Support/Process: Add comments about PageSize and AllocationGranularity on Cygwin and Win32.

llvm-svn: 189940

2 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Support/Unix/Process.inc b/llvm/lib/Support/Unix/Process.inc
index cd244f69e74..47d0a3c794d 100644
--- a/llvm/lib/Support/Unix/Process.inc
+++ b/llvm/lib/Support/Unix/Process.inc
@@ -88,8 +88,8 @@ TimeValue self_process::get_system_time() const {
   return getRUsageTimes().second;
 }
 
-// On Cygwin, getpagesize() returns 64k and offset in mmap(3) should be
-// aligned to its pagesize.
+// On Cygwin, getpagesize() returns 64k(AllocationGranularity) and
+// offset in mmap(3) should be aligned to the AllocationGranularity.
 static unsigned getPageSize() {
 #if defined(HAVE_GETPAGESIZE)
   const int page_size = ::getpagesize();
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index 38d5bc7e119..f840d064d8d 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -83,6 +83,8 @@ static unsigned getPageSize() {
   // that LLVM ought to run as 64-bits on a 64-bit system, anyway.
   SYSTEM_INFO info;
   GetSystemInfo(&info);
+  // FIXME: FileOffset in MapViewOfFile() should be aligned to not dwPageSize,
+  // but dwAllocationGranularity.
   return static_cast<unsigned>(info.dwPageSize);
 }