From bea7f0cc7c9cdd883340c80697abc0be028bf944 Mon Sep 17 00:00:00 2001
From: Valery Ushakov <uwe@stderr.spb.ru>
Date: Thu, 19 Dec 2019 14:01:01 +0300
Subject: Properly ensure 16-byte alignment on NetBSD.

---
 emu/port/alloc.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

(limited to 'emu/port/alloc.c')

diff --git a/emu/port/alloc.c b/emu/port/alloc.c
index 8b623de0..3cb45552 100644
--- a/emu/port/alloc.c
+++ b/emu/port/alloc.c
@@ -75,11 +75,7 @@ enum {
 
 /* tracing */
 enum {
-#ifdef __NetBSD__
-	Npadlong	= 4,	/* XXX: preserve 16-byte alignment */
-#else
 	Npadlong	= 2,
-#endif
 	MallocOffset = 0,
 	ReallocOffset = 1
 };
@@ -383,9 +379,22 @@ dopoolalloc(Pool *p, ulong asize, ulong pc)
 		unlock(&p->l);
 		return nil;
 	}
+#ifdef __NetBSD__
+	/* Align allocations to 16 bytes */
+	{
+		const size_t off = __builtin_offsetof(struct Bhdr, u.data)
+					+ Npadlong*sizeof(ulong);
+		struct assert_align {
+			unsigned int align_ok : (off % 8 == 0) ? 1 : -1;
+		};
+
+		const ulong align = (off - 1) % 16;
+		t = (Bhdr *)(((ulong)t + align) & ~align);
+	}
+#else
 	/* Double alignment */
 	t = (Bhdr *)(((ulong)t + 7) & ~7);
-
+#endif
 	if(p->chain != nil && (char*)t-(char*)B2LIMIT(p->chain)-ldr == 0){
 		/* can merge chains */
 		if(0)print("merging chains %p and %p in %s\n", p->chain, t, p->name);
-- 
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