Merge pull request #1 from danc86/riscv

Support RISC-V

Author: alexcrichton

ELF/Arch/RISCV.cpp

@@ -0,0 +1,277 @@
+//===- RISCV.cpp ----------------------------------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "InputFiles.h"
+#include "Target.h"
+
+using namespace llvm;
+using namespace llvm::object;
+using namespace llvm::support::endian;
+using namespace llvm::ELF;
+using namespace lld;
+using namespace lld::elf;
+
+namespace {
+
+class RISCV final : public TargetInfo {
+public:
+  virtual uint32_t calcEFlags() const override;
+  RelExpr getRelExpr(RelType Type, const Symbol &S,
+                     const uint8_t *Loc) const override;
+  void relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const override;
+};
+
+} // end anonymous namespace
+
+static uint32_t getEFlags(InputFile *F) {
+  if (Config->Is64)
+    return cast<ObjFile<ELF64LE>>(F)->getObj().getHeader()->e_flags;
+  else
+    return cast<ObjFile<ELF32LE>>(F)->getObj().getHeader()->e_flags;
+}
+
+uint32_t RISCV::calcEFlags() const {
+  assert(!ObjectFiles.empty());
+
+  uint32_t Target = getEFlags(ObjectFiles.front());
+
+  for (InputFile *F : ObjectFiles) {
+    uint32_t EFlags = getEFlags(F);
+    if (EFlags & EF_RISCV_RVC)
+      Target |= EF_RISCV_RVC;
+
+    if ((EFlags & EF_RISCV_FLOAT_ABI) != (Target & EF_RISCV_FLOAT_ABI))
+      error(toString(F) +
+            ": cannot link object files with different floating-point ABI");
+
+    if ((EFlags & EF_RISCV_RVE) != (Target & EF_RISCV_RVE))
+      error(toString(F) +
+            ": cannot link object files with different EF_RISCV_RVE");
+  }
+
+  return Target;
+}
+
+RelExpr RISCV::getRelExpr(const RelType Type, const Symbol &S,
+                          const uint8_t *Loc) const {
+  switch (Type) {
+  case R_RISCV_JAL:
+  case R_RISCV_BRANCH:
+  case R_RISCV_CALL:
+  case R_RISCV_PCREL_HI20:
+  case R_RISCV_RVC_BRANCH:
+  case R_RISCV_RVC_JUMP:
+  case R_RISCV_32_PCREL:
+    return R_PC;
+  case R_RISCV_PCREL_LO12_I:
+  case R_RISCV_PCREL_LO12_S:
+    return R_RISCV_PC_INDIRECT;
+  case R_RISCV_RELAX:
+  case R_RISCV_ALIGN:
+    return R_HINT;
+  default:
+    return R_ABS;
+  }
+}
+
+// Extract bits V[Begin:End], where range is inclusive, and Begin must be < 63.
+static uint32_t extractBits(uint64_t V, uint32_t Begin, uint32_t End) {
+  return (V & ((1ULL << (Begin + 1)) - 1)) >> End;
+}
+
+void RISCV::relocateOne(uint8_t *Loc, const RelType Type,
+                        const uint64_t Val) const {
+  switch (Type) {
+  case R_RISCV_32:
+    write32le(Loc, Val);
+    return;
+  case R_RISCV_64:
+    write64le(Loc, Val);
+    return;
+
+  case R_RISCV_RVC_BRANCH: {
+    checkInt(Loc, static_cast<int64_t>(Val) >> 1, 8, Type);
+    checkAlignment(Loc, Val, 2, Type);
+    uint16_t Insn = read16le(Loc) & 0xE383;
+    uint16_t Imm8 = extractBits(Val, 8, 8) << 12;
+    uint16_t Imm4_3 = extractBits(Val, 4, 3) << 10;
+    uint16_t Imm7_6 = extractBits(Val, 7, 6) << 5;
+    uint16_t Imm2_1 = extractBits(Val, 2, 1) << 3;
+    uint16_t Imm5 = extractBits(Val, 5, 5) << 2;
+    Insn |= Imm8 | Imm4_3 | Imm7_6 | Imm2_1 | Imm5;
+
+    write16le(Loc, Insn);
+    return;
+  }
+
+  case R_RISCV_RVC_JUMP: {
+    checkInt(Loc, static_cast<int64_t>(Val) >> 1, 11, Type);
+    checkAlignment(Loc, Val, 2, Type);
+    uint16_t Insn = read16le(Loc) & 0xE003;
+    uint16_t Imm11 = extractBits(Val, 11, 11) << 12;
+    uint16_t Imm4 = extractBits(Val, 4, 4) << 11;
+    uint16_t Imm9_8 = extractBits(Val, 9, 8) << 9;
+    uint16_t Imm10 = extractBits(Val, 10, 10) << 8;
+    uint16_t Imm6 = extractBits(Val, 6, 6) << 7;
+    uint16_t Imm7 = extractBits(Val, 7, 7) << 6;
+    uint16_t Imm3_1 = extractBits(Val, 3, 1) << 3;
+    uint16_t Imm5 = extractBits(Val, 5, 5) << 2;
+    Insn |= Imm11 | Imm4 | Imm9_8 | Imm10 | Imm6 | Imm7 | Imm3_1 | Imm5;
+
+    write16le(Loc, Insn);
+    return;
+  }
+
+  case R_RISCV_RVC_LUI: {
+    int32_t Imm = ((Val + 0x800) >> 12);
+    checkUInt(Loc, Imm, 6, Type);
