[mips] Implement the R_MIPS_JALR and R_MICROMIPS_JALR relocations.

[tomatabacu]

Summary

These relocations are used for expanding JAL instructions when PIC is enabled.

Here's the reference I used for this implementation:
http://dmz-portal.mips.com/wiki/MIPS_relocation_types#Relocation_Table

For more information about what these relocations mean, see:
http://dmz-portal.mips.com/wiki/MIPS_relocation_types#R_MIPS_JALR

[tomatabacu]

This relocation is not needed by D6231 any more, so there's no point in implementing it ATM (especially since there are no explicit tests for it).

[joerg]

What about http://llvm.org/bugs/show_bug.cgi?id=19872

[tomatabacu]

In D6230#6, @joerg wrote:

What about http://llvm.org/bugs/show_bug.cgi?id=19872

I've searched around a bit and I found this patch from Dec 2013: http://reviews.llvm.org/D2393.

Unfortunately, this is not high up on my todo list, but I'll try to take a look at it when I start doing more IAS work.

include/llvm/MC/MCExpr.h

enum VariantKind {
     VK_Mips_HIGHER,
     VK_Mips_HIGHEST,
     VK_Mips_GOT_HI16,
     VK_Mips_GOT_LO16,
     VK_Mips_CALL_HI16,
     VK_Mips_CALL_LO16,
     VK_Mips_PCREL_HI16,
     VK_Mips_PCREL_LO16,
+    VK_Mips_JALR,
 
     VK_COFF_IMGREL32 // symbol@imgrel (image-relative)
   };
 
 private:
   /// The symbol reference modifier.
   const unsigned Kind : 16;
 

include/llvm/Support/ELF.h

enum {
   R_MICROMIPS_HI16         = 134,
   R_MICROMIPS_LO16         = 135,
   R_MICROMIPS_GOT16        = 138,
   R_MICROMIPS_PC16_S1      = 141,
   R_MICROMIPS_CALL16       = 142,
   R_MICROMIPS_GOT_DISP     = 145,
   R_MICROMIPS_GOT_PAGE     = 146,
   R_MICROMIPS_GOT_OFST     = 147,
+  R_MICROMIPS_JALR         = 156,
   R_MICROMIPS_TLS_GD          = 162,
   R_MICROMIPS_TLS_LDM         = 163,
   R_MICROMIPS_TLS_DTPREL_HI16 = 164,
   R_MICROMIPS_TLS_DTPREL_LO16 = 165,
   R_MICROMIPS_TLS_TPREL_HI16  = 169,
   R_MICROMIPS_TLS_TPREL_LO16  = 170,
   R_MIPS_NUM               = 218,
   R_MIPS_PC32              = 248

lib/MC/MCExpr.cpp

StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
   case VK_Mips_HIGHER:   return "HIGHER";
   case VK_Mips_HIGHEST:  return "HIGHEST";
   case VK_Mips_GOT_HI16: return "GOT_HI16";
   case VK_Mips_GOT_LO16: return "GOT_LO16";
   case VK_Mips_CALL_HI16: return "CALL_HI16";
   case VK_Mips_CALL_LO16: return "CALL_LO16";
   case VK_Mips_PCREL_HI16: return "PCREL_HI16";
   case VK_Mips_PCREL_LO16: return "PCREL_LO16";
+  case VK_Mips_JALR: return "JALR";
   case VK_COFF_IMGREL32: return "IMGREL";
   }
   llvm_unreachable("Invalid variant kind");
 }
 
 MCSymbolRefExpr::VariantKind
 MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
   return StringSwitch<VariantKind>(Name)

lib/Object/ELF.cpp

switch (Type) {
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_HI16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_LO16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_GOT16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_PC16_S1);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_CALL16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_GOT_DISP);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_GOT_PAGE);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_GOT_OFST);
+      LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_JALR);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_TLS_GD);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_TLS_LDM);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_TLS_DTPREL_HI16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_TLS_DTPREL_LO16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_TLS_TPREL_HI16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MICROMIPS_TLS_TPREL_LO16);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MIPS_NUM);
       LLVM_ELF_SWITCH_RELOC_TYPE_NAME(R_MIPS_PC32);

