From: NAKAMURA Takumi <geek4civic@gmail.com>
Date: Wed, 4 Sep 2013 14:12:19 +0000 (+0000)
Subject: MemoryBuffer.cpp: Don't peek the next page if file is multiple of *physical* pagesize... 
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=81b135cc1e6578dba0fb6daed425f556db368034;p=oota-llvm.git

MemoryBuffer.cpp: Don't peek the next page if file is multiple of *physical* pagesize(4k) but is not multiple of AllocationGranularity(64k), when a null terminator is required, on cygwin and win32.

For example, r189780's SparcISelLowering.cpp has the size 98304. It crashed clang to touch a null terminator on cygwin.

FIXME: It's not good to hardcode 4096 here. dwPageSize shows 4096.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189939 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Support/MemoryBuffer.cpp b/lib/Support/MemoryBuffer.cpp
index 1134f5bb53e..e018ad4ecce 100644
--- a/lib/Support/MemoryBuffer.cpp
+++ b/lib/Support/MemoryBuffer.cpp
@@ -302,6 +302,15 @@ static bool shouldUseMmap(int FD,
   if (End != FileSize)
     return false;
 
+#if defined(_WIN32) || defined(__CYGWIN__)
+  // Don't peek the next page if file is multiple of *physical* pagesize(4k)
+  // but is not multiple of AllocationGranularity(64k),
+  // when a null terminator is required.
+  // FIXME: It's not good to hardcode 4096 here. dwPageSize shows 4096.
+  if ((FileSize & (4096 - 1)) == 0)
+    return false;
+#endif
+
   // Don't try to map files that are exactly a multiple of the system page size
   // if we need a null terminator.
   if ((FileSize & (PageSize -1)) == 0)