MC: Separate creating a generic object writer from creating a target object writer. NFCI.

With this we gain a little flexibility in how the generic object
writer is created.

Part of PR37466.

Differential Revision: https://reviews.llvm.org/D47045

llvm-svn: 332868

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCAsmBackend.cpp b/llvm/lib/MC/MCAsmBackend.cpp
index 8406d232863..213ea525803 100644
--- a/llvm/lib/MC/MCAsmBackend.cpp
+++ b/llvm/lib/MC/MCAsmBackend.cpp
@@ -11,7 +11,12 @@
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/MC/MCCodePadder.h"
+#include "llvm/MC/MCELFObjectWriter.h"
 #include "llvm/MC/MCFixupKindInfo.h"
+#include "llvm/MC/MCMachObjectWriter.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCWasmObjectWriter.h"
+#include "llvm/MC/MCWinCOFFObjectWriter.h"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
@@ -23,6 +28,27 @@ MCAsmBackend::MCAsmBackend(support::endianness Endian)
 
 MCAsmBackend::~MCAsmBackend() = default;
 
+std::unique_ptr<MCObjectWriter>
+MCAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
+  auto TW = createObjectTargetWriter();
+  switch (TW->getFormat()) {
+  case Triple::ELF:
+    return createELFObjectWriter(cast<MCELFObjectTargetWriter>(std::move(TW)), OS,
+                                 Endian == support::little);
+  case Triple::MachO:
+    return createMachObjectWriter(cast<MCMachObjectTargetWriter>(std::move(TW)),
+                                  OS, Endian == support::little);
+  case Triple::COFF:
+    return createWinCOFFObjectWriter(
+        cast<MCWinCOFFObjectTargetWriter>(std::move(TW)), OS);
+  case Triple::Wasm:
+    return createWasmObjectWriter(cast<MCWasmObjectTargetWriter>(std::move(TW)),
+                                  OS);
+  default:
+    llvm_unreachable("unexpected object format");
+  }
+}
+
 Optional<MCFixupKind> MCAsmBackend::getFixupKind(StringRef Name) const {
   return None;
 }