[Support] Renamed member 'Size' to 'AllocatedSize' in MemoryBlock and OwningMemoryBlock.

Rename member 'Size' to 'AllocatedSize' in order to provide a hint that the
allocated size may be different than the requested size. Comments are added to
clarify this point.  Updated the InMemoryBuffer in FileOutputBuffer.cpp to track
the requested buffer size.

Patch by Machiel van Hooren. Thanks Machiel!

https://reviews.llvm.org/D61599

llvm-svn: 361195

1 files changed, 11 insertions, 7 deletions

diff --git a/llvm/lib/Support/FileOutputBuffer.cpp b/llvm/lib/Support/FileOutputBuffer.cpp
index b0b817b4bdd..19ab2e9917a 100644
--- a/llvm/lib/Support/FileOutputBuffer.cpp
+++ b/llvm/lib/Support/FileOutputBuffer.cpp
@@ -75,20 +75,22 @@ private:
 // output file on commit(). This is used only when we cannot use OnDiskBuffer.
 class InMemoryBuffer : public FileOutputBuffer {
 public:
-  InMemoryBuffer(StringRef Path, MemoryBlock Buf, unsigned Mode)
-      : FileOutputBuffer(Path), Buffer(Buf), Mode(Mode) {}
+  InMemoryBuffer(StringRef Path, MemoryBlock Buf, std::size_t BufSize,
+                 unsigned Mode)
+      : FileOutputBuffer(Path), Buffer(Buf), BufferSize(BufSize),
+        Mode(Mode) {}
 
   uint8_t *getBufferStart() const override { return (uint8_t *)Buffer.base(); }
 
   uint8_t *getBufferEnd() const override {
-    return (uint8_t *)Buffer.base() + Buffer.size();
+    return (uint8_t *)Buffer.base() + BufferSize;
   }
 
-  size_t getBufferSize() const override { return Buffer.size(); }
+  size_t getBufferSize() const override { return BufferSize; }
 
   Error commit() override {
     if (FinalPath == "-") {
-      llvm::outs() << StringRef((const char *)Buffer.base(), Buffer.size());
+      llvm::outs() << StringRef((const char *)Buffer.base(), BufferSize);
       llvm::outs().flush();
       return Error::success();
     }
@@ -100,12 +102,14 @@ public:
             openFileForWrite(FinalPath, FD, CD_CreateAlways, OF_None, Mode))
       return errorCodeToError(EC);
     raw_fd_ostream OS(FD, /*shouldClose=*/true, /*unbuffered=*/true);
-    OS << StringRef((const char *)Buffer.base(), Buffer.size());
+    OS << StringRef((const char *)Buffer.base(), BufferSize);
     return Error::success();
   }
 
 private:
+  // Buffer may actually contain a larger memory block than BufferSize
   OwningMemoryBlock Buffer;
+  size_t BufferSize;
   unsigned Mode;
 };
 } // namespace
@@ -117,7 +121,7 @@ createInMemoryBuffer(StringRef Path, size_t Size, unsigned Mode) {
       Size, nullptr, sys::Memory::MF_READ | sys::Memory::MF_WRITE, EC);
   if (EC)
     return errorCodeToError(EC);
-  return llvm::make_unique<InMemoryBuffer>(Path, MB, Mode);
+  return llvm::make_unique<InMemoryBuffer>(Path, MB, Size, Mode);
 }
 
 static Expected<std::unique_ptr<FileOutputBuffer>>