[flang-commits] [flang] 702c0cf - [flang] runtime perf: larger I/O buffer growth increments

[Peter Klausler via flang-commits]

Author: Peter Klausler
Date: 2022-01-31T14:53:15-08:00
New Revision: 702c0cfa07597af150b0556c97ce0431a7d1de59

URL: https://github.com/llvm/llvm-project/commit/702c0cfa07597af150b0556c97ce0431a7d1de59
DIFF: https://github.com/llvm/llvm-project/commit/702c0cfa07597af150b0556c97ce0431a7d1de59.diff

LOG: [flang] runtime perf: larger I/O buffer growth increments

When reallocating an I/O buffer to accommodate a large record,
ensure that the amount of growth is at least as large as the
minimum initial record size (64KiB).  The previous policy was
causing input buffer reallocation for each byte after the minimum
buffer size when scanning input data for record termination
newlines.

Differential Revision: https://reviews.llvm.org/D118649

Added: 
    

Modified: 
    flang/runtime/buffer.h

Removed: 
    


################################################################################
diff  --git a/flang/runtime/buffer.h b/flang/runtime/buffer.h
index eec28419a58f5..0bc3e0a37ded8 100644
--- a/flang/runtime/buffer.h
+++ b/flang/runtime/buffer.h
@@ -135,7 +135,7 @@ template <typename STORE, std::size_t minBuffer = 65536> class FileFrame {
     if (bytes > size_) {
       char *old{buffer_};
       auto oldSize{size_};
-      size_ = std::max<std::int64_t>(bytes, minBuffer);
+      size_ = std::max<std::int64_t>(bytes, size_ + minBuffer);
       buffer_ =
           reinterpret_cast<char *>(AllocateMemoryOrCrash(terminator, size_));
       auto chunk{std::min<std::int64_t>(length_, oldSize - start_)};