[bpf] add big- and host- endian support

Summary:
-march=bpf    -> host endian
-march=bpf_le -> little endian
-match=bpf_be -> big endian

Test Plan:
v1 was tested by IBM s390 guys and appears to be working there.
It bit rots too fast here.

Reviewers: chandlerc, tstellarAMD

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10177

llvm-svn: 239071

9 files changed, 130 insertions, 46 deletions

diff --git a/llvm/lib/Target/BPF/BPFAsmPrinter.cpp b/llvm/lib/Target/BPF/BPFAsmPrinter.cpp
index 32375968eac..10ec6587550 100644
--- a/llvm/lib/Target/BPF/BPFAsmPrinter.cpp
+++ b/llvm/lib/Target/BPF/BPFAsmPrinter.cpp
@@ -83,5 +83,7 @@ void BPFAsmPrinter::EmitInstruction(const MachineInstr *MI) {
 
 // Force static initialization.
 extern "C" void LLVMInitializeBPFAsmPrinter() {
-  RegisterAsmPrinter<BPFAsmPrinter> X(TheBPFTarget);
+  RegisterAsmPrinter<BPFAsmPrinter> X(TheBPFleTarget);
+  RegisterAsmPrinter<BPFAsmPrinter> Y(TheBPFbeTarget);
+  RegisterAsmPrinter<BPFAsmPrinter> Z(TheBPFTarget);
 }
diff --git a/llvm/lib/Target/BPF/BPFTargetMachine.cpp b/llvm/lib/Target/BPF/BPFTargetMachine.cpp
index 9487427fef5..198fe7ae999 100644
--- a/llvm/lib/Target/BPF/BPFTargetMachine.cpp
+++ b/llvm/lib/Target/BPF/BPFTargetMachine.cpp
@@ -23,19 +23,24 @@ using namespace llvm;
 
 extern "C" void LLVMInitializeBPFTarget() {
   // Register the target.
-  RegisterTargetMachine<BPFTargetMachine> X(TheBPFTarget);
+  RegisterTargetMachine<BPFTargetMachine> X(TheBPFleTarget);
+  RegisterTargetMachine<BPFTargetMachine> Y(TheBPFbeTarget);
+  RegisterTargetMachine<BPFTargetMachine> Z(TheBPFTarget);
+}
+
+// DataLayout: little or big endian
+static std::string computeDataLayout(StringRef TT) {
+  if (Triple(TT).getArch() == Triple::bpf_be)
+    return "E-m:e-p:64:64-i64:64-n32:64-S128";
+  else
+    return "e-m:e-p:64:64-i64:64-n32:64-S128";
 }
 
-// DataLayout --> Little-endian, 64-bit pointer/ABI/alignment
-// The stack is always 8 byte aligned
-// On function prologue, the stack is created by decrementing
-// its pointer. Once decremented, all references are done with positive
-// offset from the stack/frame pointer.
 BPFTargetMachine::BPFTargetMachine(const Target &T, StringRef TT, StringRef CPU,
                                    StringRef FS, const TargetOptions &Options,
                                    Reloc::Model RM, CodeModel::Model CM,
                                    CodeGenOpt::Level OL)
-    : LLVMTargetMachine(T, "e-m:e-p:64:64-i64:64-n32:64-S128", TT, CPU, FS,
+    : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS,
                         Options, RM, CM, OL),
       TLOF(make_unique<TargetLoweringObjectFileELF>()),
       Subtarget(TT, CPU, FS, *this) {
diff --git a/llvm/lib/Target/BPF/MCTargetDesc/BPFAsmBackend.cpp b/llvm/lib/Target/BPF/MCTargetDesc/BPFAsmBackend.cpp
index 48f34e48459..339878624b2 100644
--- a/llvm/lib/Target/BPF/MCTargetDesc/BPFAsmBackend.cpp
+++ b/llvm/lib/Target/BPF/MCTargetDesc/BPFAsmBackend.cpp
@@ -25,7 +25,10 @@ using namespace llvm;
 namespace {
 class BPFAsmBackend : public MCAsmBackend {
 public:
-  BPFAsmBackend() : MCAsmBackend() {}
+  bool IsLittleEndian;
+
+  BPFAsmBackend(bool IsLittleEndian)
+    : MCAsmBackend(), IsLittleEndian(IsLittleEndian) {}
   ~BPFAsmBackend() override {}
 
   void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
@@ -69,17 +72,28 @@ void BPFAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
   }
   assert(Fixup.getKind() == FK_PCRel_2);
   Value = (uint16_t)((Value - 8) / 8);
-  Data[Fixup.getOffset() + 2] = Value & 0xFF;
-  Data[Fixup.getOffset() + 3] = Value >> 8;
+  if (IsLittleEndian) {
+    Data[Fixup.getOffset() + 2] = Value & 0xFF;
+    Data[Fixup.getOffset() + 3] = Value >> 8;
+  } else {
+    Data[Fixup.getOffset() + 2] = Value >> 8;
+    Data[Fixup.getOffset() + 3] = Value & 0xFF;
+  }
 }
 