lib/Object/ELFYAML.cpp

case ELF::EM_MIPS:
     ECase(R_MICROMIPS_HI16)
     ECase(R_MICROMIPS_LO16)
     ECase(R_MICROMIPS_GOT16)
     ECase(R_MICROMIPS_PC16_S1)
     ECase(R_MICROMIPS_CALL16)
     ECase(R_MICROMIPS_GOT_DISP)
     ECase(R_MICROMIPS_GOT_PAGE)
     ECase(R_MICROMIPS_GOT_OFST)
+    ECase(R_MICROMIPS_JALR)
     ECase(R_MICROMIPS_TLS_GD)
     ECase(R_MICROMIPS_TLS_LDM)
     ECase(R_MICROMIPS_TLS_DTPREL_HI16)
     ECase(R_MICROMIPS_TLS_DTPREL_LO16)
     ECase(R_MICROMIPS_TLS_TPREL_HI16)
     ECase(R_MICROMIPS_TLS_TPREL_LO16)
     ECase(R_MIPS_NUM)
     ECase(R_MIPS_PC32)

lib/Target/Mips/InstPrinter/MipsInstPrinter.cpp

static void printExpr(const MCExpr *Expr, raw_ostream &OS) {
   case MCSymbolRefExpr::VK_Mips_HIGHER:    OS << "%higher("; break;
   case MCSymbolRefExpr::VK_Mips_HIGHEST:   OS << "%highest("; break;
   case MCSymbolRefExpr::VK_Mips_GOT_HI16:  OS << "%got_hi("; break;
   case MCSymbolRefExpr::VK_Mips_GOT_LO16:  OS << "%got_lo("; break;
   case MCSymbolRefExpr::VK_Mips_CALL_HI16: OS << "%call_hi("; break;
   case MCSymbolRefExpr::VK_Mips_CALL_LO16: OS << "%call_lo("; break;
   case MCSymbolRefExpr::VK_Mips_PCREL_HI16: OS << "%pcrel_hi("; break;
   case MCSymbolRefExpr::VK_Mips_PCREL_LO16: OS << "%pcrel_lo("; break;
+  case MCSymbolRefExpr::VK_Mips_JALR: break;
   }
 
   OS << SRE->getSymbol();
 
   if (Offset) {
     if (Offset > 0)
       OS << '+';
     OS << Offset;
   }
 
   if ((Kind == MCSymbolRefExpr::VK_Mips_GPOFF_HI) ||
       (Kind == MCSymbolRefExpr::VK_Mips_GPOFF_LO))
     OS << ")))";
-  else if (Kind != MCSymbolRefExpr::VK_None)
+  else if (Kind != MCSymbolRefExpr::VK_None &&
+           Kind != MCSymbolRefExpr::VK_Mips_JALR)
     OS << ')';
 }
 
 void MipsInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
                                    raw_ostream &O) {
   const MCOperand &Op = MI->getOperand(OpNo);
   if (Op.isReg()) {
     printRegName(O, Op.getReg());

lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp

static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
   case Mips::fixup_Mips_GOT_DISP:
   case Mips::fixup_Mips_GOT_LO16:
   case Mips::fixup_Mips_CALL_LO16:
   case Mips::fixup_MICROMIPS_LO16:
   case Mips::fixup_MICROMIPS_GOT_PAGE:
   case Mips::fixup_MICROMIPS_GOT_OFST:
   case Mips::fixup_MICROMIPS_GOT_DISP:
   case Mips::fixup_MIPS_PCLO16:
+  case Mips::fixup_MIPS_JALR:
+  case Mips::fixup_MICROMIPS_JALR:
     break;
   case Mips::fixup_Mips_PC16:
     // So far we are only using this type for branches.
     // For branches we start 1 instruction after the branch
     // so the displacement will be one instruction size less.
     Value -= 4;
     // The displacement is then divided by 4 to give us an 18 bit
     // address range. Forcing a signed division because Value can be negative.
const static MCFixupKindInfo LittleEndianInfos[Mips::NumTargetFixupKinds] = {
     { "fixup_Mips_CALL_HI16",    0,     16,   0 },
     { "fixup_Mips_CALL_LO16",    0,     16,   0 },
     { "fixup_Mips_PC18_S3",      0,     18,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PC19_S2",      0,     19,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PC21_S2",      0,     21,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PC26_S2",      0,     26,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PCHI16",       0,     16,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PCLO16",       0,     16,  MCFixupKindInfo::FKF_IsPCRel },
+    { "fixup_MIPS_JALR",         0,     32,   0 },
     { "fixup_MICROMIPS_26_S1",   0,     26,   0 },
     { "fixup_MICROMIPS_HI16",    0,     16,   0 },
     { "fixup_MICROMIPS_LO16",    0,     16,   0 },
     { "fixup_MICROMIPS_GOT16",   0,     16,   0 },
     { "fixup_MICROMIPS_PC16_S1", 0,     16,   MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MICROMIPS_CALL16",  0,     16,   0 },
     { "fixup_MICROMIPS_GOT_DISP",        0,     16,   0 },
     { "fixup_MICROMIPS_GOT_PAGE",        0,     16,   0 },
     { "fixup_MICROMIPS_GOT_OFST",        0,     16,   0 },
+    { "fixup_MICROMIPS_JALR",            0,     32,   0 },
     { "fixup_MICROMIPS_TLS_GD",          0,     16,   0 },
     { "fixup_MICROMIPS_TLS_LDM",         0,     16,   0 },
     { "fixup_MICROMIPS_TLS_DTPREL_HI16", 0,     16,   0 },
     { "fixup_MICROMIPS_TLS_DTPREL_LO16", 0,     16,   0 },
     { "fixup_MICROMIPS_TLS_TPREL_HI16",  0,     16,   0 },
     { "fixup_MICROMIPS_TLS_TPREL_LO16",  0,     16,   0 }
   };
 
const static MCFixupKindInfo BigEndianInfos[Mips::NumTargetFixupKinds] = {
     { "fixup_Mips_CALL_HI16",   16,     16,   0 },
     { "fixup_Mips_CALL_LO16",   16,     16,   0 },
     { "fixup_Mips_PC18_S3",     14,     18,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PC19_S2",     13,     19,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PC21_S2",     11,     21,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PC26_S2",      6,     26,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PCHI16",      16,     16,  MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MIPS_PCLO16",      16,     16,  MCFixupKindInfo::FKF_IsPCRel },
+    { "fixup_MIPS_JALR",         0,     32,   0 },
     { "fixup_MICROMIPS_26_S1",   6,     26,   0 },
     { "fixup_MICROMIPS_HI16",   16,     16,   0 },
     { "fixup_MICROMIPS_LO16",   16,     16,   0 },
     { "fixup_MICROMIPS_GOT16",  16,     16,   0 },
     { "fixup_MICROMIPS_PC16_S1",16,     16,   MCFixupKindInfo::FKF_IsPCRel },
     { "fixup_MICROMIPS_CALL16", 16,     16,   0 },
     { "fixup_MICROMIPS_GOT_DISP",        16,     16,   0 },
     { "fixup_MICROMIPS_GOT_PAGE",        16,     16,   0 },
     { "fixup_MICROMIPS_GOT_OFST",        16,     16,   0 },
+    { "fixup_MICROMIPS_JALR",            0,      32,   0 },
     { "fixup_MICROMIPS_TLS_GD",          16,     16,   0 },
     { "fixup_MICROMIPS_TLS_LDM",         16,     16,   0 },
     { "fixup_MICROMIPS_TLS_DTPREL_HI16", 16,     16,   0 },
     { "fixup_MICROMIPS_TLS_DTPREL_LO16", 16,     16,   0 },
     { "fixup_MICROMIPS_TLS_TPREL_HI16",  16,     16,   0 },
     { "fixup_MICROMIPS_TLS_TPREL_LO16",  16,     16,   0 }
   };
 

