From b16a4839f3211737dccc3ff92ab2c4f325907cd3 Mon Sep 17 00:00:00 2001 From: Bin Cheng Date: Thu, 22 Jun 2017 17:16:58 +0100 Subject: [PATCH 11/13] reduction-workaround-20170607.txt --- gcc/testsuite/gcc.dg/tree-ssa/ldist-26.c | 36 ++++++++++++++++++++++++++ gcc/tree-loop-distribution.c | 43 ++++++++++++++++++++++++-------- 2 files changed, 68 insertions(+), 11 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ldist-26.c diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ldist-26.c b/gcc/testsuite/gcc.dg/tree-ssa/ldist-26.c new file mode 100644 index 0000000..3a69884 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ldist-26.c @@ -0,0 +1,36 @@ +/* { dg-do run } */ +/* { dg-options "-O3 -ftree-loop-distribution -fdump-tree-ldist-details" } */ + +extern void abort (void); + +int a[130], b[128], c[128]; + +int __attribute__((noinline,noclone)) +foo (int len, int x) +{ + int i; + for (i = 1; i <= len; ++i) + { + a[i] = a[i + 2] + 1; + b[i] = 0; + a[i + 1] = a[i] - 3; + if (i < x) + c[i] = a[i]; + } + return i; +} + +int main() +{ + int i; + for (i = 0; i < 130; ++i) + a[i] = i; + foo (127, 67); + if (a[0] != 0 || a[1] != 4 || a[127] != 130) + abort (); + return 0; +} + +/* { dg-final { scan-tree-dump "distributed: split to 2 loops and 0 library calls" "ldist" } } */ +/* { dg-final { scan-tree-dump "distributed: split to 1 loops and 1 library calls" "ldist" } } */ +/* { dg-final { scan-tree-dump "generated memset zero" "ldist" } } */ diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c index 87fdc15..b15ec04 100644 --- a/gcc/tree-loop-distribution.c +++ b/gcc/tree-loop-distribution.c @@ -1254,17 +1254,18 @@ build_rdg_partition_for_vertex (struct graph *rdg, int v) } /* Classifies the builtin kind we can generate for PARTITION of RDG and LOOP. - For the moment we detect only the memset zero pattern. */ + For the moment we detect memset, memcpy and memmove patterns. Bitmap + STMT_IN_ALL_PARTITIONS contains statements belonging to all partitions. */ static void -classify_partition (loop_p loop, struct graph *rdg, partition *partition) +classify_partition (loop_p loop, struct graph *rdg, partition *partition, + bitmap stmt_in_all_partitions) { bitmap_iterator bi; unsigned i; tree nb_iter; data_reference_p single_load, single_store; - bool volatiles_p = false; - bool plus_one = false; + bool volatiles_p = false, plus_one = false, has_reduction = false; partition->kind = PKIND_NORMAL; partition->main_dr = NULL; @@ -1279,16 +1280,31 @@ classify_partition (loop_p loop, struct graph *rdg, partition *partition) if (gimple_has_volatile_ops (stmt)) volatiles_p = true; - /* If the stmt has uses outside of the loop mark it as reduction. */ + /* If the stmt is not included by all partitions and there is uses + outside of the loop, then mark the partition as reduction. */ if (stmt_has_scalar_dependences_outside_loop (loop, stmt)) { - partition->reduction_p = true; - return; + /* Due to limitation in the transform phase we have to fuse all + reduction partitions. As a result, this could cancel valid + loop distribution especially for loop that induction variable + is used outside of loop. To workaround this issue, we skip + marking partition as reudction if the reduction stmt belongs + to all partitions. In such case, reduction will be computed + correctly no matter how partitions are fused/distributed. */ + if (!bitmap_bit_p (stmt_in_all_partitions, i)) + { + partition->reduction_p = true; + return; + } + has_reduction = true; } } /* Perform general partition disqualification for builtins. */ if (volatiles_p + /* Simple workaround to prevent classifying the partition as builtin + if it contains any use outside of loop. */ + || has_reduction || !flag_tree_loop_distribute_patterns) return; @@ -1461,9 +1477,9 @@ share_memory_accesses (struct graph *rdg, return false; } -/* Aggregate several components into a useful partition that is - registered in the PARTITIONS vector. Partitions will be - distributed in different loops. */ +/* For each seed statement in STARTING_STMTS, this function builds + partition for it by adding depended statements according to RDG. + All partitions are recorded in PARTITIONS. */ static void rdg_build_partitions (struct graph *rdg, @@ -1731,10 +1747,15 @@ distribute_loop (struct loop *loop, vec stmts, auto_vec partitions; rdg_build_partitions (rdg, stmts, &partitions); + auto_bitmap stmt_in_all_partitions; + bitmap_copy (stmt_in_all_partitions, partitions[0]->stmts); + for (i = 1; partitions.iterate (i, &partition); ++i) + bitmap_and_into (stmt_in_all_partitions, partitions[i]->stmts); + any_builtin = false; FOR_EACH_VEC_ELT (partitions, i, partition) { - classify_partition (loop, rdg, partition); + classify_partition (loop, rdg, partition, stmt_in_all_partitions); any_builtin |= partition_builtin_p (partition); } -- 1.9.1