_VINFO_MASKS (loop_vinfo),
> - 1, vectype, 0);
> + tree control;
> + if (LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
> + control = vect_get_loop_len (loop_vinfo, gsi,
> + &LOOP_VINFO_LENS (loop_vinfo), 1,
> + vectype, 0, 0);
> + else
> + control = vect_get_loop_mask (loop_vinfo, gsi,
> + &LOOP_VINFO_MASKS (loop_vinfo), 1,
> + vectype, 0);
> tree scalar_res = gimple_build (&stmts, CFN_EXTRACT_LAST, scalar_type,
> - mask, vec_lhs_phi);
> + control, vec_lhs_phi);
>
> Reuse the current codes (build EXTRACT_LAST with mask), build length instead
> if
> 'LOOP_VINFO_FULLY_WITH_LENGTH_P' is true.
>
> This patch has been fully tested in RISC-V port.
>
> Bootstrap and Regression on X86 passed.
>
> Ok for trunk ?
>
> gcc/ChangeLog:
>
> * tree-vect-loop.cc (vectorizable_live_operation): Add length control.
>
> ---
> gcc/tree-vect-loop.cc | 40 ++++++++++++++++++++++++++++------------
> 1 file changed, 28 insertions(+), 12 deletions(-)
>
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index 00058c3c13e..fde098cafde 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -10311,9 +10311,15 @@ vectorizable_live_operation (vec_info *vinfo,
> else
> {
> gcc_assert (ncopies == 1 && !slp_node);
> - vect_record_loop_mask (loop_vinfo,
> - &LOOP_VINFO_MASKS (loop_vinfo),
> - 1, vectype, NULL);
> + machine_mode vec_mode = TYPE_MODE (vectype);
> + if (get_len_load_store_mode (vec_mode, true).exists (&vec_mode))
> + vect_record_loop_len (loop_vinfo,
> + &LOOP_VINFO_LENS (loop_vinfo), 1,
> + vectype, 1);
> + else
> + vect_record_loop_mask (loop_vinfo,
> + &LOOP_VINFO_MASKS (loop_vinfo), 1,
> + vectype, NULL);
> }
> }
> /* ??? Enable for loop costing as well. */
> @@ -10339,7 +10345,9 @@ vectorizable_live_operation (vec_info *vinfo,
> gimple *vec_stmt;
> if (slp_node)
> {
> - gcc_assert (!loop_vinfo || !LOOP_VINFO_FULLY_MASKED_P (loop_vinfo));
> + gcc_assert (!loop_vinfo
> + || !LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
> + || !LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo));
that should be
|| (!LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
&& !LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
I think. It seems to imply that SLP isn't supported with
masking/lengthing.
>
> /* Get the correct slp vectorized stmt. */
> vec_lhs = SLP_TREE_VEC_DEFS (slp_node)[vec_entry];
> @@ -10383,21 +10391,29 @@ vectorizable_live_operation (vec_info *vinfo,
>
> gimple_seq stmts = NULL;
> tree new_tree;
> - if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo))
> + if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
> + || LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
> {
> /* Emit:
>
> - SCALAR_RES = EXTRACT_LAST <VEC_LHS, MASK>
> + SCALAR_RES = EXTRACT_LAST <VEC_LHS, CONTROL>
>
> - where VEC_LHS is the vectorized live-out result and MASK is
> - the loop mask for the final iteration. */
> + where VEC_LHS is the vectorized live-out result and CONTROL can
> + be either the loop mask for the final iteration or the loop len
> + for the final iteration. */
> gcc_assert (ncopies == 1 && !slp_node);
> tree scalar_type = TREE_TYPE (STMT_VINFO_VECTYPE (stmt_info));
> - tree mask = vect_get_loop_mask (loop_vinfo, gsi,
> - &LOOP_VINFO_MASKS (loop_vinfo),
> - 1, vectype, 0);
> + tree control;
> + if (LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
> + control = vect_get_loop_len (loop_vinfo, gsi,
> + &LOOP_VINFO_LENS (loop_vinfo), 1,
> + vectype, 0, 0);
> + else
> + control = vect_get_loop_mask (loop_vinfo, gsi,
> + &LOOP_VINFO_MASKS (loop_vinfo), 1,
> + vectype, 0);
> tree scalar_res = gimple_build (&stmts, CFN_EXTRACT_LAST, scalar_type,
> - mask, vec_lhs_phi);
> + control, vec_lhs_phi);
Hum, how does CFN_EXTRACT_LAST handle both mask and length transparently?
Don't you need some CFN_LEN_EXTRACT_LAST instead?
> /* Convert the extracted vector element to the scalar type. */
> new_tree = gimple_convert (&stmts, lhs_type, scalar_res);
>
Otherwise looks OK to me.
Thanks,
Richard.
