5 files changed, 9 insertions, 6 deletions
diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index 3f13d4d3552..92e39e118b9 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -417,7 +417,7 @@ static ErrorOr<std::unique_ptr<MB>>
 getOpenFileImpl(int FD, const Twine &Filename, uint64_t FileSize,
                 uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
                 bool IsVolatile) {
-  static int PageSize = sys::Process::getPageSize();
+  static int PageSize = sys::Process::getPageSizeEstimate();
 
   // Default is to map the full file.
   if (MapSize == uint64_t(-1)) {
diff --git a/llvm/lib/Support/Unix/Memory.inc b/llvm/lib/Support/Unix/Memory.inc
index b8f5df5f72e..affdb7e70d9 100644
--- a/llvm/lib/Support/Unix/Memory.inc
+++ b/llvm/lib/Support/Unix/Memory.inc
@@ -103,7 +103,7 @@ Memory::allocateMappedMemory(size_t NumBytes,
   // Use any near hint and the page size to set a page-aligned starting address
   uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
                                       NearBlock->size() : 0;
-  static const size_t PageSize = Process::getPageSize();
+  static const size_t PageSize = Process::getPageSizeEstimate();
   if (Start && Start % PageSize)
     Start += PageSize - Start % PageSize;
 
@@ -149,7 +149,7 @@ Memory::releaseMappedMemory(MemoryBlock &M) {
 
 std::error_code
 Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
-  static const size_t PageSize = Process::getPageSize();
+  static const size_t PageSize = Process::getPageSizeEstimate();
   if (M.Address == nullptr || M.Size == 0)
     return std::error_code();
 
diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index fb14422ba33..c2f78e79b87 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -786,7 +786,7 @@ const char *mapped_file_region::const_data() const {
 }
 
 int mapped_file_region::alignment() {
-  return Process::getPageSize();
+  return Process::getPageSizeEstimate();
 }
 
 std::error_code detail::directory_iterator_construct(detail::DirIterState &it,
diff --git a/llvm/lib/Support/Unix/Process.inc b/llvm/lib/Support/Unix/Process.inc
index 7c834f97114..78c123493e1 100644
--- a/llvm/lib/Support/Unix/Process.inc
+++ b/llvm/lib/Support/Unix/Process.inc
@@ -69,7 +69,7 @@ static std::pair<std::chrono::microseconds, std::chrono::microseconds> getRUsage
 
 // On Cygwin, getpagesize() returns 64k(AllocationGranularity) and
 // offset in mmap(3) should be aligned to the AllocationGranularity.
-unsigned Process::getPageSize() {
+Expected<unsigned> Process::getPageSize() {
 #if defined(HAVE_GETPAGESIZE)
   static const int page_size = ::getpagesize();
 #elif defined(HAVE_SYSCONF)
@@ -77,6 +77,9 @@ unsigned Process::getPageSize() {
 #else
 #error Cannot get the page size on this machine
 #endif
+  if (page_size == -1)
+    return errorCodeToError(std::error_code(errno, std::generic_category()));
+
   return static_cast<unsigned>(page_size);
 }
 
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index b3c9aa0b83c..4b91f9f7fc6 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -56,7 +56,7 @@ static unsigned computePageSize() {
   return static_cast<unsigned>(info.dwPageSize);
 }
 
-unsigned Process::getPageSize() {
+Expected<unsigned> Process::getPageSize() {
   static unsigned Ret = computePageSize();
   return Ret;
 }