[PATCH bpf-next v12 10/11] libbpf: Optimize the performance of determine_ptr_size

[Donglin Peng <dolinux.peng@gmail.com>]

From: Donglin Peng <pengdonglin@xiaomi.com>

Leverage the performance improvement of btf__find_by_name_kind() when
BTF is sorted. For sorted BTF, the function uses binary search with
O(log n) complexity instead of linear search, providing significant
performance benefits, especially for large BTF like vmlinux.

Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Ihor Solodrai <ihor.solodrai@linux.dev>
Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/btf.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 9a864de59597..918d9fa6ec36 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -659,29 +659,21 @@ static int determine_ptr_size(const struct btf *btf)
 		"int long unsigned",
 	};
 	const struct btf_type *t;
-	const char *name;
-	int i, j, n;
+	int i, id;
 
 	if (btf->base_btf && btf->base_btf->ptr_sz > 0)
 		return btf->base_btf->ptr_sz;
 
-	n = btf__type_cnt(btf);
-	for (i = 1; i < n; i++) {
-		t = btf__type_by_id(btf, i);
-		if (!btf_is_int(t))
+	for (i = 0; i < ARRAY_SIZE(long_aliases); i++) {
+		id = btf__find_by_name_kind(btf, long_aliases[i], BTF_KIND_INT);
+		if (id < 0)
 			continue;
 
+		t = btf__type_by_id(btf, id);
 		if (t->size != 4 && t->size != 8)
 			continue;
 
-		name = btf__name_by_offset(btf, t->name_off);
-		if (!name)
-			continue;
-
-		for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
-			if (strcmp(name, long_aliases[j]) == 0)
-				return t->size;
-		}
+		return t->size;
 	}
 
 	return -1;
-- 
2.34.1