 MCObjectWriter *BPFAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
-  return createBPFELFObjectWriter(OS, 0);
+  return createBPFELFObjectWriter(OS, 0, IsLittleEndian);
 }
 }
 
 MCAsmBackend *llvm::createBPFAsmBackend(const Target &T,
                                         const MCRegisterInfo &MRI, StringRef TT,
                                         StringRef CPU) {
-  return new BPFAsmBackend();
+  return new BPFAsmBackend(/*IsLittleEndian=*/true);
+}
+
+MCAsmBackend *llvm::createBPFbeAsmBackend(const Target &T,
+                                          const MCRegisterInfo &MRI, StringRef TT,
+                                          StringRef CPU) {
+  return new BPFAsmBackend(/*IsLittleEndian=*/false);
 }
diff --git a/llvm/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp b/llvm/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp
index a5562c1a933..05ba6183e32 100644
--- a/llvm/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp
+++ b/llvm/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp
@@ -47,7 +47,8 @@ unsigned BPFELFObjectWriter::GetRelocType(const MCValue &Target,
   }
 }
 
-MCObjectWriter *llvm::createBPFELFObjectWriter(raw_pwrite_stream &OS, uint8_t OSABI) {
+MCObjectWriter *llvm::createBPFELFObjectWriter(raw_pwrite_stream &OS,
+                                               uint8_t OSABI, bool IsLittleEndian) {
   MCELFObjectTargetWriter *MOTW = new BPFELFObjectWriter(OSABI);
-  return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);
+  return createELFObjectWriter(MOTW, OS, IsLittleEndian);
 }
diff --git a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCAsmInfo.h b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCAsmInfo.h
index faa36b816f8..edaa9ce2468 100644
--- a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCAsmInfo.h
+++ b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCAsmInfo.h
@@ -16,6 +16,7 @@
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/MC/MCAsmInfo.h"
+#include "llvm/ADT/Triple.h"
 
 namespace llvm {
 class Target;
@@ -24,6 +25,9 @@ class Triple;
 class BPFMCAsmInfo : public MCAsmInfo {
 public:
   explicit BPFMCAsmInfo(const Triple &TT) {
+    if (TT.getArch() == Triple::bpf_be)
+      IsLittleEndian = false;
+
     PrivateGlobalPrefix = ".L";
     WeakRefDirective = "\t.weak\t";
 
diff --git a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp
index 70dbd077ea2..dc4ede30f19 100644
--- a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp
+++ b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp
@@ -30,9 +30,11 @@ class BPFMCCodeEmitter : public MCCodeEmitter {
   BPFMCCodeEmitter(const BPFMCCodeEmitter &) = delete;
   void operator=(const BPFMCCodeEmitter &) = delete;
   const MCRegisterInfo &MRI;
+  bool IsLittleEndian;
 
 public:
-  BPFMCCodeEmitter(const MCRegisterInfo &mri) : MRI(mri) {}
+  BPFMCCodeEmitter(const MCRegisterInfo &mri, bool IsLittleEndian)
+    : MRI(mri), IsLittleEndian(IsLittleEndian) {}
 
   ~BPFMCCodeEmitter() {}
 
@@ -61,7 +63,13 @@ public:
 MCCodeEmitter *llvm::createBPFMCCodeEmitter(const MCInstrInfo &MCII,
                                             const MCRegisterInfo &MRI,
                                             MCContext &Ctx) {
-  return new BPFMCCodeEmitter(MRI);
+  return new BPFMCCodeEmitter(MRI, true);
+}
+
+MCCodeEmitter *llvm::createBPFbeMCCodeEmitter(const MCInstrInfo &MCII,
+                                              const MCRegisterInfo &MRI,
+                                              MCContext &Ctx) {
+  return new BPFMCCodeEmitter(MRI, false);
 }
 
 unsigned BPFMCCodeEmitter::getMachineOpValue(const MCInst &MI,
@@ -91,32 +99,53 @@ unsigned BPFMCCodeEmitter::getMachineOpValue(const MCInst &MI,
   return 0;
 }
 
