From cd676dfa57e643a4f7d8445e6ebad0f21cf3fd84 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Wed, 16 Dec 2020 13:08:07 +0100
Subject: [PATCH] bswap: Handle vector CONSTRUCTORs [PR96239]
The following patch teaches the bswap pass to handle for small (2/4/8 byte
long) vectors a CONSTRUCTOR by determining if the bytes of the constructor
come from non-vector sources and are either nop or bswap and changing the
CONSTRUCTOR in that case to VIEW_CONVERT_EXPR from scalar integer to
the vector type.
Unfortunately, as I found after the patch was written, due to pass ordering
this doesn't really fix the original testcase, just the one I wrote,
because both loop and slp vectorization is done only after the bswap pass.
A possible way out of that would be to perform just this particular bswap
optimization (i.e. for CONSTRUCTOR assignments with integral vector types
call find_bswap_or_nop and bswap_replace if successful) also during the
store merging pass, it isn't really a store, but the store merging pass
already performs bswapping when handling store, so it wouldn't be that big
hack. What do you think?
2020-12-16 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/96239
* gimple-ssa-store-merging.c (find_bswap_or_nop): Handle a vector
CONSTRUCTOR.
(bswap_replace): Likewise.
* gcc.dg/pr96239.c: New test.
---
gcc/gimple-ssa-store-merging.c | 91 ++++++++++++++++++++++++++++++++--
gcc/testsuite/gcc.dg/pr96239.c | 54 ++++++++++++++++++++
2 files changed, 140 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr96239.c
diff --git a/gcc/gimple-ssa-store-merging.c b/gcc/gimple-ssa-store-merging.c
index 17a4250d77f4..2894205fa3c3 100644
--- a/gcc/gimple-ssa-store-merging.c
+++ b/gcc/gimple-ssa-store-merging.c
@@ -865,7 +865,66 @@ find_bswap_or_nop (gimple *stmt, struct symbolic_number *n, bool *bswap)
gimple *ins_stmt = find_bswap_or_nop_1 (stmt, n, limit);
if (!ins_stmt)
- return NULL;
+ {
+ if (gimple_assign_rhs_code (stmt) != CONSTRUCTOR
+ || BYTES_BIG_ENDIAN != WORDS_BIG_ENDIAN)
+ return NULL;
+ unsigned HOST_WIDE_INT sz = tree_to_uhwi (type_size) * BITS_PER_UNIT;
+ if (sz != 16 && sz != 32 && sz != 64)
+ return NULL;
+ tree rhs = gimple_assign_rhs1 (stmt);
+ tree eltype = TREE_TYPE (TREE_TYPE (rhs));
+ unsigned HOST_WIDE_INT eltsz
+ = int_size_in_bytes (eltype) * BITS_PER_UNIT;
+ if (TYPE_PRECISION (eltype) != eltsz)
+ return NULL;
+ constructor_elt *elt;
+ unsigned int i;
+ tree type = build_nonstandard_integer_type (sz, 1);
+ FOR_EACH_VEC_SAFE_ELT (CONSTRUCTOR_ELTS (rhs), i, elt)
+ {
+ if (TREE_CODE (elt->value) != SSA_NAME
+ || !INTEGRAL_TYPE_P (TREE_TYPE (elt->value)))
+ return NULL;
+ struct symbolic_number n1;
+ gimple *source_stmt
+ = find_bswap_or_nop_1 (SSA_NAME_DEF_STMT (elt->value), &n1,
+ limit - 1);
+
+ if (!source_stmt)
+ return NULL;
+
+ n1.type = type;
+ if (!n1.base_addr)
+ n1.range = sz / BITS_PER_UNIT;
+
+ if (i == 0)
+ {
+ ins_stmt = source_stmt;
+ *n = n1;
+ }
+ else
+ {
+ if (n->vuse != n1.vuse)
+ return NULL;
+
+ struct symbolic_number n0 = *n;
+
+ if (!BYTES_BIG_ENDIAN)
+ {
+ if (!do_shift_rotate (LSHIFT_EXPR, &n1, i * eltsz))
+ return NULL;
+ }
+ else if (!do_shift_rotate (LSHIFT_EXPR, &n0, eltsz))
+ return NULL;
+ ins_stmt
+ = perform_symbolic_merge (ins_stmt, &n0, source_stmt, &n1, n);
+
+ if (!ins_stmt)
+ return NULL;
+ }
+ }
+ }
uint64_t cmpxchg, cmpnop;
find_bswap_or_nop_finalize (n, &cmpxchg, &cmpnop);
@@ -939,11 +998,18 @@ bswap_replace (gimple_stmt_iterator gsi, gimple *ins_stmt, tree fndecl,
{
tree src, tmp, tgt = NULL_TREE;
gimple *bswap_stmt;
+ tree_code conv_code = NOP_EXPR;
gimple *cur_stmt = gsi_stmt (gsi);
src = n->src;
if (cur_stmt)
- tgt = gimple_assign_lhs (cur_stmt);
+ {
+ tgt = gimple_assign_lhs (cur_stmt);