+    if (Imm == 0) { // `c.lui rd, 0` is illegal, convert to `c.li rd, 0`
+      write16le(Loc, (read16le(Loc) & 0x0F83) | 0x4000);
+    } else {
+      uint16_t Imm17 = extractBits(Val + 0x800, 17, 17) << 12;
+      uint16_t Imm16_12 = extractBits(Val + 0x800, 16, 12) << 2;
+      write16le(Loc, (read16le(Loc) & 0xEF83) | Imm17 | Imm16_12);
+    }
+    return;
+  }
+
+  case R_RISCV_JAL: {
+    checkInt(Loc, static_cast<int64_t>(Val) >> 1, 20, Type);
+    checkAlignment(Loc, Val, 2, Type);
+
+    uint32_t Insn = read32le(Loc) & 0xFFF;
+    uint32_t Imm20 = extractBits(Val, 20, 20) << 31;
+    uint32_t Imm10_1 = extractBits(Val, 10, 1) << 21;
+    uint32_t Imm11 = extractBits(Val, 11, 11) << 20;
+    uint32_t Imm19_12 = extractBits(Val, 19, 12) << 12;
+    Insn |= Imm20 | Imm10_1 | Imm11 | Imm19_12;
+
+    write32le(Loc, Insn);
+    return;
+  }
+
+  case R_RISCV_BRANCH: {
+    checkInt(Loc, static_cast<int64_t>(Val) >> 1, 12, Type);
+    checkAlignment(Loc, Val, 2, Type);
+
+    uint32_t Insn = read32le(Loc) & 0x1FFF07F;
+    uint32_t Imm12 = extractBits(Val, 12, 12) << 31;
+    uint32_t Imm10_5 = extractBits(Val, 10, 5) << 25;
+    uint32_t Imm4_1 = extractBits(Val, 4, 1) << 8;
+    uint32_t Imm11 = extractBits(Val, 11, 11) << 7;
+    Insn |= Imm12 | Imm10_5 | Imm4_1 | Imm11;
+
+    write32le(Loc, Insn);
+    return;
+  }
+
+  // auipc + jalr pair
+  case R_RISCV_CALL: {
+    checkInt(Loc, Val, 32, Type);
+    if (isInt<32>(Val)) {
+      relocateOne(Loc, R_RISCV_PCREL_HI20, Val);
+      relocateOne(Loc + 4, R_RISCV_PCREL_LO12_I, Val);
+    }
+    return;
+  }
+
+  case R_RISCV_PCREL_HI20:
+  case R_RISCV_HI20: {
+    checkInt(Loc, Val, 32, Type);
+    uint32_t Hi = Val + 0x800;
+    write32le(Loc, (read32le(Loc) & 0xFFF) | (Hi & 0xFFFFF000));
+    return;
+  }
+
+  case R_RISCV_PCREL_LO12_I:
+  case R_RISCV_LO12_I: {
+    checkInt(Loc, Val, 32, Type);
+    uint32_t Hi = Val + 0x800;
+    uint32_t Lo = Val - (Hi & 0xFFFFF000);
+    write32le(Loc, (read32le(Loc) & 0xFFFFF) | ((Lo & 0xFFF) << 20));
+    return;
+  }
+
+  case R_RISCV_PCREL_LO12_S:
+  case R_RISCV_LO12_S: {
+    checkInt(Loc, Val, 32, Type);
+    uint32_t Hi = Val + 0x800;
+    uint32_t Lo = Val - (Hi & 0xFFFFF000);
+    uint32_t Imm11_5 = extractBits(Lo, 11, 5) << 25;
+    uint32_t Imm4_0 = extractBits(Lo, 4, 0) << 7;
+    write32le(Loc, (read32le(Loc) & 0x1FFF07F) | Imm11_5 | Imm4_0);
+    return;
+  }
+
+  case R_RISCV_ADD8:
+    *Loc += Val;
+    return;
+  case R_RISCV_ADD16:
+    write16le(Loc, read16le(Loc) + Val);
+    return;
+  case R_RISCV_ADD32:
+    write32le(Loc, read32le(Loc) + Val);
+    return;
+  case R_RISCV_ADD64:
+    write64le(Loc, read64le(Loc) + Val);
+    return;
+  case R_RISCV_SUB6:
+    *Loc = (*Loc & 0xc0) | (((*Loc & 0x3f) - Val) & 0x3f);
+    return;
+  case R_RISCV_SUB8:
+    *Loc -= Val;
+    return;
+  case R_RISCV_SUB16:
+    write16le(Loc, read16le(Loc) - Val);
+    return;
+  case R_RISCV_SUB32:
+    write32le(Loc, read32le(Loc) - Val);
+    return;
+  case R_RISCV_SUB64:
+    write64le(Loc, read64le(Loc) - Val);
+    return;
+  case R_RISCV_SET6:
+    *Loc = (*Loc & 0xc0) | (Val & 0x3f);
+    return;
+  case R_RISCV_SET8:
+    *Loc = Val;
+    return;
+  case R_RISCV_SET16:
+    write16le(Loc, Val);
+    return;
+  case R_RISCV_SET32:
+  case R_RISCV_32_PCREL:
+    write32le(Loc, Val);
+    return;
+
+  case R_RISCV_ALIGN:
+  case R_RISCV_RELAX:
+    return; // Ignored (for now)
+  case R_RISCV_NONE:
+    return; // Do nothing
+
+  // These are handled by the dynamic linker
+  case R_RISCV_RELATIVE:
+  case R_RISCV_COPY:
+  case R_RISCV_JUMP_SLOT:
+  // GP-relative relocations are only produced after relaxation, which
+  // we don't support for now
+  case R_RISCV_GPREL_I:
+  case R_RISCV_GPREL_S:
+  default:
+    error(getErrorLocation(Loc) +
+          "unimplemented relocation: " + toString(Type));
+    return;
+  }
+}
+
+TargetInfo *elf::getRISCVTargetInfo() {
+  static RISCV Target;
+  return &Target;
+}

