From 19d1a529fa9f78e7ec7be38d423c90e00cec8f8c Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 9 Aug 2021 11:42:47 +0200 Subject: [PATCH] tree-optimization/101801 - rework generic vector vectorization more This builds ontop of the vect_worthwhile_without_simd_p refactoring done earlier. It was wrong in dropping the appearant double checks for operation support since the optab check can happen with an integer vector emulation mode and thus succeed but vector lowering might not actually support the operation on word_mode. The following patch adds a vect_emulated_vector_p helper and re-instantiates the check where it was previously. It also adds appropriate costing of the scalar stmts emitted by vector lowering to vectorizable_operation which should be the only place such operations are synthesized. I've also cared for the case where the vector mode is supported but the operation is not (though I think this will be unlikely given we're talking about plus, minus and negate). This fixes the observed FAIL of gcc.dg/tree-ssa/gen-vect-11b.c with -m32 where we end up vectorizing a multiplication that ends up being teared down to scalars again by vector lowering. I'm not super happy about all the other places where we're now and previously feeding scalar modes to optab checks where we want to know whether we can vectorize sth but well. 2021-09-08 Richard Biener PR tree-optimization/101801 PR tree-optimization/101819 * tree-vectorizer.h (vect_emulated_vector_p): Declare. * tree-vect-loop.c (vect_emulated_vector_p): New function. (vectorizable_reduction): Re-instantiate a check for emulated operations. * tree-vect-stmts.c (vectorizable_shift): Likewise. (vectorizable_operation): Likewise. Cost emulated vector operations according to the scalar sequence synthesized by vector lowering. --- gcc/tree-vect-loop.c | 18 ++++++++++++++++++ gcc/tree-vect-stmts.c | 45 +++++++++++++++++++++++++++++++++++++-------- gcc/tree-vectorizer.h | 1 + 3 files changed, 56 insertions(+), 8 deletions(-) diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c index 37c7daa..995d143 100644 --- a/gcc/tree-vect-loop.c +++ b/gcc/tree-vect-loop.c @@ -7234,6 +7234,14 @@ vectorizable_reduction (loop_vec_info loop_vinfo, dump_printf (MSG_NOTE, "proceeding using word mode.\n"); } + if (vect_emulated_vector_p (vectype_in) + && !vect_can_vectorize_without_simd_p (code)) + { + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, "using word mode not possible.\n"); + return false; + } + /* lane-reducing operations have to go through vect_transform_reduction. For the other cases try without the single cycle optimization. */ if (!ok) @@ -7936,6 +7944,16 @@ vectorizable_phi (vec_info *, return true; } +/* Return true if VECTYPE represents a vector that requires lowering + by the vector lowering pass. */ + +bool +vect_emulated_vector_p (tree vectype) +{ + return (!VECTOR_MODE_P (TYPE_MODE (vectype)) + && (!VECTOR_BOOLEAN_TYPE_P (vectype) + || TYPE_PRECISION (TREE_TYPE (vectype)) != 1)); +} /* Return true if we can emulate CODE on an integer mode representation of a vector. */ diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c index 5b94d41..5a5a4da 100644 --- a/gcc/tree-vect-stmts.c +++ b/gcc/tree-vect-stmts.c @@ -5682,15 +5682,11 @@ vectorizable_shift (vec_info *vinfo, if (dump_enabled_p ()) dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location, "op not supported by target.\n"); - /* Check only during analysis. */ - if (maybe_ne (GET_MODE_SIZE (vec_mode), UNITS_PER_WORD) - || (!vec_stmt - && !vect_can_vectorize_without_simd_p (code))) - return false; - if (dump_enabled_p ()) - dump_printf_loc (MSG_NOTE, vect_location, - "proceeding using word mode.\n"); + return false; } + /* vector lowering cannot optimize vector shifts using word arithmetic. */ + if (vect_emulated_vector_p (vectype)) + return false; if (!vec_stmt) /* transformation not required. */ { @@ -6076,6 +6072,7 @@ vectorizable_operation (vec_info *vinfo, != CODE_FOR_nothing); } + bool using_emulated_vectors_p = vect_emulated_vector_p (vectype); if (!target_support_p) { if (dump_enabled_p ()) @@ -6088,6 +6085,15 @@ vectorizable_operation (vec_info *vinfo, if (dump_enabled_p ()) dump_printf_loc (MSG_NOTE, vect_location, "proceeding using word mode.\n"); + using_emulated_vectors_p = true; + } + + if (using_emulated_vectors_p + && !vect_can_vectorize_without_simd_p (code)) + { + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, "using word mode not possible.\n"); + return false; } int reduc_idx = STMT_VINFO_REDUC_IDX (stmt_info); @@ -6134,6 +6140,29 @@ vectorizable_operation (vec_info *vinfo, DUMP_VECT_SCOPE ("vectorizable_operation"); vect_model_simple_cost (vinfo, stmt_info, ncopies, dt, ndts, slp_node, cost_vec); + if (using_emulated_vectors_p) + { + /* The above vect_model_simple_cost call handles constants + in the prologue and (mis-)costs one of the stmts as + vector stmt. See tree-vect-generic.c:do_plus_minus/do_negate + for the actual lowering that will be applied. */ + unsigned n + = slp_node ? SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node) : ncopies; + switch (code) + { + case PLUS_EXPR: + n *= 5; + break; + case MINUS_EXPR: + n *= 6; + break; + case NEGATE_EXPR: + n *= 4; + break; + default:; + } + record_stmt_cost (cost_vec, n, scalar_stmt, stmt_info, 0, vect_body); + } return true; } diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h index de0ecf8..9c2c29d 100644 --- a/gcc/tree-vectorizer.h +++ b/gcc/tree-vectorizer.h @@ -2061,6 +2061,7 @@ extern bool vectorizable_lc_phi (loop_vec_info, stmt_vec_info, gimple **, slp_tree); extern bool vectorizable_phi (vec_info *, stmt_vec_info, gimple **, slp_tree, stmt_vector_for_cost *); +extern bool vect_emulated_vector_p (tree); extern bool vect_can_vectorize_without_simd_p (tree_code); extern int vect_get_known_peeling_cost (loop_vec_info, int, int *, stmt_vector_for_cost *, -- 2.7.4