+ if (gimple_assign_rhs_code (cur_stmt) == CONSTRUCTOR
+ && tgt
+ && VECTOR_TYPE_P (TREE_TYPE (tgt)))
+ conv_code = VIEW_CONVERT_EXPR;
+ }
/* Need to load the value from memory first. */
if (n->base_addr)
@@ -1031,7 +1097,9 @@ bswap_replace (gimple_stmt_iterator gsi, gimple *ins_stmt, tree fndecl,
load_stmt = gimple_build_assign (val_tmp, val_expr);
gimple_set_vuse (load_stmt, n->vuse);
gsi_insert_before (&gsi, load_stmt, GSI_SAME_STMT);
- gimple_assign_set_rhs_with_ops (&gsi, NOP_EXPR, val_tmp);
+ if (conv_code == VIEW_CONVERT_EXPR)
+ val_tmp = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (tgt), val_tmp);
+ gimple_assign_set_rhs_with_ops (&gsi, conv_code, val_tmp);
update_stmt (cur_stmt);
}
else if (cur_stmt)
@@ -1073,7 +1141,9 @@ bswap_replace (gimple_stmt_iterator gsi, gimple *ins_stmt, tree fndecl,
{
if (!is_gimple_val (src))
return NULL_TREE;
- g = gimple_build_assign (tgt, NOP_EXPR, src);
+ if (conv_code == VIEW_CONVERT_EXPR)
+ src = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (tgt), src);
+ g = gimple_build_assign (tgt, conv_code, src);
}
else if (cur_stmt)
g = gimple_build_assign (tgt, src);
@@ -1153,7 +1223,10 @@ bswap_replace (gimple_stmt_iterator gsi, gimple *ins_stmt, tree fndecl,
gimple *convert_stmt;
tmp = make_temp_ssa_name (bswap_type, NULL, "bswapdst");
- convert_stmt = gimple_build_assign (tgt, NOP_EXPR, tmp);
+ tree atmp = tmp;
+ if (conv_code == VIEW_CONVERT_EXPR)
+ atmp = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (tgt), tmp);
+ convert_stmt = gimple_build_assign (tgt, conv_code, atmp);
gsi_insert_after (&gsi, convert_stmt, GSI_SAME_STMT);
}
@@ -1258,6 +1331,14 @@ pass_optimize_bswap::execute (function *fun)
/* Fall through. */
case BIT_IOR_EXPR:
break;
+ case CONSTRUCTOR:
+ {
+ tree rhs = gimple_assign_rhs1 (cur_stmt);
+ if (VECTOR_TYPE_P (TREE_TYPE (rhs))
+ && INTEGRAL_TYPE_P (TREE_TYPE (TREE_TYPE (rhs))))
+ break;
+ }
+ continue;
default:
continue;
}
diff --git a/gcc/testsuite/gcc.dg/pr96239.c b/gcc/testsuite/gcc.dg/pr96239.c
new file mode 100644
index 000000000000..8af56e12bb43
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr96239.c
@@ -0,0 +1,54 @@
+/* PR tree-optimization/96239 */
+/* { dg-do run { target { ilp32 || lp64 } } } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times " r>> 8;" 1 "optimized" { target bswap } } } */
+/* { dg-final { scan-tree-dump-times " = __builtin_bswap64 " 1 "optimized" { target bswap } } } */
+/* { dg-final { scan-tree-dump-not " >> \(8\|16\|24\|32\|40\|48\|56\);" "optimized" { target bswap } } } */
+
+typedef unsigned char V __attribute__((vector_size (2)));
+typedef unsigned char W __attribute__((vector_size (8)));
+
+__attribute__((noipa)) void
+foo (unsigned short x, V *p)
+{
+ *p = (V) { x >> 8, x };
+}
+
+__attribute__((noipa)) void
+bar (unsigned long long x, W *p)
+{
+ *p = (W) { x >> 56, x >> 48, x >> 40, x >> 32, x >> 24, x >> 16, x >> 8, x };
+}
+
+__attribute__((noipa)) void
+baz (unsigned short x, V *p)
+{
+ *p = (V) { x, x >> 8 };
+}
+
+__attribute__((noipa)) void
+qux (unsigned long long x, W *p)
+{
+ *p = (W) { x, x >> 8, x >> 16, x >> 24, x >> 32, x >> 40, x >> 48, x >> 56 };
+}
+
+int
+main ()
+{
+ V a, c, e, g;
+ W b, d, f, h;
+ foo (0xcafe, &a);
+ bar (0xdeadbeefcafebabeULL, &b);
+ baz (0xdead, &c);
+ qux (0xfeedbac1beefdeadULL, &d);
+ e = (V) { 0xca, 0xfe };
+ f = (W) { 0xde, 0xad, 0xbe, 0xef, 0xca, 0xfe, 0xba, 0xbe };
+ g = (V) { 0xad, 0xde };
+ h = (W) { 0xad, 0xde, 0xef, 0xbe, 0xc1, 0xba, 0xed, 0xfe };
+ if (__builtin_memcmp (&a, &e, sizeof (V))
+ || __builtin_memcmp (&b, &f, sizeof (W))
+ || __builtin_memcmp (&c, &g, sizeof (V))
+ || __builtin_memcmp (&d, &h, sizeof (W)))
+ __builtin_abort ();
+ return 0;
+}
--
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