[PATCH] D96626: Support: mapped_file_region: Pass MAP_NORESERVE to mmap

[Joseph Tremoulet via Phabricator via llvm-commits]

JosephTremoulet created this revision.
Herald added subscribers: dexonsmith, hiraditya, krytarowski, arichardson, emaste.
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This allows mapping larger files, delaying OOM failures until too many
pages of them are accessed.  This is makes the behavior of the
mapped_file_region in this regard consistent between its "Unix" and
"Windows" implementations.

Guard the code witih #if defined(MAP_NORESERVE), consistent with other
uses of MAP_NORESERVE in llvm-project, because some FreeBSD versions do
not provide this flag.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D96626

Files:
  llvm/lib/Support/Unix/Path.inc


Index: llvm/lib/Support/Unix/Path.inc
===================================================================
--- llvm/lib/Support/Unix/Path.inc
+++ llvm/lib/Support/Unix/Path.inc
@@ -815,6 +815,9 @@
 
   int flags = (Mode == readwrite) ? MAP_SHARED : MAP_PRIVATE;
   int prot = (Mode == readonly) ? PROT_READ : (PROT_READ | PROT_WRITE);
+#if defined(MAP_NORESERVE)
+  flags |= MAP_NORESERVE;
+#endif
 #if defined(__APPLE__)
   //----------------------------------------------------------------------
   // Newer versions of MacOSX have a flag that will allow us to read from


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