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author | Richard Sandiford <richard.sandiford@arm.com> | 2019-01-07 12:17:10 +0000 |
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committer | Richard Sandiford <rsandifo@gcc.gnu.org> | 2019-01-07 12:17:10 +0000 |
commit | f4bf2aabe36633d75852313caafe7efab71d5ba7 (patch) | |
tree | 4b1605d010ed5331fcd70d90790c5ce41dd2f7c2 /gcc/tree.c | |
parent | 46c66a46aa33077bda821e0428cc7859945c04c8 (diff) | |
download | gcc-f4bf2aabe36633d75852313caafe7efab71d5ba7.zip gcc-f4bf2aabe36633d75852313caafe7efab71d5ba7.tar.gz gcc-f4bf2aabe36633d75852313caafe7efab71d5ba7.tar.bz2 |
[2/2] PR88598: Optimise reduc (bit_and)
This patch folds certain reductions of X & CST to X[I] & CST[I] if I is
the only nonzero element of CST. This includes the motivating case in
which CST[I] is -1.
We could do the same for REDUC_MAX on unsigned types, but I wasn't sure
that that special case was worth it.
2019-01-07 Richard Sandiford <richard.sandiford@arm.com>
gcc/
PR tree-optimization/88598
* tree.h (single_nonzero_element): Declare.
* tree.c (single_nonzero_element): New function.
* match.pd: Fold certain reductions of X & CST to X[I] & CST[I]
if I is the only nonzero element of CST.
gcc/testsuite/
PR tree-optimization/88598
* gcc.dg/vect/pr88598-1.c: New test.
* gcc.dg/vect/pr88598-2.c: Likewise.
* gcc.dg/vect/pr88598-3.c: Likewise.
* gcc.dg/vect/pr88598-4.c: Likewise.
* gcc.dg/vect/pr88598-5.c: Likewise.
* gcc.dg/vect/pr88598-6.c: Likewise.
From-SVN: r267646
Diffstat (limited to 'gcc/tree.c')
-rw-r--r-- | gcc/tree.c | 32 |
1 files changed, 32 insertions, 0 deletions
@@ -11340,6 +11340,38 @@ uniform_integer_cst_p (tree t) return NULL_TREE; } +/* If VECTOR_CST T has a single nonzero element, return the index of that + element, otherwise return -1. */ + +int +single_nonzero_element (const_tree t) +{ + unsigned HOST_WIDE_INT nelts; + unsigned int repeat_nelts; + if (VECTOR_CST_NELTS (t).is_constant (&nelts)) + repeat_nelts = nelts; + else if (VECTOR_CST_NELTS_PER_PATTERN (t) == 2) + { + nelts = vector_cst_encoded_nelts (t); + repeat_nelts = VECTOR_CST_NPATTERNS (t); + } + else + return -1; + + int res = -1; + for (unsigned int i = 0; i < nelts; ++i) + { + tree elt = vector_cst_elt (t, i); + if (!integer_zerop (elt) && !real_zerop (elt)) + { + if (res >= 0 || i >= repeat_nelts) + return -1; + res = i; + } + } + return res; +} + /* Build an empty statement at location LOC. */ tree |