From: Simon Marlow <marlowsd@gmail.com>
Date: Thu, 9 Sep 2010 11:08:05 +0000 (+0000)
Subject: newAlignedPinnedByteArray#: avoid allocating an extra word sometimes
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=9fdce342ee41c788a1dfe76fc81707367f2e7675

newAlignedPinnedByteArray#: avoid allocating an extra word sometimes
---

diff --git a/rts/PrimOps.cmm b/rts/PrimOps.cmm
index 3c7dbdd..1cc9544 100644
--- a/rts/PrimOps.cmm
+++ b/rts/PrimOps.cmm
@@ -109,6 +109,11 @@ stg_newAlignedPinnedByteArrayzh
     n = R1;
     alignment = R2;
 
+    /* we always supply at least word-aligned memory, so there's no
+       need to allow extra space for alignment if the requirement is less
+       than a word.  This also prevents mischief with alignment == 0. */
+    if (alignment <= SIZEOF_W) { alignment = 1; }
+
     bytes = n;
 
     /* payload_words is what we will tell the profiler we had to allocate */