From 5b6788ae5a365aecd6776f563e44022acb93a57a Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Wed, 19 Jan 2022 12:31:30 +0100 Subject: [PATCH] tree-optimization/104112 - add check for vect epilogue reduc reuse This adds a missing check for the availability of intermediate vector types required to re-use the accumulator of a vectorized reduction in the vectorized epilogue. For SVE and VNx2DF vs V2DF with -msve-vector-bits=512 for example V4DF is not available. In addition to that we have to verify the reduction operation is supported, otherwise we for example on i?86 get vector code that's later decomposed again by vector lowering when trying to use a V2HI epilogue for a V8HI reduction with a target without TARGET_MMX_WITH_SSE. It might be we want -Wvector-operation-performance for all vect.exp tests but that seems to have existing regressions. 2022-01-19 Richard Biener PR tree-optimization/104112 * tree-vect-loop.cc (vect_find_reusable_accumulator): Check for required intermediate vector types. * gcc.dg/vect/pr104112-1.c: New testcase. * gcc.dg/vect/pr104112-2.c: New testcase. --- gcc/testsuite/gcc.dg/vect/pr104112-1.c | 18 ++++++++++++++++++ gcc/testsuite/gcc.dg/vect/pr104112-2.c | 11 +++++++++++ gcc/tree-vect-loop.cc | 15 ++++++++++++++- 3 files changed, 43 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/vect/pr104112-1.c create mode 100644 gcc/testsuite/gcc.dg/vect/pr104112-2.c diff --git a/gcc/testsuite/gcc.dg/vect/pr104112-1.c b/gcc/testsuite/gcc.dg/vect/pr104112-1.c new file mode 100644 index 0000000..84e69b8 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr104112-1.c @@ -0,0 +1,18 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-Ofast" } */ +/* { dg-additional-options "-march=armv8.2-a+sve -msve-vector-bits=512" { target aarch64-*-* } } */ + +void +boom(int n, double *a, double *x) +{ + int i, j; + double temp; + + for (j = n; j >= 1; --j) + { + temp = x[j]; + for (i = j - 1; i >= 1; --i) + temp += a[i + j] * x[i]; + x[j] = temp; + } +} diff --git a/gcc/testsuite/gcc.dg/vect/pr104112-2.c b/gcc/testsuite/gcc.dg/vect/pr104112-2.c new file mode 100644 index 0000000..7469b3c --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr104112-2.c @@ -0,0 +1,11 @@ +/* { dg-do compile } */ +/* Diagnose vector ops that are later decomposed. */ +/* { dg-additional-options "-Wvector-operation-performance" } */ + +unsigned short foo (unsigned short *a, int n) +{ + unsigned short sum = 0; + for (int i = 0; i < n; ++i) + sum += a[i]; + return sum; +} diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index 0fe3529..0b2785a 100644 --- a/gcc/tree-vect-loop.cc +++ b/gcc/tree-vect-loop.cc @@ -4979,9 +4979,22 @@ vect_find_reusable_accumulator (loop_vec_info loop_vinfo, /* Handle the case where we can reduce wider vectors to narrower ones. */ tree vectype = STMT_VINFO_VECTYPE (reduc_info); tree old_vectype = TREE_TYPE (accumulator->reduc_input); + unsigned HOST_WIDE_INT m; if (!constant_multiple_p (TYPE_VECTOR_SUBPARTS (old_vectype), - TYPE_VECTOR_SUBPARTS (vectype))) + TYPE_VECTOR_SUBPARTS (vectype), &m)) return false; + /* Check the intermediate vector types are available. */ + while (m > 2) + { + m /= 2; + tree intermediate_vectype = get_related_vectype_for_scalar_type + (TYPE_MODE (vectype), TREE_TYPE (vectype), + exact_div (TYPE_VECTOR_SUBPARTS (old_vectype), m)); + if (!intermediate_vectype + || !directly_supported_p (STMT_VINFO_REDUC_CODE (reduc_info), + intermediate_vectype)) + return false; + } /* Non-SLP reductions might apply an adjustment after the reduction operation, in order to simplify the initialization of the accumulator. -- 2.7.4