[mlir] BytecodeWriter: invoke `reserveExtraSpace` (#126953)

Update `BytecodeWriter` to invoke `reserveExtraSpace` on the stream
before writing to it. This will give clients implementing custom output
streams the opportunity to allocate an appropriately sized buffer for
the write.

1 files changed, 3 insertions, 0 deletions

diff --git a/mlir/lib/Bytecode/Writer/BytecodeWriter.cpp b/mlir/lib/Bytecode/Writer/BytecodeWriter.cpp
index 2b4697434717..cc5aaed41651 100644
--- a/mlir/lib/Bytecode/Writer/BytecodeWriter.cpp
+++ b/mlir/lib/Bytecode/Writer/BytecodeWriter.cpp
@@ -613,6 +613,9 @@ private:
 } // namespace
 
 void EncodingEmitter::writeTo(raw_ostream &os) const {
+  // Reserve space in the ostream for the encoded contents.
+  os.reserveExtraSpace(size());
+
   for (auto &prevResult : prevResultList)
     os.write((const char *)prevResult.data(), prevResult.size());
   os.write((const char *)currentResult.data(), currentResult.size());