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| author | Jakub Jelinek <jakub@redhat.com> | 2023-04-20 19:44:27 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2023-04-20 19:44:27 +0200 |
| commit | 87c9bae4e32b54829dce0a93ff735412d5f684f8 (patch) | |
| tree | 5a8469b8623f17a132801ec6c336f03ddbe7a959 | |
| parent | 3d7ab53d6c59499624aa41c8dea0664976820b3b (diff) | |
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tree-vect-patterns: One small vect_recog_ctz_ffs_pattern tweak [PR109011]
I've noticed I've made a typo, ifn in this function this late
is always only IFN_CTZ or IFN_FFS, never IFN_CLZ.
Due to this typo, we weren't using the originally intended
.CTZ (X) = .POPCOUNT ((X - 1) & ~X)
but
.CTZ (X) = PREC - .POPCOUNT (X | -X)
instead when we want to emit __builtin_ctz*/.CTZ using .POPCOUNT.
Both compute the same value, both are defined at 0 with the
same value (PREC), both have same number of GIMPLE statements,
but I think the former ought to be preferred, because lots of targets
have andn as a single operation rather than two, and also putting
a -1 constant into a vector register is often cheaper than vector
with broadcast PREC power of two value.
2023-04-20 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/109011
* tree-vect-patterns.cc (vect_recog_ctz_ffs_pattern): Use
.CTZ (X) = .POPCOUNT ((X - 1) & ~X) in preference to
.CTZ (X) = PREC - .POPCOUNT (X | -X).
| -rw-r--r-- | gcc/tree-vect-patterns.cc | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc index d1b86e8..a49b095 100644 --- a/gcc/tree-vect-patterns.cc +++ b/gcc/tree-vect-patterns.cc @@ -1630,7 +1630,7 @@ vect_recog_ctz_ffs_pattern (vec_info *vinfo, stmt_vec_info stmt_vinfo, && defined_at_zero_new && val == prec && val_new == prec) - || (ifnnew == IFN_POPCOUNT && ifn == IFN_CLZ)) + || (ifnnew == IFN_POPCOUNT && ifn == IFN_CTZ)) { /* .CTZ (X) = PREC - .CLZ ((X - 1) & ~X) .CTZ (X) = .POPCOUNT ((X - 1) & ~X). */ |