ELF/CMakeLists.txt

@@ -17,6 +17,7 @@ add_lld_library(lldELF
   Arch/MipsArchTree.cpp
   Arch/PPC.cpp
   Arch/PPC64.cpp
+  Arch/RISCV.cpp
   Arch/SPARCV9.cpp
   Arch/X86.cpp
   Arch/X86_64.cpp

ELF/Driver.cpp

@@ -125,9 +125,11 @@ static std::tuple<ELFKind, uint16_t, uint8_t> parseEmulation(StringRef Emul) {
           .Case("elf32_x86_64", {ELF32LEKind, EM_X86_64})
           .Cases("elf32btsmip", "elf32btsmipn32", {ELF32BEKind, EM_MIPS})
           .Cases("elf32ltsmip", "elf32ltsmipn32", {ELF32LEKind, EM_MIPS})
+          .Case("elf32lriscv", {ELF32LEKind, EM_RISCV})
           .Case("elf32ppc", {ELF32BEKind, EM_PPC})
           .Case("elf64btsmip", {ELF64BEKind, EM_MIPS})
           .Case("elf64ltsmip", {ELF64LEKind, EM_MIPS})
+          .Case("elf64lriscv", {ELF64LEKind, EM_RISCV})
           .Case("elf64ppc", {ELF64BEKind, EM_PPC64})
           .Case("elf64lppc", {ELF64LEKind, EM_PPC64})
           .Cases("elf_amd64", "elf_x86_64", {ELF64LEKind, EM_X86_64})
@@ -994,7 +996,8 @@ static void setConfigs(opt::InputArgList &Args) {
   // ABI defines which one you need to use. The following expression expresses
   // that.
   Config->IsRela =
-      (Config->Is64 || IsX32 || Machine == EM_PPC) && Machine != EM_MIPS;
+      (Config->Is64 || IsX32 || Machine == EM_PPC || Machine == EM_RISCV) &&
+      Machine != EM_MIPS;
 
