bcachefs: bch2_bkey_cmp_packed_inlined()

This adds an inlined version of bch2_bkey_cmp_packed(), and uses it in
bch2_sort_keys(), where it's part of the inner loop.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 129 insertions, 0 deletions

diff --git a/fs/bcachefs/bkey_cmp.h b/fs/bcachefs/bkey_cmp.h
new file mode 100644
index 000000000000..5f42a6e69360
--- /dev/null
+++ b/fs/bcachefs/bkey_cmp.h
@@ -0,0 +1,129 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHEFS_BKEY_CMP_H
+#define _BCACHEFS_BKEY_CMP_H
+
+#include "bkey.h"
+
+#ifdef CONFIG_X86_64
+static inline int __bkey_cmp_bits(const u64 *l, const u64 *r,
+				  unsigned nr_key_bits)
+{
+	long d0, d1, d2, d3;
+	int cmp;
+
+	/* we shouldn't need asm for this, but gcc is being retarded: */
+
+	asm(".intel_syntax noprefix;"
+	    "xor eax, eax;"
+	    "xor edx, edx;"
+	    "1:;"
+	    "mov r8, [rdi];"
+	    "mov r9, [rsi];"
+	    "sub ecx, 64;"
+	    "jl 2f;"
+
+	    "cmp r8, r9;"
+	    "jnz 3f;"
+
+	    "lea rdi, [rdi - 8];"
+	    "lea rsi, [rsi - 8];"
+	    "jmp 1b;"
+
+	    "2:;"
+	    "not ecx;"
+	    "shr r8, 1;"
+	    "shr r9, 1;"
+	    "shr r8, cl;"
+	    "shr r9, cl;"
+	    "cmp r8, r9;"
+
+	    "3:\n"
+	    "seta al;"
+	    "setb dl;"
+	    "sub eax, edx;"
+	    ".att_syntax prefix;"
+	    : "=&D" (d0), "=&S" (d1), "=&d" (d2), "=&c" (d3), "=&a" (cmp)
+	    : "0" (l), "1" (r), "3" (nr_key_bits)
+	    : "r8", "r9", "cc", "memory");
+
+	return cmp;
+}
+#else
+static inline int __bkey_cmp_bits(const u64 *l, const u64 *r,
+				  unsigned nr_key_bits)
+{
+	u64 l_v, r_v;
+
+	if (!nr_key_bits)
+		return 0;
+
+	/* for big endian, skip past header */
+	nr_key_bits += high_bit_offset;
+	l_v = *l & (~0ULL >> high_bit_offset);
+	r_v = *r & (~0ULL >> high_bit_offset);
+
+	while (1) {
+		if (nr_key_bits < 64) {
+			l_v >>= 64 - nr_key_bits;
+			r_v >>= 64 - nr_key_bits;
+			nr_key_bits = 0;
+		} else {
+			nr_key_bits -= 64;
+		}
+
+		if (!nr_key_bits || l_v != r_v)
+			break;
+
+		l = next_word(l);
+		r = next_word(r);
+
+		l_v = *l;
+		r_v = *r;
+	}
+
+	return cmp_int(l_v, r_v);
+}
+#endif
+
+static inline __pure __flatten
+int __bch2_bkey_cmp_packed_format_checked_inlined(const struct bkey_packed *l,
+					  const struct bkey_packed *r,
+					  const struct btree *b)
+{
+	const struct bkey_format *f = &b->format;
+	int ret;
+
+	EBUG_ON(!bkey_packed(l) || !bkey_packed(r));
+	EBUG_ON(b->nr_key_bits != bkey_format_key_bits(f));
+
+	ret = __bkey_cmp_bits(high_word(f, l),
+			      high_word(f, r),
+			      b->nr_key_bits);
+
+	EBUG_ON(ret != bpos_cmp(bkey_unpack_pos(b, l),
+				bkey_unpack_pos(b, r)));
+	return ret;
+}
+
+static inline __pure __flatten
+int bch2_bkey_cmp_packed_inlined(const struct btree *b,
+			 const struct bkey_packed *l,
+			 const struct bkey_packed *r)
+{
+	struct bkey unpacked;
+
+	if (likely(bkey_packed(l) && bkey_packed(r)))
+		return __bch2_bkey_cmp_packed_format_checked_inlined(l, r, b);
+
+	if (bkey_packed(l)) {
+		__bkey_unpack_key_format_checked(b, &unpacked, l);
+		l = (void *) &unpacked;
+	} else if (bkey_packed(r)) {
+		__bkey_unpack_key_format_checked(b, &unpacked, r);
+		r = (void *) &unpacked;
+	}
+
+	return bpos_cmp(((struct bkey *) l)->p, ((struct bkey *) r)->p);
+}
+
+#endif /* _BCACHEFS_BKEY_CMP_H */