MemoryBuffer: Use GetNativeSystemInfo()

Removes old 4096 byte workaround. This functionality has been available since
Windows XP.

llvm-svn: 209137

2 files changed, 6 insertions, 17 deletions

diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index 9be05d6b7a2..629d8855f32 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -310,15 +310,6 @@ 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)
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index a87c9e88c71..c3df801dc01 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -82,16 +82,14 @@ TimeValue self_process::get_system_time() const {
   return getTimeValueFromFILETIME(KernelTime);
 }
 
-// This function retrieves the page size using GetSystemInfo and is present
-// solely so it can be called once to initialize the self_process member below.
+// This function retrieves the page size using GetNativeSystemInfo() and is
+// present solely so it can be called once to initialize the self_process member
+// below.
 static unsigned getPageSize() {
-  // NOTE: A 32-bit application running under WOW64 is supposed to use
-  // GetNativeSystemInfo.  However, this interface is not present prior
-  // to Windows XP so to use it requires dynamic linking.  It is not clear
-  // how this affects the reported page size, if at all.  One could argue
-  // that LLVM ought to run as 64-bits on a 64-bit system, anyway.
+  // GetNativeSystemInfo() provides the physical page size which may differ
+  // from GetSystemInfo() in 32-bit applications running under WOW64.
   SYSTEM_INFO info;
-  GetSystemInfo(&info);
+  GetNativeSystemInfo(&info);
   // FIXME: FileOffset in MapViewOfFile() should be aligned to not dwPageSize,
   // but dwAllocationGranularity.
   return static_cast<unsigned>(info.dwPageSize);