Move the ARM specific parts of the ELF writer to Target/ARM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147115 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 286 insertions, 0 deletions

diff --git a/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp b/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
new file mode 100644
index 0000000..b669a48
--- /dev/null
+++ b/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
@@ -0,0 +1,286 @@
+//===-- X86ELFObjectWriter.cpp - X86 ELF Writer ---------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/ARMFixupKinds.h"
+#include "MCTargetDesc/ARMMCTargetDesc.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/MC/MCELFObjectWriter.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCValue.h"
+
+using namespace llvm;
+
+namespace {
+  class ARMELFObjectWriter : public MCELFObjectTargetWriter {
+    enum { DefaultEABIVersion = 0x05000000U };
+
+    const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
+                                   const MCValue &Target,
+                                   const MCFragment &F,
+                                   const MCFixup &Fixup,
+                                   bool IsPCRel) const;
+    unsigned GetRelocTypeInner(const MCValue &Target,
+                               const MCFixup &Fixup,
+                               bool IsPCRel) const;
+
+
+  public:
+    ARMELFObjectWriter(uint8_t OSABI);
+
+    virtual ~ARMELFObjectWriter();
+  protected:
+    virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
+                                  bool IsPCRel, bool IsRelocWithSymbol,
+                                  int64_t Addend) const;
+    virtual unsigned getEFlags() const;
+  };
+}
+
+ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI)
+  : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI,
+                            ELF::EM_ARM,
+                            /*HasRelocationAddend*/ false) {}
+
+ARMELFObjectWriter::~ARMELFObjectWriter() {}
+
+// FIXME: get the real EABI Version from the Triple.
+unsigned ARMELFObjectWriter::getEFlags() const {
+  return ELF::EF_ARM_EABIMASK & DefaultEABIVersion;
+}
+
+// In ARM, _MergedGlobals and other most symbols get emitted directly.
+// I.e. not as an offset to a section symbol.
+// This code is an approximation of what ARM/gcc does.
+
+STATISTIC(PCRelCount, "Total number of PIC Relocations");
+STATISTIC(NonPCRelCount, "Total number of non-PIC relocations");
+
+const MCSymbol *ARMELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm,
+                                                   const MCValue &Target,
+                                                   const MCFragment &F,
+                                                   const MCFixup &Fixup,
+                                                   bool IsPCRel) const {
+  const MCSymbol &Symbol = Target.getSymA()->getSymbol();
+  bool EmitThisSym = false;
+
+  const MCSectionELF &Section =
+    static_cast<const MCSectionELF&>(Symbol.getSection());
+  bool InNormalSection = true;
+  unsigned RelocType = 0;
+  RelocType = GetRelocTypeInner(Target, Fixup, IsPCRel);
+
+  DEBUG(
+      const MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
+      MCSymbolRefExpr::VariantKind Kind2;
+      Kind2 = Target.getSymB() ?  Target.getSymB()->getKind() :
+        MCSymbolRefExpr::VK_None;
+      dbgs() << "considering symbol "
+        << Section.getSectionName() << "/"
+        << Symbol.getName() << "/"
+        << " Rel:" << (unsigned)RelocType
+        << " Kind: " << (int)Kind << "/" << (int)Kind2
+        << " Tmp:"
+        << Symbol.isAbsolute() << "/" << Symbol.isDefined() << "/"
+        << Symbol.isVariable() << "/" << Symbol.isTemporary()
+        << " Counts:" << PCRelCount << "/" << NonPCRelCount << "\n");
+
+  if (IsPCRel) { ++PCRelCount;
+    switch (RelocType) {
+    default:
+      // Most relocation types are emitted as explicit symbols
+      InNormalSection =
+        StringSwitch<bool>(Section.getSectionName())
+        .Case(".data.rel.ro.local", false)
+        .Case(".data.rel", false)
+        .Case(".bss", false)
+        .Default(true);
+      EmitThisSym = true;
+      break;
+    case ELF::R_ARM_ABS32:
+      // But things get strange with R_ARM_ABS32
+      // In this case, most things that go in .rodata show up
+      // as section relative relocations
+      InNormalSection =
+        StringSwitch<bool>(Section.getSectionName())
+        .Case(".data.rel.ro.local", false)
+        .Case(".data.rel", false)
+        .Case(".rodata", false)
+        .Case(".bss", false)
+        .Default(true);
+      EmitThisSym = false;
+      break;
+    }
+  } else {
+    NonPCRelCount++;
+    InNormalSection =
+      StringSwitch<bool>(Section.getSectionName())
+      .Case(".data.rel.ro.local", false)
+      .Case(".rodata", false)