   // If the output uses REL relocations we must store the dynamic relocation
   // addends to the output sections. We also store addends for RELA relocations

ELF/InputSection.cpp

@@ -487,6 +487,33 @@ static uint64_t getARMStaticBase(const Symbol &Sym) {
   return OS->PtLoad->FirstSec->Addr;
 }
 
+// For R_RISCV_PC_INDIRECT (R_RISCV_PCREL_LO12_{I,S}), the symbol actually
+// points the corresponding R_RISCV_PCREL_HI20 relocation, and the target VA
+// is calculated using PCREL_HI20's symbol.
+//
+// This function returns the R_RISCV_PCREL_HI20 relocation from
+// R_RISCV_PCREL_LO12's symbol and addend.
+Relocation *lld::elf::getRISCVPCRelHi20(const Symbol *Sym, uint64_t Addend) {
+  const Defined *D = cast<Defined>(Sym);
+  InputSection *IS = cast<InputSection>(D->Section);
+
+  if (Addend != 0)
+    warn("Non-zero addend in R_RISCV_PCREL_LO12 relocation to " +
+         IS->getObjMsg(D->Value) + " is ignored");
+
+  // Relocations are sorted by offset, so we can use std::equal_range to do
+  // binary search.
+  auto Range = std::equal_range(IS->Relocations.begin(), IS->Relocations.end(),
+                                D->Value, RelocationOffsetComparator{});
+  for (auto It = std::get<0>(Range); It != std::get<1>(Range); ++It)
+    if (isRelExprOneOf<R_PC>(It->Expr))
+      return &*It;
+
+  error("R_RISCV_PCREL_LO12 relocation points to " + IS->getObjMsg(D->Value) +
+        " without an associated R_RISCV_PCREL_HI20 relocation");
+  return nullptr;
+}
+
 static uint64_t getRelocTargetVA(const InputFile *File, RelType Type, int64_t A,
                                  uint64_t P, const Symbol &Sym, RelExpr Expr) {
   switch (Expr) {
@@ -578,6 +605,13 @@ static uint64_t getRelocTargetVA(const InputFile *File, RelType Type, int64_t A,
       Dest = getAArch64Page(Sym.getVA(A));
     return Dest - getAArch64Page(P);
   }
+  case R_RISCV_PC_INDIRECT: {
+    const Relocation *HiRel = getRISCVPCRelHi20(&Sym, A);
+    if (!HiRel)
+      return 0;
+    return getRelocTargetVA(File, HiRel->Type, HiRel->Addend, Sym.getVA(),
+                            *HiRel->Sym, HiRel->Expr);
+  }
   case R_PC: {
     uint64_t Dest;
     if (Sym.isUndefWeak()) {

ELF/InputSection.h

@@ -353,6 +353,8 @@ class InputSection : public InputSectionBase {
 
 // The list of all input sections.
 extern std::vector<InputSectionBase *> InputSections;
+
+Relocation *getRISCVPCRelHi20(const Symbol *Sym, const uint64_t Addend);
 } // namespace elf
 
 std::string toString(const elf::InputSectionBase *);

ELF/Relocations.cpp

@@ -1047,6 +1047,11 @@ static void scanRelocs(InputSectionBase &Sec, ArrayRef<RelTy> Rels) {
 
   for (auto I = Rels.begin(), End = Rels.end(); I != End;)
     scanReloc<ELFT>(Sec, GetOffset, I, End);
+
+  // Sort relocations by offset to binary search for R_RISCV_PCREL_HI20
+  if (Config->EMachine == EM_RISCV)
+    std::stable_sort(Sec.Relocations.begin(), Sec.Relocations.end(),
+                     RelocationOffsetComparator{});
 }
 
 template <class ELFT> void elf::scanRelocations(InputSectionBase &S) {