[PATCH] D116603: [AIX][z/OS][Support] Provide alternate mapped_file_region::dontNeedImpl implementations

[David Tenty via Phabricator via llvm-commits]

daltenty created this revision.
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mapped_file_region::dontNeedImpl added in D116366 <https://reviews.llvm.org/D116366> calls madvise, which causes problems for z/OS and AIX.

For AIX, it doesn't have a standardized signature, so it'd require additional casts and it needs certain feature test macros (i.e. _ALL_SOURCE) we don't set by default on AIX, so prefer posix_madvise.

For z/OS, we don't have either madvise, so treat this as a no-op, same as Windows does.


https://reviews.llvm.org/D116603

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
@@ -873,7 +873,16 @@
 void mapped_file_region::dontNeedImpl() {
   assert(Mode == mapped_file_region::readonly);
   if (Mapping)
+#if defined(__MVS__)
+    // z/OS doesn't have either madvise, so treat this as a nop.
+    return;
+#elif defined(_AIX)
+    // Prefer the POSIX implementation on AIX, since the signature for madvise is non-standardised
+    // and only exists with certain feature test macros.
+    ::posix_madvise(Mapping, Size, POSIX_MADV_DONTNEED);
+#else
     ::madvise(Mapping, Size, MADV_DONTNEED);
+#endif
 }

 int mapped_file_region::alignment() {


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