+      .Case(".data.rel", false)
+      .Case(".bss", false)
+      .Default(true);
+
+    switch (RelocType) {
+    default: EmitThisSym = true; break;
+    case ELF::R_ARM_ABS32: EmitThisSym = false; break;
+    }
+  }
+
+  if (EmitThisSym)
+    return &Symbol;
+  if (! Symbol.isTemporary() && InNormalSection) {
+    return &Symbol;
+  }
+  return NULL;
+}
+
+// Need to examine the Fixup when determining whether to 
+// emit the relocation as an explicit symbol or as a section relative
+// offset
+unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
+                                          const MCFixup &Fixup,
+                                          bool IsPCRel,
+                                          bool IsRelocWithSymbol,
+                                          int64_t Addend) const {
+  return GetRelocTypeInner(Target, Fixup, IsPCRel);
+}
+
+unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
+                                               const MCFixup &Fixup,
+                                               bool IsPCRel) const  {
+  MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
+    MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
+
+  unsigned Type = 0;
+  if (IsPCRel) {
+    switch ((unsigned)Fixup.getKind()) {
+    default: assert(0 && "Unimplemented");
+    case FK_Data_4:
+      switch (Modifier) {
+      default: llvm_unreachable("Unsupported Modifier");
+      case MCSymbolRefExpr::VK_None:
+        Type = ELF::R_ARM_REL32;
+        break;
+      case MCSymbolRefExpr::VK_ARM_TLSGD:
+        assert(0 && "unimplemented");
+        break;
+      case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
+        Type = ELF::R_ARM_TLS_IE32;
+        break;
+      }
+      break;
+    case ARM::fixup_arm_uncondbranch:
+      switch (Modifier) {
+      case MCSymbolRefExpr::VK_ARM_PLT:
+        Type = ELF::R_ARM_PLT32;
+        break;
+      default:
+        Type = ELF::R_ARM_CALL;
+        break;
+      }
+      break;
+    case ARM::fixup_arm_condbranch:
+      Type = ELF::R_ARM_JUMP24;
+      break;
+    case ARM::fixup_arm_movt_hi16:
+    case ARM::fixup_arm_movt_hi16_pcrel:
+      Type = ELF::R_ARM_MOVT_PREL;
+      break;
+    case ARM::fixup_arm_movw_lo16:
+    case ARM::fixup_arm_movw_lo16_pcrel:
+      Type = ELF::R_ARM_MOVW_PREL_NC;
+      break;
+    case ARM::fixup_t2_movt_hi16:
+    case ARM::fixup_t2_movt_hi16_pcrel:
+      Type = ELF::R_ARM_THM_MOVT_PREL;
+      break;
+    case ARM::fixup_t2_movw_lo16:
+    case ARM::fixup_t2_movw_lo16_pcrel:
+      Type = ELF::R_ARM_THM_MOVW_PREL_NC;
+      break;
+    case ARM::fixup_arm_thumb_bl:
+    case ARM::fixup_arm_thumb_blx:
+      switch (Modifier) {
+      case MCSymbolRefExpr::VK_ARM_PLT:
+        Type = ELF::R_ARM_THM_CALL;
+        break;
+      default:
+        Type = ELF::R_ARM_NONE;
+        break;
+      }
+      break;
+    }
+  } else {
+    switch ((unsigned)Fixup.getKind()) {
+    default: llvm_unreachable("invalid fixup kind!");
+    case FK_Data_4:
+      switch (Modifier) {
+      default: llvm_unreachable("Unsupported Modifier"); break;
+      case MCSymbolRefExpr::VK_ARM_GOT:
+        Type = ELF::R_ARM_GOT_BREL;
+        break;
+      case MCSymbolRefExpr::VK_ARM_TLSGD:
+        Type = ELF::R_ARM_TLS_GD32;
+        break;
+      case MCSymbolRefExpr::VK_ARM_TPOFF:
+        Type = ELF::R_ARM_TLS_LE32;
+        break;
+      case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
+        Type = ELF::R_ARM_TLS_IE32;
+        break;
+      case MCSymbolRefExpr::VK_None:
+        Type = ELF::R_ARM_ABS32;
+        break;
+      case MCSymbolRefExpr::VK_ARM_GOTOFF:
+        Type = ELF::R_ARM_GOTOFF32;
+        break;
+      }
+      break;
+    case ARM::fixup_arm_ldst_pcrel_12:
+    case ARM::fixup_arm_pcrel_10:
+    case ARM::fixup_arm_adr_pcrel_12:
+    case ARM::fixup_arm_thumb_bl:
+    case ARM::fixup_arm_thumb_cb:
+    case ARM::fixup_arm_thumb_cp:
+    case ARM::fixup_arm_thumb_br:
+      assert(0 && "Unimplemented");
+      break;
+    case ARM::fixup_arm_uncondbranch:
+      Type = ELF::R_ARM_CALL;
+      break;
+    case ARM::fixup_arm_condbranch:
+      Type = ELF::R_ARM_JUMP24;
+      break;
+    case ARM::fixup_arm_movt_hi16:
+      Type = ELF::R_ARM_MOVT_ABS;
+      break;
+    case ARM::fixup_arm_movw_lo16:
+      Type = ELF::R_ARM_MOVW_ABS_NC;
+      break;
+    case ARM::fixup_t2_movt_hi16:
+      Type = ELF::R_ARM_THM_MOVT_ABS;
+      break;
+    case ARM::fixup_t2_movw_lo16:
+      Type = ELF::R_ARM_THM_MOVW_ABS_NC;
+      break;
+    }
+  }
+
+  return Type;
+}
+
+MCObjectWriter *llvm::createARMELFObjectWriter(raw_ostream &OS,
+                                               uint8_t OSABI) {
+  MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI);
+  return createELFObjectWriter(MOTW, OS,  /*IsLittleEndian=*/true);
+}