[llvm-branch-commits] [llvm] [HLSL] Refactor Offset calculation while writing Root Signatures. (PR #128577)

[Damyan Pepper via llvm-branch-commits]

================
@@ -7,53 +7,109 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/MC/DXContainerRootSignature.h"
-#include "llvm/Support/EndianStream.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+#include <cstdint>
+#include <sys/types.h>
 
 using namespace llvm;
 using namespace llvm::mcdxbc;
 
-void RootSignatureDesc::write(raw_ostream &OS) const {
-  // Root signature header in dxcontainer has 6 uint_32t values.
-  const uint32_t HeaderSize = 24;
-  const uint32_t ParameterByteSize = Parameters.size_in_bytes();
-  const uint32_t NumParametes = Parameters.size();
+Error setRewrite(BinaryStreamWriter &Stream, uint32_t &Offset) {
+  const uint32_t DummyValue = std::numeric_limits<uint32_t>::max();
+
+  Offset = Stream.getOffset();
+
+  if (Error Err = Stream.writeInteger(DummyValue))
+    return Err;
+
+  return Error::success();
+}
+
+Error rewriteOffset(BinaryStreamWriter &Stream, uint32_t Offset) {
+  uint64_t Value = Stream.getOffset();
+  Stream.setOffset(Offset);
+  if (Error Err = Stream.writeInteger((uint32_t)Value))
+    return Err;
+
+  Stream.setOffset(Value);
+
+  return Error::success();
+}
+
+Error RootSignatureDesc::write(raw_ostream &OS) const {
+  std::vector<uint8_t> Buffer(getSizeInBytes());
+  BinaryStreamWriter Writer(Buffer, llvm::endianness::little);
----------------
damyanp wrote:

Something like:

```c++
  buffer_ostream BS(OS);
  /// use BS as usual
  // buffer_ostream destructor writes everything written to BS to OS.
```


https://github.com/llvm/llvm-project/pull/128577