Move the resize file feature from mapped_file_region to the only user.

This removes a duplicated stat on every file that llvm-ar looks at.

llvm-svn: 224138

2 files changed, 5 insertions, 13 deletions

diff --git a/llvm/lib/Support/FileOutputBuffer.cpp b/llvm/lib/Support/FileOutputBuffer.cpp
index e6e4da34652..df4ae9322bc 100644
--- a/llvm/lib/Support/FileOutputBuffer.cpp
+++ b/llvm/lib/Support/FileOutputBuffer.cpp
@@ -77,6 +77,10 @@ FileOutputBuffer::create(StringRef FilePath, size_t Size,
   if (EC)
     return EC;
 
+  EC = sys::fs::resize_file(FD, Size);
+  if (EC)
+    return EC;
+
   auto MappedFile = llvm::make_unique<mapped_file_region>(
       FD, mapped_file_region::readwrite, Size, 0, EC);
   int Ret = close(FD);
diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index 75bcc03bbd3..bd6a605a93d 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -414,19 +414,7 @@ std::error_code setLastModificationAndAccessTime(int FD, TimeValue Time) {
 
 std::error_code mapped_file_region::init(int FD, uint64_t Offset,
                                          mapmode Mode) {
-  // Figure out how large the file is.
-  struct stat FileInfo;
-  if (fstat(FD, &FileInfo) == -1)
-    return std::error_code(errno, std::generic_category());
-  uint64_t FileSize = FileInfo.st_size;
-
-  if (Size == 0)
-    Size = FileSize;
-  else if (FileSize < Size) {
-    // We need to grow the file.
-    if (ftruncate(FD, Size) == -1)
-      return std::error_code(errno, std::generic_category());
-  }
+  assert(Size != 0);
 
   int flags = (Mode == readwrite) ? MAP_SHARED : MAP_PRIVATE;
   int prot = (Mode == readonly) ? PROT_READ : (PROT_READ | PROT_WRITE);