From 97e52238b292ca744368f66980533c578838e94c Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Tue, 23 Jan 2018 10:42:10 +0000 Subject: [PATCH] Disable some patterns for fold-left reductions (PR 83965) In this PR we recognised a PLUS_EXPR as a fold-left reduction, then applied pattern matching to convert it to a WIDEN_SUM_EXPR. We need to keep the original code in this case since we implement the reduction using scalar rather than vector operations. 2018-01-23 Richard Sandiford gcc/ PR tree-optimization/83965 * tree-vect-patterns.c (vect_reassociating_reduction_p): New function. (vect_recog_dot_prod_pattern, vect_recog_sad_pattern): Use it instead of checking only for a reduction. (vect_recog_widen_sum_pattern): Likewise. gcc/testsuite/ PR tree-optimization/83965 * gcc.dg/vect/pr83965.c: New test. From-SVN: r256976 --- gcc/ChangeLog | 8 ++++++++ gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.dg/vect/pr83965.c | 18 ++++++++++++++++++ gcc/tree-vect-patterns.c | 16 +++++++++++++--- 4 files changed, 44 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/vect/pr83965.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 747c3b4..bf5743b 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2018-01-23 Richard Sandiford + + PR tree-optimization/83965 + * tree-vect-patterns.c (vect_reassociating_reduction_p): New function. + (vect_recog_dot_prod_pattern, vect_recog_sad_pattern): Use it + instead of checking only for a reduction. + (vect_recog_widen_sum_pattern): Likewise. + 2018-01-23 Jan Hubicka * predict.c (probably_never_executed): Only use precise profile info. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 760422a..b42031b 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2018-01-23 Richard Sandiford + + PR tree-optimization/83965 + * gcc.dg/vect/pr83965.c: New test. + 2018-01-23 Richard Biener PR tree-optimization/83963 diff --git a/gcc/testsuite/gcc.dg/vect/pr83965.c b/gcc/testsuite/gcc.dg/vect/pr83965.c new file mode 100644 index 0000000..5bf0f90 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr83965.c @@ -0,0 +1,18 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-ftrapv" } */ + +int +mac (const short *a, const short *b, int sqr, int *sum) +{ + int i; + int dotp = *sum; + + for (i = 0; i < 150; i++) + { + dotp += b[i] * a[i]; + sqr += b[i] * b[i]; + } + + *sum = dotp; + return sqr; +} diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c index 0831b7e..1279352 100644 --- a/gcc/tree-vect-patterns.c +++ b/gcc/tree-vect-patterns.c @@ -217,6 +217,16 @@ vect_recog_temp_ssa_var (tree type, gimple *stmt) return make_temp_ssa_name (type, stmt, "patt"); } +/* Return true if STMT_VINFO describes a reduction for which reassociation + is allowed. */ + +static bool +vect_reassociating_reduction_p (stmt_vec_info stmt_vinfo) +{ + return (STMT_VINFO_DEF_TYPE (stmt_vinfo) == vect_reduction_def + && STMT_VINFO_REDUC_TYPE (stmt_vinfo) != FOLD_LEFT_REDUCTION); +} + /* Function vect_recog_dot_prod_pattern Try to find the following pattern: @@ -336,7 +346,7 @@ vect_recog_dot_prod_pattern (vec *stmts, tree *type_in, { gimple *def_stmt; - if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_reduction_def + if (!vect_reassociating_reduction_p (stmt_vinfo) && ! STMT_VINFO_GROUP_FIRST_ELEMENT (stmt_vinfo)) return NULL; oprnd0 = gimple_assign_rhs1 (last_stmt); @@ -557,7 +567,7 @@ vect_recog_sad_pattern (vec *stmts, tree *type_in, { gimple *def_stmt; - if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_reduction_def + if (!vect_reassociating_reduction_p (stmt_vinfo) && ! STMT_VINFO_GROUP_FIRST_ELEMENT (stmt_vinfo)) return NULL; plus_oprnd0 = gimple_assign_rhs1 (last_stmt); @@ -1181,7 +1191,7 @@ vect_recog_widen_sum_pattern (vec *stmts, tree *type_in, if (gimple_assign_rhs_code (last_stmt) != PLUS_EXPR) return NULL; - if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_reduction_def + if (!vect_reassociating_reduction_p (stmt_vinfo) && ! STMT_VINFO_GROUP_FIRST_ELEMENT (stmt_vinfo)) return NULL; -- 2.7.4