From d21dff5b4fee51ae432143065bededfc763dc344 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Thu, 26 Mar 2020 08:33:57 +0100 Subject: [PATCH] widening_mul: restrict ops to be defined in the same basic-block when convert plusminus to widen In the testcase for PR94269, widening_mul moves two multiply instructions from outside the loop to inside the loop, merging with two add instructions separately. This increases the cost of the loop. Like FMA detection in the same pass, simply restrict ops to be defined in the same basic-block to avoid possibly moving multiply to a different block with a higher execution frequency. 2020-03-26 Felix Yang PR tree-optimization/94269 * tree-ssa-math-opts.c (convert_plusminus_to_widen): Restrict this operation to single basic block. * gcc.dg/pr94269.c: New test. --- gcc/ChangeLog | 7 +++++++ gcc/testsuite/ChangeLog | 5 +++++ gcc/testsuite/gcc.dg/pr94269.c | 26 ++++++++++++++++++++++++++ gcc/tree-ssa-math-opts.c | 6 +++++- 4 files changed, 43 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/pr94269.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 3ad7a7aae0d..9f7927d748f 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2020-03-26 Felix Yang + + PR tree-optimization/94269 + * tree-ssa-math-opts.c (convert_plusminus_to_widen): Restrict + this + operation to single basic block. + 2020-03-25 Jeff Law PR rtl-optimization/90275 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index e750dcbc790..f8512d3fb32 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-03-26 Felix Yang + + PR tree-optimization/94269 + * gcc.dg/pr94269.c: New test. + 2020-03-25 Andrew Stubbs * gcc.dg/vect/bb-slp-pr69907.c: Disable the dump scan for amdgcn. diff --git a/gcc/testsuite/gcc.dg/pr94269.c b/gcc/testsuite/gcc.dg/pr94269.c new file mode 100644 index 00000000000..49d57044f78 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr94269.c @@ -0,0 +1,26 @@ +/* { dg-do compile { target aarch64*-*-* } } */ +/* { dg-options "-O2 -ftree-loop-vectorize -funsafe-math-optimizations -march=armv8.2-a+sve -msve-vector-bits=256" } */ + +float +foo(long n, float *x, int inc_x, + float *y, int inc_y) +{ + float dot = 0.0; + int ix = 0, iy = 0; + + if (n < 0) { + return dot; + } + + int i = 0; + while (i < n) { + dot += y[iy] * x[ix]; + ix += inc_x; + iy += inc_y; + i++; + } + + return dot; +} + +/* { dg-final { scan-assembler-not "smaddl" { target aarch64*-*-* } } } */ diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c index 54ba035f5ee..969c1a6b6c6 100644 --- a/gcc/tree-ssa-math-opts.c +++ b/gcc/tree-ssa-math-opts.c @@ -2715,11 +2715,14 @@ convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple *stmt, multiply-and-accumulate instructions. If the widened-multiplication result has more than one uses, it is - probably wiser not to do the conversion. */ + probably wiser not to do the conversion. Also restrict this operation + to single basic block to avoid moving the multiply to a different block + with a higher execution frequency. */ if (code == PLUS_EXPR && (rhs1_code == MULT_EXPR || rhs1_code == WIDEN_MULT_EXPR)) { if (!has_single_use (rhs1) + || gimple_bb (rhs1_stmt) != gimple_bb (stmt) || !is_widening_mult_p (rhs1_stmt, &type1, &mult_rhs1, &type2, &mult_rhs2)) return false; @@ -2729,6 +2732,7 @@ convert_plusminus_to_widen (gimple_stmt_iterator *gsi, gimple *stmt, else if (rhs2_code == MULT_EXPR || rhs2_code == WIDEN_MULT_EXPR) { if (!has_single_use (rhs2) + || gimple_bb (rhs2_stmt) != gimple_bb (stmt) || !is_widening_mult_p (rhs2_stmt, &type1, &mult_rhs1, &type2, &mult_rhs2)) return false; -- 2.30.2