commit 03f1516d6075f42dce95bcf9fde3f6fde97abd35
author Fangrui Song <i@maskray.me> Tue Sep 15 10:20:08 2020 -0700
committer Fangrui Song <i@maskray.me> Tue Sep 15 10:21:05 2020 -0700
tree 7f2a5034466e1735bea1e3ad772cb98b68b01e8f
parent 3a59628f3cc26eb085acfc9cbdc97243ef71a6c5

[MemoryBuffer] Revert unintended MemoryBuffer change from D86996

Fixes SupportsTest MemoryBufferTest.mmapVolatileNoNull

llvm/lib/Support/MemoryBuffer.cpp

diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index e31c8e6..248fb72 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -457,7 +457,8 @@
     MapSize = FileSize;
   }
 
-  if (false) {
+  if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
+                    PageSize, IsVolatile)) {
     std::error_code EC;
     std::unique_ptr<MB> Result(
         new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile<MB>(