From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by sourceware.org (Postfix) with ESMTP id 26D753858D28 for ; Wed, 24 May 2023 15:07:30 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 26D753858D28 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B61361042; Wed, 24 May 2023 08:08:14 -0700 (PDT) Received: from localhost (e121540-lin.manchester.arm.com [10.32.110.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 17FF43F762; Wed, 24 May 2023 08:07:28 -0700 (PDT) From: Richard Sandiford To: juzhe.zhong@rivai.ai Mail-Followup-To: juzhe.zhong@rivai.ai,gcc-patches@gcc.gnu.org, rguenther@suse.de, richard.sandiford@arm.com Cc: gcc-patches@gcc.gnu.org, rguenther@suse.de Subject: Re: [PATCH V14] VECT: Add decrement IV iteration loop control by variable amount support References: <20230524144801.73537-1-juzhe.zhong@rivai.ai> Date: Wed, 24 May 2023 16:07:27 +0100 In-Reply-To: <20230524144801.73537-1-juzhe.zhong@rivai.ai> (juzhe zhong's message of "Wed, 24 May 2023 22:48:01 +0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-28.6 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_NONE,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Thanks for trying it. I'm still surprised that no multiplication is needed though. Does the patch work for: short x[100]; int y[200]; void f() { for (int i = 0, j = 0; i < 100; i += 2, j += 4) { x[i + 0] += 1; x[i + 1] += 2; y[j + 0] += 1; y[j + 1] += 2; y[j + 2] += 3; y[j + 3] += 4; } } ? Here, there should be a single-control rgroup for x, counting 2 units per scalar iteration. I'd expect the IV to use this scale. There should also be a 4-control rgroup for y, counting 4 units per scalar iteration. So I think the IV would need to be multiplied by 2 before being used for the y rgroup. Thanks, Richard juzhe.zhong@rivai.ai writes: > From: Ju-Zhe Zhong > > This patch is supporting decrement IV by following the flow designed by Richard: > > (1) In vect_set_loop_condition_partial_vectors, for the first iteration of: > call vect_set_loop_controls_directly. > > (2) vect_set_loop_controls_directly calculates "step" as in your patch. > If rgc has 1 control, this step is the SSA name created for that control. > Otherwise the step is a fresh SSA name, as in your patch. > > (3) vect_set_loop_controls_directly stores this step somewhere for later > use, probably in LOOP_VINFO. Let's use "S" to refer to this stored step. > > (4) After the vect_set_loop_controls_directly call above, and outside > the "if" statement that now contains vect_set_loop_controls_directly, > check whether rgc->controls.length () > 1. If so, use > vect_adjust_loop_lens_control to set the controls based on S. > > Then the only caller of vect_adjust_loop_lens_control is > vect_set_loop_condition_partial_vectors. And the starting > step for vect_adjust_loop_lens_control is always S. > > This patch has well tested for single-rgroup and multiple-rgroup (SLP) and > passed all testcase in RISC-V port. > > Also, pass tests for multiple-rgroup (non-SLP) tested on vec_pack_trunk. > > --- > gcc/tree-vect-loop-manip.cc | 178 +++++++++++++++++++++++++++++++++--- > gcc/tree-vect-loop.cc | 13 +++ > gcc/tree-vectorizer.h | 12 +++ > 3 files changed, 192 insertions(+), 11 deletions(-) > > diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc > index ff6159e08d5..578ac5b783e 100644 > --- a/gcc/tree-vect-loop-manip.cc > +++ b/gcc/tree-vect-loop-manip.cc > @@ -468,6 +468,38 @@ vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo, > gimple_stmt_iterator incr_gsi; > bool insert_after; > standard_iv_increment_position (loop, &incr_gsi, &insert_after); > + if (LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo)) > + { > + /* single rgroup: > + ... > + _10 = (unsigned long) count_12(D); > + ... > + # ivtmp_9 = PHI > + _36 = MIN_EXPR ; > + ... > + vect__4.8_28 = .LEN_LOAD (_17, 32B, _36, 0); > + ... > + ivtmp_35 = ivtmp_9 - _36; > + ... > + if (ivtmp_35 != 0) > + goto ; [83.33%] > + else > + goto ; [16.67%] > + */ > + nitems_total = gimple_convert (preheader_seq, iv_type, nitems_total); > + tree step = rgc->controls.length () == 1 ? rgc->controls[0] > + : make_ssa_name (iv_type); > + /* Create decrement IV. */ > + create_iv (nitems_total, MINUS_EXPR, step, NULL_TREE, loop, &incr_gsi, > + insert_after, &index_before_incr, &index_after_incr); > + gimple_seq_add_stmt (header_seq, gimple_build_assign (step, MIN_EXPR, > + index_before_incr, > + nitems_step)); > + LOOP_VINFO_DECREMENTING_IV_STEP (loop_vinfo) = step; > + return index_after_incr; > + } > + > + /* Create increment IV. */ > create_iv (build_int_cst (iv_type, 0), PLUS_EXPR, nitems_step, NULL_TREE, > loop, &incr_gsi, insert_after, &index_before_incr, > &index_after_incr); > @@ -683,6 +715,63 @@ vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo, > return next_ctrl; > } > > +/* Try to use adjust loop lens for multiple-rgroups. > + > + _36 = MIN_EXPR ; > + > + First length (MIN (X, VF/N)): > + loop_len_15 = MIN_EXPR <_36, VF/N>; > + > + Second length: > + tmp = _36 - loop_len_15; > + loop_len_16 = MIN (tmp, VF/N); > + > + Third length: > + tmp2 = tmp - loop_len_16; > + loop_len_17 = MIN (tmp2, VF/N); > + > + Last length: > + loop_len_18 = tmp2 - loop_len_17; > +*/ > + > +static void > +vect_adjust_loop_lens_control (tree iv_type, gimple_seq *seq, > + rgroup_controls *dest_rgm, tree step) > +{ > + tree ctrl_type = dest_rgm->type; > + poly_uint64 nitems_per_ctrl > + = TYPE_VECTOR_SUBPARTS (ctrl_type) * dest_rgm->factor; > + tree length_limit = build_int_cst (iv_type, nitems_per_ctrl); > + > + for (unsigned int i = 0; i < dest_rgm->controls.length (); ++i) > + { > + tree ctrl = dest_rgm->controls[i]; > + if (i == 0) > + { > + /* First iteration: MIN (X, VF/N) capped to the range [0, VF/N]. */ > + gassign *assign > + = gimple_build_assign (ctrl, MIN_EXPR, step, length_limit); > + gimple_seq_add_stmt (seq, assign); > + } > + else if (i == dest_rgm->controls.length () - 1) > + { > + /* Last iteration: Remain capped to the range [0, VF/N]. */ > + gassign *assign = gimple_build_assign (ctrl, MINUS_EXPR, step, > + dest_rgm->controls[i - 1]); > + gimple_seq_add_stmt (seq, assign); > + } > + else > + { > + /* (MIN (remain, VF*I/N)) capped to the range [0, VF/N]. */ > + step = gimple_build (seq, MINUS_EXPR, iv_type, step, > + dest_rgm->controls[i - 1]); > + gassign *assign > + = gimple_build_assign (ctrl, MIN_EXPR, step, length_limit); > + gimple_seq_add_stmt (seq, assign); > + } > + } > +} > + > /* Set up the iteration condition and rgroup controls for LOOP, given > that LOOP_VINFO_USING_PARTIAL_VECTORS_P is true for the vectorized > loop. LOOP_VINFO describes the vectorization of LOOP. NITERS is > @@ -753,17 +842,84 @@ vect_set_loop_condition_partial_vectors (class loop *loop, > continue; > } > > - /* See whether zero-based IV would ever generate all-false masks > - or zero length before wrapping around. */ > - bool might_wrap_p = vect_rgroup_iv_might_wrap_p (loop_vinfo, rgc); > - > - /* 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); > + if (!LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo) > + || !LOOP_VINFO_DECREMENTING_IV_STEP (loop_vinfo)) > + { > + /* See whether zero-based IV would ever generate all-false masks > + or zero length before wrapping around. */ > + bool might_wrap_p = vect_rgroup_iv_might_wrap_p (loop_vinfo, rgc); > + > + /* 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); > + } > + > + /* Decrement IV only run vect_set_loop_controls_directly once. */ > + if (LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo) > + && rgc->controls.length () > 1) > + { > + /* > + - Multiple rgroup (SLP): > + ... > + _38 = (unsigned long) bnd.7_29; > + _39 = _38 * 2; > + ... > + # ivtmp_41 = PHI > + ... > + _43 = MIN_EXPR ; > + loop_len_26 = MIN_EXPR <_43, 16>; > + loop_len_25 = _43 - loop_len_26; > + ... > + .LEN_STORE (_6, 8B, loop_len_26, ...); > + ... > + .LEN_STORE (_25, 8B, loop_len_25, ...); > + _33 = loop_len_26 / 2; > + ... > + .LEN_STORE (_8, 16B, _33, ...); > + _36 = loop_len_25 / 2; > + ... > + .LEN_STORE (_15, 16B, _36, ...); > + ivtmp_42 = ivtmp_41 - _43; > + ... > + > + - Multiple rgroup (non-SLP): > + ... > + _38 = (unsigned long) n_12(D); > + ... > + # ivtmp_38 = PHI > + ... > + _40 = MIN_EXPR ; > + loop_len_21 = MIN_EXPR <_40, POLY_INT_CST [2, 2]>; > + _41 = _40 - loop_len_21; > + loop_len_20 = MIN_EXPR <_41, POLY_INT_CST [2, 2]>; > + _42 = _40 - loop_len_20; > + loop_len_19 = MIN_EXPR <_42, POLY_INT_CST [2, 2]>; > + _43 = _40 - loop_len_19; > + loop_len_16 = MIN_EXPR <_43, POLY_INT_CST [2, 2]>; > + ... > + vect__4.8_15 = .LEN_LOAD (_6, 64B, loop_len_21, 0); > + ... > + vect__4.9_8 = .LEN_LOAD (_13, 64B, loop_len_20, 0); > + ... > + vect__4.10_28 = .LEN_LOAD (_46, 64B, loop_len_19, 0); > + ... > + vect__4.11_30 = .LEN_LOAD (_49, 64B, loop_len_16, 0); > + vect__7.13_31 = VEC_PACK_TRUNC_EXPR <...>, > + vect__7.13_32 = VEC_PACK_TRUNC_EXPR <...>; > + vect__7.12_33 = VEC_PACK_TRUNC_EXPR <...>; > + ... > + .LEN_STORE (_14, 16B, _40, vect__7.12_33, 0); > + ivtmp_39 = ivtmp_38 - _40; > + ... > + */ > + tree iv_type = LOOP_VINFO_RGROUP_IV_TYPE (loop_vinfo); > + tree step = LOOP_VINFO_DECREMENTING_IV_STEP (loop_vinfo); > + gcc_assert (step); > + vect_adjust_loop_lens_control (iv_type, &header_seq, rgc, step); > + } > } > > /* Emit all accumulated statements. */ > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc > index cf10132b0bf..456f50fa7cc 100644 > --- a/gcc/tree-vect-loop.cc > +++ b/gcc/tree-vect-loop.cc > @@ -973,6 +973,8 @@ _loop_vec_info::_loop_vec_info (class loop *loop_in, vec_info_shared *shared) > vectorizable (false), > can_use_partial_vectors_p (param_vect_partial_vector_usage != 0), > using_partial_vectors_p (false), > + using_decrementing_iv_p (false), > + decrementing_iv_step (NULL_TREE), > epil_using_partial_vectors_p (false), > partial_load_store_bias (0), > peeling_for_gaps (false), > @@ -2725,6 +2727,17 @@ start_over: > && !vect_verify_loop_lens (loop_vinfo)) > LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false; > > + /* If we're vectorizing an loop that uses length "controls" and > + can iterate more than once, we apply decrementing IV approach > + in loop control. */ > + if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) > + && !LOOP_VINFO_LENS (loop_vinfo).is_empty () > + && LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo) == 0 > + && !(LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo) > + && known_le (LOOP_VINFO_INT_NITERS (loop_vinfo), > + LOOP_VINFO_VECT_FACTOR (loop_vinfo)))) > + LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo) = true; > + > /* If we're vectorizing an epilogue loop, the vectorized loop either needs > to be able to handle fewer than VF scalars, or needs to have a lower VF > than the main loop. */ > diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h > index 02d2ad6fba1..7ed079f543a 100644 > --- a/gcc/tree-vectorizer.h > +++ b/gcc/tree-vectorizer.h > @@ -818,6 +818,16 @@ public: > the vector loop can handle fewer than VF scalars. */ > bool using_partial_vectors_p; > > + /* True if we've decided to use a decrementing loop control IV that counts > + scalars. This can be done for any loop that: > + > + (a) uses length "controls"; and > + (b) can iterate more than once. */ > + bool using_decrementing_iv_p; > + > + /* The variable amount step for decrement IV. */ > + tree decrementing_iv_step; > + > /* True if we've decided to use partially-populated vectors for the > epilogue of loop. */ > bool epil_using_partial_vectors_p; > @@ -890,6 +900,8 @@ public: > #define LOOP_VINFO_VECTORIZABLE_P(L) (L)->vectorizable > #define LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P(L) (L)->can_use_partial_vectors_p > #define LOOP_VINFO_USING_PARTIAL_VECTORS_P(L) (L)->using_partial_vectors_p > +#define LOOP_VINFO_USING_DECREMENTING_IV_P(L) (L)->using_decrementing_iv_p > +#define LOOP_VINFO_DECREMENTING_IV_STEP(L) (L)->decrementing_iv_step > #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