+static uint8_t SwapBits(uint8_t Val)
+{
+  return (Val & 0x0F) << 4 | (Val & 0xF0) >> 4;
+}
+
 void BPFMCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
                                          SmallVectorImpl<MCFixup> &Fixups,
                                          const MCSubtargetInfo &STI) const {
   unsigned Opcode = MI.getOpcode();
   support::endian::Writer<support::little> LE(OS);
+  support::endian::Writer<support::big> BE(OS);
 
   if (Opcode == BPF::LD_imm64 || Opcode == BPF::LD_pseudo) {
     uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
     LE.write<uint8_t>(Value >> 56);
-    LE.write<uint8_t>(((Value >> 48) & 0xff));
+    if (IsLittleEndian)
+      LE.write<uint8_t>((Value >> 48) & 0xff);
+    else
+      LE.write<uint8_t>(SwapBits((Value >> 48) & 0xff));
     LE.write<uint16_t>(0);
-    LE.write<uint32_t>(Value & 0xffffFFFF);
+    if (IsLittleEndian)
+      LE.write<uint32_t>(Value & 0xffffFFFF);
+    else
+      BE.write<uint32_t>(Value & 0xffffFFFF);
 
     const MCOperand &MO = MI.getOperand(1);
     uint64_t Imm = MO.isImm() ? MO.getImm() : 0;
     LE.write<uint8_t>(0);
     LE.write<uint8_t>(0);
     LE.write<uint16_t>(0);
-    LE.write<uint32_t>(Imm >> 32);
+    if (IsLittleEndian)
+      LE.write<uint32_t>(Imm >> 32);
+    else
+      BE.write<uint32_t>(Imm >> 32);
   } else {
     // Get instruction encoding and emit it
     uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
     LE.write<uint8_t>(Value >> 56);
-    LE.write<uint8_t>((Value >> 48) & 0xff);
-    LE.write<uint16_t>((Value >> 32) & 0xffff);
-    LE.write<uint32_t>(Value & 0xffffFFFF);
+    if (IsLittleEndian) {
+      LE.write<uint8_t>((Value >> 48) & 0xff);
+      LE.write<uint16_t>((Value >> 32) & 0xffff);
+      LE.write<uint32_t>(Value & 0xffffFFFF);
+    } else {
+      LE.write<uint8_t>(SwapBits((Value >> 48) & 0xff));
+      BE.write<uint16_t>((Value >> 32) & 0xffff);
+      BE.write<uint32_t>(Value & 0xffffFFFF);
+    }
   }
 }
 
diff --git a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.cpp b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.cpp
index c4cf4b82450..7cedba90a74 100644
--- a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.cpp
+++ b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.cpp
@@ -79,32 +79,43 @@ static MCInstPrinter *createBPFMCInstPrinter(const Triple &T,
 }
 
 extern "C" void LLVMInitializeBPFTargetMC() {
-  // Register the MC asm info.
-  RegisterMCAsmInfo<BPFMCAsmInfo> X(TheBPFTarget);
+  for (Target *T : {&TheBPFleTarget, &TheBPFbeTarget, &TheBPFTarget}) {
+    // Register the MC asm info.
+    RegisterMCAsmInfo<BPFMCAsmInfo> X(*T);
 
-  // Register the MC codegen info.
-  TargetRegistry::RegisterMCCodeGenInfo(TheBPFTarget, createBPFMCCodeGenInfo);
+    // Register the MC codegen info.
+    TargetRegistry::RegisterMCCodeGenInfo(*T, createBPFMCCodeGenInfo);
 
-  // Register the MC instruction info.
-  TargetRegistry::RegisterMCInstrInfo(TheBPFTarget, createBPFMCInstrInfo);
+    // Register the MC instruction info.
+    TargetRegistry::RegisterMCInstrInfo(*T, createBPFMCInstrInfo);
 
-  // Register the MC register info.
-  TargetRegistry::RegisterMCRegInfo(TheBPFTarget, createBPFMCRegisterInfo);
+    // Register the MC register info.
+    TargetRegistry::RegisterMCRegInfo(*T, createBPFMCRegisterInfo);
 
-  // Register the MC subtarget info.
-  TargetRegistry::RegisterMCSubtargetInfo(TheBPFTarget,
-                                          createBPFMCSubtargetInfo);
+    // Register the MC subtarget info.
+    TargetRegistry::RegisterMCSubtargetInfo(*T,
+                                            createBPFMCSubtargetInfo);
 
