[llvm] r189939 - 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.

[NAKAMURA Takumi]

Author: chapuni
Date: Wed Sep  4 09:12:19 2013
New Revision: 189939

URL: http://llvm.org/viewvc/llvm-project?rev=189939&view=rev
Log:
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.

Modified:
    llvm/trunk/lib/Support/MemoryBuffer.cpp

Modified: llvm/trunk/lib/Support/MemoryBuffer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/MemoryBuffer.cpp?rev=189939&r1=189938&r2=189939&view=diff
==============================================================================
--- llvm/trunk/lib/Support/MemoryBuffer.cpp (original)
+++ llvm/trunk/lib/Support/MemoryBuffer.cpp Wed Sep  4 09:12:19 2013
@@ -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)