lib/Target/Mips/MCTargetDesc/MipsELFObjectWriter.cpp

case Mips::fixup_MICROMIPS_GOT_DISP:
     Type = ELF::R_MICROMIPS_GOT_DISP;
     break;
   case Mips::fixup_MICROMIPS_GOT_PAGE:
     Type = ELF::R_MICROMIPS_GOT_PAGE;
     break;
   case Mips::fixup_MICROMIPS_GOT_OFST:
     Type = ELF::R_MICROMIPS_GOT_OFST;
     break;
+  case Mips::fixup_MICROMIPS_JALR:
+    Type = ELF::R_MICROMIPS_JALR;
+    break;
   case Mips::fixup_MICROMIPS_TLS_GD:
     Type = ELF::R_MICROMIPS_TLS_GD;
     break;
   case Mips::fixup_MICROMIPS_TLS_LDM:
     Type = ELF::R_MICROMIPS_TLS_LDM;
     break;
   case Mips::fixup_MICROMIPS_TLS_DTPREL_HI16:
     Type = ELF::R_MICROMIPS_TLS_DTPREL_HI16;
case Mips::fixup_MIPS_PC26_S2:
     Type = ELF::R_MIPS_PC26_S2;
     break;
   case Mips::fixup_MIPS_PCHI16:
     Type = ELF::R_MIPS_PCHI16;
     break;
   case Mips::fixup_MIPS_PCLO16:
     Type = ELF::R_MIPS_PCLO16;
     break;
+  case Mips::fixup_MIPS_JALR:
+    Type = ELF::R_MIPS_JALR;
+    break;
   }
   return Type;
 }
 
 bool
 MipsELFObjectWriter::needsRelocateWithSymbol(const MCSymbolData &SD,
                                              unsigned Type) const {
   // FIXME: This is extremelly conservative. This really needs to use a

lib/Target/Mips/MCTargetDesc/MipsFixupKinds.h

enum Fixups {
     fixup_MIPS_PC26_S2,
 
     // resulting in - R_MIPS_PCHI16
     fixup_MIPS_PCHI16,
 
     // resulting in - R_MIPS_PCLO16
     fixup_MIPS_PCLO16,
 
+    // resulting in - R_MIPS_JALR
+    fixup_MIPS_JALR,
+
     // resulting in - R_MICROMIPS_26_S1
     fixup_MICROMIPS_26_S1,
 
     // resulting in - R_MICROMIPS_HI16
     fixup_MICROMIPS_HI16,
 
     // resulting in - R_MICROMIPS_LO16
     fixup_MICROMIPS_LO16,
enum Fixups {
     fixup_MICROMIPS_GOT_DISP,
 
     // resulting in - R_MICROMIPS_GOT_PAGE
     fixup_MICROMIPS_GOT_PAGE,
 
     // resulting in - R_MICROMIPS_GOT_OFST
     fixup_MICROMIPS_GOT_OFST,
 
+    // resulting in - R_MICROMIPS_JALR
+    fixup_MICROMIPS_JALR,
+
     // resulting in - R_MICROMIPS_TLS_GD
     fixup_MICROMIPS_TLS_GD,
 
     // resulting in - R_MICROMIPS_TLS_LDM
     fixup_MICROMIPS_TLS_LDM,
 
     // resulting in - R_MICROMIPS_TLS_DTPREL_HI16
     fixup_MICROMIPS_TLS_DTPREL_HI16,

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp

if (Kind == MCExpr::SymbolRef) {
     case MCSymbolRefExpr::VK_Mips_ABS_HI:
       FixupKind = isMicroMips(STI) ? Mips::fixup_MICROMIPS_HI16
                               : Mips::fixup_Mips_HI16;
       break;
     case MCSymbolRefExpr::VK_Mips_ABS_LO:
       FixupKind = isMicroMips(STI) ? Mips::fixup_MICROMIPS_LO16
                               : Mips::fixup_Mips_LO16;
       break;
+    case MCSymbolRefExpr::VK_Mips_JALR:
+      FixupKind = isMicroMips(STI) ? Mips::fixup_MICROMIPS_JALR
+                              : Mips::fixup_MIPS_JALR;
+      break;
     case MCSymbolRefExpr::VK_Mips_TLSGD:
       FixupKind = isMicroMips(STI) ? Mips::fixup_MICROMIPS_TLS_GD
                               : Mips::fixup_Mips_TLSGD;
       break;
     case MCSymbolRefExpr::VK_Mips_TLSLDM:
       FixupKind = isMicroMips(STI) ? Mips::fixup_MICROMIPS_TLS_LDM
                               : Mips::fixup_Mips_TLSLDM;
       break;