-  // Register the MC code emitter
-  TargetRegistry::RegisterMCCodeEmitter(TheBPFTarget,
-                                        llvm::createBPFMCCodeEmitter);
+    // Register the object streamer
+    TargetRegistry::RegisterELFStreamer(*T, createBPFMCStreamer);
 
-  // Register the ASM Backend
-  TargetRegistry::RegisterMCAsmBackend(TheBPFTarget, createBPFAsmBackend);
+    // Register the MCInstPrinter.
+    TargetRegistry::RegisterMCInstPrinter(*T, createBPFMCInstPrinter);
+  }
 
-  // Register the object streamer
-  TargetRegistry::RegisterELFStreamer(TheBPFTarget, createBPFMCStreamer);
+  // Register the MC code emitter
+  TargetRegistry::RegisterMCCodeEmitter(TheBPFleTarget, createBPFMCCodeEmitter);
+  TargetRegistry::RegisterMCCodeEmitter(TheBPFbeTarget, createBPFbeMCCodeEmitter);
 
-  // Register the MCInstPrinter.
-  TargetRegistry::RegisterMCInstPrinter(TheBPFTarget, createBPFMCInstPrinter);
+  // Register the ASM Backend
+  TargetRegistry::RegisterMCAsmBackend(TheBPFleTarget, createBPFAsmBackend);
+  TargetRegistry::RegisterMCAsmBackend(TheBPFbeTarget, createBPFbeAsmBackend);
+
+  if (sys::IsLittleEndianHost) {
+    TargetRegistry::RegisterMCCodeEmitter(TheBPFTarget, createBPFMCCodeEmitter);
+    TargetRegistry::RegisterMCAsmBackend(TheBPFTarget, createBPFAsmBackend);
+  } else {
+    TargetRegistry::RegisterMCCodeEmitter(TheBPFTarget, createBPFbeMCCodeEmitter);
+    TargetRegistry::RegisterMCAsmBackend(TheBPFTarget, createBPFbeAsmBackend);
+  }
 }
diff --git a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.h b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.h
index ce08b7cf76e..a9ba7d990e1 100644
--- a/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.h
+++ b/llvm/lib/Target/BPF/MCTargetDesc/BPFMCTargetDesc.h
@@ -30,16 +30,24 @@ class StringRef;
 class raw_ostream;
 class raw_pwrite_stream;
 
+extern Target TheBPFleTarget;
+extern Target TheBPFbeTarget;
 extern Target TheBPFTarget;
 
 MCCodeEmitter *createBPFMCCodeEmitter(const MCInstrInfo &MCII,
                                       const MCRegisterInfo &MRI,
                                       MCContext &Ctx);
+MCCodeEmitter *createBPFbeMCCodeEmitter(const MCInstrInfo &MCII,
+                                        const MCRegisterInfo &MRI,
+                                        MCContext &Ctx);
 
 MCAsmBackend *createBPFAsmBackend(const Target &T, const MCRegisterInfo &MRI,
                                   StringRef TT, StringRef CPU);
+MCAsmBackend *createBPFbeAsmBackend(const Target &T, const MCRegisterInfo &MRI,
+                                    StringRef TT, StringRef CPU);
 
-MCObjectWriter *createBPFELFObjectWriter(raw_pwrite_stream &OS, uint8_t OSABI);
+MCObjectWriter *createBPFELFObjectWriter(raw_pwrite_stream &OS,
+                                         uint8_t OSABI, bool IsLittleEndian);
 }
 
 // Defines symbolic names for BPF registers.  This defines a mapping from
diff --git a/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp b/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp
index 87716e6775c..406165bca1e 100644
--- a/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp
+++ b/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp
@@ -11,8 +11,18 @@
 #include "llvm/Support/TargetRegistry.h"
 using namespace llvm;
 
-Target llvm::TheBPFTarget;
+namespace llvm {
+Target TheBPFleTarget;
+Target TheBPFbeTarget;
+Target TheBPFTarget;
+}
 
 extern "C" void LLVMInitializeBPFTargetInfo() {
-  RegisterTarget<Triple::bpf, /*HasJIT=*/true> X(TheBPFTarget, "bpf", "BPF");
+  TargetRegistry::RegisterTarget(TheBPFTarget, "bpf",
+                                 "BPF (host endian)",
+                                 [](Triple::ArchType) { return false; }, true);
+  RegisterTarget<Triple::bpf_le, /*HasJIT=*/true> X(
+      TheBPFleTarget, "bpf_le", "BPF (little endian)");
+  RegisterTarget<Triple::bpf_be, /*HasJIT=*/true> Y(
+      TheBPFbeTarget, "bpf_be", "BPF (big endian)");
 }