1 files changed, 149 insertions, 0 deletions
diff --git a/lib/ReaderWriter/ELF/Mips/MipsELFFlagsMerger.cpp b/lib/ReaderWriter/ELF/Mips/MipsELFFlagsMerger.cpp
new file mode 100644
index 0000000000000..0ef2c70b81564
--- /dev/null
+++ b/lib/ReaderWriter/ELF/Mips/MipsELFFlagsMerger.cpp
@@ -0,0 +1,149 @@
+//===- lib/ReaderWriter/ELF/MipsELFFlagsMerger.cpp ------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MipsELFFlagsMerger.h"
+#include "lld/Core/Error.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/ELF.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace lld;
+using namespace lld::elf;
+using namespace llvm::ELF;
+
+struct MipsISATreeEdge {
+  unsigned child;
+  unsigned parent;
+};
+
+static MipsISATreeEdge isaTree[] = {
+    // MIPS32R6 and MIPS64R6 are not compatible with other extensions
+
+    // MIPS64 extensions.
+    {EF_MIPS_ARCH_64R2, EF_MIPS_ARCH_64},
+    // MIPS V extensions.
+    {EF_MIPS_ARCH_64, EF_MIPS_ARCH_5},
+    // MIPS IV extensions.
+    {EF_MIPS_ARCH_5, EF_MIPS_ARCH_4},
+    // MIPS III extensions.
+    {EF_MIPS_ARCH_4, EF_MIPS_ARCH_3},
+    // MIPS32 extensions.
+    {EF_MIPS_ARCH_32R2, EF_MIPS_ARCH_32},
+    // MIPS II extensions.
+    {EF_MIPS_ARCH_3, EF_MIPS_ARCH_2},
+    {EF_MIPS_ARCH_32, EF_MIPS_ARCH_2},
+    // MIPS I extensions.
+    {EF_MIPS_ARCH_2, EF_MIPS_ARCH_1},
+};
+
+static bool matchMipsISA(unsigned base, unsigned ext) {
+  if (base == ext)
+    return true;
+  if (base == EF_MIPS_ARCH_32 && matchMipsISA(EF_MIPS_ARCH_64, ext))
+    return true;
+  if (base == EF_MIPS_ARCH_32R2 && matchMipsISA(EF_MIPS_ARCH_64R2, ext))
+    return true;
+  for (const auto &edge : isaTree) {
+    if (ext == edge.child) {
+      ext = edge.parent;
+      if (ext == base)
+        return true;
+    }
+  }
+  return false;
+}
+
+MipsELFFlagsMerger::MipsELFFlagsMerger(bool is64Bits)
+    : _is64Bit(is64Bits), _flags(0) {}
+
+uint32_t MipsELFFlagsMerger::getMergedELFFlags() const { return _flags; }
+
+std::error_code MipsELFFlagsMerger::merge(uint8_t newClass, uint32_t newFlags) {
+  // Check bitness.
+  if (_is64Bit != (newClass == ELFCLASS64))
+    return make_dynamic_error_code(
+        Twine("Bitness is incompatible with that of the selected target"));
+
+  // We support two ABI: O32 and N64. The last one does not have
+  // the corresponding ELF flag.
+  uint32_t inAbi = newFlags & EF_MIPS_ABI;
+  uint32_t supportedAbi = _is64Bit ? 0 : uint32_t(EF_MIPS_ABI_O32);
+  if (inAbi != supportedAbi)
+    return make_dynamic_error_code(Twine("Unsupported ABI"));
+
+  // ... and reduced set of architectures ...
+  uint32_t newArch = newFlags & EF_MIPS_ARCH;
+  switch (newArch) {
+  case EF_MIPS_ARCH_1:
+  case EF_MIPS_ARCH_2:
+  case EF_MIPS_ARCH_3:
+  case EF_MIPS_ARCH_4:
+  case EF_MIPS_ARCH_5:
+  case EF_MIPS_ARCH_32:
+  case EF_MIPS_ARCH_64:
+  case EF_MIPS_ARCH_32R2:
+  case EF_MIPS_ARCH_64R2:
+  case EF_MIPS_ARCH_32R6:
+  case EF_MIPS_ARCH_64R6:
+    break;
+  default:
+    return make_dynamic_error_code(Twine("Unsupported instruction set"));
+  }
+
+  // ... and still do not support MIPS-16 extension.
+  if (newFlags & EF_MIPS_ARCH_ASE_M16)
+    return make_dynamic_error_code(Twine("Unsupported extension: MIPS16"));
+
+  // PIC code is inherently CPIC and may not set CPIC flag explicitly.
+  // Ensure that this flag will exist in the linked file.
+  if (newFlags & EF_MIPS_PIC)
+    newFlags |= EF_MIPS_CPIC;
+
+  std::lock_guard<std::mutex> lock(_mutex);
+
+  // If the old set of flags is empty, use the new one as a result.
+  if (!_flags) {
+    _flags = newFlags;
+    return std::error_code();
+  }
+
+  // Check PIC / CPIC flags compatibility.
+  uint32_t newPic = newFlags & (EF_MIPS_PIC | EF_MIPS_CPIC);
+  uint32_t oldPic = _flags & (EF_MIPS_PIC | EF_MIPS_CPIC);
+
+  if ((newPic != 0) != (oldPic != 0))
+    llvm::errs() << "lld warning: linking abicalls and non-abicalls files\n";
+
+  if (!(newPic & EF_MIPS_PIC))
+    _flags &= ~EF_MIPS_PIC;
+  if (newPic)
+    _flags |= EF_MIPS_CPIC;
+
+  // Check mixing -mnan=2008 / -mnan=legacy modules.
+  if ((newFlags & EF_MIPS_NAN2008) != (_flags & EF_MIPS_NAN2008))
+    return make_dynamic_error_code(
+        Twine("Linking -mnan=2008 and -mnan=legacy modules"));
+
+  // Check ISA compatibility and update the extension flag.
+  uint32_t oldArch = _flags & EF_MIPS_ARCH;
+  if (!matchMipsISA(newArch, oldArch)) {
+    if (!matchMipsISA(oldArch, newArch))
+      return make_dynamic_error_code(
+          Twine("Linking modules with incompatible ISA"));
+    _flags &= ~EF_MIPS_ARCH;
+    _flags |= newArch;
+  }
+
+  _flags |= newFlags & EF_MIPS_NOREORDER;
+  _flags |= newFlags & EF_MIPS_MICROMIPS;
+  _flags |= newFlags & EF_MIPS_NAN2008;
+  _flags |= newFlags & EF_MIPS_32BITMODE;
+
+  return std::error_code();
+}