[Sparc] Add initial implementation of MC Code emitter for sparc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198533 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Sparc/MCTargetDesc/SparcAsmBackend.cpp

@@ -0,0 +1,101 @@
+//===-- SparcAsmBackend.cpp - Sparc Assembler Backend ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCAsmBackend.h"
+#include "MCTargetDesc/SparcMCTargetDesc.h"
+#include "MCTargetDesc/SparcFixupKinds.h"
+#include "llvm/MC/MCFixupKindInfo.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/Support/TargetRegistry.h"
+
+using namespace llvm;
+
+namespace {
+  class SparcAsmBackend : public MCAsmBackend {
+
+  public:
+    SparcAsmBackend(const Target &T) : MCAsmBackend() {}
+
+    unsigned getNumFixupKinds() const {
+      return Sparc::NumTargetFixupKinds;
+    }
+
+    const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const {
+      const static MCFixupKindInfo Infos[Sparc::NumTargetFixupKinds] = {
+        // name                    offset bits  flags
+        { "fixup_sparc_call30",     0,     30,  MCFixupKindInfo::FKF_IsPCRel },
+        { "fixup_sparc_br22",       0,     22,  MCFixupKindInfo::FKF_IsPCRel },
+        { "fixup_sparc_br19",       0,     19,  MCFixupKindInfo::FKF_IsPCRel }
+      };
+
+      if (Kind < FirstTargetFixupKind)
+        return MCAsmBackend::getFixupKindInfo(Kind);
+
+      assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
+             "Invalid kind!");
+      return Infos[Kind - FirstTargetFixupKind];
+    }
+
+    bool mayNeedRelaxation(const MCInst &Inst) const {
+      // FIXME.
+      return false;
+    }
+
+    /// fixupNeedsRelaxation - Target specific predicate for whether a given
+    /// fixup requires the associated instruction to be relaxed.
+    bool fixupNeedsRelaxation(const MCFixup &Fixup,
+                              uint64_t Value,
+                              const MCRelaxableFragment *DF,
+                              const MCAsmLayout &Layout) const {
+      // FIXME.
+      assert(0 && "fixupNeedsRelaxation() unimplemented");
+      return false;
+    }
+    void relaxInstruction(const MCInst &Inst, MCInst &Res) const {
+      // FIXME.
+      assert(0 && "relaxInstruction() unimplemented");
+    }
+
+    bool writeNopData(uint64_t Count, MCObjectWriter *OW) const {
+      // FIXME: Zero fill for now.
+      for (uint64_t i = 0; i != Count; ++i)
+        OW->Write8(0);
+      return true;
+    }
+  };
+
+  class ELFSparcAsmBackend : public SparcAsmBackend {
+  public:
+    ELFSparcAsmBackend(const Target &T, Triple::OSType OSType) :
+      SparcAsmBackend(T) { }
+
+    void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
+                    uint64_t Value) const {
+      assert(0 && "applyFixup not implemented yet");
+    }
+
+    MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
+      assert(0 && "Object Writer not implemented yet");
+      return 0;
+    }
+
+    virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
+      return false;
+    }
+  };
+
+} // end anonymous namespace
+
+
+MCAsmBackend *llvm::createSparcAsmBackend(const Target &T,
+                                          const MCRegisterInfo &MRI,
+                                          StringRef TT,
+                                          StringRef CPU) {
+  return new ELFSparcAsmBackend(T, Triple(TT).getOS());
+}