From d9dd06ad51b7479f09acb88adf404664a1e18b2a Mon Sep 17 00:00:00 2001 From: Robin Dapp Date: Fri, 8 Dec 2023 12:50:01 +0100 Subject: RISC-V: Recognize stepped series in expand_vec_perm_const. We currently try to recognize various forms of stepped (const_vector) sequence variants in expand_const_vector. Because of complications with canonicalization and encoding it is easier to identify such patterns in expand_vec_perm_const_1 already where perm.series_p () is available. This patch introduces shuffle_series as new permutation pattern and tries to recognize series like [base0 base1 base1 + step ...]. If such a series is found the series is expanded by expand_vec_series and a gather is emitted. On top the patch fixes the step recognition in expand_const_vector for stepped series where such a series would end up before. This fixes several execution failures when running code compiled for a scalable vector size of 128 on a target with vlen = 256 or higher. The problem was only noticed there because the encoding for a reversed [2 2]-element vector ("3 2 1 0") is { [1 2], [0 2], [1 4] }. Some testcases that failed were: vect-alias-check-18.c vect-alias-check-1.F90 pr64365.c On a 128-bit target, only the first two elements are used. The third element causing the complications only comes into effect at vlen = 256. With this patch the testsuite results are similar with vlen = 128, vlen = 256 as well as vlen = 512 (apart from the fixed-vlmax tests of course). gcc/ChangeLog: PR target/112853 * config/riscv/riscv-v.cc (expand_const_vector): Fix step calculation. (modulo_sel_indices): Also perform modulo for variable-length constants. (shuffle_series): Recognize series permutations. (expand_vec_perm_const_1): Add shuffle_series. --- gcc/config/riscv/riscv-v.cc | 66 +++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 64 insertions(+), 2 deletions(-) (limited to 'gcc') diff --git a/gcc/config/riscv/riscv-v.cc b/gcc/config/riscv/riscv-v.cc index 9b99d0a..484c690 100644 --- a/gcc/config/riscv/riscv-v.cc +++ b/gcc/config/riscv/riscv-v.cc @@ -1378,12 +1378,15 @@ expand_const_vector (rtx target, rtx src) { base0, base1, base1 + step, base1 + step * 2, ... } */ rtx base0 = builder.elt (0); rtx base1 = builder.elt (1); - rtx step = builder.elt (2); + rtx base2 = builder.elt (2); + + scalar_mode elem_mode = GET_MODE_INNER (mode); + rtx step = simplify_binary_operation (MINUS, elem_mode, base2, base1); + /* Step 1 - { base1, base1 + step, base1 + step * 2, ... } */ rtx tmp = gen_reg_rtx (mode); expand_vec_series (tmp, base1, step); /* Step 2 - { base0, base1, base1 + step, base1 + step * 2, ... } */ - scalar_mode elem_mode = GET_MODE_INNER (mode); if (!rtx_equal_p (base0, const0_rtx)) base0 = force_reg (elem_mode, base0); @@ -3395,6 +3398,63 @@ shuffle_extract_and_slide1up_patterns (struct expand_vec_perm_d *d) return true; } +static bool +shuffle_series_patterns (struct expand_vec_perm_d *d) +{ + if (!d->one_vector_p || d->perm.encoding ().npatterns () != 1) + return false; + + poly_int64 el1 = d->perm[0]; + poly_int64 el2 = d->perm[1]; + poly_int64 el3 = d->perm[2]; + + poly_int64 step1 = el2 - el1; + poly_int64 step2 = el3 - el2; + + bool need_insert = false; + bool have_series = false; + + /* Check for a full series. */ + if (known_ne (step1, 0) && d->perm.series_p (0, 1, el1, step1)) + have_series = true; + + /* Check for a series starting at the second element. */ + else if (known_ne (step2, 0) && d->perm.series_p (1, 1, el2, step2)) + { + have_series = true; + need_insert = true; + } + + if (!have_series) + return false; + + /* Get a vector int-mode to be used for the permute selector. */ + machine_mode sel_mode = related_int_vector_mode (d->vmode).require (); + insn_code icode = optab_handler (vec_shl_insert_optab, sel_mode); + + /* We need to be able to insert an element and shift the vector. */ + if (need_insert && icode == CODE_FOR_nothing) + return false; + + /* Success! */ + if (d->testing_p) + return true; + + /* Create the series. */ + machine_mode eltmode = Pmode; + rtx series = gen_reg_rtx (sel_mode); + expand_vec_series (series, gen_int_mode (need_insert ? el2 : el1, eltmode), + gen_int_mode (need_insert ? step2 : step1, eltmode)); + + /* Insert the remaining element if necessary. */ + if (need_insert) + emit_insn (GEN_FCN (icode) (series, series, gen_int_mode (el1, eltmode))); + + emit_vlmax_gather_insn (d->target, d->op0, series); + + return true; +} + /* Recognize the pattern that can be shuffled by generic approach. */ static bool @@ -3475,6 +3535,8 @@ expand_vec_perm_const_1 (struct expand_vec_perm_d *d) return true; if (shuffle_extract_and_slide1up_patterns (d)) return true; + if (shuffle_series_patterns (d)) + return true; if (shuffle_generic_patterns (d)) return true; return false; -- cgit v1.1