[flang-commits] [flang] 5c9aca1 - [flang] Descriptor-based I/O using wrong size for contiguous unformatted I/O

[peter klausler via flang-commits]

Author: peter klausler
Date: 2020-08-13T10:46:43-07:00
New Revision: 5c9aca1e9396c54151b066189748209554230b59

URL: https://github.com/llvm/llvm-project/commit/5c9aca1e9396c54151b066189748209554230b59
DIFF: https://github.com/llvm/llvm-project/commit/5c9aca1e9396c54151b066189748209554230b59.diff

LOG: [flang] Descriptor-based I/O using wrong size for contiguous unformatted I/O

The descriptor-based I/O routine was using the size of the descriptor
rather than the size of the described data for the transfer.  Fix,
and add a comment to the relevant API.

Differential Revision: https://reviews.llvm.org/D85863

Added: 
    

Modified: 
    flang/runtime/descriptor-io.h
    flang/runtime/descriptor.h

Removed: 
    


################################################################################
diff  --git a/flang/runtime/descriptor-io.h b/flang/runtime/descriptor-io.h
index 22ae4f9917ab..ce0f39740c5f 100644
--- a/flang/runtime/descriptor-io.h
+++ b/flang/runtime/descriptor-io.h
@@ -223,16 +223,16 @@ static bool DescriptorIO(IoStatementState &io, const Descriptor &descriptor) {
     std::size_t elementBytes{descriptor.ElementBytes()};
     SubscriptValue subscripts[maxRank];
     descriptor.GetLowerBounds(subscripts);
+    std::size_t numElements{descriptor.Elements()};
     if (descriptor.IsContiguous()) { // contiguous unformatted I/O
       char &x{ExtractElement<char>(io, descriptor, subscripts)};
-      auto totalBytes{descriptor.SizeInBytes()};
+      auto totalBytes{numElements * elementBytes};
       if constexpr (DIR == Direction::Output) {
         return unf->Emit(&x, totalBytes, elementBytes);
       } else {
         return unf->Receive(&x, totalBytes, elementBytes);
       }
     } else { // non-contiguous unformatted I/O
-      std::size_t numElements{descriptor.Elements()};
       for (std::size_t j{0}; j < numElements; ++j) {
         char &x{ExtractElement<char>(io, descriptor, subscripts)};
         if constexpr (DIR == Direction::Output) {

diff  --git a/flang/runtime/descriptor.h b/flang/runtime/descriptor.h
index 3462bb612dff..983d483788b9 100644
--- a/flang/runtime/descriptor.h
+++ b/flang/runtime/descriptor.h
@@ -255,6 +255,7 @@ class Descriptor {
     }
   }
 
+  // Returns size in bytes of the descriptor (not the data)
   static constexpr std::size_t SizeInBytes(
       int rank, bool addendum = false, int lengthTypeParameters = 0) {
     std::size_t bytes{sizeof(Descriptor) - sizeof(Dimension)};