[NFC] Refactor byteswapped writes

[beanz]

Summary

This is an extremely small refactoring to writing byte-swapped values
in the PSV data. I've broken the PPC-BE bots a few times with changes
here because of the fragility of how byte-swapping was being done. This
should make it less likely for me to break BE builders in the future.

[bob80905]

llvm/lib/MC/DXContainerPSVInfo.cpp

19

Am I understanding this correctly:
This function is only implemented for all integral types, and always returns void?

[efriedma]

llvm/lib/MC/DXContainerPSVInfo.cpp

20

Please use the existing helpers in EndianStream.h.

[beanz]

Updating to use support::endian::write. Thank you @efriedma!

[bogner]

lg

llvm/lib/MC/DXContainerPSVInfo.cpp

 //===- llvm/MC/DXContainerPSVInfo.cpp - DXContainer PSVInfo -----*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/MC/DXContainerPSVInfo.h"
 #include "llvm/BinaryFormat/DXContainer.h"
+#include "llvm/Support/EndianStream.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 using namespace llvm::mcdxbc;
 using namespace llvm::dxbc::PSV;
 
 void PSVRuntimeInfo::write(raw_ostream &OS, uint32_t Version) const {
   uint32_t InfoSize;
   uint32_t BindingSize;
   switch (Version) {
   case 0:
     InfoSize = sizeof(dxbc::PSV::v0::RuntimeInfo);
     BindingSize = sizeof(dxbc::PSV::v0::ResourceBindInfo);
     break;
   case 1:
     InfoSize = sizeof(dxbc::PSV::v1::RuntimeInfo);
     BindingSize = sizeof(dxbc::PSV::v0::ResourceBindInfo);
     break;
   case 2:
   default:
     InfoSize = sizeof(dxbc::PSV::v2::RuntimeInfo);
     BindingSize = sizeof(dxbc::PSV::v2::ResourceBindInfo);
   }
-  uint32_t InfoSizeSwapped = InfoSize;
-  if (sys::IsBigEndianHost)
-    sys::swapByteOrder(InfoSizeSwapped);
   // Write the size of the info.
-  OS.write(reinterpret_cast<const char *>(&InfoSizeSwapped), sizeof(uint32_t));
+
+  support::endian::write(OS, InfoSize, support::little);
   // Write the info itself.
   OS.write(reinterpret_cast<const char *>(&BaseData), InfoSize);
 
   uint32_t ResourceCount = static_cast<uint32_t>(Resources.size());
-  uint32_t BindingSizeSwapped = BindingSize;
-  if (sys::IsBigEndianHost) {
-    sys::swapByteOrder(ResourceCount);
-    sys::swapByteOrder(BindingSizeSwapped);
-  }
 
-  OS.write(reinterpret_cast<const char *>(&ResourceCount), sizeof(uint32_t));
-  OS.write(reinterpret_cast<const char *>(&BindingSizeSwapped),
-           sizeof(uint32_t));
+  support::endian::write(OS, ResourceCount, support::little);
+  support::endian::write(OS, BindingSize, support::little);
 
   for (const auto &Res : Resources)
     OS.write(reinterpret_cast<const char *>(&Res), BindingSize);
 }